GSK (GSK) 20-F 15 Mar 19 2018 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Dec. 31, 2018shares
Document and entity information [abstract]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	GSK
Entity Registrant Name	GLAXOSMITHKLINE PLC
Entity Central Index Key	0001131399
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	5,379,067,624

Consolidated income statement

Consolidated income statement - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Profit or loss [abstract]
Turnover	£ 30,821	£ 30,186	£ 27,889
Cost of sales	(10,241)	(10,342)	(9,290)
Gross profit	20,580	19,844	18,599
Selling, general and administration	(9,915)	(9,672)	(9,366)
Research and development	(3,893)	(4,476)	(3,628)
Royalty income	299	356	398
Other operating income/(expense)	(1,588)	(1,965)	(3,405)
Operating profit	5,483	4,087	2,598
Finance income	81	65	72
Finance expense	(798)	(734)	(736)
Profit on disposal of interest in associates	3	94
Share of after tax profits of associates and joint ventures	31	13	5
Profit before taxation	4,800	3,525	1,939
Taxation	(754)	(1,356)	(877)
Profit after taxation for the year	4,046	2,169	1,062
Profit attributable to non-controlling interests	423	637	150
Profit attributable to shareholders	3,623	1,532	912
Profit after taxation for the year	£ 4,046	£ 2,169	£ 1,062
Basic earnings per share (pence)	£ 0.737	£ 0.314	£ 0.188
Diluted earnings per share (pence)	£ 0.729	£ 0.310	£ 0.186

Consolidated statement of compr

Consolidated statement of comprehensive income - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of comprehensive income [abstract]
Profit after taxation for the year	£ 4,046	£ 2,169	£ 1,062
Items that may be subsequently reclassified to income statement:
Exchange movements on overseas net assets and net investment hedges	(480)	462	646
Reclassification of exchange on liquidation or disposal of overseas subsidiaries	0	109
Fair value movements on equity investments		(14)	251
Deferred tax on fair value movements on equity investments		47
Reclassification of fair value movements on equity investments	0	(42)	(245)
Deferred tax reversed on reclassification of equity investments	0	(18)	51
Fair value movements on cash flow hedges	140	(10)	2
Deferred tax on fair value movements on cash flow hedges	(22)		2
Reclassification of cash flow hedges to income statement	(175)		1
Deferred tax reversed on reclassification of cash flow hedges	20
Items that may be subsequently reclassified to income statement	(517)	534	708
Items that will not be reclassified to income statement:
Exchange movements on overseas net assets of non-controlling interests	(1)	(149)	603
Fair value movements on equity investments	180
Deferred tax on fair value movements on equity investments	10
Remeasurement gains/(losses) on defined benefit plans	728	549	(475)
Tax on remeasurement of defined benefit plans	(146)	(221)	126
Items that will not be reclassified to income statement	771	179	254
Other comprehensive income for the year	254	713	962
Total comprehensive income/(expense) for the year	4,300	2,882	2,024
Total comprehensive income for the year attributable to:
Shareholders	3,878	2,394	1,271
Non-controlling interests	422	488	753
Total comprehensive income/(expense) for the year	£ 4,300	£ 2,882	£ 2,024

Consolidated balance sheet

Consolidated balance sheet - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Non-current assets
Property, plant and equipment	£ 11,058	£ 10,860
Goodwill	5,789	5,734
Other intangible assets	17,202	17,562
Investments in associates and joint ventures	236	183
Other investments	1,322	918
Deferred tax assets	3,887	3,796
Derivative financial instruments	69	8
Other non-current assets	1,576	1,413
Total non-current assets	41,139	40,474
Current assets
Inventories	5,476	5,557
Current tax recoverable	229	258
Trade and other receivables	6,423	6,000
Derivative financial instruments	188	68
Liquid investments	84	78
Cash and cash equivalents	3,874	3,833
Assets held for sale	653	113
Current assets	16,927	15,907
Total assets	58,066	56,381
Current liabilities
Short-term borrowings	(5,793)	(2,825)
Contingent consideration liabilities	(837)	(1,076)
Trade and other payables	(14,037)	(20,970)
Derivative financial instruments	(127)	(74)
Current tax payable	(965)	(995)
Short-term provisions	(732)	(629)
Total current liabilities	(22,491)	(26,569)
Non-current liabilities
Long-term borrowings	(20,271)	(14,264)
Corporation tax payable	(272)	(411)
Deferred tax liabilities	(1,156)	(1,396)
Pensions and other post-employment benefits	(3,125)	(3,539)
Other provisions	(691)	(636)
Derivative financial instruments	(1)
Contingent consideration liabilities	(5,449)	(5,096)
Other non-current liabilities	(938)	(981)
Total non-current liabilities	(31,903)	(26,323)
Total liabilities	(54,394)	(52,892)
Net assets	3,672	3,489
Equity
Share capital	1,345	1,343
Share premium account	3,091	3,019
Retained earnings	(2,137)	(6,477)
Other reserves	2,061	2,047
Shareholders' equity	4,360	(68)
Non-controlling interests	(688)	3,557
Total equity	£ 3,672	£ 3,489

Consolidated statement of chang

Consolidated statement of changes in equity - GBP (£) £ in Millions	Total	Share capital [member]	Share premium [member]	Retained earnings [member]	Other reserves [member]	Total [member]	Non- controlling interests [member]
Equity at beginning of period at Dec. 31, 2015	£ 8,878	£ 1,340	£ 2,831	£ (1,397)	£ 2,340	£ 5,114	£ 3,764
Profit after taxation for the year	1,062			912		912	150
Other comprehensive income/(expense) for the year	962			284	75	359	603
Total comprehensive income for the year	2,024			1,196	75	1,271	753
Distributions to non-controlling interests	(534)						(534)
Dividends to shareholders	(4,850)			(4,850)		(4,850)
Recognition of liabilities with non-controlling interests	(2,172)			(2,013)		(2,013)	(159)
Derecognition of liabilities with non-controlling interests	1,244			1,244		1,244
Changes in non-controllinginterests	32			17		17	15
Shares issued	89	2	87			89
Shares acquired by ESOP Trusts	(74)		36	466	(576)	(74)
Write-down of shares held by ESOP Trusts				(381)	381
Share-based incentive plans	319			319		319
Tax on share-based incentive plans	7			7		7
Equity at end of period at Dec. 31, 2016	4,963	1,342	2,954	(5,392)	2,220	1,124	3,839
Profit after taxation for the year	2,169			1,532		1,532	637
Other comprehensive income/(expense) for the year	713			899	(37)	862	(149)
Total comprehensive income for the year	2,882			2,431	(37)	2,394	488
Distributions to non-controlling interests	(789)						(789)
Contribution from non-controlling interests	21						21
Dividends to shareholders	(3,906)			(3,906)		(3,906)
Changes in non-controllinginterests	(2)						(2)
Shares issued	56	1	55			56
Shares acquired by ESOP Trusts	(65)		10	581	(656)	(65)
Write-down of shares held by ESOP Trusts				(520)	520
Share-based incentive plans	333			333		333
Tax on share-based incentive plans	(4)			(4)		(4)
Equity at end of period (Previously stated [member]) at Dec. 31, 2017	3,489	1,343	3,019	(6,477)	2,047	(68)	3,557
Equity at end of period (IFRS 15 adjustments [member]) at Dec. 31, 2017	(4)			(4)		(4)
Equity at end of period (IFRS 9 adjustments [member]) at Dec. 31, 2017	(11)			277	(288)	(11)
Equity at end of period at Dec. 31, 2017	3,489		3,019
Equity at end of period at Dec 31, 2017, as adjusted	3,474	1,343	3,019	(6,204)	1,759	(83)	3,557
Profit after taxation for the year	4,046			3,623		3,623	423
Other comprehensive income/(expense) for the year	254			124	131	255	(1)
Total comprehensive income for the year	4,300			3,747	131	3,878	422
Distributions to non-controlling interests	(570)	0	0	0	0	0	(570)
Contribution from non-controlling interests	21	0	0	0	0	0	21
Derecognition of non-controlling interests in Consumer Healthcare Joint Venture	(62)	0	0	4,056	0	4,056	(4,118)
Dividends to shareholders	(3,927)	0	0	(3,927)	0	(3,927)	0
Realised profits on disposal of equity investments	0	0	0	56	(56)	0	0
Share of associates and joint ventures realised profits on disposal of equity investments	0	0	0	38	(38)	0	0
Shares issued	74	2	72	0	0	74	0
Shares acquired by ESOP Trusts	0
Write-down of shares held by ESOP Trusts	0	0	0	(265)	265	0	0
Share-based incentive plans	360	0	0	360	0	360	0
Tax on share-based incentive plans	2	0	0	2	0	2	0
Equity at end of period at Dec. 31, 2018	£ 3,672	£ 1,345	£ 3,091	£ (2,137)	£ 2,061	£ 4,360	£ (688)

Consolidated cash flow statemen

Consolidated cash flow statement - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flow from operating activities
Profit after taxation for the year	£ 4,046	£ 2,169	£ 1,062
Adjustments reconciling profit after tax to operating cash flows	5,701	6,089	7,044
Cash generated from operations	9,747	8,258	8,106
Taxation paid	(1,326)	(1,340)	(1,609)
Net cash inflow from operating activities	8,421	6,918	6,497
Cash flow from investing activities
Purchase of property, plant and equipment	(1,344)	(1,545)	(1,543)
Proceeds from sale of property, plant and equipment	168	281	98
Purchase of intangible assets	(452)	(657)	(809)
Proceeds from sale of intangible assets	256	48	283
Purchase of equity investments	(309)	(80)	(96)
Proceeds from sale of equity investments	151	64	683
Contingent consideration paid	(153)	(91)	(73)
Purchase of businesses, net of cash acquired	0		17
Disposal of businesses	26	282	72
Investments in associates and joint ventures	(10)	(15)	(11)
Proceeds from disposal of interests in associates	3	196
Decrease in liquid investments	0	4
Interest received	72	64	68
Dividends from associates, joint ventures and equity investments	39	6	42
Cash inflow	(1,553)	(1,443)	(1,269)
Cash flow from financing activities
Shares acquired by ESOP Trusts	0	(65)	(74)
Issue of share capital	74	56	89
Purchase of non-controlling interests	(9,320)	(29)
Increase in long-term loans	10,138	2,233
Repayment of short-term Notes	(2,067)	(2,636)	(865)
Increase in/(repayment of) other short-term loans	81	(564)	1,013
Net repayment of obligations under finance leases	(28)	(23)	(18)
Interest paid	(766)	(781)	(732)
Dividends paid to shareholders	(3,927)	(3,906)	(4,850)
Distributions to non-controlling interests	(570)	(779)	(534)
Contributions from non-controlling interests	21	21
Other financing cash flows	(25)	93	(421)
Net cash outflow from financing activities	(6,389)	(6,380)	(6,392)
Increase/(decrease) in cash and bank overdrafts	479	(905)	(1,164)
Cash and bank overdrafts at beginning of year	3,600	4,605	5,486
Exchange adjustments	8	(100)	283
Increase/(decrease) in cash and bank overdrafts	479	(905)	(1,164)
Cash and bank overdrafts at end of year	4,087	3,600	4,605
Cash and bank overdrafts at end of year comprise:
Cash and cash equivalents	3,874	3,833	4,897
Cash and cash equivalents reported in assets held for sale	485
Cash and cash equivalents after assets held for sale reported	4,359	3,833	4,897
Overdrafts	(272)	(233)	(292)
Cash and bank overdrafts at end of year	£ 4,087	£ 3,600	£ 4,605

Presentation of the financial s

Presentation of the financial statements	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Presentation of the financial statements	1. Presentation of the financial statements Description of business GSK is a major global healthcare group which is engaged in the creation and discovery, development, manufacture and marketing of pharmaceutical products, vaccines, over-the-counter Compliance with applicable law and IFRS The financial statements have been prepared in accordance with the Companies Act 2006, Article 4 of the IAS Regulation and International Financial Reporting Standards (IFRS) and related interpretations, as adopted by the European Union. The financial statements are also in compliance with IFRS as issued by the International Accounting Standards Board. Composition of financial statements The consolidated financial statements are drawn up in Sterling, the functional currency of GlaxoSmithKline plc, and in accordance with IFRS accounting presentation. The financial statements comprise: • Consolidated income statement • Consolidated statement of comprehensive income • Consolidated balance sheet • Consolidated statement of changes in equity • Consolidated cash flow statement • Notes to the financial statements. Composition of the Group A list of the subsidiaries and associates which, in the opinion of the Directors, principally affected the amount of profit or net assets of the Group is given in Note 44, ‘Principal Group companies’. Financial period These financial statements cover the financial year from 1 January to 31 December 2018, with comparative figures for the financial years from 1 January to 31 December 2017 and, where appropriate, from 1 January to 31 December 2016. Accounting principles and policies The financial statements have been prepared using the historical cost convention modified by the revaluation of certain items, as stated in the accounting policies, and on a going concern basis. The financial statements have been prepared in accordance with the Group’s accounting policies approved by the Board and described in Note 2, ‘Accounting principles and policies’. Information on the application of these accounting policies, including areas of estimation and judgement is given in Note 3, ‘Key accounting judgements and estimates’. The preparation of the financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Implementation of IFRS 9 ‘Financial instruments’ The Group has applied IFRS 9 ‘Financial instruments’ with effect from 1 January 2018. IFRS 9 introduces new requirements for the classification and measurement of financial assets and financial liabilities, impairments for financial assets and general hedge accounting. Details of these new requirements as well as their impact on the Group’s consolidated financial statements are described below. The Group has adopted IFRS 9 retrospectively but with certain permitted exceptions as detailed below. Classification and measurement of financial assets The date of initial application was 1 January 2018. The Group has not applied the requirements of IFRS 9 to instruments that were derecognised prior to 1 January 2018 and has not restated prior years. Any difference between the previous carrying amount and the revised carrying amount at 1 January 2018 has been recognised as an adjustment to opening retained earnings at 1 January 2018. All financial assets that are within the scope of IFRS 9 are required to be measured at amortised cost or fair value, with movements through other comprehensive income or the income statement on the basis of GSK’s business model for managing the financial assets and the contractual cash flow characteristics of the financial assets. IFRS 9 had the following impact on the Group’s assets: • The Group has elected to recognise movements in the fair value of equity investments in other comprehensive income under IFRS 9. Investments in equity instruments that were previously classified as available-for-sale • The Group’s investments in limited life funds included in Other investments that were previously classified as available-for-sale • Liquid investments that were classified as available-for-sale • Investments in money market funds included in Cash and cash equivalents that were classified as amortised cost financial assets under IAS 39 have been classified as FVTPL under IFRS 9 as the contractual cash flows are not solely payments of principal and interest on the principal amount outstanding. • The Group’s trade receivables were all classified as financial assets measured at amortised cost under IAS 39. Under IFRS 9, the business model under which each portfolio of trade receivables held has been assessed. The Group has portfolios in each of the three business models under IFRS 9: to collect the contractual cash flows (measured at amortised cost), to sell the contractual cash flows (measured at FVTPL), and both to collect and to sell the contractual cash flows (measured at FVTOCI). • Amounts receivable under insurance contracts included in Other non-current There were no material changes in carrying value of financial assets as a result of these changes in measurement basis. Impairment of financial assets IFRS 9 requires an expected credit loss (ECL) model to be applied to financial assets rather than the incurred credit loss model required under IAS 39. The expected credit loss model requires the Group to account for expected losses as a result of credit risk on initial recognition of financial assets and to recognise changes in those expected credit losses at each reporting date. 12-month reflecting lifetime ECLs using the simplified approach. An additional ECL allowance of £15 million for trade receivables was recognised on transition to IFRS 9. There were no other transition adjustments arising from the change in impairment basis. The additional ECL allowance of £15 million at 1 January 2018 has been recognised against opening retained earnings, together with a related deferred tax impact of £3 million. General hedge accounting The new general hedge accounting requirements retain the three types of hedge accounting which were available under IAS 39: fair value hedges, cash flow hedges and net investment hedges. However, the effectiveness testing requirements have been simplified. The Group has applied the IFRS 9 hedge accounting requirements prospectively from the date of initial application of 1 January 2018. All existing hedging relationships are eligible, and continued to be effective, under IFRS 9. Implementation of IFRS 15 ‘Revenue from contracts with customers’ The Group has applied IFRS 15 ‘Revenue from contracts with customers’ with effect from 1 January 2018. IFRS 15 provides a single, principles-based approach to the recognition of revenue from all contracts with customers. It focuses on the identification of performance obligations in a contract and requires revenue to be recognised when or as those performance obligations are satisfied. GSK adopted IFRS 15 applying the modified retrospective approach. IFRS 15 did not have a material impact on the amount or timing of recognition of reported revenue. At 1 January 2018, a cumulative adjustment to decrease retained earnings of £4 million was recognised. In accordance with the requirements of IFRS 15 where the modified retrospective approach is adopted, prior year results have not been restated. Impact of new standards on each financial statement line item The table below shows the amount of adjustment for each financial statement line item affected by the application of IFRS 9 and IFRS 15 at 1 January 2018. As IFRS 9 IFRS 15 As Trade and other receivables 6,000 (15 ) 0 5,985 Liquid investments 78 1 0 79 Other payables - returns and rebates (3,463 ) 0 (29 ) (3,492 ) Other payables - deferred income (240 ) 0 27 (213 ) Deferred tax assets 3,796 3 (2 ) 3,797 Total effect on net assets 3,489 (11 ) (4 ) 3,474 Fair value reserve 329 (288 ) 0 41 Retained earnings (6,477 ) 277 (4 ) (6,204 ) Total effect on equity 3,489 (11 ) (4 ) 3,474 The £288 million transfer between retained earnings and the fair value reserve resulted from the reclassification of previous impairment losses on equity investments now designated as measured at FVTOCI under IFRS 9 from retained earnings to the fair value reserve. The application of IFRS 9 and IFRS 15 has had no impact on the consolidated cash flows of the Group. Parent company financial statements The financial statements of the parent company, GlaxoSmithKline plc, have been prepared in accordance with UK GAAP and with UK accounting presentation. The company balance sheet is presented on page 219 and the accounting policies are given on page 220.

Accounting principles and polic

Accounting principles and policies	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Accounting principles and policies	2. Accounting principles and policies Consolidation The consolidated financial statements include: • the assets and liabilities, and the results and cash flows, of the company and its subsidiaries, including ESOP Trusts • the Group’s share of the results and net assets of associates and joint ventures • the Group’s share of assets, liabilities, revenue and expenses of joint operations. The financial statements of entities consolidated are made up to 31 December each year. Entities over which the Group has the power to direct the relevant activities so as to affect the returns to the Group, generally through control over the financial and operating policies, are accounted for as subsidiaries. Where the Group has the ability to exercise joint control over, and rights to the net assets of, entities, the entities are accounted for as joint ventures. Where the Group has the ability to exercise joint control over an arrangement, but has rights to specified assets and obligations for specified liabilities of the arrangement, the arrangement is accounted for as a joint operation. Where the Group has the ability to exercise significant influence over entities, they are accounted for as associates. The results and assets and liabilities of associates and joint ventures are incorporated into the consolidated financial statements using the equity method of accounting. The Group’s rights to assets, liabilities, revenue and expenses of joint operations are included in the consolidated financial statements in accordance with those rights and obligations. Interests acquired in entities are consolidated from the date the Group acquires control and interests sold are de-consolidated Transactions and balances between subsidiaries are eliminated and no profit before tax is taken on sales between subsidiaries until the products are sold to customers outside the Group. The relevant proportion of profits on transactions with joint ventures, joint operations and associates is also deferred until the products are sold to third parties. Transactions with non-controlling Business combinations Business combinations are accounted for using the acquisition accounting method. Identifiable assets, liabilities and contingent liabilities acquired are measured at fair value at acquisition date. The consideration transferred is measured at fair value and includes the fair value of any contingent consideration. The fair value of contingent consideration liabilities are re-assessed The part of each payment relating to the original estimate of the fair value of the contingent consideration on acquisition is reported within investing activities in the cash flow statement and the part of each payment relating to the increase in the liability since the acquisition date is reported within operating cash flows. Where the consideration transferred, together with the non-controlling Goodwill is capitalised as a separate item in the case of subsidiaries and as part of the cost of investment in the case of joint ventures and associates. Goodwill is denominated in the currency of the operation acquired. Where the cost of acquisition is below the fair value of the net assets acquired, the difference is recognised directly in the income statement. Where not all of the equity of a subsidiary is acquired the non-controlling non-controlling case-by-case Foreign currency translation Foreign currency transactions are booked in the functional currency of the Group company at the exchange rate ruling on the date of transaction. Foreign currency monetary assets and liabilities are retranslated into the functional currency at rates of exchange ruling at the balance sheet date. Exchange differences are included in the income statement. On consolidation, assets and liabilities, including related goodwill, of overseas subsidiaries, associates and joint ventures, are translated into Sterling at rates of exchange ruling at the balance sheet date. The results and cash flows of overseas subsidiaries, associates and joint ventures are translated into Sterling using average rates of exchange. Exchange adjustments arising when the opening net assets and the profits for the year retained by overseas subsidiaries, associates and joint ventures are translated into Sterling, less exchange differences arising on related foreign currency borrowings which hedge the Group’s net investment in these operations, are taken to a separate component of equity. When translating into Sterling the assets, liabilities, results and cash flows of overseas subsidiaries, associates and joint ventures which are reported in currencies of hyper-inflationary economies, adjustments are made where material to reflect current price levels. Any loss on net monetary assets is charged to the consolidated income statement. Revenue (applicable from 1 January 2018) The Group receives revenue for supply of goods to external customers against orders received. The majority of contracts that GSK enters into relate to sales orders containing single performance obligations for the delivery of pharmaceutical, vaccine and consumer healthcare products. The average duration of a sales order is less than 12 months. Product revenue is recognised when control of the goods is passed to the customer. The point at which control passes is determined by each customer arrangement, but generally occurs on delivery to the customer. Product revenue represents net invoice value including fixed and variable consideration. Variable consideration arises on the sale of goods as a result of discounts and allowances given and accruals for estimated future returns and rebates. Revenue is not recognised in full until it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur. The methodology and assumptions used to estimate rebates and returns are monitored and adjusted regularly in the light of contractual and legal obligations, historical trends, past experience and projected market conditions. Once the uncertainty associated with the returns and rebates is resolved, revenue is adjusted accordingly. GSK enters into development and marketing collaborations and out-licences Income dependent on the achievement of a development milestone is recognised when it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur, which is usually when the related event occurs. Sales-based milestone income is recognised when it is highly probable that the sales threshold will be reached. Sales-based royalties on a licence of intellectual property are not recognised until the relevant product sale occurs. If the time between the recognition of revenue and payment from the customer is expected to be more than one year and the impact is material, the amount of consideration is discounted using appropriate discount rates. Value added tax and other sales taxes are excluded from revenue. Expenditure Expenditure is recognised in respect of goods and services received when supplied in accordance with contractual terms. Provision is made when an obligation exists for a future liability in respect of a past event and where the amount of the obligation can be reliably estimated. Manufacturing start-up Restructuring costs are recognised and provided for, where appropriate, in respect of the direct expenditure of a business reorganisation where the plans are sufficiently detailed and well advanced, and where appropriate communication to those affected has been undertaken. Research and development Research and development expenditure is charged to the income statement in the period in which it is incurred. Development expenditure is capitalised when the criteria for recognising an asset are met, usually when a regulatory filing has been made in a major market and approval is considered highly probable. Property, plant and equipment used for research and development is capitalised and depreciated in accordance with the Group’s policy. Environmental expenditure Environmental expenditure related to existing conditions resulting from past or current operations and from which no current or future benefit is discernible is charged to the income statement. The Group recognises its liability on a site-by-site clean-up Legal and other disputes Provision is made for the anticipated settlement costs of legal or other disputes against the Group where an outflow of resources is considered probable and a reliable estimate can be made of the likely outcome. In addition, provision is made for legal or other expenses arising from claims received or other disputes. In respect of product liability claims related to certain products, there is sufficient history of claims made and settlements to enable management to make a reliable estimate of the provision required to cover unasserted claims. In certain cases, an incurred but not reported (IBNR) actuarial technique is used to determine this estimate. The Group may become involved in legal proceedings, in respect of which it is not possible to make a reliable estimate of the expected financial effect, if any, that could result from ultimate resolution of the proceedings. In these cases, appropriate disclosure about such cases would be included but no provision would be made. Costs associated with claims made by the Group against third parties are charged to the income statement as they are incurred. Pensions and other post-employment benefits The costs of providing pensions under defined benefit schemes are calculated using the projected unit credit method and spread over the period during which benefit is expected to be derived from the employees’ services, consistent with the advice of qualified actuaries. Pension obligations are measured as the present value of estimated future cash flows discounted at rates reflecting the yields of high-quality corporate bonds. Pension scheme assets are measured at fair value at the balance sheet date. The costs of other post-employment liabilities are calculated in a similar way to defined benefit pension schemes and spread over the period during which benefit is expected to be derived from the employees’ services, in accordance with the advice of qualified actuaries. Actuarial gains and losses and the effect of changes in actuarial assumptions, are recognised in the statement of comprehensive income in the year in which they arise. The Group’s contributions to defined contribution plans are charged to the income statement as incurred. Employee share plans Incentives in the form of shares are provided to employees under share option and share award schemes. The fair values of these options and awards are calculated at their grant dates using a Black-Scholes option pricing model and charged to the income statement over the relevant vesting periods. The Group provides finance to ESOP Trusts to purchase company shares to meet the obligation to provide shares when employees exercise their options or awards. Costs of running the ESOP Trusts are charged to the income statement. Shares held by the ESOP Trusts are deducted from other reserves. A transfer is made between other reserves and retained earnings over the vesting periods of the related share options or awards to reflect the ultimate proceeds receivable from employees on exercise. Property, plant and equipment Property, plant and equipment (PP&E) is stated at the cost of purchase or construction, less provisions for depreciation and impairment. Financing costs are capitalised within the cost of qualifying assets in construction. Depreciation is calculated to write off the cost less residual value of PP&E, excluding freehold land, using the straight-line basis over the expected useful life. Residual values and lives are reviewed, and where appropriate adjusted annually. The normal expected useful lives of the major categories of PP&E are: Freehold buildings 20 to 50 years Leasehold land and buildings Lease term or 20 to 50 years Plant and machinery 10 to 20 years Equipment and vehicles 3 to 10 years On disposal of PP&E, the cost and related accumulated depreciation and impairments are removed from the financial statements and the net amount, less any proceeds, is taken to the income statement. Leases Leasing agreements which transfer to the Group substantially all the benefits and risks of ownership of an asset are treated as finance leases, as if the asset had been purchased outright. The assets are included in PP&E or computer software and the capital elements of the leasing commitments are shown as obligations under finance leases. Assets held under finance leases are depreciated on a basis consistent with similar owned assets or the lease term, if shorter. The interest element of the lease rental is included in the income statement. All other leases are operating leases and the rental costs are charged to the income statement on a straight-line basis over the lease term. Goodwill Goodwill is stated at cost less impairments. Goodwill is deemed to have an indefinite useful life and is tested for impairment at least annually. Where the fair value of the interest acquired in an entity’s assets, liabilities and contingent liabilities exceeds the consideration paid, this excess is recognised immediately as a gain in the income statement. Other intangible assets Intangible assets are stated at cost less provisions for amortisation and impairments. Licences, patents, know-how non-exclusivity. Contingent milestone payments are recognised at the point that the contingent event becomes probable. Any development costs incurred by the Group and associated with acquired licences, patents, know-how Acquired brands are valued independently as part of the fair value of businesses acquired from third parties where the brand has a value which is substantial and long term and where the brands either are contractual or legal in nature or can be sold separately from the rest of the businesses acquired. Brands are amortised over their estimated useful lives of up to 20 years, except where it is considered that the useful economic life is indefinite. The costs of acquiring and developing computer software for internal use and internet sites for external use are capitalised as intangible fixed assets where the software or site supports a significant business system and the expenditure leads to the creation of a durable asset. ERP systems software is amortised over seven to ten years and other computer software over three to five years. Impairment of non-current The carrying values of all non-current Impairments of goodwill are not reversed. Impairment losses on other non-current Investments in associates, joint ventures and joint operations Investments in associates and joint ventures are carried in the consolidated balance sheet at the Group’s share of their net assets at date of acquisition and of their post-acquisition retained profits or losses together with any goodwill arising on the acquisition. The Group recognises its rights to assets, liabilities, revenue and expenses of joint operations. Expected credit losses are recognised in the income statement on financial assets measured at amortised cost and at fair value through other comprehensive income apart from equity investments. Inventories Inventories are included in the financial statements at the lower of cost (including raw materials, direct labour, other direct costs and related production overheads) and net realisable value. Cost is generally determined on a first in, first out basis. Pre-launch Financial instruments (applicable from 1 January 2018) Financial assets Financial assets are measured at amortised cost, fair value through other comprehensive income (FVTOCI) or fair value through profit or loss (FVTPL). The measurement basis is determined by reference to both the business model for managing the financial asset and the contractual cash flow characteristics of the financial asset. For financial assets other than trade receivables a 12-month Other investments Other investments comprise equity investments and investments in limited life funds. The Group has elected to designate equity investments as measured at FVTOCI. They are initially recorded at fair value plus transaction costs and then remeasured at subsequent reporting dates to fair value. Unrealised gains and losses are recognised in other comprehensive income. On disposal of the equity investment, gains and losses that have been deferred in other comprehensive Income are transferred directly to retained earnings. Investments in limited life funds are measured at FVTPL. They are initially recorded at fair value and then remeasured at subsequent reporting dates to fair value. Unrealised gains and losses are recognised in the income statement. Dividends on equity investments and distributions from funds are recognised in the income statement when the Group’s right to receive payment is established. Purchases and sales of Other investments are accounted for on the trade date. Trade receivables Trade receivables are measured in accordance with the business model under which each portfolio of trade receivables is held. The Group has portfolios in each of the three business models under IFRS 9: to collect the contractual cash flows (measured at amortised cost), to sell the contractual cash flows (measured at FVTPL), and both to collect and to sell the contractual cash flows (measured at FVTOCI). Trade receivables measured at amortised cost are carried at the original invoice amount less allowances for expected credit losses. Expected credit losses are calculated in accordance with the simplified approach permitted by IFRS 9, using a provision matrix applying lifetime historical credit loss experience to the trade receivables. The expected credit loss rate varies depending on whether and the extent to which settlement of the trade receivables is overdue and it is also adjusted as appropriate to reflect current economic conditions and estimates of future conditions. For the purpose of determining credit loss rates, customers are classified into groupings that have similar loss patterns. The key drivers of the loss rate are the nature of the business unit and the location and type of customer. When a trade receivable is determined to have no reasonable expectation of recovery it is written off, firstly against any expected credit loss allowance available and then to the income statement. Subsequent recoveries of amounts previously provided for or written off are credited to the income statement. Long-term receivables are discounted where the effect is material. Cash and cash equivalents Cash held in deposit accounts is measured at amortised cost. Investments in money market funds are held at fair value through profit or loss. Borrowings All borrowings are initially recorded at the amount of proceeds received, net of transaction costs. Borrowings are subsequently carried at amortised cost, with the difference between the proceeds, net of transaction costs, and the amount due on redemption being recognised as a charge to the income statement over the period of the relevant borrowing. Derivative financial instruments Derivative financial instruments are used to manage exposure to market risks. The principal derivative instruments used by GSK are foreign currency swaps, interest rate swaps, foreign exchange forward contracts and options. The Group does not hold or issue derivative financial instruments for trading or speculative purposes. Derivative financial assets and liabilities, including derivatives embedded in host contracts which have been separated from the host contract, are classified as held-for-trading Hedge accounting Derivatives designated as hedging instruments are classified on inception as cash flow hedges, net investment hedges or fair value hedges. Changes in the fair value of derivatives designated as cash flow hedges are recognised in other comprehensive income to the extent that the hedges are effective. Ineffective portions are recognised in profit or loss immediately. Amounts deferred in other comprehensive income are reclassified to the income statement when the hedged item affects profit or loss. Net investment hedges are accounted for in a similar way to cash flow hedges. Changes in the fair value of derivatives designated as fair value hedges are recorded in the income statement, together with the changes in the fair value of the hedged asset or liability. Taxation Current tax is provided at the amounts expected to be paid applying tax rates that have been enacted or substantively enacted by the balance sheet date. Deferred tax is provided in full, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the financial statements. Deferred tax assets are recognised to the extent that it is probable that future taxable profits will be available against which the temporary differences can be utilised. Deferred tax is provided on temporary differences arising on investments in subsidiaries, associates and joint ventures, except where the timing of the reversal of the temporary difference can be controlled and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is provided using rates of tax that have been enacted or substantively enacted by the balance sheet date. Where an uncertain tax position is identified, management will make a judgement as to what the probable outcome will be. Where it is assessed that an economic outflow is probable to arise a provision is made for the best estimate of the liability. In estimating any such liability GSK applies a risk-based approach which takes into account, as appropriate, the probability that the Group would be able to obtain compensatory adjustments under international tax treaties. These estimates take into account the specific circumstances of each dispute and relevant external advice. Discounting Where the time value of money is material, balances are discounted to current values using appropriate discount rates. The unwinding of the discounts is recorded in finance income and finance expense. Revenue (applicable up to 31 December 2017) Revenue is recognised in the income statement when goods or services are supplied or made available to external customers against orders received, title and risk of loss is passed to the customer, reliable estimates can be made of relevant deductions and all relevant obligations have been fulfilled, such that the earnings process is regarded as being complete. Turnover represents net invoice value after the deduction of discounts and allowances given and accruals for estimated future rebates and returns. The methodology and assumptions used to estimate rebates and returns are monitored and adjusted regularly in the light of contractual and legal obligations, historical trends, past experience and projected market conditions. Market conditions are evaluated using wholesaler and other third-party analyses, market research data and internally generated information. Value added tax and other sales taxes are excluded from revenue. Where the Group co-promotes a product and the counterparty records the sale, the Group records its share of revenue as co-promotion co-promotion Royalty income is recognised on an accruals basis in accordance with the terms of the relevant licensing agreements. Financial instruments (applicable up to 31 December 2017) Available-for-sale Liquid investments and other investments are classified as available-for-sale available-for-sale On disposal or impairment of the investments, any gains and losses that have been deferred in other comprehensive income are reclassified to the income statement. Dividends on equity investments are recognised in the income statement when the Group’s right to receive payment is established. Equity investments are recorded in non-current Purchases and sales of equity investments are accounted for on the trade date and purchases and sales of other available-for-sale Trade receivables Trade receivables are carried at original invoice amount less any provisions for doubtful debts. Provisions are made where there is evidence of a risk of non-payment, Subsequent recoveries of amounts previously provided for are credited to the income statement. Long-term receivables are discounted where the effect is material. Borrowings All borrowings are initially recorded at the amount of proceeds received, net of transaction costs. Borrowings are subsequently carried at amortised cost, with the difference between the proceeds, net of transaction costs, and the amount due on redemption being recognised as a charge to the income statement over the period of the relevant borrowing. Derivative financial instruments and hedging Derivative financial instruments are used to manage exposure to market risks. The principal derivative instruments used by GSK are foreign currency swaps, interest rate swaps, foreign exchange forward contracts and options. The Group does not hold or issue derivative financial instruments for trading or speculative purposes. Derivative financial instruments are classified as held-for-trading Changes in the fair value of derivatives designated as cash flow hedges are recognised in other comprehensive income to the extent that the hedges are effective. Ineffective portions are recognised in profit or loss immediately. Amounts deferred in other comprehensive income are reclassified to the income statement when the hedged item affects profit or loss. Net investment hedges are accounted for in a similar way to cash flow hedges. Changes in the fair value of derivatives designated as fair value hedges are recorded in the income statement, together with the changes in the fair value of the hedged asset or liability. Changes in the fair value of any derivative instruments that do not qualify for hedge accounting are recognised immediately in the income statement.

Key accounting judgements and e

Key accounting judgements and estimates	12 Months Ended
	Dec. 31, 2018
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Key accounting judgements and estimates	3. Key accounting judgements and estimates In preparing the financial statements, management is required to make judgements about when or how items should be recognised in the financial statements and estimates and assumptions that affect the amounts of assets, liabilities, revenue and expenses reported in the financial statements. Actual amounts and results could differ from those estimates. The following are considered to be the critical accounting judgements and key sources of estimation uncertainty. Turnover Reported Group turnover for 2018 was £30,821 million (2017 – £30,186 million). Estimates Gross turnover is reduced by rebates, discounts, allowances and product returns given or expected to be given, which vary by product arrangements and buying groups. These arrangements with purchasing organisations are dependent upon the submission of claims some time after the initial recognition of the sale. Accruals are made at the time of sale for the estimated rebates, discounts or allowances payable or returns to be made, based on available market information and historical experience. Because the amounts are estimated they may not fully reflect the final outcome, and the amounts are subject to change dependent upon, amongst other things, the types of buying group and product sales mix. The level of accrual for rebates and returns is reviewed and adjusted regularly in the light of contractual and legal obligations, historical trends, past experience and projected market conditions. Market conditions are evaluated using wholesaler and other third-party analyses, market research data and internally generated information. Revenue is not recognised in full until it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur. The amount of turnover recognised in the year from performance obligations satisfied in previous periods is set out in Note 6, ‘Turnover and segment information’. Future events could cause the assumptions on which the accruals are based to change, which could affect the future results of the Group. Taxation The tax charge for the year was £754 million (2017 – £1,356 million). At December 2018, current tax payable was £965 million (2017 – £995 million), non-current Judgement The Group has open tax issues with a number of revenue authorities. Management makes a judgement of whether there is sufficient information to be able to make a reliable estimate of the outcome of the dispute. If insufficient information is available, no provision is made. Estimates If sufficient information is available, in estimating a potential tax liability GSK applies a risk-based approach which takes into account, as appropriate, the probability that the Group would be able to obtain compensatory adjustments under international tax treaties. These estimates take into account the specific circumstances of each dispute and relevant external advice, are inherently judgemental and could change substantially over time as each dispute progresses and new facts emerge. At 31 December 2018, the Group had recognised provisions of £1,082 million in respect of uncertain tax positions (2017 – £1,175 million). Because of the nature of these uncertain positions, it is not practicable to give meaningful sensitivity estimates. Factors affecting the tax charge in future years are set out in Note 14, ‘Taxation’. GSK continues to believe that it has made adequate provision for the liabilities likely to arise from open assessments. Where open issues exist the ultimate liability for such matters may vary from the amounts provided and is dependent upon the outcome of negotiations with the relevant tax authorities or, if necessary, litigation proceedings. Legal and other disputes Legal costs for the year were £117 million (2017 – £166 million). At 31 December 2018 provisions for legal and other disputes amounted to £219 million (2017 – £186 million). Judgement Management makes a judgement of whether there is sufficient information to be able to make a reliable estimate of the likely outcome of the dispute and legal and other expenses arising from claims against the Group. If insufficient information is available, no provision is made and disclosure of the claim is given. Estimates The estimated provisions take into account the specific circumstances of each dispute and relevant external advice, are inherently judgemental and could change substantially over time as each dispute progresses and new facts emerge. Details of the status and various uncertainties involved in the significant unresolved disputes are set out in Note 45, ‘Legal proceedings’. The company’s Directors, having taken legal advice, have established provisions after taking into account the relevant facts and circumstances of each matter and in accordance with accounting requirements. In respect of product liability claims related to certain products there is sufficient history of claims made and settlements to enable management to make a reliable estimate of the provision required to cover unasserted claims. The Group may become involved in legal proceedings, in respect of which it is not possible to make a reliable estimate of the expected financial effect, if any, that could result from ultimate resolution of the proceedings. In these cases, appropriate disclosure about such cases would be provided, but no provision would be made and no contingent liability can be quantified. The ultimate liability for legal claims may vary from the amounts provided and is dependent upon the outcome of litigation proceedings, investigations and possible settlement negotiations. The position could change over time and, therefore, there can be no assurance that any losses that result from the outcome of any legal proceedings will not exceed the amount of the provisions reported in the Group’s financial statements by a material amount. Contingent consideration and put option liabilities The 2018 income statement charge for contingent consideration and put option liabilities was £1,851 million (2017 – £2,134 million). At 31 December 2018, the liability for contingent consideration amounted to £ 6,286 million (2017 – £6,172 million). Of this amount, £5,937 million (2017 – £5,542 million) related to the acquisition of the former Shionogi-ViiV Healthcare joint venture in 2012 and £296 million (2017 – £584 million) related to the acquisition of the Vaccines business from Novartis in 2015. Estimates Any contingent consideration included in the consideration payable for a business combination is recorded at fair value at the date of acquisition. These fair values are generally based on risk-adjusted future cash flows discounted using appropriate post-tax In June 2018, GSK acquired Novartis’ shareholding in the Consumer Healthcare Joint Venture for $13 billion. This resulted in a net charge in the period of £ 658 million to remeasure the Consumer Healthcare Joint Venture put option to the agreed valuation. Pfizer may request an IPO of ViiV Healthcare at any time and if either GSK does not consent to such IPO or an offering is not completed within nine months, Pfizer could require GSK to acquire its shareholding. The liability for the Pfizer put option, which is derived from an internal valuation of the ViiV Healthcare business, utilising both discounted forecast future cash flow and multiples-based methodologies amounted to £1,240 million at 31 December 2018 (2017 – £1,304 million). Sensitivity analysis is given in Note 27, ‘Trade and other payables’. Pensions and other post-employment benefits Judgement Where a surplus on a defined benefit scheme arises, or there is potential for a surplus to arise from committed future contributions, the rights of the Trustees to prevent the Group obtaining a refund of that surplus in the future are considered in determining whether it is necessary to restrict the amount of the surplus that is recognised. Four UK schemes are in surplus, with a combined surplus of £711 million at 31 December 2018 (2017 – £ 470 million). GSK has made the judgement that these amounts meet the requirements of recoverability. Estimates The costs of providing pensions and other post-employment benefits are assessed on the basis of assumptions selected by management. These assumptions include future earnings and pension increases, discount rates, expected long-term rates of return on assets and mortality rates, and are disclosed in Note 28, ‘Pensions and other post-employment benefits’. Discount rates are derived from AA rated corporate bond yields except in countries where there is no deep market in corporate bonds where government bond yields are used. A sensitivity analysis is provided in Note 28, ‘Pensions and other post-employment benefits’, but a 0.25% reduction in the discount rate would lead to an increase in the net pension deficit of approximately £707 million and an increase in the annual pension cost of approximately £28 million. The selection of different assumptions could affect the future results of the Group.

New accounting requirements

New accounting requirements	12 Months Ended
	Dec. 31, 2018
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New accounting requirements	4. New accounting requirements The following new and amended accounting standards have been issued by the IASB and are likely to affect future Annual Reports. IFRS 16 ‘Leases’ was issued in January 2016 and will be implemented by the Group from 1 January 2019. The Standard will replace IAS 17 ‘Leases’ and will require lease liabilities and ‘right of use’ assets to be recognised on the balance sheet for almost all leases. This is expected to result in a significant increase in both assets and liabilities recognised. The costs of operating leases currently included within operating costs will be split and the financing element of the charge will be reported within finance expense. The overall impact on earnings is not expected to be material. Finance lease obligations at 31 December 2018 are set out in Note 31, ‘Net debt’ and the undiscounted commitments under non-cancellable GSK will implement IFRS 16 applying the modified retrospective approach. For larger leases, the right of use asset at 1 January 2019 will be calculated based on the original lease inception date and for smaller leases the right of use asset will be set equal to the lease liability, adjusted for any prepaid or accrued lease payments, onerous lease provisions and business combination fair value adjustments. On the transition date of 1 January 2019, the Group expects to recognise right of use assets of £1.1 billion and a lease liability of £1.3 billion, including existing finance leases. The implementation is expected to reduce net assets and total equity by £0.1 billion.

Exchange rates

Exchange rates	12 Months Ended
	Dec. 31, 2018
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Exchange rates	5. Exchange rates The Group uses the average of exchange rates prevailing during the period to translate the results and cash flows of overseas subsidiaries, joint ventures and associates into Sterling and period end rates to translate the net assets of those entities. The currencies which most influence these translations and the relevant exchange rates were: 2018 2017 2016 Average rates: US$/£ 1.33 1.30 1.36 Euro/£ 1.13 1.15 1.23 Yen/£ 147 145 149 2018 2017 2016 Period end rates: US$/£ 1.27 1.35 1.24 Euro/£ 1.11 1.13 1.17 Yen/£ 140 152 144

Turnover and segment informatio

Turnover and segment information	12 Months Ended
	Dec. 31, 2018
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Turnover and segment information	6. Turnover and segment information Operating segments are reported based on the financial information provided to the Chief Executive Officer and the responsibilities of the Corporate Executive Team (CET). GSK reports results under four segments: Pharmaceuticals; Pharmaceuticals R&D; Vaccines and Consumer Healthcare, and individual members of the CET are responsible for each segment. The Group’s management reporting process allocates intra-Group profit on a product sale to the market in which that sale is recorded, and the profit analyses below have been presented on that basis. Corporate and other unallocated costs included the costs of corporate functions. Revenue recognised in the year from performance obligations satisfied in previous periods totalled £426 million and included £122 million reported in turnover arising from changes to prior year estimates of RAR accruals and £299 million of royalty income. 2018 2017 2016 Turnover by segment £m £m £m Pharmaceuticals 17,269 17,276 16,104 Vaccines 5,894 5,160 4,592 Consumer Healthcare 7,658 7,750 7,193 30,821 30,186 27,889 2018 2017 2016 Pharmaceuticals turnover by therapeutic area £m £m £m Respiratory 6,928 6,991 6,510 HIV 4,722 4,350 3,556 Immuno-inflammation 472 377 340 Established Pharmaceuticals 5,147 5,558 5,698 17,269 17,276 16,104 2018 2017 2016 Vaccines turnover by category £m £m £m Meningitis 881 890 662 Influenza 523 488 414 Shingles 784 22 — Established Vaccines 3,706 3,760 3,516 5,894 5,160 4,592 During 2018, the US operations of the Pharmaceuticals and Vaccines businesses made sales to three wholesalers of approximately £2,709 million (2017 – £2,449 million; 2016 – £2,139 million), £2,962 million (2017 – £3,043 million; 2016 – £2,691 million) and £2,656 million (2017 – £2,356 million; 2016 – £2,129 million) respectively, after allocating final-customer discounts to the wholesalers. 2018 2017 2016 Consumer Healthcare turnover by category £m £m £m Wellness 3,940 4,001 3,726 Oral care 2,496 2,466 2,223 Nutrition 643 680 674 Skin health 579 603 570 7,658 7,750 7,193 2018 2017 2016 Segment profit £m £m £m Pharmaceuticals 8,420 8,667 7,976 Pharmaceuticals R&D (2,676 ) (2,740 ) (2,488 ) Pharmaceuticals, including R&D 5,744 5,927 5,488 Vaccines 1,943 1,644 1,429 Consumer Healthcare 1,517 1,373 1,116 Segment profit 9,204 8,944 8,033 Corporate and other unallocated costs (459 ) (376 ) (362 ) Other reconciling items between segment profit and operating profit (3,262 ) (4,481 ) (5,073 ) Operating profit 5,483 4,087 2,598 Finance income 81 65 72 Finance costs (798 ) (734 ) (736 ) Profit on disposal of interest in associates 3 94 — Share of after tax profits of associates and joint ventures 31 13 5 Profit before taxation 4,800 3,525 1,939 Taxation (754 ) (1,356 ) (877 ) Profit after taxation for the year 4,046 2,169 1,062 Other reconciling items between segment profit and operating profit comprise items not specifically allocated to segment profit. These include impairment and amortisation of intangible assets; major restructuring costs, which include impairments of tangible assets and computer software; transaction-related adjustments related to significant acquisitions; proceeds and costs of disposals of associates, products and businesses, significant legal charges and expenses on the settlement of litigation and government investigations, other operating income other than royalty income and other items, and the pre-tax 2018 2017 2016 Depreciation and amortisation by segment £m £m £m Pharmaceuticals 506 551 440 Pharmaceuticals R&D 123 96 211 Pharmaceuticals, including R&D 629 647 651 Vaccines 395 405 315 Consumer Healthcare 146 135 126 Segment depreciation and amortisation 1,170 1,187 1,092 Corporate and other unallocated depreciation and amortisation 106 144 94 Other reconciling items between segment depreciation and amortisation and total depreciation and amortisation 580 591 588 Total depreciation and amortisation 1,856 1,922 1,774 PP&E, intangible asset and goodwill impairment by segment 2018 £m 2017 2016 Pharmaceuticals 51 38 29 Pharmaceuticals R&D 15 10 88 Pharmaceuticals, including R&D 66 48 117 Vaccines 5 13 34 Consumer Healthcare 4 10 46 Segment impairment 75 71 197 Corporate and other unallocated impairment 14 3 24 Other reconciling items between segment impairment and total impairment 261 995 68 Total impairment 350 1,069 289 PP&E and intangible asset impairment reversals by segment Pharmaceuticals (4 ) (13 ) (15 ) Pharmaceuticals R&D (1 ) (2 ) (10 ) Pharmaceuticals, including R&D (5 ) (15 ) (25 ) Vaccines 0 — (19 ) Consumer Healthcare 0 (1 ) (8 ) Segment impairment reversals (5 ) (16 ) (52 ) Corporate and other unallocated impairment reversals 0 — (26 ) Other reconciling items between segment impairment reversals and total impairment reversals (8 ) (36 ) (9 ) Total impairment reversals (13 ) (52 ) (87 ) Net assets by segment 2018 £m 2017 Pharmaceuticals 869 2,017 Pharmaceuticals R&D 502 522 Pharmaceuticals, including R&D 1,371 2,539 Vaccines 9,966 9,707 Consumer Healthcare 10,559 2,003 Segment net operating assets 21,896 14,249 Corporate and other unallocated net operating assets 1,141 868 Net operating assets 23,037 15,117 Net debt (21,621 ) (13,178 ) Investments in associates and joint ventures 236 183 Derivative financial instruments 129 2 Current and deferred taxation 1,723 1,252 Assets held for sale (excluding cash and cash equivalents) 168 113 Net assets 3,672 3,489 The Pharmaceuticals segment includes the Shionogi-ViiV Healthcare contingent consideration liability of £5,937 million (2017 – £5,542 million) and the Pfizer put option of £1,240 million (2017 – £1,304 million). The put option liability (2017 – £8,606 million) related to the Consumer Healthcare segment was extinguished during 2018. Geographical information The UK is regarded as being the Group’s country of domicile. Turnover by location of customer 2018 2017 2016 UK 923 940 1,056 US 11,982 11,263 10,197 Rest of World 17,916 17,983 16,636 External turnover 30,821 30,186 27,889 Non-current 2018 2017 UK 6,118 6,824 US 7,540 6,841 Rest of World 20,768 20,901 Non-current 34,426 34,566 Non-current non-current

Other operating income_(expense

Other operating income/(expense)	12 Months Ended
	Dec. 31, 2018
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Other operating income/(expense)	7. Other operating income/(expense) 2018 2017 2016 £m £m £m Fair value remeasurements of equity investments under IFRS 9 16 Disposal of businesses and assets 258 195 283 Fair value remeasurements on contingent consideration recognised in business combinations (1,252 ) (1,012 ) (2,205 ) Remeasurement of ViiV Healthcare put option liabilities and preferential dividends 58 13 (577 ) Remeasurement of Consumer Healthcare put option liability (658 ) (1,186 ) (1,133 ) Fair value adjustments on derivative financial instruments (3 ) 9 (3 ) Other (expense)/income (7 ) 9 23 Impairment of available-for-sale (30 ) (47 ) Disposal of available-for-sale 37 254 (1,588 ) (1,965 ) (3,405 ) Disposal of businesses and assets in 2018 included a profit of £119 million on the disposal of tapinarof to Dermavant Sciences, a profit of £33 million on the disposal of Consumer Healthcare tail brands in the US and a gain arising from the increase in value of the shares in Hindustan Unilever Limited to be received on the disposal of Horlicks Fair value remeasurements on contingent consideration recognised in business combinations included £1,188 million related to the acquisition of the former Shionogi-ViiV Healthcare joint venture and £56 million payable to Novartis related to the Vaccines acquisition and fair value movements on derivatives hedging foreign exchange exposure.

Operating profit

Operating profit	12 Months Ended
	Dec. 31, 2018
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Operating profit	8. Operating profit The following items have been included in operating profit: 2018 2017 2016 Employee costs (Note 9) 9,440 9,122 8,212 Advertising 1,376 1,351 1,265 Distribution costs 389 405 395 Depreciation of property, plant and equipment 954 988 978 Impairment of property, plant and equipment, net of reversals 203 327 180 Amortisation of intangible assets 902 934 796 Impairment of intangible assets, net of reversals 134 690 22 Net foreign exchange losses 81 215 53 Inventories: Cost of inventories included in cost of sales 8,713 8,526 8,093 Write-down of inventories 695 701 533 Reversal of prior year write-down of inventories (302 ) (352 ) (145 ) Operating lease rentals: Minimum lease payments 188 110 91 Contingent rents 12 4 4 Sub-lease 5 5 4 Fees payable to the company’s auditor and its associates in relation to the Group (see below) 29.8 29.2 29.7 The reversals of prior year write-downs of inventories principally arise from the reassessment of usage or demand expectations prior to inventory expiration. Net foreign exchange losses include a net loss of £nil (2017 – £109 million; 2016 – £nil) of exchange arising on the reclassification of exchange on liquidation or disposal of overseas subsidiaries. Included within operating profit are major restructuring charges of £809 million (2017 – £1,056 million; 2016 – £970 million), see Note 10, ‘Major restructuring costs’. Fees payable to the company’s auditor and its associates: 2018 2017 2016 Audit of parent company and consolidated financial statements 6.7 7.0 5.8 Audit of the company’s subsidiaries 12.9 16.2 16.4 Attestation under s.404 of Sarbanes-Oxley Act 2002 6.6 4.5 4.4 Audit and audit-related services 26.2 27.7 26.6 Taxation compliance 0.1 0.2 0.2 Taxation advice 0 0.1 1.8 Other assurance services 3.0 1.0 0.3 All other services 0.5 0.2 0.8 29.8 29.2 29.7 The other assurance services provided by the auditor relate to agreed upon procedures and other assurance services outside of statutory audit requirements. All other services provided by the auditor primarily related to advisory services for the year ended 31 December 2018. In addition to the above, fees paid in respect of the GSK pension schemes were: 2018 2017 2016 Audit 0.3 0.3 0.4 Other services 0 0.1 —

Employee costs

Employee costs	12 Months Ended
	Dec. 31, 2018
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Employee costs	9. Employee costs 2018 2017 2016 £m £m £m Wages and salaries 7,203 7,116 6,391 Social security costs 795 802 733 Pension and other post-employment costs, including augmentations (Note 28) 586 616 541 Cost of share-based incentive plans 393 347 338 Severance and other costs from integration and restructuring activities 463 241 209 9,440 9,122 8,212 The increase in wages and salaries included the impact of movements in exchange rates. The Group provides benefits to employees, commensurate with local practice in individual countries, including, in some markets, healthcare insurance, subsidised car schemes and personal life assurance. The cost of share-based incentive plans is analysed as follows: 2018 2017 2016 £m £m £m Share Value Plan 304 276 271 Performance Share Plan 49 47 39 Share option plans 4 4 4 Cash settled and other plans 36 20 24 393 347 338 The average monthly number of persons employed by the Group (including Directors) during the year was: 2018 Number 2017 2016 Manufacturing 37,296 38,632 38,611 Selling, general and administration 47,887 49,141 49,961 Research and development 11,668 11,576 11,255 96,851 99,349 99,827 The average monthly number of Group employees excludes temporary and contract staff. The numbers of Group employees at the end of each financial year are given in the financial record on page 231. The monthly average number of persons employed by GlaxoSmithKline plc in 2018 was nil (2017 – nil). The compensation of the Directors and Senior Management (members of the CET) in aggregate, was as follows: 2018 2017 2016 Wages and salaries 29 26 25 Social security costs 3 4 4 Pension and other post-employment costs 3 3 2 Cost of share-based incentive plans 20 22 15 55 55 46 Further information on the remuneration of the Directors is given in the Remuneration report on pages 96 to 124.

Major restructuring costs

Major restructuring costs	12 Months Ended
	Dec. 31, 2018
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Major restructuring costs	10. Major restructuring costs Within the Pharmaceuticals sector, the highly regulated manufacturing operations and supply chains and long lifecycle of the business mean that restructuring programmes, particularly those that involve the rationalisation or closure of manufacturing or R&D sites, are likely to take several years to complete. Major restructuring costs are those related to specific Board approved Major restructuring programmes, including integration costs following material acquisitions, which are structural and are of a significant scale where the costs of individual or related projects exceed £25 million. The existing Combined restructuring and integration programme incorporates the previous Major Change programme, the Pharmaceuticals restructuring programme and the restructuring and integration programme following the Novartis transaction in 2015. In July 2018, the Board approved a new Major restructuring programme, which is designed to significantly improve the competitiveness and efficiency of the Group’s cost base with savings delivered primarily through supply chain optimisation and reductions in administrative costs. The total restructuring costs of £809 million in 2018 were incurred in a number of areas, including the following: • Restructuring of the commercial operating model, including staff reductions in the US, Europe and International Pharmaceutical commercial operations and the US Respiratory field sales force • Manufacturing site restructuring, including the GSK steriles manufacturing facility at Ulverston, United Kingdom • Vaccines transformation and remediation • Restructuring of the Pharmaceutical and Consumer Healthcare supply chains leading to simplification of the operating model and improved resource allocation • Transformation of central functions, including GSK technology platforms and interfaces, to deliver greater digital synergies, simplification of applications and staff reductions. The analysis of the costs charged to operating profit under these programmes was as follows: 2018 2017 2016 Increase in provision for Major restructuring programmes (see Note 29) 450 259 163 Amount of provision reversed unused (see Note 29) (99 ) (43 ) (140 ) Impairment losses recognised 130 278 158 Other non-cash 72 247 108 Other cash costs 256 315 681 809 1,056 970 Asset impairments and other non-cash The analysis of Major restructuring charges by income statement line was as follows: 2018 2017 2016 Cost of sales 443 545 297 Selling, general and administration 315 248 514 Research and development 49 263 159 Other operating income/(expense) 2 — — 809 1,056 970

Finance income

Finance income	12 Months Ended
	Dec. 31, 2018
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Finance income	11. Finance income 2018 2017 2016 Year to 31 December 2018 under IFRS 9 Finance income arising from: Financial assets measured at amortised cost 73 Financial assets measured at fair value through profit or loss 1 Net gains arising from hedge ineffectiveness on net investment hedges 7 Years to 31 December 2017 and 31 December 2016 under IAS 39 Interest income arising from: Cash and cash equivalents 60 67 Available-for-sale 2 1 Loans and receivables 1 2 Fair value adjustments on derivatives at fair value through profit or loss 2 2 81 65 72 Interest income arising from financial assets measured at amortised cost in 2018 includes interest income arising from assets which would have been classified as available-for-sale Net gains arising from hedge ineffectiveness on net investment hedges were recorded in ‘Fair value adjustments on derivatives at fair value through profit or loss’ in 2017 and 2016. All derivatives accounted for at fair value through profit or loss other than designated and effective hedging instruments (see Note 42, ‘Financial instruments and related disclosures’) are classified as held-for-trading

Finance expense

Finance expense	12 Months Ended
	Dec. 31, 2018
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Finance expense	12. Finance expense 2018 2017 2016 £m £m £m Finance expense arising on: Financial liabilities at amortised cost (677 ) (698 ) (671 ) Derivatives at fair value through profit or loss (38 ) (22 ) (30 ) Net losses arising from: Financial instruments mandatorily measured at fair value through profit or loss 3 (4 ) (3 ) Reclassification of hedges from other comprehensive income (2 ) — (1 ) Unwinding of discounts on provisions (15 ) (16 ) (16 ) Other finance expense (69 ) 6 (15 ) (798 ) (734 ) (736 ) All derivatives accounted for at fair value through profit or loss, other than designated and effective hedging instruments (see Note 42, ‘Financial instruments and related disclosures’), are classified as held-for-trading

Associates and joint ventures

Associates and joint ventures	12 Months Ended
	Dec. 31, 2018
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Associates and joint ventures	13. Associates and joint ventures The Group’s share of after tax profits and losses of associates and joint ventures is set out below: 2018 2017 2016 Share of after tax profits of associates 28 16 9 Share of after tax profits/(losses) of joint ventures 3 (3 ) (4 ) 31 13 5 At 31 December 2018, the Group held one significant associate, Innoviva, Inc. Summarised income statement information in respect of Innoviva is set out below for the periods in which the Group accounted for its investment in Innoviva as an associate. The Group’s 2018 share of after tax profits of associates and other comprehensive income includes a profit of £33 million and other comprehensive income of £nil in respect of Innoviva. 2018 2017 2016 Turnover 183 165 98 Profit after taxation 134 103 44 Other comprehensive income 0 — — Total comprehensive income 134 103 44 The results of Innoviva included in the summarised income statement information above represent the estimated earnings of Innoviva in the relevant periods, based on publicly available information. Innoviva’s turnover is from royalty income from GSK in relation to Relvar/Breo Ellipta Anoro Ellipta Trelegy Ellipta Aggregated financial information in respect of GSK’s share of other associated undertakings and joint ventures is set out below: 2018 2017 2016 Share of turnover 242 252 133 Share of after tax (losses)/profits (2 ) (5 ) (1 ) Share of other comprehensive income 0 — — Share of total comprehensive (expense)/income (2 ) (5 ) (1 ) The Group’s sales to associates and joint ventures were £43 million in 2018 (2017 – £41 million; 2016 – £43 million).

Taxation

Taxation	12 Months Ended
	Dec. 31, 2018
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Taxation	14. Taxation The Group’s tax charge is the sum of the total current and deferred tax expense. Taxation charge based on profits for the year 2018 2017 2016 UK current year charge 234 199 241 Rest of World current year charge 1,426 1,928 1,326 Credit in respect of prior periods (492 ) (508 ) (149 ) Total current taxation 1,168 1,619 1,418 Total deferred taxation (414 ) (263 ) (541 ) Total tax 754 1,356 877 In 2018, GSK made payments of £113 million in UK corporation tax to HMRC. These amounts are for UK corporation tax only, and do not include the various other business taxes borne in the UK by GSK each year. The deferred tax credit in 2018 reflected the origination of current year tax losses, where offset against taxable profits in future periods is probable, as well as an uplift in the tax carrying value of certain Consumer Healthcare brands as a result of the acquisition of Novartis’ interest in the former Consumer Healthcare Joint Venture. The deferred tax credit in 2017 reflected the revaluation of existing deferred tax liabilities to reflect a lower Swiss tax rate applicable following Swiss tax reform, and an increase in deferred tax assets related to intra-Group profit on inventory. The impact of these items was partly offset by the revaluation of existing deferred tax assets to reflect the lower US tax rate applicable following the enactment of US tax reform. In 2016, the net deferred tax credit was impacted to a greater extent by remeasurement of the contingent consideration in relation to the former Shionogi-ViiV Healthcare Joint Venture. The following table reconciles the tax charge calculated at the UK statutory rate on the Group profit before tax with the actual tax charge for the year. Reconciliation of taxation on Group profits 2018 2018 2017 2017 2016 2016 Profit before tax 4,800 3,525 1,939 UK statutory rate of taxation 912 19.0 679 19.25 388 20.0 Differences in overseas taxation rates 675 14.1 635 18.0 593 30.6 Benefit of intellectual property incentives (522 ) (10.9 ) (458 ) (13.0 ) (321 ) (16.5 ) R&D credits (73 ) (1.5 ) (75 ) (2.1 ) (93 ) (4.8 ) FV remeasurement of non-taxable 221 4.6 227 6.4 340 17.5 Tax losses where no benefit is recognised 24 0.5 28 0.8 (15 ) (0.8 ) Permanent differences on disposals and acquisitions (7 ) (0.1 ) 4 0.1 (21 ) (1.1 ) Other permanent differences 85 1.7 196 5.6 122 6.3 Re-assessments (436 ) (9.1 ) (475 ) (13.5 ) (116 ) (6.0 ) US and Swiss Tax Reform (125 ) (2.6 ) 595 16.9 Tax charge/tax rate 754 15.7 1,356 38.5 877 45.2 GSK has a substantial business presence in many countries around the world. The impact of differences in overseas taxation rates arose from profits being earned in countries with tax rates higher than the UK statutory rate, the most significant of which in 2018 were the US, Belgium, India and Japan. The adverse impact was partly offset by the increased benefit of intellectual property incentives such as the UK Patent box and Belgian Patent income deduction regimes. Such regimes provide a reduced rate of corporate income tax on profits earned from qualifying patents. The Group’s 2018 tax rate of 15.7% has been influenced by the reassessment of open issues with tax authorities in various jurisdictions, together with the £125 million credit related to a reduced estimate of the 2017 impact of US Tax Reform following additional guidance being released by the US tax authorities and the transaction related charges arising on the Group’s put option liabilities to ViiV Healthcare and the former Consumer Healthcare Joint Venture with Novartis. Future tax charges, and therefore the Group’s effective tax rate, may be affected by factors such as acquisitions, disposals, restructuring, the location of research and development activity, tax regime reforms and resolution of open matters as tax affairs are brought up to date around the world. 2018 2017 2016 Tax on items charged to equity and statement of comprehensive income £m £m £m Current taxation Share-based payments 0 — 7 Defined benefit plans (2 ) 26 32 (2 ) 26 39 Deferred taxation Share-based payments 2 (4 ) — Defined benefit plans (144 ) (247 ) 94 Fair value movements on cash flow hedges (2 ) — 2 Fair value movements on equity investments 10 29 51 (134 ) (222 ) 147 Total (charge)/credit to equity and statement of comprehensive income (136 ) (196 ) 186 All of the above items have been charged to the statement of comprehensive income except for tax on share-based payments. Issues relating to taxation The integrated nature of the Group’s worldwide operations involves significant investment in research and strategic manufacture at a limited number of locations, with consequential cross-border supply routes into numerous end-markets. The calculation of the Group’s total tax charge therefore necessarily involves a degree of estimation and judgement in respect of certain items whose tax treatment cannot be finally determined until resolution has been reached with the relevant tax authority or, as appropriate, through a formal legal process. At 31 December 2018 the Group had recognised provisions of £1,082 million in respect of such uncertain tax positions (2017 – £1,175 million). The decrease in recognised provisions during 2018 was driven by the reassessment of estimates and the utilisation of provisions for uncertain tax positions following the settlement of a number of open issues with tax authorities in various jurisdictions. Whilst the ultimate liability for such matters may vary from the amounts provided and is dependent upon the outcome of agreements with the relevant tax authorities, or litigation where appropriate, the Group continues to believe that it has made appropriate provision for periods which are open and not yet agreed by the tax authorities. GSK does not currently anticipate any material changes to the amounts provided for transfer pricing or tax contingencies during the next 12 months. A provision for deferred tax liabilities of £185 million as at 31 December 2018 (2017 – £209 million) has been made in respect of withholding taxation that would be payable on the remittance of profits by certain overseas subsidiaries. Whilst the aggregate amount of unremitted profits at the balance sheet date was approximately £18 billion (2017 – £17 billion), the majority of these unremitted profits would not be subject to tax (including withholding tax) on repatriation, as UK legislation relating to company distributions provides for exemption from tax for most overseas profits, subject to certain exceptions. Deferred tax is not provided on temporary differences of £231 million (2017 – £nil) arising on unremitted profits as management has the ability to control any future reversal and does not consider such a reversal to be probable. Movement in deferred tax assets and liabilities Accelerated Intangible Contingent Intra-Group Pensions & Tax Share Other Total At 1 January 2017 (377 ) (2,324 ) 1,138 1,054 1,262 227 110 1,350 2,440 Exchange adjustments (7 ) 75 — (58 ) (48 ) (5 ) (4 ) (18 ) (65 ) Credit/(charge) to income statement 62 330 (52 ) 256 3 59 (1 ) (88 ) 569 Credit/(charge) to income statement associated with US tax reform 5 116 (218 ) (235 ) (210 ) (20 ) (27 ) (216 ) (805 ) Credit to income statement associated with Swiss tax reform — 483 — — — — — — 483 (Charge)/credit to statement of comprehensive income and equity — — — — (247 ) — (4 ) 29 (222 ) At 1 January 2018 (317 ) (1,320 ) 868 1,017 760 261 74 1,057 2,400 Exchange adjustments (6 ) (4 ) 0 43 38 2 2 9 84 Credit/(charge) to income statement (12 ) 365 (34 ) (31 ) 33 183 (7 ) (101 ) 396 Credit/(charge) to statement of comprehensive income and equity 0 0 0 0 (144 ) 0 2 8 (134 ) Reclassification on disposal 0 0 0 0 7 1 0 (23 ) (15 ) At 31 December 2018 (335 ) (959 ) 834 1,029 694 447 71 950 2,731 The net credit to the income statement of £396 million included an £18 million charge related to R&D incentives recognised within Operating profit (and not the taxation charge) in the income statement. Deferred tax liabilities provided in relation to intangible assets predominately relate to temporary differences arising on assets and liabilities acquired as part of historic business combinations. The Group continues to recognise deferred tax assets on future obligations in respect of contingent consideration amounts payable to minority shareholders. These payments are tax deductible at the point in time at which payment is made. A deferred tax asset is recognised on intra-Group profits arising on inter-company inventory which are eliminated within the consolidated accounts. As intra-Group profits are not eliminated from the individual entities’ tax returns a temporary difference arises that will reverse at the point in time inventory is sold externally. The deferred tax asset recognised on tax losses of £447 million (2017 – £261 million) related to trading losses. Other net temporary differences included accrued expenses for which a tax deduction is only available on a paid basis, such as for pensions. Deferred tax asset and liabilities are recognised on the balance sheet as follows: 2018 2017 £m £m Deferred tax assets 3,887 3,796 Deferred tax liabilities (1,156 ) (1,396 ) 2,731 2,400 Deferred tax assets are recognised on US foreign tax credits only where it is probable that future taxable profits will be available. The net amount of foreign tax credits on which deferred tax has not been provided was £114 million at 31 December 2018 (2017 – £151 million). 2018 2017 Unrecognised Unrecognised deferred tax deferred tax Tax losses asset Tax losses asset Unrecognised tax losses £m £m £m £m Trading losses expiring: Within 10 years 678 148 802 187 More than 10 years 957 93 872 99 Available indefinitely 89 15 86 14 At 31 December 1,724 256 1,760 300 Capital losses expiring: Available indefinitely 2,042 399 1,924 372 At 31 December 2,042 399 1,924 372 Deferred tax assets are only recognised where it is probable that future taxable

Earnings per share

Earnings per share	12 Months Ended
	Dec. 31, 2018
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Earnings per share	15. Earnings per share 2018 2017 2016 pence pence pence Basic earnings per share 73.7 31.4 18.8 Diluted earnings per share 72.9 31.0 18.6 Basic earnings per share has been calculated by dividing the profit attributable to shareholders by the weighted average number of shares in issue during the period after deducting shares held by the ESOP Trusts and Treasury shares. The trustees have waived their rights to dividends on the shares held by the ESOP Trusts. Diluted earnings per share has been calculated after adjusting the weighted average number of shares used in the basic calculation to assume the conversion of all potentially dilutive shares. A potentially dilutive share forms part of the employee share schemes where its exercise price is below the average market price of GSK shares during the period and any performance conditions attaching to the scheme have been met at the balance sheet date. The numbers of shares used in calculating basic and diluted earnings per share are reconciled below. 2018 2017 2016 Weighted average number of shares in issue millions millions millions Basic 4,914 4,886 4,860 Dilution for share options and awards 57 55 49 Diluted 4,971 4,941 4,909

Dividends

Dividends	12 Months Ended
	Dec. 31, 2018
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Dividends	16. Dividends 2018 2017 2016 Dividend Total Dividend Total Dividend Total per share dividend per share dividend per share dividend Paid/payable (pence) £m Paid (pence) £m Paid (pence) £m First interim 12 July 2018 19 934 13 July 2017 19 928 14 July 2016 19 923 Second interim 11 October 2018 19 934 12 October 2017 19 929 13 October 2016 19 925 Third interim 10 January 2019 19 935 11 January 2018 19 929 12 January 2017 19 925 Fourth interim 11 April 2019 23 1,132 12 April 2018 23 1,130 13 April 2017 23 1,124 Total 80 3,935 80 3,916 80 3,897 Under IFRS, interim dividends are only recognised in the financial statements when paid and not when declared. GSK normally pays a dividend two quarters after the quarter to which it relates and one quarter after it is declared. The 2018 financial statements recognise those dividends paid in 2018, namely the third and fourth interim dividends for 2017, and the first and second interim dividends for 2018. The amounts recognised in each year were as follows: 2018 2017 2016 £m £m £m Dividends to shareholders 3,927 3,906 4,850

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2018
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Property, plant and equipment	17. Property, plant and equipment Plant, Land and equipment Assets in buildings and vehicles construction Total £m £m £m £m Cost at 1 January 2017 7,761 11,235 3,168 22,164 Exchange adjustments (127 ) (62 ) (45 ) (234 ) Other additions 69 296 1,219 1,584 Capitalised borrowing costs — — 30 30 Disposals and write-offs (376 ) (685 ) (31 ) (1,092 ) Reclassifications 602 1,186 (1,826 ) (38 ) Transfer to assets held for sale (462 ) (219 ) (14 ) (695 ) Cost at 31 December 2017 7,467 11,751 2,501 21,719 Exchange adjustments 150 187 25 362 Other additions 33 190 1,135 1,358 Capitalised borrowing costs 0 0 21 21 Disposals and write-offs (90 ) (440 ) (53 ) (583 ) Reclassifications 403 1,016 (1,486 ) (67 ) Transfer to assets held for sale (152 ) (167 ) (3 ) (322 ) Cost at 31 December 2018 7,811 12,537 2,140 22,488 Depreciation at 1 January 2017 (3,259 ) (7,410 ) — (10,669 ) Exchange adjustments 50 110 — 160 Charge for the year (299 ) (689 ) — (988 ) Disposals and write-offs 158 539 — 697 Transfer to assets held for sale 314 190 — 504 Depreciation at 31 December 2017 (3,036 ) (7,260 ) 0 (10,296 ) Exchange adjustments (61 ) (111 ) 0 (172 ) Charge for the year (268 ) (686 ) 0 (954 ) Disposals and write-offs 77 401 0 478 Transfer to assets held for sale 55 122 0 177 Depreciation at 31 December 2018 (3,233 ) (7,534 ) 0 (10,767 ) Impairment at 1 January 2017 (279 ) (344 ) (64 ) (687 ) Exchange adjustments 8 2 (2 ) 8 Disposals and write-offs 210 104 28 342 Impairment losses (194 ) (138 ) (17 ) (349 ) Reversal of impairments 7 9 1 17 Transfer to assets held for sale 87 8 11 106 Impairment at 31 December 2017 (161 ) (359 ) (43 ) (563 ) Exchange adjustments (8 ) (4 ) (1 ) (13 ) Disposals and write-offs 10 59 22 91 Impairment losses (16 ) (143 ) (46 ) (205 ) Reversal of impairments 1 6 0 7 Transfer to assets held for sale 0 20 0 20 Impairment at 31 December 2018 (174 ) (421 ) (68 ) (663 ) Total depreciation and impairment at 31 December 2017 (3,197 ) (7,619 ) (43 ) (10,859 ) Total depreciation and impairment at 31 December 2018 (3,407 ) (7,955 ) (68 ) (11,430 ) Net book value at 1 January 2017 4,223 3,481 3,104 10,808 Net book value at 31 December 2017 4,270 4,132 2,458 10,860 Net book value at 31 December 2018 4,404 4,582 2,072 11,058 The weighted average interest rate for capitalised borrowing costs in the year was 3% (2017 – 4%). Disposals and write-offs in the year included a number of assets with nil net book value that are no longer in use in the business. The net book value at 31 December 2018 of the Group’s land and buildings included £24 million (2017 – £27 million) held under finance leases. In addition, the net book value of plant, equipment and vehicles held under finance lease at 31 December 2018 was £59 million (2017 – £55 million). The impairment losses principally arose from decisions to rationalise facilities and are calculated based on either fair value less costs of disposal or value in use. The fair value less costs of disposal valuation methodology uses significant inputs which are not based on observable market data, and therefore this valuation technique is classified as level 3 of the fair value hierarchy. These calculations determine the net present value of the projected risk-adjusted, post-tax post-tax pre-tax pre-tax pre-tax pre-tax Reversals of impairment arose from subsequent reviews of the impaired assets where the conditions which gave rise to the original impairments were deemed no longer to apply. All of the reversals have been credited to cost of sales. The carrying value at 31 December 2018 of assets for which impairments have been charged or reversed in the year was £95 million (2017 – £33 million). During 2018, £67 million (2017 – £38 million) of computer software was reclassified from assets in construction to intangible assets on becoming ready for use.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2018
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Goodwill	18. Goodwill 2018 2017 £m £m Cost at 1 January 5,734 5,965 Exchange adjustments 199 (228 ) Transfer to assets held for sale (144 ) (3 ) Cost at 31 December 5,789 5,734 Net book value at 1 January 5,734 5,965 Net book value at 31 December 5,789 5,734 Goodwill is allocated to the Group’s segments as follows: 2018 2017 £m £m Pharmaceuticals 3,273 3,172 Vaccines 1,342 1,302 Consumer Healthcare 1,174 1,260 Net book value at 31 December 5,789 5,734 The recoverable amounts of the cash generating units are assessed using a fair value less costs of disposal model. Fair value less costs of disposal is calculated using a discounted cash flow approach, with a post-tax post-tax The discount rate used is based on the Group WACC of 7%, as most cash generating units have integrated operations across large parts of the Group. The discount rate is adjusted where appropriate for specific segment, country and currency risks. The valuation methodology uses significant inputs which are not based on observable market data, therefore this valuation technique is classified as level 3 in the fair value hierarchy. Details relating to the discounted cash flow models used in the impairment tests of the Pharmaceuticals, Vaccines and Consumer Healthcare cash generating units are as follows: Valuation basis Fair value less costs of disposal Key assumptions Sales growth rates Profit margins Terminal growth rate Discount rate Taxation rate Determination of assumptions Growth rates are internal forecasts based on both internal and external market information. Margins reflect past experience, adjusted for expected changes. Terminal growth rates based on management’s estimate of future long-term average growth rates. Discount rates based on Group WACC, adjusted where appropriate. Taxation rates based on appropriate rates for each region. Period of specific projected cash flows Five years Terminal growth rate and discount rate Terminal growth rate Discount rate Pharmaceuticals 1% p.a. 7.5% Vaccines 1% p.a. 7.5% Consumer Healthcare 2% p.a. 6% The terminal growth rates do not exceed the long-term projected growth rates for the relevant markets, reflect the impact of future generic competition and take account of new product launches. In each case the valuations indicated sufficient headroom such that a reasonably possible change to key assumptions is unlikely to result in an impairment of the related goodwill. Goodwill is monitored at the segmental level. The Pharmaceuticals cash generating unit comprises a collection of smaller cash generating units including assets with indefinite lives with a carrying value of £236 million (2017 – £228 million). The Consumer Healthcare cash generating unit also comprises a collection of smaller cash generating units including brands with indefinite lives with a carrying value of £8.5 billion (2017 – £8.5 billion). Details of indefinite life brands are given in Note 19, ‘Other intangible assets’.

Other intangible assets

Other intangible assets	12 Months Ended
	Dec. 31, 2018
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Other intangible assets	19. Other intangible assets Computer Licences, Amortised Indefinite life software patents, etc. brands brands Total £m £m £m £m £m Cost at 1 January 2017 2,156 15,143 427 9,375 27,101 Exchange adjustments (37 ) (215 ) (4 ) (272 ) (528 ) Capitalised development costs — 251 — — 251 Capitalised borrowing costs 2 3 — — 5 Other additions 233 221 — — 454 Disposals and asset write-offs (217 ) (38 ) — — (255 ) Transfer to assets held for sale (1 ) (90 ) — (44 ) (135 ) Reclassifications 38 — 66 (66 ) 38 Cost at 31 December 2017 2,174 15,275 489 8,993 26,931 Exchange adjustments 32 235 29 63 359 Capitalised development costs — 203 — — 203 Capitalised borrowing costs 1 — — — 1 Other additions 173 154 — — 327 Disposals and asset write-offs (80 ) (129 ) — — (209 ) Transfer to assets held for sale (2 ) (81 ) (9 ) — (92 ) Reclassifications 67 — — — 67 Cost at 31 December 2018 2,365 15,657 509 9,056 27,587 Amortisation at 1 January 2017 (1,184 ) (4,983 ) (224 ) — (6,391 ) Exchange adjustments 25 141 — — 166 Charge for the year (163 ) (761 ) (10 ) — (934 ) Disposals and asset write-offs 210 25 — — 235 Transfer to assets held for sale 1 25 — — 26 Amortisation at 31 December 2017 (1,111 ) (5,553 ) (234 ) — (6,898 ) Exchange adjustments (24 ) (104 ) (3 ) — (131 ) Charge for the year (240 ) (645 ) (17 ) — (902 ) Disposals and asset write-offs 67 124 — — 191 Transfer to assets held for sale 1 18 1 — 20 Amortisation at 31 December 2018 (1,307 ) (6,160 ) (253 ) — (7,720 ) Impairment at 1 January 2017 (9 ) (1,652 ) (143 ) (130 ) (1,934 ) Exchange adjustments — 110 — 3 113 Impairment losses (2 ) (546 ) — (132 ) (680 ) Disposals and asset write-offs 2 5 — — 7 Transfer to assets held for sale — 19 — 4 23 Impairment at 31 December 2017 (9 ) (2,064 ) (143 ) (255 ) (2,471 ) Exchange adjustments — (69 ) (20 ) — (89 ) Impairment losses (17 ) (51 ) — (69 ) (137 ) Reversal of impairments — 3 — — 3 Disposals and asset write-offs 14 4 — — 18 Transfer to assets held for sale — 11 — — 11 Impairment at 31 December 2018 (12 ) (2,166 ) (163 ) (324 ) (2,665 ) Total amortisation and impairment at 31 December 2017 (1,120 ) (7,617 ) (377 ) (255 ) (9,369 ) Total amortisation and impairment at 31 December 2018 (1,319 ) (8,326 ) (416 ) (324 ) (10,385 ) Net book value at 1 January 2017 963 8,508 60 9,245 18,776 Net book value at 31 December 2017 1,054 7,658 112 8,738 17,562 Net book value at 31 December 2018 1,046 7,331 93 8,732 17,202 The weighted average interest rate for capitalised borrowing costs in the year was 3% (2017 – 4%). The net book value of computer software included £578 million (2017 – £669 million) of internally generated costs. The carrying value at 31 December 2018 of intangible assets, for which impairments have been charged or reversed in the year, following those impairments or reversals, was £73 million (2017 – £300 million). The patent expiry dates of the Group’s most significant assets, where relevant, are set out on pages 238 and 239. Amortisation and impairment losses, net of reversals, have been charged in the income statement as follows: Amortisation Net impairment losses 2018 2017 2018 2017 £m £m £m £m Cost of sales 593 578 69 400 Selling, general and administration 178 116 19 2 Research and development 131 240 46 278 902 934 134 680 Licences, patents, etc. includes a large number of acquired licences, patents, know-how 2018 2017 £m £m Meningitis portfolio 2,363 2,450 Dolutegravir 1,319 1,389 Benlysta 905 965 Fluarix/FluLaval 274 321 HIV assets acquired from BMS 277 277 Selzentry 136 162 Okairos technology platform 205 202 Others 1,852 1,892 7,331 7,658 The Meningitis portfolio includes Menveo Bexsero Menjugate Indefinite life brands comprise a portfolio of Consumer Healthcare products primarily acquired with the acquisitions of Sterling Winthrop, Inc. in 1994, Block Drug Company, Inc. in 2001, CNS, Inc. in 2006 and the Novartis Consumer Healthcare business in 2015, together with a number of pharmaceutical brands from the acquisition of Stiefel Laboratories, Inc. in 2009. The book values of the major brands are as follows: 2018 2017 £m £m Voltaren 2,735 2,716 Otrivin 1,385 1,380 Fenistil 651 648 Theraflu 449 441 Panadol 388 386 Sensodyne 265 265 Lamisil 293 289 Breathe Right 262 236 Stiefel trade name 236 228 Excedrin 193 185 Physiogel 150 166 Polident 112 112 Others 1,613 1,686 8,732 8,738 Each of these brands is considered to have an indefinite life, given the strength and durability of the brand and the level of marketing support. The brands are in relatively similar stable and profitable market sectors, with similar risk profiles, and their size, diversification and market shares mean that the risk of market-related factors causing a reduction in the lives of the brands is considered to be relatively low. The Group is not aware of any material legal, regulatory, contractual, competitive, economic or other factors which could limit their useful lives. Accordingly, they are not amortised. Each brand is tested annually for impairment and other amortised intangible assets are tested when indicators of impairment arise. This testing applies a fair value less costs of disposal methodology, generally using post-tax post-tax

Investments in associates and j

Investments in associates and joint ventures	12 Months Ended
	Dec. 31, 2018
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Investments in associates and joint ventures	20. Investments in associates and joint ventures Joint 2018 Joint 2017 ventures Associates Total ventures Associates Total £m £m £m £m £m £m At 1 January 13 170 183 19 244 263 Exchange adjustments 1 11 12 (2 ) (10 ) (12 ) Additions 1 9 10 — 15 15 Disposals 0 0 0 — (92 ) (92 ) Distributions received 0 (40 ) (40 ) (1 ) (1 ) (2 ) Other movements 1 39 40 — (2 ) (2 ) Profit/(loss) after tax recognised in the consolidated income statement 3 28 31 (3 ) 16 13 At 31 December 19 217 236 13 170 183 The Group held one significant associate at 31 December 2018, Innoviva, Inc. At 31 December 2018, the Group owned 32 million shares or 31.7% of Innoviva, which is a biopharmaceutical company listed on NASDAQ. Innoviva partnered with GSK in the development of the long acting beta agonist vilanterol and currently receives royalty income from sales of products that contain this component, namely Relvar/Breo Ellipta Anoro Ellipta Trelegy Ellipta Summarised balance sheet information, based on published information, in respect of Innoviva is set out below: At At 2018 2017 £m £m Non-current 275 124 Current assets 157 148 Current liabilities (4 ) (26 ) Non-current (302 ) (426 ) Net assets/(liabilities) 126 (180 ) 2018 2017 £m £m Interest in associated undertaking 40 (57 ) Goodwill 91 86 Fair value and other adjustments 58 118 Carrying value at 31 December 189 147

Other investments

Other investments	12 Months Ended
	Dec. 31, 2018
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Other investments	21. Other investments Investments Investments 2018 2017 £m £m £m £m At 1 January 869 49 918 985 Exchange adjustments 48 4 52 (64 ) Additions 363 9 372 80 Net fair value movements through Other comprehensive income 118 0 118 11 Net fair value movements through profit or loss 0 16 16 — Impairment losses 0 0 0 (30 ) Disposals and settlements (89 ) (6 ) (95 ) (64 ) Transfers to Assets held for sale (59 ) 0 (59 ) — At 31 December 1,250 72 1,322 918 Other investments comprise non-current GSK has elected to designate the majority of its equity investments as measured at fair value through other comprehensive income (FVTOCI). The most significant of these investments held at 31 December 2018 were in Theravance Biopharma, Inc. in which the Group holds 17.4% of the common stock, Orchard in which the group holds 14.5% and 23andMe in which the Group holds 14.5%. These investments had a fair value at 31 December 2018 of £194 million (2017 – £199 million), £154 million and £229 million respectively. No other investment is individually material. The other investments include equity stakes in companies with which GSK has research collaborations and in companies which provide access to biotechnology developments of potential interest. Information on dividends received from investments measured at FVTOCI is provided in Note 7 ‘Other operating income/(expense)’. On disposal of equity investments measured at FVTOCI, the accumulated fair value movements are reclassified from the fair value reserve to retained earnings. Investments with a fair value of £148 million were disposed of during the year. The cumulative gain on these investments after tax was £56 million. Certain other investments, such as investments in funds with limited lives, are measured at fair value through profit or loss (FVTPL). The cumulative gain/loss on investments measured at FVTPL which were disposed of during the year was £nil. The fair value of these investments on derecognition was £nil. In 2017, prior to the Group’s implementation of IFRS 9, the cumulative fair value movements, based on average cost for shares acquired at different times, for all other investments disposed of during the period were reclassified from the fair value reserve to the income statement. The impairment losses recorded above for the prior year were recognised in the income statement within Other operating income, together with amounts reclassified from the fair value reserve on recognition of the impairments. These impairments resulted from prolonged or significant declines in the fair value of the equity investments below acquisition cost. The carrying value at 31 December 2017 of Other investments which had been impaired was as follows: 2017 Original cost 475 Cumulative impairments recognised in the income statement (283 ) Subsequent fair value increases 210 Carrying value at 31 December 2017 402 Cumulative impairments on those Other investments designated as measured at FVTOCI under IFRS 9 were transferred from retained earnings to the fair value reserve on 1 January 2018 on adoption of IFRS 9.

Other non-current assets

Other non-current assets	12 Months Ended
	Dec. 31, 2018
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Other non-current assets	22. Other non-current 2018 2017 £m £m Amounts receivable under insurance contracts 675 648 Pension schemes in surplus 760 538 Other receivables 141 227 1,576 1,413 Amounts receivable under insurance contacts are held at fair value through profit or loss. In regards to the other receivables of £141 million, £89 million is classified as financial assets of which £41 million is classified as fair value through profit or loss. Of the remaining balance of £48 million, the expected credit loss allowance was immaterial at 31 December 2018.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2018
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Inventories	23. Inventories 2018 2017 £m £m Raw materials and consumables 1,122 1,193 Work in progress 2,286 2,381 Finished goods 2,068 1,983 5,476 5,557

Trade and other receivables

Trade and other receivables	12 Months Ended
	Dec. 31, 2018
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Trade and other receivables	24. Trade and other receivables 2018 2017 £m £m Trade receivables, net of loss allowance 5,176 4,672 Accrued income 9 21 Other prepayments 330 308 Interest receivable 4 10 Employee loans and advances 14 19 Other receivables 890 970 6,423 6,000 Trade receivables included £15 million (2017 – £11 million) due from associates and joint ventures. Other receivables included £nil (2017 – £7 million) due from associates and joint ventures. Loss allowance 2018 2017 At 1 January 140 207 Implementation of IFRS 9 15 — At 1 January, as adjusted 155 — Exchange adjustments 0 (4 ) Charge for the year 7 31 Subsequent recoveries of amounts provided for (30 ) (79 ) Utilised (4 ) (15 ) At 31 December 128 140 Of the total trade receivables balance, £71 million was considered credit impaired, against which a £7 million expected credit loss allowance has been applied. No amount was purchased or originated credit impaired. Of the other receivables of £890 million, £376 million was classified as financial assets of which £41 million was classified as at fair value through profit and loss. On the remaining balance of £335 million, an expected credit loss allowance of £5 million was recognised at 31 December 2018 with no charge reported in profit or loss during the year. For more discussion on credit risk practices, please refer to Note 42.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Dec. 31, 2018
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Cash and cash equivalents	25. Cash and cash equivalents 2018 2017 £m £m Cash at bank and in hand 569 826 Short-term deposits 3,305 3,007 3,874 3,833 In addition, £485 million of cash and cash equivalents has been reported in Assets held for sale, see Note 26, ‘Assets held for sale’. Cash and cash equivalents included £0.2 billion (2017 – £ 0.8 billion) not available for general use due to restrictions applying in the subsidiaries where it is held. Restrictions include exchange controls and taxes on repatriation.

Assets held for sale

Assets held for sale	12 Months Ended
	Dec. 31, 2018
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Assets held for sale	26. Assets held for sale 2018 2017 £m £m Property, plant and equipment 109 57 Goodwill 144 — Other intangibles 1 49 Inventory 50 7 Cash and cash equivalents 485 — Other (136 ) — 653 113 Non-current Assets held for sale primarily reflect the disposal group arising from GSK’s agreement to divest Horlicks Included within assets held for sale are assets which were written down to fair value less costs to sell of £51 million (2017 – £63 million). The valuation methodology used significant inputs which were not based on observable market data and therefore this valuation is classified as level 3 in the fair value hierarchy.

Trade and other payables

Trade and other payables	12 Months Ended
	Dec. 31, 2018
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Trade and other payables	27. Trade and other payables 2018 2017 £m £m Trade payables 3,645 3,528 Wages and salaries 1,355 1,228 Social security 139 166 Consumer Healthcare put option 0 8,606 ViiV Healthcare put option 1,240 1,304 Other payables 401 363 Deferred income 216 240 Customer return and rebate accruals 5,064 3,463 Other accruals 1,977 2,072 14,037 20,970 Trade and other payables included £64 million (2017 – £53 million) due to associates and joint ventures. The Group provides limited supplier financing arrangements to certain customers. The amounts involved at 31 December 2018 were not material. Revenue recognised in the year that was included in deferred income at 1 January 2018 was £66 million. Of the remaining balance, £64 million related to proceeds from a site disposal in India, which was expected to complete in 2018, but is now expected to complete in 2019. Customer return and rebate accruals are provided for by the Group at the point of sale in respect of the estimated rebates, discounts or allowances payable to customers, and included £ 4,356 million (2017 – £2,837 million) in respect of US Pharmaceuticals and Vaccines, as more fully described in the Group financial review on page 63. Accruals are made at the time of sale but the actual amounts paid are based on claims made some time after the initial recognition of the sale. As the amounts are estimated, they may not fully reflect the final outcome and are subject to change dependent upon, amongst other things, the types of buying group and product sales mix. The level of accrual is reviewed and adjusted quarterly in light of historical experience of actual amounts paid and any changes in arrangements. Future events could cause the assumptions on which the accruals are based to change, which could affect the future results of the Group. Pfizer’s put option over its shareholding in ViiV Healthcare is currently exercisable. The amount of the liability recognised is derived from several valuation methodologies, including reference to market multiples of comparable companies. The table below shows on an indicative basis the income statement and balance sheet sensitivity of the Pfizer put option to reasonably possible changes in key assumptions. Increase/(decrease) in financial liability and loss/(gain) in Income statement 2018 10% increase in sales forecasts 140 10% decrease in sales forecasts (140 ) 10 cent appreciation of US Dollar 75 10 cent depreciation of US Dollar (64 ) 10 cent appreciation of Euro 44 10 cent depreciation of Euro (37 ) An explanation of the accounting for ViiV Healthcare is set out on page 41.

Pensions and other post-employm

Pensions and other post-employment benefits	12 Months Ended
	Dec. 31, 2018
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Pensions and other post-employment benefits	28. Pensions and other post-employment benefits 2018 2017 2016 Pension and other post-employment costs £m £m £m UK pension schemes 246 198 205 US pension schemes 100 113 106 Other overseas pension schemes 190 218 140 Unfunded post-retirement healthcare schemes 50 87 90 586 616 541 Analysed as: Funded defined benefit/hybrid pension schemes 369 335 304 Unfunded defined benefit pension schemes 43 55 43 Unfunded post-retirement healthcare schemes 50 87 90 Defined benefit schemes 462 477 437 Defined contribution pension schemes 124 139 104 586 616 541 The costs of the defined benefit pension and post-retirement healthcare schemes are charged in the income statement as follows: 2018 2017 2016 £m £m £m Cost of sales 160 162 135 Selling, general and administration 228 238 221 Research and development 74 77 81 462 477 437 GSK entities operate pension arrangements which cover the Group’s material obligations to provide pensions to retired employees. These arrangements have been developed in accordance with local practices in the countries concerned. Pension benefits can be provided by state schemes; by defined contribution schemes, whereby retirement benefits are determined by the value of funds arising from contributions paid in respect of each employee; or by defined benefit schemes, whereby retirement benefits are based on employee pensionable remuneration and length of service. Pension costs of defined benefit schemes for accounting purposes have been calculated using the projected unit method. In certain countries pension benefits are provided on an unfunded basis, some administered by trustee companies. Formal, independent, actuarial valuations of the Group’s main plans are undertaken regularly, normally at least every three years. Actuarial movements in the year are recognised through the statement of comprehensive income. Discount rates are derived from AA rated corporate bond yields except in countries where there is no deep market in corporate bonds where government bond yields are used. Discount rates are selected to reflect the term of the expected benefit payments. Projected inflation rate and pension increases are long-term predictions based on the yield gap between long-term index-linked and fixed interest Gilts. In the UK, mortality rates are determined by adjusting the SAPS S2 standard mortality tables to reflect recent scheme experience. These rates are then projected to reflect improvements in life expectancy in line with the CMI 2017 projections with a long-term rate of improvement of 1.25% per year for both males and females. In the US, mortality rates are calculated using the RP2014 white collar table adjusted to reflect recent experience. These rates are projected using MP-2017 The average life expectancy assumed now for an individual at the age of 60 and projected to apply in 2038 for an individual then at the age of 60 is as follows: UK US Male Female Male Female Current 27.5 29.1 27.0 28.7 Projected for 2038 29.0 30.6 28.7 30.3 The assets of funded schemes are generally held in separately administered trusts, either as specific assets or as a proportion of a general fund, or are insurance contracts. Assets are invested in different classes in order to maintain a balance between risk and return. Investments are diversified to limit the financial effect of the failure of any individual investment. The physical asset allocation strategy for three of the four UK plans remains unchanged, with 55% in return-seeking assets and 45% in liability-matching assets. The remaining plan has materially de-risked The pension plans are exposed to risk that arises because the estimated market value of the plans’ assets might decline, the investment returns might reduce, or the estimated value of the plans’ liabilities might increase. In line with the agreed mix of return-seeking assets to generate future returns and liability-matching assets to better match future pension obligations, the Group has defined an overall long-term investment strategy for the plans, with investments across a broad range of assets. The main market risks within the asset and hedging portfolio are against credit risk, interest rates, long-term inflation, equities, property, currency and bank counterparty risk. The plan liabilities are a series of future cash flows with relatively long duration. On an IAS 19 basis, these cash flows are sensitive to changes in the expected long-term inflation rate and the discount rate (AA corporate bond yield curve) where an increase in long-term inflation corresponds with an increase in the liabilities, and an increase in the discount rate corresponds with a decrease in the liabilities. The interest rate risk and credit rate risk in the US are partially hedged. The targets are based on an accounting measure of the plan liabilities. For the UK plans, there is an interest rate and inflation hedging strategy in place. The targets are based on an economic measure of the plan liabilities. Furthermore, the plans also currently hedge a portion of their equity exposure with a staggered maturity profile. In the UK, the defined benefit pension schemes operated for the benefit of former Glaxo Wellcome employees and former SmithKline Beecham employees remain separate. These schemes were closed to new entrants in 2001 and subsequent UK employees are entitled to join a defined contribution scheme. In addition, the Group operates a number of post-retirement healthcare schemes, the principal one of which is in the US. The Group has applied the following financial assumptions in assessing the defined benefit liabilities: UK US Rest of World 2018 2017 2016 2018 2017 2016 2018 2017 2016 Rate of increase of future earnings 2.00 2.00 2.00 4.00 4.00 4.00 2.70 2.80 2.70 Discount rate 2.90 2.50 2.70 4.20 3.60 3.90 1.80 1.60 1.60 Expected pension increases 3.20 3.20 3.20 n/a n/a n/a 2.10 2.20 2.10 Cash balance credit/conversion rate n/a n/a n/a 3.20 2.90 3.20 0.40 0.30 0.30 Inflation rate 3.20 3.20 3.20 2.25 2.25 2.25 1.50 1.70 1.50 Sensitivity analysis detailing the effect of changes in assumptions is provided on page 182. The analysis provided reflects the assumption changes which have the most material impact on the results of the Group. The amounts recorded in the income statement and statement of comprehensive income for the three years ended 31 December 2018 in relation to the defined benefit pension and post-retirement healthcare schemes were as follows: Pensions Post-retirement benefits 2018 UK US Rest of World Group £m Group £m Amounts charged to operating profit Current service cost 75 72 134 281 29 Past service cost/(credit) 93 1 0 94 (27 ) Net interest (income)/cost (3 ) 20 19 36 49 Gains from settlements 0 0 (14 ) (14 ) (1 ) Expenses 8 7 0 15 0 173 100 139 412 50 Remeasurement gains/(losses) recorded in the statement of comprehensive income 495 (108 ) 196 583 145 Pensions Post-retirement 2017 UK US Rest of World Group Group Amounts charged to operating profit Current service cost 79 70 131 280 30 Past service cost/(credit) 37 — — 37 (2 ) Net interest cost 7 31 16 54 59 Expenses 7 12 — 19 — 130 113 147 390 87 Remeasurement gains/(losses) recorded in the statement of comprehensive income 259 240 (14 ) 485 64 Pensions Post-retirement 2016 UK US Rest of World Group Group £m Amounts charged to operating profit Current service cost 70 66 110 246 31 Past service cost 52 1 1 54 3 Net interest cost 9 27 20 56 56 Gains from settlements — — (28 ) (28 ) — Expenses 7 12 — 19 — 138 106 103 347 90 Remeasurement losses recorded in the statement of comprehensive income (165 ) (27 ) (224 ) (416 ) (59 ) The amounts included within past service costs in the UK include a charge of £40 million in relation to the estimated impact of GMP equalisation and £43 million (2017 – £37 million; 2016 – £52 million) of augmentation costs of which £21 million is arising from major restructuring programmes (see Note 29, ‘Other provisions’). A summarised balance sheet presentation of the Group defined benefit pension schemes and other post-retirement benefits is set out in the table below: 2018 2017 2016 £m £m £m Recognised in Other non-current Pension schemes in surplus 760 538 313 Recognised in Assets held for sale: Post-retirement benefits (9 ) — — Recognised in Pensions and other post-employment benefits: Pension schemes in deficit (1,755 ) (2,043 ) (2,397 ) Post-retirement benefits (1,370 ) (1,496 ) (1,693 ) (3,125 ) (3,539 ) (4,090 ) In the event of a plan wind-up, The fair values of the assets and liabilities of the UK and US defined benefit pension schemes, together with aggregated data for other defined benefit pension schemes in the Group are as follows: UK US Rest of World Group At 31 December 2018 £m £m £m £m Equities: – listed 3,257 1,280 518 5,055 – unlisted 0 0 7 7 Multi-asset funds 2,997 0 0 2,997 Property: – listed 0 0 33 33 – unlisted 423 231 4 658 Corporate bonds: – listed 404 783 111 1,298 – unlisted 306 0 25 331 Government bonds: – listed 3,835 286 795 4,916 Insurance contracts 770 0 831 1,601 Other assets 589 228 66 883 Fair value of assets 12,581 2,808 2,390 17,779 Present value of scheme obligations (12,087 ) (3,474 ) (3,213 ) (18,774 ) Net surplus/(obligation) 494 (666 ) (823 ) (995 ) Included in Other non-current 711 0 49 760 Included in Pensions and other post-employment benefits (217 ) (666 ) (872 ) (1,755 ) 494 (666 ) (823 ) (995 ) Actual return on plan assets (88 ) (123 ) 55 (156 ) The multi-asset funds comprise investments in pooled investment vehicles that are invested across a range of asset classes, increasing diversification within the growth portfolio. The ‘Other assets’ category comprises cash and mark to market values of derivative positions. In previous years, index-linked gilts held as part of a UK repo programme were included in government bonds. The related loan was included within ‘Other assets’ at a value of £(773) million at 31 December 2017 (2016 – £(1,686) million). This programme was cancelled during 2018. At 31 December 2017 UK US Rest of World Group Equities: – listed 4,902 1,448 544 6,894 – unlisted — — 13 13 Multi-asset funds 2,517 — — 2,517 Property: – unlisted 352 209 32 593 Corporate bonds: – listed 297 820 103 1,220 – unlisted 326 — 20 346 Government bonds: – listed 5,127 239 762 6,128 Insurance contracts 849 — 707 1,556 Other assets (1,216 ) 158 71 (987 ) Fair value of assets 13,154 2,874 2,252 18,280 Present value of scheme obligations (13,101 ) (3,445 ) (3,239 ) (19,785 ) Net surplus/(obligation) 53 (571 ) (987 ) (1,505 ) Included in Other non-current 470 — 68 538 Included in Pensions and other post-employment benefits (417 ) (571 ) (1,055 ) (2,043 ) 53 (571 ) (987 ) (1,505 ) Actual return on plan assets 893 394 82 1,369 At 31 December 2016 UK US Rest of World Group Equities: – listed 5,357 1,358 486 7,201 – unlisted — — 14 14 Multi-asset funds 1,545 — — 1,545 Property: – unlisted 314 216 28 558 Corporate bonds: – listed 292 213 96 601 – unlisted 321 — 24 345 Government bonds: – listed 6,165 815 739 7,719 Insurance contracts 856 — 637 1,493 Other assets (2,267 ) 288 73 (1,906 ) Fair value of assets 12,583 2,890 2,097 17,570 Present value of scheme obligations (12,884 ) (3,752 ) (3,018 ) (19,654 ) Net obligation (301 ) (862 ) (921 ) (2,084 ) Included in Other non-current 276 — 37 313 Included in Pensions and other post-employment benefits (577 ) (862 ) (958 ) (2,397 ) (301 ) (862 ) (921 ) (2,084 ) Actual return on plan assets 2,473 153 99 2,725 Post-retirement Pensions benefits UK US Rest of World Group Group Movements in fair values of assets £m £m £m £m £m Assets at 1 January 2016 10,284 2,501 1,750 14,535 — Exchange adjustments — 459 305 764 — Interest income 385 108 37 530 — Expenses (7 ) (12 ) — (19 ) — Settlements and curtailments — — (110 ) (110 ) — Remeasurement 2,088 45 62 2,195 — Employer contributions 319 31 131 481 91 Scheme participants’ contributions 4 — 14 18 17 Benefits paid (490 ) (242 ) (92 ) (824 ) (108 ) Assets at 31 December 2016 12,583 2,890 2,097 17,570 — Exchange adjustments — (244 ) 24 (220 ) — Interest income 333 104 33 470 — Expenses (7 ) (12 ) — (19 ) — Settlements and curtailments — — (4 ) (4 ) — Remeasurement 560 290 49 899 — Employer contributions 225 103 116 444 101 Scheme participants’ contributions 4 — 17 21 17 Benefits paid (544 ) (257 ) (80 ) (881 ) (118 ) Assets at 31 December 2017 13,154 2,874 2,252 18,280 0 Exchange adjustments 0 171 53 224 0 Interest income 323 102 29 454 0 Expenses (8 ) (7 ) 0 (15 ) 0 Settlements and curtailments 0 0 (14 ) (14 ) 0 Remeasurement (411 ) (225 ) 26 (610 ) 0 Employer contributions 119 150 117 386 93 Scheme participants’ contributions 4 0 16 20 16 Benefits paid (600 ) (257 ) (89 ) (946 ) (109 ) Assets at 31 December 2018 12,581 2,808 2,390 17,779 0 During 2018, the Group made no special funding contributions to the UK pension schemes (2017 – £136 million; 2016 – £191 million) but £125 million (2017 – £78 million; 2016 – £nil) to the US scheme. In 2018, GSK reached a revised agreement with the trustees of the UK pension schemes to make additional contributions to eliminate the pension deficits identified within the schemes at the 31 December 2017 actuarial funding valuation. Based on these funding agreements, the additional contributions to eliminate the pension deficit are expected to be £75 million in 2019. Further payments have been agreed for the years 2020 to 2022 and these are included within Note 41, ‘Commitments’ on page 197. This funding commitment supersedes the previous agreement made in 2016. The contributions were based on a government bond yield curve approach to selecting the discount rate; the rate chosen included an allowance for expected investment returns which reflected the asset mix of the schemes. Employer contributions for 2019, including special funding contributions, are estimated to be approximately £420 million in respect of defined benefit pension schemes and £100 million in respect of post-retirement benefits. Post-retirement Pensions benefits UK US Rest of World Group Group Movements in defined benefit obligations £m £m £m £m £m Obligations at 1 January 2016 (10,601 ) (3,134 ) (2,384 ) (16,119 ) (1,387 ) Exchange adjustments — (586 ) (396 ) (982 ) (248 ) Service cost (70 ) (66 ) (110 ) (246 ) (31 ) Past service cost (52 ) (1 ) (1 ) (54 ) (3 ) Interest cost (394 ) (135 ) (57 ) (586 ) (56 ) Settlements and curtailments — — 138 138 — Remeasurement (2,253 ) (72 ) (286 ) (2,611 ) (59 ) Scheme participants’ contributions (4 ) — (14 ) (18 ) (17 ) Benefits paid 490 242 92 824 108 Obligations at 31 December 2016 (12,884 ) (3,752 ) (3,018 ) (19,654 ) (1,693 ) Exchange adjustments — 305 (45 ) 260 119 Service cost (79 ) (70 ) (131 ) (280 ) (30 ) Past service cost/(credit) (37 ) — — (37 ) 2 Interest cost (340 ) (135 ) (49 ) (524 ) (59 ) Settlements and curtailments — — 4 4 — Remeasurement (301 ) (50 ) (63 ) (414 ) 64 Scheme participants’ contributions (4 ) — (17 ) (21 ) (17 ) Benefits paid 544 257 80 881 118 Obligations at 31 December 2017 (13,101 ) (3,445 ) (3,239 ) (19,785 ) (1,496 ) Exchange adjustments 0 (208 ) (63 ) (271 ) (71 ) Service cost (75 ) (72 ) (134 ) (281 ) (29 ) Past service cost (93 ) (1 ) 0 (94 ) 27 Interest cost (320 ) (122 ) (48 ) (490 ) (49 ) Settlements and curtailments 0 0 28 28 1 Remeasurement 906 117 170 1,193 145 Scheme participants’ contributions (4 ) 0 (16 ) (20 ) (16 ) Benefits paid 600 257 89 946 109 Obligations at 31 December 2018 (12,087 ) (3,474 ) (3,213 ) (18,774 ) (1,379 ) The defined benefit pension obligation is analysed as follows: 2018 2017 2016 £m £m £m Funded (18,025 ) (19,052 ) (18,974 ) Unfunded (749 ) (733 ) (680 ) (18,774 ) (19,785 ) (19,654 ) The liability for the US post-retirement healthcare scheme has been assessed using the same assumptions as for the US pension scheme, together with the assumption for future medical inflation of 6.50% (2017 – 6.75%), grading down to 5.0% in 2025 and thereafter. At 31 December 2018, the US post-retirement healthcare scheme obligation was £1,179 million (2017 – £1,254 million; 2016 – £1,463 million). Post-retirement benefits are unfunded. The movement in the net defined benefit liability is as follows: 2018 2017 2016 £m £m £m At 1 January (1,505 ) (2,084 ) (1,584 ) Exchange adjustments (47 ) 40 (218 ) Service cost (281 ) (280 ) (246 ) Past service cost (94 ) (37 ) (54 ) Interest cost (36 ) (54 ) (56 ) Settlements and curtailments 14 — 28 Remeasurements: Return on plan assets, excluding amounts included in interest (610 ) 899 2,195 Gain from change in demographic assumptions 131 209 85 Gain/(loss) from change in financial assumptions 1,149 (555 ) (2,770 ) Experience (losses)/gains (87 ) (68 ) 74 Employer contributions 386 444 481 Expenses (15 ) (19 ) (19 ) At 31 December (995 ) (1,505 ) (2,084 ) The remeasurements included within post-retirement benefits are detailed below: 2018 2017 2016 £m £m £m Gain from change in demographic assumptions 6 47 — Gain/(loss) from change in financial assumptions 100 (1 ) (81 ) Experience gains 39 18 22 145 64 (59 ) The defined benefit pension obligation analysed by membership category is as follows: 2018 2017 2016 Active 4,427 4,611 4,576 Retired 9,542 9,805 9,574 Deferred 4,805 5,369 5,504 18,774 19,785 19,654 The post-retirement benefit obligation analysed by membership category is as follows: 2018 2017 2016 £m £m £m Active 499 514 594 Retired 879 981 1,099 Deferred 1 1 — 1,379 1,496 1,693 The weighted average duration of the defined benefit obligation is as follows: 2018 2017 2016 Pension benefits 15 16 16 Post-retirement benefits 11 11 12 Sensitivity analysis The effect of changes in assumptions used on the benefit obligations and on the 2019 annual defined benefit pension and post-retirement costs are detailed below. This information has been determined by taking into account the duration of the liabilities and the overall profile of the plan memberships. £m A 0.25% decrease in discount rate would have the following approximate effect: Increase in annual pension cost 28 Decrease in annual post-retirement benefits cost (1 ) Increase in pension obligation 707 Increase in post-retirement benefits obligation 34 A one-year Increase in annual pension cost 21 Increase in annual post-retirement benefits cost 2 Increase in pension obligation 592 Increase in post-retirement benefits obligation 33 A 1% increase in the rate of future healthcare inflation would have the following approximate effect: Increase in annual post-retirement benefits cost 1 Increase in post-retirement benefits obligation 38 A 0.25% increase in inflation would have the following approximate effect: Increase in annual pension cost 18 Increase in pension obligation 447

Other provisions

Other provisions	12 Months Ended
	Dec. 31, 2018
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Other provisions	29. Other provisions Legal Major Employee Other Total At 1 January 2018 186 504 304 271 1,265 Exchange adjustments 13 17 9 5 44 Charge for the year 119 450 105 50 724 Reversed unused (2 ) (99 ) (25 ) (46 ) (172 ) Unwinding of discount 2 4 0 9 15 Utilised (98 ) (226 ) (41 ) (79 ) (444 ) Reclassifications and other movements (1 ) 12 (2 ) 3 12 Transfer to Pension obligations 0 (21 ) 0 0 (21 ) At 31 December 2018 219 641 350 213 1,423 To be settled within one year 156 362 145 69 732 To be settled after one year 63 279 205 144 691 At 31 December 2018 219 641 350 213 1,423 Legal and other disputes The Group is involved in a substantial number of legal and other disputes, including notification of possible claims, as set out in Note 45 ‘Legal proceedings’. Provisions for legal and other disputes include amounts relating to product liability, anti-trust, government investigations, contract terminations, self insurance and environmental clean-up. The charge for the year of £117 million (net of reversals and estimated insurance recoveries) primarily related to provisions for product liability cases, commercial disputes and various other government investigations. The discount on the provisions increased by £2 million in 2018 (2017 – increased by £2 million). The discount was calculated using risk-adjusted projected cash flows and risk-free rates of return. In respect of product liability claims related to certain products, there is sufficient history of claims made and settlements to enable management to make a reliable estimate of the provision required to cover unasserted claims. The ultimate liability for such matters may vary from the amounts provided and is dependent upon the outcome of litigation proceedings, investigations and possible settlement negotiations. It is in the nature of the Group’s business that a number of these matters may be the subject of negotiation and litigation over many years. Litigation proceedings, including the various appeal procedures, often take many years to reach resolution, and out-of-court The Group is in potential settlement discussions in a number of the disputes for which amounts have been provided and, based on its current assessment of the progress of these disputes, estimates that £156 million of the amount provided at 31 December 2018 will be settled within one year. At 31 December 2018, it was expected that £37 million (2017 – £nil) of the provision made for legal and other disputes will be reimbursed by third parties. For a discussion of legal issues, see Note 45, ‘Legal proceedings’. Major restructuring programmes The Group is undertaking two major restructuring programmes: the Combined restructuring and integration programme and the 2018 major restructuring programme. The programmes are focused primarily on simplifying supply chain processes, rationalising the Group’s manufacturing network and restructuring the Pharmaceuticals commercial operations. Provisions for staff severance payments are made when management has made a formal decision to eliminate certain positions and this has been communicated to the groups of employees affected and appropriate consultation procedures completed, where appropriate. No provision is made for staff severance payments that are made immediately. Pension augmentations arising from staff redundancies of £21 million (2017 – £18 million) have been charged during the year and then transferred to the pension obligations provision as shown in Note 28, ‘Pensions and other post-employment benefits’. Asset write-downs have been recognised as impairments of property, plant and equipment in Note 17, ‘Property, plant and equipment’. The majority of the amounts provided are expected to be utilised in the next two years. Employee-related provisions Employee related provisions include obligations for certain medical benefits to disabled employees and their spouses in the US. At 31 December 2018, the provision for these benefits amounted to £87 million (2017 – £108 million). Other employee benefits reflect a variety of provisions for severance costs, jubilee awards and other long-service benefits. Given the nature of these provisions, the amounts are likely to be settled over many years. Other provisions Included in other provisions are insurance provisions of £7 million (2017 – £6 million), onerous property lease provisions of £6 million (2017 – £38 million) and a number of other provisions including vehicle insurance and regulatory matters.

Other non-current liabilities

Other non-current liabilities	12 Months Ended
	Dec. 31, 2018
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Other non-current liabilities	30. Other non-current 2018 2017 £m £m Accruals 71 82 Deferred Income 19 22 Other payables 848 877 938 981 Other payables includes acquisition accounting market value lease adjustments and a number of employee-related liabilities.

Net debt

Net debt	12 Months Ended
	Dec. 31, 2018
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Net debt	31. Net debt Listing exchange 2018 £m 2017 Current assets: Liquid investments 84 78 Cash and cash equivalents 3,874 3,833 Cash and cash equivalents reported in Assets held for sale 485 — 4,443 3,911 Short-term borrowings: Commercial paper (630 ) (529 ) Bank loans and overdrafts (290 ) (236 ) Obligations under finance leases (24 ) (23 ) Drawn bank facility (3,500 ) — 5.650% US$ US Medium Term Note 2018 New York Stock Exchange 0 (2,037 ) 0.625% € European Medium Term Note 2019 London Stock Exchange (1,349 ) — (5,793 ) (2,825 ) Long-term borrowings: 0.625% € European Medium Term Note 2019 London Stock Exchange 0 (1,324 ) EURIBOR +0.20% € European Medium Term Note 2020 London Stock Exchange (677 ) — 0.000% € European Medium Term Note 2020 London Stock Exchange (1,079 ) (1,060 ) 3.125% US$ US Medium Term Note 2021 New York Stock Exchange (980 ) — LIBOR +0.35% US$ US Medium Term Note 2021 New York Stock Exchange (589 ) — 2.850% US$ US Medium Term Note 2022 New York Stock Exchange (1,568 ) (1,474 ) 2.800% US$ US Medium Term Note 2023 New York Stock Exchange (978 ) (919 ) 3.375% US$ US Medium Term Note 2023 New York Stock Exchange (977 ) — 1.375% € European Medium Term Note 2024 London Stock Exchange (893 ) (876 ) 4.000% € European Medium Term Note 2025 London Stock Exchange (670 ) (659 ) 3.625% US$ US Medium Term Note 2025 New York Stock Exchange (780 ) — 1.000% € European Medium Term Note 2026 London Stock Exchange (629 ) (617 ) 1.250% € European Medium Term Note 2026 London Stock Exchange (897 ) — 3.375% £ European Medium Term Note 2027 London Stock Exchange (593 ) (593 ) 3.875% US$ US Medium Term Note 2028 New York Stock Exchange (1,372 ) — 1.375% € European Medium Term Note 2029 London Stock Exchange (447 ) (439 ) 1.750% € European Medium Term Note 2030 London Stock Exchange (673 ) — 5.250% £ European Medium Term Note 2033 London Stock Exchange (982 ) (986 ) 5.375% US$ US Medium Term Note 2034 New York Stock Exchange (390 ) (368 ) 6.375% US$ US Medium Term Note 2038 New York Stock Exchange (2,143 ) (2,021 ) 6.375% £ European Medium Term Note 2039 London Stock Exchange (694 ) (695 ) 5.250% £ European Medium Term Note 2042 London Stock Exchange (986 ) (989 ) 4.200% US$ US Medium Term Note 2043 New York Stock Exchange (386 ) (363 ) 4.250% £ European Medium Term Note 2045 London Stock Exchange (788 ) (789 ) Obligations under finance leases (44 ) (43 ) Other long-term borrowings (56 ) (49 ) (20,271 ) (14,264 ) Net debt (21,621 ) (13,178 ) Current assets Liquid investments are classified as financial assets at amortised cost (previously available-for-sale The effective interest rate on cash and cash equivalents at 31 December 2018 was approximately 1.9% (2017 – approximately 1.3%). Cash and cash equivalents at 31 December 2018 earning interest at floating and fixed rates amount to £4,094 million and £2 million respectively (2017 – £3,832 million and £1 million) and non-interest GSK’s policy regarding the credit quality of cash and cash equivalents is referred to in Note 42, ‘Financial instruments and related disclosures’. Short-term borrowings GSK has a $10 billion (£7.9 billion) US commercial paper programme, of which $0.8 billion (£0.6 billion) was in issue at 31 December 2018 (2017 – $0.7 billion (£ 0.5 billion)). GSK has a £1.9 billion five-year committed facility and $2.5 billion (£2.0 billion) under a 364 day committed facility. The five-year committed facility was agreed in September 2015 and extended by one year to 2021 in September 2016. The 364 day committed facility was agreed in September 2018. Additional bank facilities were agreed in 2018 to support transactions and two remained active at 31 December 2018. In June 2018, £3.5 billion was drawn to support the acquisition from Novartis of the remaining stake in the Consumer Healthcare Joint Venture. In addition, a $5.0 billion bank facility was agreed in December 2018 to support the acquisition of Tesaro and was undrawn at 31 December 2018. Liquid investments, cash and cash equivalents were as shown in the table on page 184. The weighted average interest rate on commercial paper borrowings at 31 December 2018 was 2.5% (2017 – 1.5%). The weighted average interest rate on current bank loans and overdrafts at 31 December 2018 was 12.0% (2017 – 4.7%). At 31 December 2018, short-term loan rates of 60% in Argentina had a disproportionate effect on the weighted average interest rate. Excluding this impact the weighted average interest rate on current bank loans and overdrafts stands at 4.4%. The average effective pre-swap Long-term borrowings At the year-end, pre-swap Long-term borrowings repayable after five years carry interest at effective rates between 1.1% and 6.4%, with repayment dates ranging from 2024 to 2045. Pledged assets The Group held pledged investments in US Treasury Notes with a par value of $50 million (£ 39 million), (2017 – $105 million (£78 million)) as security against irrevocable letters of credit issued on the Group’s behalf in respect of the Group’s self-insurance activity. Provisions in respect of self-insurance are included within the provisions for legal and other disputes discussed in Note 29, ‘Other provisions’. In addition, in 2017, £20 million of assets included in Note 22, ‘Other non-current Finance lease obligations 2018 2017 £m £m Rental payments due within one year 29 25 Rental payments due between one and two years 20 29 Rental payments due between two and three years 13 9 Rental payments due between three and four years 7 3 Rental payments due between four and five years 4 2 Rental payments due after five years 11 10 Total future rental payments 84 78 Future finance charges (16 ) (12 ) Total finance lease obligations 68 66

Contingent liabilities

Contingent liabilities	12 Months Ended
	Dec. 31, 2018
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Contingent liabilities	32. Contingent liabilities At 31 December 2018, contingent liabilities, comprising guarantees, discounted bills and other items arising in the normal course of business, amounted to £93 million (2017 – £434 million). At 31 December 2018, £nil (2017 – £2 million) of financial assets were pledged as collateral for contingent liabilities. Provision is made for the outcome of tax, legal and other disputes where it is both probable that the Group will suffer an outflow of funds and it is possible to make a reliable estimate of that outflow. At 31 December 2018, other than for those disputes where provision has been made, it was not possible to make a reliable estimate of the potential outflow of funds that might be required to settle disputes where the possibility of there being an outflow was more than remote. Descriptions of the significant legal and other disputes to which the Group is a party are set out in Note 45, ‘Legal proceedings’.

Share capital and share premium

Share capital and share premium account	12 Months Ended
	Dec. 31, 2018
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Share capital and share premium account	33. Share capital and share premium account Ordinary Shares of 25p each Share Number £m £m Share capital authorised At 31 December 2016 10,000,000,000 2,500 At 31 December 2017 10,000,000,000 2,500 At 31 December 2018 10,000,000,000 2,500 Share capital issued and fully paid At 1 January 2016 5,361,307,647 1,340 2,831 Issued under employee share schemes 7,008,415 2 87 Ordinary shares acquired by ESOP Trusts — — 36 At 31 December 2016 5,368,316,062 1,342 2,954 Issued under employee share schemes 4,237,758 1 55 Ordinary shares acquired by ESOP Trusts — — 10 At 31 December 2017 5,372,553,820 1,343 3,019 Issued under employee share schemes 6,513,804 2 72 At 31 December 2018 5,379,067,624 1,345 3,091 31 December 2018 31 December 2017 000 000 Number of shares issuable under employee share schemes 56,723 38,647 Number of unissued shares not under option 4,564,209 4,588,799 At 31 December 2018, of the issued share capital, 41,530,909 shares were held in the ESOP Trusts, 414,605,950 shares were held as Treasury shares and 4,922,930,765 shares were in free issue. All issued shares are fully paid. The nominal, carrying and market values of the shares held in the ESOP Trusts are disclosed in Note 43, ‘Employee share schemes’.

Movements in equity

Movements in equity	12 Months Ended
	Dec. 31, 2018
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Movements in equity	34. Movements in equity Retained losses and other reserves amounted to £76 million at 31 December 2018 (2017 – £4,430 million loss; 2016 – £3,172 million loss) of which £ 337 million (2017 – £ 334 million; 2016 – £329 million) relates to joint ventures and associated undertakings. The cumulative translation exchange in equity is as follows: Net translation exchange included in: Non- Total Retained Fair value controlling translation earnings reserve interests exchange £m £m £m £m At 1 January 2016 (761 ) 10 (109 ) (860 ) Exchange movements on overseas net assets 633 13 603 1,249 At 31 December 2016 (128 ) 23 494 389 Exchange movements on overseas net assets 462 — (149 ) 313 Reclassification of exchange on liquidation or disposal of overseas subsidiaries 109 — — 109 At 31 December 2017 443 23 345 811 Exchange movements on overseas net assets (458 ) (22 ) (1 ) (481 ) At 31 December 2018 (15 ) 1 344 330 The analysis of other comprehensive income by equity category is as follows: Non- Retained Other controlling earnings reserves interests Total 2018 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges (458 ) (22 ) 0 (480 ) Fair value movements on cash flow hedges 0 140 0 140 Reclassification of cash flow hedges on income and expense 0 (175 ) 0 (175 ) Deferred tax on fair value movements on cash flow hedges 0 (22 ) 0 (22 ) Deferred tax reversed on reclassification of cash flow hedges 0 20 0 20 Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling 0 0 (1 ) (1 ) Fair value movements on equity investments 0 180 0 180 Deferred tax on fair value movements on equity investments 0 10 0 10 Remeasurement gains on defined benefit plans 728 0 0 728 Tax on remeasurement gains in defined benefit plans (146 ) 0 0 (146 ) Other comprehensive income/(expense) for the year 124 131 (1 ) 254 Non- Retained Other controlling earnings reserves interests Total 2017 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges 462 — — 462 Reclassification of exchange on liquidation or disposal of overseas subsidiaries 109 — — 109 Fair value movements on available-for-sale — (14 ) — (14 ) Reclassification of fair value movements on available-for-sale — (42 ) — (42 ) Deferred tax on fair value movements on available-for-sale — 47 — 47 Deferred tax reversed on reclassification of available-for-sale — (18 ) — (18 ) Fair value movements on cash flow hedges — (10 ) — (10 ) Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling — — (149 ) (149 ) Remeasurement gains on defined benefit plans 549 — — 549 Tax on remeasurement gains in defined benefit plans (221 ) — — (221 ) Other comprehensive income/(expense) for the year 899 (37 ) (149 ) 713 Non- Retained Other controlling earnings reserves interests Total 2016 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges 633 13 — 646 Fair value movements on available-for-sale — 251 — 251 Reclassification of fair value movements on available-for-sale — (245 ) — (245 ) Deferred tax reversed on reclassification of available-for-sale — 51 — 51 Reclassification of cash flow hedges to income statement — 1 — 1 Fair value movements on cash flow hedges — 2 — 2 Deferred tax on fair value movements on cash flow hedges — 2 — 2 Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling — — 603 603 Remeasurement losses on defined benefit plans (475 ) — — (475 ) Tax on remeasurement losses in defined benefit plans 126 — — 126 Other comprehensive income for the year 284 75 603 962 The analysis of other reserves is as follows: ESOP Trust Fair value Cash flow Other shares reserve hedge reserve reserves Total £m £m £m £m £m At 1 January 2016 (75 ) 295 (9 ) 2,129 2,340 Exchange adjustments (16 ) — — — (16 ) Transferred to income and expense in the year on disposals — (268 ) — — (268 ) Transferred to income and expense in the year on impairments — 23 — — 23 Net fair value movement in the year — 330 6 — 336 Ordinary shares acquired by ESOP Trusts (576 ) — — — (576 ) Write-down of shares held by ESOP Trusts 381 — — — 381 At 31 December 2016 (286 ) 380 (3 ) 2,129 2,220 Exchange adjustments 22 — — — 22 Transferred to income and expense in the year on disposals — (42 ) — — (42 ) Net fair value movement in the year — (9 ) (8 ) — (17 ) Ordinary shares acquired by ESOP Trusts (656 ) — — — (656 ) Write-down of shares held by ESOP Trusts 520 — — — 520 At 31 December 2017 (400 ) 329 (11 ) 2,129 2,047 Implementation of IFRS 9 — (288 ) — — (288 ) At 31 December, as adjusted (400 ) 41 (11 ) 2,129 1,759 Exchange adjustments (26 ) 0 0 0 (26 ) Transferred to Retained earnings in the year on disposal of equity investments 0 (94 ) 0 0 (94 ) Net fair value movement in the year 0 193 (36 ) 0 157 Write-down of shares held by ESOP Trusts 265 0 0 0 265 At 31 December 2018 (161 ) 140 (47 ) 2,129 2,061 Other reserves include various non-distributable pre-merger buy-back

Related party transactions

Related party transactions	12 Months Ended
	Dec. 31, 2018
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Related party transactions	35. Related party transactions At 31 December 2018, GSK owned 32 million shares or 31.7% of Innoviva Inc. which is a biopharmaceutical company listed on NASDAQ. GSK began recognising Innoviva as an associate on 1 September 2015. The royalties due from GSK to Innoviva in the year were £209 million (2017 – £173 million). At 31 December 2018, the balance payable by GSK to Innoviva was £64 million (2017 – £53 million). At 31 December 2018, GSK held a 50% interest in Japan Vaccine Co. Ltd (JVC) through its subsidiary GlaxoSmithKline K.K. This joint venture with Daiichi Sankyo Co., Ltd is primarily responsible for the development and marketing of certain prophylactic vaccines in Japan. During 2018, GSK sold £ 43 million (2017 – £41 million) of its vaccine products into the joint venture. At 31 December 2018, the trading balance due to GSK from JVC was £15 million (2017 – £11 million) and the balance payable by GSK to JVC was £nil (2017 – £nil). Loans of £5 million to Medicxi Ventures I LP and £6 million to Index Ventures Life VI (Jersey) LP remained due to GSK at 31 December 2018. In 2018, GSK increased the equity investment in the Kurma Biofund II, FCPR by £3 million, Apollo Therapeutics LLP by £2 million and Longwood Founders Fund LP by £ 0.2 million, and reduced a liability with Qura Therapeutics LLC by £3 million. As at 31 December 2018, the outstanding liability to Qura was £4 million. The aggregate compensation of the Directors and CET is given in Note 9, ‘Employee costs’.

Adjustments reconciling profit

Adjustments reconciling profit after tax to operating cash flows	12 Months Ended
	Dec. 31, 2018
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Adjustments reconciling profit after tax to operating cash flows	36. Adjustments reconciling profit after tax to operating cash flows 2018 2017 2016 £m £m £m Profit after tax 4,046 2,169 1,062 Tax on profits 754 1,356 877 Share of after tax profits of associates and joint ventures (31 ) (13 ) (5 ) Finance expense net of finance income 717 669 664 Depreciation 954 988 978 Amortisation of intangible assets 902 934 796 Impairment and assets written off 350 1,061 226 Profit on sale of businesses (63 ) (157 ) (5 ) Profit on sale of intangible assets (201 ) (46 ) (178 ) Profit on sale of investments in associates (3 ) (94 ) — Profit on sale of equity investments (4 ) (37 ) (254 ) Gain on Consumer Healthcare Joint Venture put hedging (513 ) — — Business acquisition costs 47 — — Changes in working capital: Decrease/(increase) in inventories 51 (461 ) 70 Increase in trade receivables (429 ) (287 ) (188 ) Increase in trade payables 131 11 96 Decrease in other receivables 18 74 381 Contingent consideration paid (see Note •) (984 ) (594 ) (358 ) Other non-cash 1,250 961 2,281 Increase in other payables 2,362 1,741 1,989 Increase/(decrease) in pension and other provisions 102 (255 ) (621 ) Share-based incentive plans 360 333 319 Fair value adjustments (7 ) — (3 ) Other (62 ) (95 ) (21 ) 5,701 6,089 7,044 Cash generated from operations 9,747 8,258 8,106

Reconciliation of net cash flow

Reconciliation of net cash flow to movement in net debt	12 Months Ended
	Dec. 31, 2018
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Reconciliation of net cash flow to movement in net debt	37. Reconciliation of net cash flow to movement in net debt 2018 2017 2016 £m £m £m Net debt at beginning of year (13,178 ) (13,804 ) (10,727 ) Increase/(decrease) in cash and bank overdrafts 479 (905 ) (1,164 ) Decrease in liquid investments 0 (4 ) — Net increase in long-term loans (10,138 ) (2,233 ) — Repayment of short-term Notes 2,067 2,636 865 (Increase in)/repayment of other short-term loans (81 ) 564 (1,013 ) Net repayment of obligations under finance leases 28 23 18 Exchange adjustments (776 ) 585 (1,781 ) Other non-cash (22 ) (40 ) (2 ) Movement in net debt (8,443 ) 626 (3,077 ) Net debt at end of year (21,621 ) (13,178 ) (13,804 ) At 1 January Profit Reclass- At 31 December Analysis of changes in net debt 2018 Exchange Other and loss ifications Cash flow 2018 £m £m £m £m £m £m £m Liquid investments 78 5 1 0 0 0 84 Cash and cash equivalents 3,833 4 0 0 (485 ) 522 3,874 Cash and cash equivalents – AHFS 0 485 485 Overdrafts (233 ) 4 0 0 0 (43 ) (272 ) 3,600 8 0 0 0 479 4,087 Debt due within one year: Commercial paper (529 ) (36 ) 0 0 0 (65 ) (630 ) European/US Medium Term Notes and bank facilities (2,037 ) (55 ) 0 0 (4,824 ) 2,067 (4,849 ) Other (26 ) (1 ) (11 ) 0 (16 ) 12 (42 ) (2,592 ) (92 ) (11 ) 0 (4,840 ) 2,014 (5,521 ) Debt due after one year: European/US Medium Term Notes and bank facilities (14,221 ) (696 ) 0 4 4,824 (10,138 ) (20,227 ) Other (43 ) (1 ) (16 ) 0 16 0 (44 ) (14,264 ) (697 ) (16 ) 4 4,840 (10,138 ) (20,271 ) Net debt (13,178 ) (776 ) (26 ) 4 0 (7,645 ) (21,621 ) Analysis of changes in liabilities from financing activities Debt due within one year (2,592 ) (92 ) (11 ) 0 (4,840 ) 2,014 (5,521 ) Debt due after one year (14,264 ) (697 ) (16 ) 4 4,840 (10,138 ) (20,271 ) Hedge of borrowings: Derivative financial instruments 2 1 130 (10 ) 0 6 129 Other financing items 0 (19 ) 0 0 0 19 0 Interest payable (203 ) (2 ) 2 (802 ) 0 766 (239 ) Total liabilities from financing activities (17,057 ) (809 ) 105 (808 ) 0 (7,333 ) (25,902 ) For further information on significant changes in net debt see Note 31, ‘Net debt’.

Acquisitions and disposals

Acquisitions and disposals	12 Months Ended
	Dec. 31, 2018
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Acquisitions and disposals	38. Acquisitions and disposals Details of the acquisition and disposal of significant subsidiaries and associates, joint ventures and other businesses are given below: 2018 Business acquisitions There were no business acquisitions during 2018. Business disposals GSK made a number of small business disposals during the year for a net cash consideration of £2 million. Cash flows Associates Associates Business and joint and joint venture venture disposals investments disposals £m £m £m Cash consideration 2 (10 ) 3 Net deferred consideration received 24 0 0 Cash and cash equivalents divested 0 0 0 Cash inflow 26 (10 ) 3 Transactions signed but not yet completed In December 2018, GSK agreed to divest Horlicks The Group has entered into forward foreign exchange contracts which have been designated as a cash flow hedge of part of the foreign exchange exposure arising on the transaction. In addition, the exposure to share price movements in the forward purchase of shares in Hindustan Unilever Limited has been recognised as an embedded derivative. The embedded derivative was in an asset position and had a fair value of £100 million at 31 December 2018. In December 2018, GSK agreed to acquire 100% of Tesaro, Inc., an oncology-focused biopharmaceutical company, for $5.1 billion (£4.0 billion) in cash. This transaction completed on 22nd January 2019. The exercise to determine the acquisition fair values of assets and liabilities is not yet complete. Initial transaction costs were recognised in December 2018. In December 2018, GSK agreed to form a new Consumer Healthcare Joint Venture by acquiring Pfizer’s consumer health business in an all-share 2017 Business acquisitions There were no business acquisitions during 2017. Business disposals GSK made a number of small business disposals during the year for a net cash consideration of £342 million, including contingent consideration receivable of £86 million. The profit on disposal was determined as follows: Total £m Consideration including currency forwards and purchase adjustments 342 Net assets sold: Goodwill (16 ) Intangible assets (21 ) Property, plant and equipment (18 ) Inventory (11 ) Cash and cash equivalents (6 ) Other net assets (5 ) (77 ) Transaction costs (8 ) Reclassification of exchange from other comprehensive income (100 ) Profit on disposal 157 Investment in associates and joint ventures During the year, GSK made cash investments of £15 million into associates and joint ventures. In addition, GSK sold its holdings in two associates for £198 million in cash. Total £m Cash consideration 198 Net book value of shares (92 ) Reclassification of exchange from other comprehensive income (7 ) Transaction costs (5 ) Profit on disposal 94 Cash flows Associates Associates Business and joint and joint venture venture disposals investments disposals £m £m £m Cash consideration 256 (15 ) 198 Net deferred consideration received 39 — — Cash and cash equivalents divested (6 ) — — Transaction costs paid (7 ) — (2 ) Cash inflow 282 (15 ) 196 2016 Business acquisitions GSK completed two small business acquisitions during 2016. Cash consideration of £24 million was paid in the year to acquire the HIV R&D preclinical and discovery stage portfolio from Bristol Myers Squibb. Further consideration, contingent on commercial milestones and future sales performance, may be due, and an initial estimate of £40 million was recognised for this contingent consideration. Intangible assets acquired were valued at £57 million and goodwill of £7 million was recognised. GSK formed Galvani Bioelectronics Limited during the year and acquired intangible assets of £45 million and cash and cash equivalents of £ 41 million from Verily Life Sciences LLC in return for a 45% shareholding in Galvani Bioelectronics. The fair value of this shareholding was £47 million, and GSK also recognised a credit of £39 million in non-controlling Business disposals GSK also made a number of small business disposals in the year for net cash consideration of £72 million. In addition, deferred consideration receivable of £43 million was recognised. Cash flows Business Business acquisitions disposals £m £m Cash consideration (paid)/received after purchase adjustments (24 ) 72 Cash and cash equivalents acquired 41 — Cash inflow 17 72 In addition, GSK made cash investments of £11 million into associates and joint ventures.

Contingent consideration liabil

Contingent consideration liabilities	12 Months Ended
	Dec. 31, 2018
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Contingent consideration liabilities	39. Contingent consideration liabilities The consideration for certain acquisitions includes amounts contingent on future events such as development milestones or sales performance. The Group has provided for the fair value of this contingent consideration as follows: Shionogi- ViiV Novartis Healthcare Vaccines Other Total £m £m £m £m At 1 January 2016 3,409 405 41 3,855 Additions through business combinations 154 — 40 194 Remeasurement through income statement 2,162 152 (33 ) 2,281 Cash payments: operating cash flows (351 ) (5 ) (2 ) (358 ) Cash payments: investing activities (66 ) (7 ) — (73 ) Other movements (4 ) — 1 (3 ) At 31 December 2016 5,304 545 47 5,896 Remeasurement through income statement 909 53 (1 ) 961 Cash payments: operating cash flows (587 ) (7 ) — (594 ) Cash payments: investing activities (84 ) (7 ) — (91 ) At 31 December 2017 5,542 584 46 6,172 Remeasurement through income statement 1,188 56 7 1,251 Cash payments: operating cash flows (703 ) (281 ) 0 (984 ) Cash payments: investing activities (90 ) (63 ) 0 (153 ) At 31 December 2018 5,937 296 53 6,286 Of the contingent consideration payable at 31 December 2018, £837 million (2017 – £1,076 million) is expected to be paid within one year. The contingent consideration payable in respect of the Novartis Vaccines business included a sales milestone of $450 million which was settled in January 2018. The consideration payable for the acquisition of the Shionogi-ViiV Healthcare joint venture and the Novartis Vaccines business is expected to be paid over a number of years. As a result, the total estimated liabilities are discounted to their present values, shown above. The Shionogi-ViiV Healthcare contingent consideration liability is discounted at 8.5% and the Novartis Vaccines contingent consideration liability is discounted partly at 8% and partly at 9%. The Shionogi-ViiV Healthcare and Novartis Vaccines contingent consideration liabilities are calculated principally based on the forecast sales performance of specified products over the lives of those products. The table below shows on an indicative basis the income statement and balance sheet sensitivity to reasonably possible changes in key inputs to the valuations of the contingent consideration liabilities. Shionogi- Novartis ViiV Healthcare Vaccines Increase/(decrease) in financial liability and loss/(gain) in Income statement £m £m 10% increase in sales forecasts 569 62 10% decrease in sales forecasts (569 ) (62 ) 1% increase in discount rate (238 ) (22 ) 1% decrease in discount rate 256 26 5% increase in probability of milestone success 7 5% decrease in probability of milestone success (7 ) 10 cent appreciation of US Dollar 367 (13 ) 10 cent depreciation of US Dollar (313 ) 11 10 cent appreciation of Euro 114 29 10 cent depreciation of Euro (95 ) (25 ) An explanation of the accounting for ViiV Healthcare is set out on page 41.

Non-controlling interests

Non-controlling interests	12 Months Ended
	Dec. 31, 2018
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Non-controlling interests	40. Non-controlling ViiV Healthcare The ViiV Healthcare subgroup has a material non-controlling 2018 2017 2016 Turnover 4,665 4,269 3,527 Profit/(loss) after taxation 560 825 (1,249 ) Other comprehensive income 19 20 36 Total comprehensive income/(expense) 579 845 (1,213 ) 2018 2017 Non-current 2,787 2,736 Current assets 2,643 2,533 Total assets 5,430 5,269 Current liabilities (2,638 ) (2,409 ) Non-current (8,895 ) (8,011 ) Total liabilities (11,533 ) (10,420 ) Net liabilities (6,103 ) (5,151 ) 2018 2017 2016 Net cash inflow from operating activities 2,212 2,132 1,750 Net cash outflow from investing activities (237 ) (207 ) (326 ) Net cash outflow from financing activities (1,982 ) (1,820 ) (1,023 ) (Decrease)/increase in cash and bank overdrafts in the year (7 ) 105 401 The above financial information relates to the ViiV Healthcare group on a stand-alone basis, before the impact of Group-related adjustments, primarily related to the recognition of preferential dividends. The profit after taxation of £560 million (2017 – profit after taxation of £825 million; 2016 – loss after taxation of £1,249 million) is stated after charging preferential dividends payable to GSK, Shionogi and Pfizer and after a charge of £1,194 million (2017 – £909 million; 2016 – £2,186 million) for remeasurement of the contingent consideration payable for the acquisition of the former Shionogi-ViiV Healthcare joint venture. This consideration is expected to be paid over a number of years. The following amounts attributable to the ViiV Healthcare group are included in GSK’s Consolidated statement of comprehensive income, Consolidated statement of changes in equity and Consolidated balance sheet: 2018 2017 2016 Total comprehensive income/(expense) for the year attributable to non-controlling 254 187 (83 ) Dividends paid to non-controlling 332 316 152 Non-controlling (543 ) (476 ) Consumer Healthcare Joint Venture During 2018, the Group acquired Novartis’ interest in the Consumer Healthcare Joint Venture to obtain 100% ownership. The acquisition became unconditional on 3 May 2018 and completed on 1 June 2018. Summarised financial information in respect of the Consumer Healthcare Joint Venture is as follows: Period ended 3 May 2018 2017 2016 £m £m £m Turnover 2,306 7,003 6,530 Profit after taxation 7 1,211 660 Other comprehensive (expense)/income (79 ) (387 ) 1,640 Total comprehensive (expense)/income (72 ) 824 2,300 2017 £m Non-current 12,771 Current assets 3,282 Total assets 16,053 Current liabilities (2,675 ) Non-current (1,537 ) Total liabilities (4,212 ) Net assets 11,841 Period ended 3 May 2018 2017 2016 £m £m £m Net cash inflow from operating activities 65 883 1,496 Net cash inflow/(outflow) from investing activities 442 270 (537 ) Net cash outflow from financing activities (504 ) (1,194 ) (980 ) Increase/(decrease) in cash and bank overdrafts in the year 3 (41 ) (21 ) The above financial information relates to the Consumer Healthcare Joint Venture on a stand-alone basis, before the impact of Group-related adjustments but after major restructuring charges. The following amounts attributable to the Consumer Healthcare Joint Venture are included in GSK’s Consolidated statement of comprehensive income, Consolidated statement of changes in equity and Consolidated balance sheet: 2018 2017 2016 £m £m £m Total comprehensive income for the year attributable to non-controlling 111 296 730 Dividends paid to non-controlling 183 420 346 Non-controlling 0 3,631

Commitments

Commitments	12 Months Ended
	Dec. 31, 2018
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Commitments	41. Commitments 2018 2017 Contractual obligations and commitments £m £m Contracted for but not provided in the financial statements: Intangible assets 4,762 5,254 Property, plant and equipment 665 584 Investments 82 107 Purchase commitments 561 346 Pensions 238 738 Other commitments 0 38 Interest on loans 9,418 8,510 Finance lease charges 16 12 15,742 15,589 The commitments related to intangible assets include milestone payments, which are dependent on successful clinical development or on meeting specified sales targets, and which represent the maximum that would be paid if all milestones, however unlikely, are achieved. The amounts are not risk-adjusted or discounted. The decrease in intangible commitments in 2018 is mainly attributable to the reduction in commitments to third parties such as Nkarta, Inc. In 2018, GSK reached an agreement with the trustees of the UK pension schemes to make additional contributions to eliminate the pension deficit identified at the 31 December 2017 actuarial funding valuation. A payment of £75 million is due in both 2019 and 2020 and a payment of £44 million is due in both 2021 and 2022. The table above includes this commitment, but excludes the normal ongoing annual funding requirement in the UK of approximately £140 million. The Group also has other commitments which principally relate to revenue payments to be made under licences and other alliances. Commitments in respect of future interest payable on loans are disclosed before taking into account the effect of interest rate swaps. Commitments under non-cancellable 2018 2017 Commitments under non-cancellable £m £m Rental payments due within one year 223 186 Rental payments due between one and two years 173 149 Rental payments due between two and three years 143 122 Rental payments due between three and four years 123 107 Rental payments due between four and five years 105 94 Rental payments due after five years 371 387 Total commitments under non-cancellable 1,138 1,045

Financial instruments and relat

Financial instruments and related disclosures	12 Months Ended
	Dec. 31, 2018
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Financial instruments and related disclosures	42. Financial instruments and related disclosures The objective of our Treasury activity is to minimise the post-tax Derivatives are used exclusively for hedging purposes in relation to underlying business activities and not as trading or speculative instruments. Capital management GSK’s financial strategy supports the Group’s strategic priorities and is regularly reviewed by the Board. GSK manages the capital structure of the Group through an appropriate mix of debt and equity. The capital structure of the Group consists of net debt of £21.6 billion (see Note 31, ‘Net debt’) and total equity, including items related to non-controlling non-controlling The Group continues to manage its financial policies to a credit profile that particularly targets short-term credit ratings of A-1 P-1 A-1 P-1 Liquidity risk management GSK’s policy is to borrow centrally in order to meet anticipated funding requirements. The strategy is to diversify liquidity sources using a range of facilities and to maintain broad access to financial markets. At 31 December 2018, GSK had £5.8 billion of borrowings repayable within one year and held £ 4.5 billion of cash and cash equivalents and liquid investments of which £2.9 billion was held centrally. GSK has access to short-term finance under a $10.0 billion (£7.9 billion) US commercial paper programme; $0.8 billion (£0.6 billion) was in issue at 31 December 2018 (2017 – $0.7 billion). GSK has a £1.9 billion five-year committed facility and a $2.5 billion (£2.0 billion) 364-day 364-day Additional bank facilities were agreed in 2018 to support transactions and two remain active at 31 December 2018. In June 2018, £3.5 billion was drawn to support the acquisition from Novartis of the remaining stake in the Consumer Healthcare Joint Venture. This facility, which is due to mature in December 2019 includes one extension option through to June 2020. In addition a $5.0 billion bank facility was agreed in December 2018 to support the acquisition of Tesaro and was undrawn at 31 December 2018. This 12-month six-month GSK has a £20.0 billion European Medium Term Note programme and at 31 December 2018, £11.4 billion of notes were in issue under this programme. The Group also had $12.9 billion (£10.2 billion) of notes in issue at 31 December 2018 under a US shelf registration. GSK’s borrowings mature at dates between 2019 and 2045. The put option owned by Pfizer in ViiV Healthcare is exercisable. In reviewing liquidity requirements GSK considers that sufficient financing options are available should the put option be exercised. Market risk Interest rate risk management The objective of GSK’s Treasury activity is to minimise the effective net interest cost and to balance the mix of debt at fixed and floating rates over time. The Group’s main interest rate risk arises from borrowings and investments with floating rates and refinancing of maturing fixed rate debt where any changes in interest rates will affect future cash flows or the fair values of financial instruments. The policy on interest rate risk management limits the net amount of floating rate debt to a specific cap, reviewed and agreed no less than annually by the Board. The majority of debt is issued at fixed interest rates and changes in the floating rates of interest do not significantly affect the Group’s net interest charge. This includes some borrowings for which interest rate swaps are in place which removes the impact of the associated periodic repricing. Short-term borrowings including bank facilities are exposed to the risk of future changes in market interest rate as are the majority of cash and liquid investments. Foreign exchange risk management Foreign currency transaction exposures arising on external trade flows are not normally hedged. Foreign currency transaction exposures arising on internal trade flows are selectively hedged. The Group’s objective is to minimise the exposure of overseas operating subsidiaries to transaction risk by matching local currency income with local currency costs where possible. GSK’s internal trading transactions are matched centrally and inter-company payment terms are managed to reduce foreign currency risk. Foreign currency cash flows can be hedged selectively including hedges of the foreign exchange risk arising from acquisitions and disposals of assets. Where possible, GSK manages the cash surpluses or borrowing requirements of subsidiary companies centrally using forward contracts to hedge future repayments back into the originating currency. In order to reduce foreign currency translation exposure, the Group seeks to denominate borrowings in the currencies of our principal assets and cash flows. These are primarily denominated in US Dollars, Euros and Sterling. Borrowings can be swapped into other currencies as required. Borrowings denominated in, or swapped into, foreign currencies that match investments in overseas Group assets may be treated as a hedge against the relevant assets. Forward contracts in major currencies are also used to reduce exposure to the Group’s investment in overseas assets (see ‘Net investment hedges’ section of this note for further details). Credit risk Credit risk is the risk that a counterparty will default on its contractual obligations resulting in financial loss to the Group and arises on cash and cash equivalents, favourable derivative financial instruments held with banks and financial institutions as well as credit exposures to wholesale and retail customers, including outstanding receivables. The Group considers its maximum credit risk at 31 December 2018 to be £11,080 million (31 December 2017 – £9,988 million) which is the total of the Group’s financial assets with the exception of ’Other investments’ (comprising equity investments) which bear equity risk rather than credit risk. See page 201 for details on the Group’s total financial assets. At 31 December 2018, GSK’s greatest concentration of credit risk was £ 0.7 billion with Citibank (A+/A1) (2017 – £0.5 billion with Citibank (A/A1) and £0.5 billion with one US wholesaler (BBB+/Baa2)). There has been no change in the estimation techniques or significant assumptions made during the current reporting period in assessing the loss allowance for financial assets at amortised cost since the adoption of IFRS 9 at the start of the current reporting period. Treasury-related credit risk GSK sets global counterparty limits for each of GSK’s banking and investment counterparties based on long-term credit ratings from Moody’s and Standard and Poor’s. Usage of these limits is monitored daily. GSK actively manages its exposure to credit risk, reducing surplus cash balances wherever possible. This is part of GSK’s strategy to regionalise cash management and to concentrate cash centrally as much as possible. The table below sets out the credit exposure to counterparties by rating for liquid investments, cash and cash equivalents and derivatives. The gross asset position on each derivative contract is considered for the purpose of this table, although, under ISDA agreements, the amount at risk is the net position with each counterparty. Table (e) on page 208 sets out the Group’s financial assets and liabilities on an offset basis. At 31 December 2018, £20 million of cash is categorised as held with unrated or sub-investment BBB-/Baa3) BBB-/ GSK measures expected credit losses over cash and cash equivalents as a function of individual counterparty credit ratings and associated 12 month default rates. Expected credit losses over cash and cash equivalents and third-party financial derivatives are deemed to be immaterial and no such loss has been experienced during 2018. 2018 AAA/Aaa AA/Aa A/A BBB/Baa BB+/Ba1 Total Bank balances and deposits 0 662 1,275 381 20 2,338 US Treasury and Treasury repo only money market funds 449 0 0 0 0 449 Liquidity funds 1,572 0 0 0 0 1,572 Government securities 0 83 0 1 0 84 3rd party financial derivatives 0 19 127 4 0 150 Total 2,021 764 1,402 386 20 4,593 2017 AAA/Aaa AA/Aa A/A BBB/Baa BB+/Ba1 Total Bank balances and deposits — 423 1,167 80 45 1,715 US Treasury and Treasury repo only money market funds 1,715 — — — — 1,715 Liquidity funds 403 — — — — 403 Government securities — 77 — 1 — 78 3rd party financial derivatives — 26 42 — — 68 Total 2,118 526 1,209 81 45 3,979 Credit ratings are assigned by Standard and Poor’s and Moody’s respectively. Where the opinions of the two rating agencies differ, GSK assigns the lower rating of the two to the counterparty. Where local rating agency or Fitch data is the only source available, the ratings are converted to global ratings equivalent to those of Standard and Poor’s or Moody’s using published conversion tables. These credit ratings form the basis of the assessment of the expected credit loss on Treasury related balances held at amortised cost being bank balances and deposits and Government securities. GSK’s centrally managed cash reserves amounted to £2.9 billion at 31 December 2018, all available within three months. This includes £1.7 billion of cash managed by the Group for ViiV Healthcare, a 78.3% owned subsidiary. The Group has invested centrally managed liquid assets in bank deposits, Aaa/AAA rated US Treasury and Treasury repo only money market funds and Aaa/AAA rated liquidity funds. Wholesale and retail credit risk Outside the US, no customer accounts for more than 5% of the Group’s trade receivables balance. In the US, in line with other pharmaceutical companies, the Group sells its products through a small number of wholesalers in addition to hospitals, pharmacies, physicians and other groups. Sales to the three largest wholesalers amounted to approximately 82% of the sales of the US Pharmaceuticals and Vaccines businesses in 2018. At 31 December 2018, the Group had trade receivables due from these three wholesalers totalling £2,134 million (2017 – £1,265 million). The Group is exposed to a concentration of credit risk in respect of these wholesalers such that, if one or more of them encounters financial difficulty, it could materially and adversely affect the Group’s financial results. The Group’s credit risk monitoring activities relating to these wholesalers include a review of their quarterly financial information and Standard & Poor’s credit ratings, development of GSK internal risk ratings, and establishment and periodic review of credit limits. All new customers are subject to a credit vetting process and existing customers will be subject to a review at least annually. The vetting process and subsequent reviews involves obtaining information including the customer’s status as a government or private sector entity, audited financial statements, credit bureau reports, debt rating agency (e.g. Moody’s, Standard & Poor’s) reports, payment performance history (from trade references, industry credit groups) and bank references. Trade receivables consist of a large number of customers, spread across diverse industries and geographical areas. Ongoing credit evaluation is performed on the financial condition of accounts receivable and, where appropriate, credit insurance is purchased or factoring arrangements put in place. The amount of information obtained is proportional to the level of exposure being considered. The information is evaluated quantitatively (i.e., credit score) and qualitatively (i.e. judgement) in conjunction with the customer’s credit requirements to determine a credit limit. Trade receivables are grouped into customer segments that have similar loss patterns to assess credit risk while other receivables other financial assets are assessed individually. Historical and forward-looking information is considered to determine the appropriate expected credit loss allowance. The Group believes there is no further credit risk provision required in excess of the allowance for expected credit losses (see Note 24, ‘Trade and other receivables’). Credit enhancements The Group uses credit enhancements including factoring and credit insurance to minimise credit risk of the trade receivables in the Group. During 2018, a new Global Insurance Programme was launched in order to consolidate all locally negotiated programmes and to expand the use of credit insurance to new markets. At 31 December 2018, £240 million of GSK trade receivables were insured protecting GSK’s account receivables balance from loss due to credit risks such as default, insolvency and bankruptcy. Each Group entity assesses the credit risk of its private customers to determine if credit insurance is required. Factoring arrangements are managed locally by entities and are used to mitigate risk arising from large credit risk concentrations. All factoring arrangements are non-recourse. Fair value of financial assets and liabilities The table on pages 201 and 202 presents the carrying amounts and the fair values of the Group’s financial assets and liabilities at 31 December 2018 and 31 December 2017. The fair values of the financial assets and liabilities are included at the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The following methods and assumptions were used to estimate the fair values: • Cash and cash equivalents – approximates to the carrying amount • Liquid investments – approximates to the carrying amount • Other investments – equity investments traded in an active market determined by reference to the relevant stock exchange quoted bid price; other equity investments determined by reference to the current market value of similar instruments or by reference to the discounted cash flows of the underlying net assets • Short-term loans, overdrafts and commercial paper – approximates to the carrying amount because of the short maturity of these instruments • Long-term loans – based on quoted market prices (a level 1 fair value measurement) in the case of European and US Medium Term Notes; approximates to the carrying amount in the case of other fixed rate borrowings and floating rate bank loans • Contingent consideration for business acquisitions – based on present values of expected future cash flows • Interest rate swaps, foreign exchange forward contracts, swaps and options – based on the present value of contractual cash flows or option valuation models using market sourced data (exchange rates or interest rates) at the balance sheet date • Receivables and payables, including put options – approximates to the carrying amount • Company-owned life insurance policies – based on cash surrender value, and • Lease obligations – approximates to the carrying amount. 2018 Notes Carrying Fair Financial assets measured at fair value through other comprehensive income (FVTOCI): Other investments designated at FVTOCI a 1,250 1,250 Trade and other receivables a,b 1,687 1,687 Financial assets measured at amortised cost: Other non-current b 49 49 Trade and other receivables b 3,761 3,761 Liquid investments 84 84 Cash and cash equivalents 2,338 2,338 Other items in Assets held for sale b 47 47 Financial assets mandatorily measured at fair value through profit or loss (FVTPL): Other investments a 72 72 Other non-current a,b 716 716 Trade and other receiveables a,b 120 120 Derivatives designated and effective as hedging instruments a,d,e 69 69 Held for trading derivatives that are not in a designated and effective hedging relationship a,d,e 188 188 Cash and cash equivalents a 2,021 2,021 Total financial assets 12,402 12,402 Financial liabilities measured at amortised cost: Borrowings excluding obligations under finance leases: – bonds in a designated hedging relationship d (8,213 ) (8,279 ) – other bonds (13,307 ) (15,475 ) – bank loans and overdrafts (290 ) (290 ) – commercial paper (630 ) (630 ) – other borrowings (3,556 ) (3,556 ) Total borrowings excluding obligations under finance leases f (25,996 ) (28,230 ) Obligations under finance leases (68 ) (68 ) Total borrowings (26,064 ) (28,298 ) Trade and other payables c (13,338 ) (13,338 ) Other provisions c (58 ) (58 ) Other non-current c (149 ) (149 ) Other items in Assets held for sale c (167 ) (167 ) Financial liabilities mandatorily at fair value through profit or loss (FVTPL): Contingent consideration liabilities a,c (6,286 ) (6,286 ) Derivatives designated and effective as hedging instruments a,d,e (105 ) (105 ) Held for trading derivatives that are not in a designated and effective hedging relationship a,d,e (23 ) (23 ) Total financial liabilities (46,190 ) (48,424 ) Net financial assets and financial liabilities (33,788 ) (36,022 ) The valuation methodology used to measure fair value in the above table and the table on page 202 is described and categorised on page 200. Trade and other receivables, Other non-current non-current Cash and cash equivalents in the table above include £485 million reported in Assets held for sale (see Note 26, ‘Assets held for sale’). 2017 Notes Carrying Fair Available-for-sale Liquid investments (Government bonds) a 78 78 Other investments a 918 918 Loans and receivables: Cash and cash equivalents 3,833 3,833 Trade and other receivables and Other non-current b 5,495 5,495 Financial assets at fair value through profit or loss: Trade and other receivables and Other non-current a,b 506 506 Derivatives designated as at fair value through profit or loss a,d,e 5 5 Derivatives classified as held for trading under IAS 39 a,d,e 71 71 Total financial assets 10,906 10,906 Financial liabilities measured at amortised cost: Borrowings excluding obligations under finance leases: – bonds in a designated hedging relationship d (4,315 ) (4,405 ) – other bonds (11,894 ) (14,743 ) – bank loans and overdrafts (236 ) (236 ) – commercial paper (529 ) (529 ) – other borrowings (49 ) (49 ) Total borrowings excluding obligations under finance leases f (17,023 ) (19,962 ) Obligations under finance leases (66 ) (66 ) Total borrowings (17,089 ) (20,028 ) Trade and other payables, Other provisions and certain Other non-current c (20,325 ) (20,325 ) Financial liabilities at fair value through profit or loss: Contingent consideration liabilities a,c (6,172 ) (6,172 ) Derivatives designated as at fair value through profit or loss a,d,e (26 ) (26 ) Derivatives classified as held for trading under IAS 39 a,d,e (48 ) (48 ) Total financial liabilities (43,660 ) (46,599 ) Net financial assets and financial liabilities (32,754 ) (35,693 ) Fair value of investments in GSK shares At 31 December 2018, the Employee Share Ownership Plan (ESOP) Trusts held GSK shares with a carrying value of £161 million (2017 – £400 million) and a market value of £619 million (2017 – £882 million) based on quoted market price. The shares are held by the ESOP Trusts to satisfy future exercises of options and awards under employee incentive schemes. In 2018, the carrying value, which is the lower of cost or expected proceeds, of these shares has been recognised as a deduction from other reserves. At 31 December 2018, GSK held Treasury shares at a cost of £5,800 million (2017 – £5,800 million) which has been deducted from retained earnings. (a) Financial instruments held at fair value The following tables categorise the Group’s financial assets and liabilities held at fair value by the valuation methodology applied in determining their fair value. Where possible, quoted prices in active markets are used (Level 1). Where such prices are not available, the asset or liability is classified as Level 2, provided all significant inputs to the valuation model used are based on observable market data. If one or more of the significant inputs to the valuation model is not based on observable market data, the instrument is classified as Level 3. Other investments classified as Level 3 in the tables below comprise equity investments in unlisted entities with which the Group has entered into research collaborations and also investments in emerging life science companies. At 31 December 2018 Level 1 Level 2 Level 3 Total Financial assets at fair value Financial assets at fair value through other comprehensive income (FVTOCI): Other investments designated at FVTOCI 656 0 594 1,250 Trade and other receivables 0 1,687 0 1,687 Financial assets mandatorily measured at fair value through profit or loss (FVTPL): Other investments 0 0 72 72 Other non-current 0 675 41 716 Trade and other receivables 0 79 41 120 Derivatives designated and effective as hedging instruments 0 69 0 69 Held for trading derivatives that are not in a designated and effective hedging relationship 0 182 6 188 Cash and cash equivalents 2,021 0 0 2,021 2,677 2,692 754 6,123 Financial liabilities at fair value Financial liabilities mandatorily at fair value through profit or loss (FVTPL): Contingent consideration liabilities 0 0 (6,286 ) (6,286 ) Derivatives designated and effective as hedging instruments 0 (105 ) 0 (105 ) Held for trading derivatives that are not in a designated and effective hedging relationship 0 (23 ) 0 (23 ) 0 (128 ) (6,286 ) (6,414 ) At 31 December 2017 Level 1 Level 2 Level 3 Total Financial assets at fair value Available-for-sale Liquid investments 77 1 — 78 Other investments 535 — 383 918 Other non-current — — 38 38 Financial assets at fair value through profit or loss: Other non-current — 382 44 426 Trade and other receivables — — 42 42 Derivatives designated as at fair value through profit or loss — 5 — 5 Derivatives classified as held for trading under IAS 39 — 62 9 71 612 450 516 1,578 Financial liabilities at fair value Financial liabilities at fair value through profit or loss: Contingent consideration liabilities — — (6,172 ) (6,172 ) Derivatives designated as at fair value through profit or loss — (26 ) — (26 ) Derivatives classified as held for trading under IAS 39 — (47 ) (1 ) (48 ) — (73 ) (6,173 ) (6,246 ) Movements in the year for financial instruments measured using Level 3 valuation methods are presented below: 2018 2017 £m £m At 1 January (5,657 ) (5,486 ) Net losses recognised in the income statement (1,233 ) (970 ) Net gains recognised in other comprehensive income 123 22 Contingent consideration for businesses divested/acquired during the year 0 80 Payment of contingent consideration liabilities 1,095 685 Additions 381 117 Disposals and settlements (27 ) (52 ) Transfers from Level 3 (241 ) (24 ) Exchange adjustments 27 (29 ) At 31 December (5,532 ) (5,657 ) The net losses of £1,233 million (2017 – £970 million) attributable to Level 3 financial instruments which were recognised in the income statement were all attributable to financial instruments which were held at the end of the year. Losses of £1,233 million were reported in Other operating income (2017 – £971 million losses in Other operating income and £1 million income in Finance income). £1,188 million (2017 – £909 million) arose from remeasurement of the contingent consideration payable for the acquisition of the former Shionogi-ViiV Healthcare joint venture and £56 million (2017 – £ 53 million) arose from remeasurement of the contingent consideration payable for the acquisition of the Novartis Vaccines business. Net gains of £123 million (2017 – £22 million) attributable to Level 3 financial instruments reported in Other comprehensive income as Fair value movements on equity investments included net gains of £117 million (2017 – net losses of £6 million) in respect of financial instruments held at the end of the year, of which net gains of £98 million (2017 – net losses of £6 million) arose prior to transfer from Level 3 on equity investments which transferred to a Level 1 valuation methodology as a result of listing on a recognised stock exchange during the year. Financial liabilities measured using Level 3 valuation methods at 31 December included £5,937 million (2017 – £5,542 million) in respect of contingent consideration payable for the acquisition in 2012 of the former Shionogi-ViiV Healthcare joint venture. This consideration is expected to be paid over a number of years and will vary in line with the future performance of specified products and movements in certain foreign currencies. They also included £296 million (2017 – £584 million) in respect of contingent consideration for the acquisition in 2015 of the Novartis Vaccines business. This consideration is expected to be paid over a number of years and will vary in line with the future performance of specified products, the achievement of certain milestone targets and movements in certain foreign currencies. Sensitivity analysis on these balances is provided in Note 39, ‘Contingent consideration liabilities’. (b) Trade and other receivables, Other non-current The following table reconciles financial instruments within Trade and other receivables, Other non-current non-interest non-current Non-financial 2018 2017 At FVTPL At FVTOCI Amortised Financial Non- Total At FVTPL Loans and Financial Non-financial Total Trade and other receivables (Note 24) 120 1,687 3,761 5,568 855 6,423 42 5,148 5,190 810 6,000 Other non-current 716 0 49 765 811 1,576 464 347 811 602 1,413 Other items in Assets held for sale (Note 26) 0 0 47 47 37 84 — — — — — 836 1,687 3,857 6,380 1,703 8,083 506 5,495 6,001 1,412 7,413 The Group applied IFRS 9 ‘Financial Instruments’ with effect from 1 January 2018 and therefore now accounts for expected credit losses on initial recognition of financial assets. The following table shows the ageing of financial assets which were past due at 31 December 2017 and for which no provision for bad or doubtful debts had been made at that date under IAS 39: 2017 Past due by 1–30 days 142 Past due by 31–90 days 70 Past due by 91–180 days 64 Past due by 181–365 days 27 Past due by more than 365 days 108 411 (c) Trade and other payables, Other provisions, Other non- The following table reconciles financial instruments within Trade and other payables, Other provisions, Other non-current non-interest Non-financial 2018 2017 Amortised Financial Non-financial Amortised Financial Non-financial At FVTPL cost instruments instruments Total At FVTPL cost instruments instruments Total £m £m £m £m £m £m £m £m £m £m Trade and other payables (Note 27) 0 (13,338 ) (13,338 ) (699 ) (14,037 ) — (20,129 ) (20,129 ) (841 ) (20,970 ) Other provisions (Note 29) 0 (58 ) (58 ) (1,365 ) (1,423 ) — (117 ) (117 ) (1,148 ) (1,265 ) Other non-current 0 (149 ) (149 ) (789 ) (938 ) — (79 ) (79 ) (902 ) (981 ) Contingent consideration liabilities (Note 39) (6,286 ) 0 (6,286 ) 0 (6,286 ) (6,172 ) — (6,172 ) — (6,172 ) Other items in Assets held for sale (Note 26) 0 (167 ) (167 ) (53 ) (220 ) — — — — — (6,286 ) (13,712 ) (19,998 ) (2,906 ) (22,904 ) (6,172 ) (20,325 ) (26,497 ) (2,891 ) (29,388 ) (d) Derivative financial instruments and hedging programmes Derivatives are only used for economic hedging purposes and not as speculative investments and are classified as ‘held for trading’, other than designated and effective hedging instruments, and are presented as current assets or liabilities if they are expected to be settled within 12 months after the end of the reporting period, otherwise they are classified as non-current. 2018 Fair value 2017 Assets Liabilities Assets Liabilities Non-current Cash flow hedges – Interest rate swap contracts (principal amount – £1,266 million (2017 – £nil)) 0 (1 ) — — Net investment hedges – Cross currency swaps (principal amount – £1,575 million (2017 – £nil)) 64 0 — — Current Cash flow hedges – Foreign exchange contracts (principal amount – £1,809 million (2017 – £38 million)) 1 (56 ) — (1 ) Net investment hedges – Foreign exchange contracts (principal amount – £7,316 million (2017 – £6,333 million)) 4 (48 ) 5 (25 ) Derivatives designated and effective as hedging instruments 69 (105 ) 5 (26 ) Non-current Embedded and other derivatives 4 0 8 — Current Foreign exchange contracts (principal amount – £18,537 million (2017 – £14,449 million)) 82 (23 ) 62 (47 ) Embedded and other derivatives 102 0 1 (1 ) Derivatives classified as held for trading 188 (23 ) 71 (48 ) Total derivative instruments 257 (128 ) 76 (74 ) Fair value hedges At 31 December 2018, the Group had no designated fair value hedges. Net investment hedges During the year, certain foreign exchange contracts were designated as net investment hedges in respect of the foreign currency translation risk arising on consolidation of the Group’s net investment in its European (Euro) foreign operations as shown in the table above. The carrying value of bonds on page 201 includes £8,213 million (2017 – £4,315 million) that are designated as hedging instruments in net investment hedges. Cash flow hedges During 2018, the Group entered into forward foreign exchange contracts which have been designated as cash flow hedges. These were entered into to hedge the foreign exchange exposure arising on cash flows from Euro denominated coupon payments relating to notes issued under the Group’s European Medium Term Note programme, on the buyout of Novartis’ non-controlling Horlicks The Group manages its cash flow interest rate risk by using floating-to-fixed pre-hedging Foreign exchange forward contracts and swaps In the current year, the Group has designated certain foreign exchange forward contracts and swaps as cash flow and net investment hedges. The following tables detail the foreign exchange forward contracts and swaps outstanding at the end of the reporting period, as well as information on the related hedged items. Foreign exchange derivative financial assets and liabilities are presented in the line ‘Derivative financial instruments’ (either as assets or liabilities) on the Consolidated balance sheet. The notional value of foreign exchange forward contracts and swaps is the absolute total of outstanding positions at the balance sheet date. Hedge effectiveness is determined at the inception of the hedge relationship, and through periodic prospective effectiveness assessments to ensure that an economic relationship exists between the hedged item and hedging instrument. The Group enters into hedge relationships where the critical terms of the hedging instrument match exactly with the terms of the hedged item, and so a qualitative assessment of effectiveness is performed. If changes in circumstances affect the terms of the hedged item such that the critical terms no longer match exactly with the critical terms of the hedging instrument, the Group uses the hypothetical derivative method to assess effectiveness. The main source of hedge ineffectiveness in these hedging relationships is the effect of the counterparty and the Group’s own credit risk on the fair value of the foreign exchange forward contracts and swaps, which is not reflected in the fair value of the hedged item attributable to changes in foreign exchange rates. No other sources of ineffectiveness emerged from these hedging relationships. Consequently, there was no ineffectiveness to be recorded from cash flow hedges and net investments in foreign entity hedges. 2018 Hedging instruments Average exchange Foreign Notional Fair Cash flow hedges Foreign exchange contracts Buy foreign currency: Less than 3 months 0 0 0 0 3 to 6 months 1.13 Euro 26 1 Over 6 months 0 0 0 0 Sell foreign currency: Less than 3 months 0 0 0 0 3 to 6 months 0 0 0 0 Over 6 months 96.40 Indian Rupee 1,783 (56 ) 1,809 (55 ) Net investment hedges Foreign exchange contracts Sell foreign currency: Less than 3 months 1.11 Euro 6,933 (40 ) 3 to 6 months 0 0 0 0 Over 6 months 1.11 Euro 383 (4 ) 7,316 (44) 2018 Hedged items Change in value for Balance in cash flow hedge Cash flow hedges Variability in cash flows from a highly probable forecast transaction 56 (49 ) Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued (1 ) 1 Net investment hedges Investment in European foreign operations 50 286 The following table details the effectiveness of the hedging relationships and the amounts reclassified from the hedging reserve to profit or loss: 2018 Amount reclassified to profit or loss Hedging Amount Line item Hedged As hedged Line item Cash flow hedges Variability in cash flows from a highly probable forecast transaction 127 0 Other 0 (176 ) Other Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued 1 0 Finance (expense ) 0 0 Finance Net investment hedges Net investment in European foreign operations 286 7 Finance 0 0 Finance Interest rate swap contracts The Group manages its cash flow interest rate risk by using floating-to-fixed The interest rate swap contracts, exchanging floating rate interest for fixed interest, have been designated as ca

Employee share schemes

Employee share schemes	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Employee share schemes	43. Employee share schemes GSK operates several employee share schemes, including the Share Value Plan, whereby awards are granted to employees to acquire shares or ADS in GlaxoSmithKline plc at no cost after a three year vesting period and the Performance Share Plan, whereby awards are granted to employees to acquire shares or ADS in GlaxoSmithKline plc at no cost, subject to the achievement by the Group of specified performance targets. The granting of these restricted share awards has replaced the granting of options to employees as the cost of the schemes more readily equates to the potential gain to be made by the employee. The Group also operates savings related share option schemes, whereby options are granted to employees to acquire shares in GlaxoSmithKline plc at a discounted price. Grants of restricted share awards are normally exercisable at the end of the three-year vesting or performance period. Awards are normally granted to employees to acquire shares or ADS in GlaxoSmithKline plc but in some circumstances may be settled in cash. Grants under savings-related share option schemes are normally exercisable after three years’ saving. In accordance with UK practice, the majority of options under the savings-related share option schemes are granted at a price 20% below the market price ruling at the date of grant. Options under historical share option schemes were granted at the market price ruling at the date of grant. The total charge for share-based incentive plans in 2018 was £393 million (2017 – £347 million; 2016 – £338 million). Of this amount, £304 million (2017 – £276 million; 2016 – £271 million) arose from the Share Value Plan. See Note 9, ‘Employee Costs’ for further details. GlaxoSmithKline share award schemes Share Value Plan Under the Share Value Plan, share awards are granted to certain employees at no cost. The awards vest after two and a half to three years and there are no performance criteria attached. The fair value of these awards is determined based on the closing share price on the day of grant, after deducting the expected future dividend yield of 4.8% (2017 – 4.8%; 2016 – 4.5%) over the duration of the award. Shares Weighted ADS Weighted Number of shares and ADS issuable Number (000) fair value Number (000) fair value At 1 January 2016 32,577 17,520 Awards granted 12,983 £ 14.97 6,589 $ 39.18 Awards exercised (11,198 ) (6,214 ) Awards cancelled (1,507 ) (812 ) At 31 December 2016 32,855 17,083 Awards granted 13,018 £ 13.68 6,610 $ 35.63 Awards exercised (10,596 ) (5,674 ) Awards cancelled (1,352 ) (627 ) At 31 December 2017 33,925 17,392 Awards granted 12,751 £ 13.74 6,503 $ 35.28 Awards exercised (11,089 ) (5,583 ) Awards cancelled (1,519 ) (925 ) At 31 December 2018 34,068 17,387 Performance Share Plan Under the Performance Share Plan, share awards are granted to Directors and senior executives at no cost. The percentage of each award that vests is based upon the performance of the Group over a defined measurement period with dividends reinvested during the same period. For awards granted from 2015, the performance conditions are based on three equally weighted measures over a three-year performance period. These are adjusted free cash flow, TSR and R&D new product performance. The fair value of the awards is determined based on the closing share price on the day of grant. For TSR performance elements, this is adjusted by the likelihood of that condition being met, as assessed at the time of grant. During 2018, awards were made of 4.7 million shares at a weighted fair value of £10.46 and 1.3 million ADS at a weighted fair value of $29.43. At 31 December 2018, there were outstanding awards over 13.1 million shares and 3.4 million ADS. Share options and savings-related options For the purposes of valuing savings-related options to arrive at the share-based payment charge, a Black-Scholes option pricing model has been used. The assumptions used in the model are as follows: 2018 Grant 2017 Grant 2016 Grant Risk-free interest rate 0.76 % 0.54 % 0.32 % Dividend yield 5.3 % 5.9 % 4.9 % Volatility 21 % 23 % 23 % Expected life 3 years 3 years 3 years Savings-related options grant price (including 20% discount) £ 12.09 £ 10.86 £ 12.95 Share option Share option Savings-related Options outstanding schemes – shares schemes – ADS share option schemes Weighted Weighted Weighted Number exercise Number exercise Number exercise 000 price 000 price 000 price At 31 December 2018 1,796 £ 11.96 1,216 $ 36.19 5,929 £ 11.70 Range of exercise prices on options outstanding at year end £ 11.60 – £ 12.21 $ 33.42 – $ 38.14 £ 10.13 – £ 12.95 Weighted average market price on exercise during year £ 14.43 $ 39.77 £ 15.13 Weighted average remaining contractual life 0.9 years 0.9 years 2.6 years Options over 2.9 million shares were granted during the year under the savings-related share option scheme at a weighted average fair value of £2.40. At 31 December 2018, 5.5 million of the savings-related share options were not exercisable. All of the other share options and ADS options are currently exercisable and all will expire if not exercised on or before 22 July 2020. There has been no change in the effective exercise price of any outstanding options during the year. Employee Share Ownership Plan Trusts The Group sponsors Employee Share Ownership Plan (ESOP) Trusts to acquire and hold shares in GlaxoSmithKline plc to satisfy awards made under employee incentive plans and options granted under employee share option schemes. The trustees of the ESOP Trusts purchase shares with finance provided by the Group by way of loans or contributions. The costs of running the ESOP Trusts are charged to the income statement. Shares held by the ESOP Trusts are deducted from other reserves and amortised down to the value of proceeds, if any, receivable from employees on exercise by a transfer to retained earnings. The trustees have waived their rights to dividends on the shares held by the ESOP Trusts. Shares held for share award schemes 2018 2017 Number of shares (000) 41,391 66,558 £m £m Nominal value 10 17 Carrying value 160 399 Market value 617 880 Shares held for share option schemes 2018 2017 Number of shares (000) 139 139 £m £m Nominal value 0 — Carrying value 1 1 Market value 2 2

Principal Group companies

Principal Group companies	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Principal Group companies	44. Principal Group companies The following represent the principal subsidiaries and their countries of incorporation of the Group at 31 December 2018. The equity share capital of these entities is wholly owned by the Group except where its percentage interest is shown otherwise. All companies are incorporated in their principal country of operation except where stated. England US Glaxo Group Limited Block Drug Company, Inc. Glaxo Operations UK Limited Corixa Corporation GlaxoSmithKline Capital plc GlaxoSmithKline Capital Inc. GlaxoSmithKline Consumer Healthcare Holdings Limited GlaxoSmithKline Consumer Healthcare Holdings (US) LLC GlaxoSmithKline Consumer Healthcare (UK) Trading Limited GlaxoSmithKline Consumer Healthcare, L.P. (88%) GlaxoSmithKline Consumer Trading Services Limited GlaxoSmithKline Holdings (Americas) Inc. GlaxoSmithKline Export Limited GlaxoSmithKline LLC GlaxoSmithKline Finance plc Human Genome Sciences, Inc. GlaxoSmithKline Holdings Limited * GSK Consumer Health, Inc. (formerly Novartis Consumer Health, Inc.) GlaxoSmithKline Research & Development Limited S.R. One, Limited GlaxoSmithKline Services Unlimited * Stiefel Laboratories, Inc. GlaxoSmithKline UK Limited ViiV Healthcare Company (78.3%) Setfirst Limited SmithKline Beecham Limited ViiV Healthcare Limited (78.3%) ViiV Healthcare UK Limited (78.3%) Europe Others GlaxoSmithKline Biologicals SA (Belgium) GlaxoSmithKline Argentina S.A. (Argentina) GlaxoSmithKline Pharmaceuticals SA (Belgium) GlaxoSmithKline Australia Pty Ltd (Australia) GlaxoSmithKline Biologicals S.A.S. (France) GlaxoSmithKline Consumer Healthcare Australia Pty Ltd (Australia) GlaxoSmithKline Sante Grand Public SAS (France) GlaxoSmithKline Brasil Limitada (Brazil) Laboratoire GlaxoSmithKline (France) GlaxoSmithKline Consumer Healthcare Inc. (Canada) ViiV Healthcare SAS (France) (78.3%) GlaxoSmithKline Inc. (Canada) GlaxoSmithKline Consumer Healthcare GmbH & Co. KG (Germany) ID Biomedical Corporation of Quebec (Canada) GlaxoSmithKline GmbH & Co. KG (Germany) GlaxoSmithKline Limited (China (Hong Kong)) GSK Vaccines GmbH (Germany) GlaxoSmithKline (Tianjin) Co. Ltd (China) (90%) GlaxoSmithKline Consumer Healthcare S.p.A. (Italy) Sino-American Tianjin Smith Kline & French Laboratories Ltd (China) (55%) GlaxoSmithKline S.p.A. (Italy) GlaxoSmithKline Consumer Healthcare Limited (India) (72.5%) GSK Vaccines S.r.l. (Italy) GlaxoSmithKline Pharmaceuticals Limited (India) (75%) GlaxoSmithKline B.V. (Netherlands) GlaxoSmithKline Consumer Healthcare Japan K.K. (Japan) GlaxoSmithKline Consumer Healthcare Sp.z.o.o. (Poland) GlaxoSmithKline K.K. (Japan) GSK Services Sp z o.o. (Poland) ViiV Healthcare Kabushiki Kaisha (Japan) (78.3%) GlaxoSmithKline Trading Services Limited (Republic of Ireland) (i) GlaxoSmithKline Pakistan Limited (Pakistan) (82.6%) GlaxoSmithKline Healthcare AO (Russia) Glaxo Wellcome Manufacturing Pte Ltd. (Singapore) GlaxoSmithKline S.A. (Spain) GlaxoSmithKline Korea Limited (Republic of Korea) Laboratorios ViiV Healthcare, S.L. (Spain) (78.3%) GlaxoSmithKline llaclari Sanayi ve Ticaret A.S. (Turkey) GSK Consumer Healthcare S.A. (Switzerland) (i) Exempt from the provisions of section 347 and 348 of the Companies Act 2014 (Ireland), in accordance with the exemptions noted in Section 357 of that Act. Further subsidiaries, as disclosed on pages 260 to 270, are exempt from these provisions as they are also consolidated in the group financial statements. * Directly held wholly owned subsidiary of GlaxoSmithKline plc. The subsidiaries and associates listed above principally affect the figures in the Group’s financial statements. Each of GlaxoSmithKline Capital Inc., GlaxoSmithKline Capital plc and GlaxoSmithKline LLC, is a wholly-owned finance subsidiary of the company, and the company has fully and unconditionally guaranteed the securities issued by each of GlaxoSmithKline Capital Inc., GlaxoSmithKline Capital plc and GlaxoSmithKline LLC. See pages 260 to 270 for a complete list of subsidiary undertakings, associates and joint ventures, which form part of these financial statements.

Legal proceedings

Legal proceedings	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Legal proceedings	45. Legal proceedings The Group is involved in significant legal and administrative proceedings, principally product liability, intellectual property, tax, anti-trust and governmental investigations, as well as related private litigation. The most significant of these matters, other than tax matters, are described below. The Group makes provision for these proceedings on a regular basis as summarised in Note 2, ‘Accounting principles and policies’ and Note 29, ‘Other provisions’. The Group may become involved in significant legal proceedings in respect of which it is not possible to make a reliable estimate of the expected financial effect, if any, that could result from ultimate resolution of the proceedings. In these cases, appropriate disclosures about such cases would be included in this note, but no provision would be made for the cases. With respect to each of the legal proceedings described below, other than those for which a provision has been made, the Group is unable to make a reliable estimate of the expected financial effect at this stage. The Group does not believe that information about the amount sought by the plaintiffs, if that is known, would be meaningful with respect to those legal proceedings. This is due to a number of factors, including, but not limited to, the stage of proceedings, the entitlement of parties to appeal a decision and clarity as to theories of liability, damages and governing law. Legal expenses incurred and provisions related to legal claims are charged to selling, general and administration costs. Provisions are made, after taking appropriate legal and other specialist advice, where an outflow of resources is considered probable and a reliable estimate can be made of the likely outcome of the dispute. For certain product liability claims, the Group will make a provision where there is sufficient history of claims made and settlements to enable management to make a reliable estimate of the provision required to cover unasserted claims. At 31 December 2018, the Group’s aggregate provision for legal and other disputes (not including tax matters described in Note 14, ‘Taxation’) was £219 million. However, this provision is offset by a related £37 million receivable which means the net exposure to the Group is £182 million. The ultimate liability for legal claims may vary from the amounts provided and is dependent upon the outcome of litigation proceedings, investigations and possible settlement negotiations. The Group’s position could change over time, and, therefore, there can be no assurance that any losses that result from the outcome of any legal proceedings will not exceed by a material amount the amount of the provisions reported in the Group’s financial statements. If this were to happen, it could have a material adverse impact on the results of operations of the Group in the reporting period in which the judgements are incurred or the settlements entered into. Intellectual property Intellectual property claims include challenges to the validity and enforceability of the Group’s patents on various products or processes as well as assertions of non-infringement Dolutegravir / Tivicay/Triumeq In September and October 2017, ViiV Healthcare received patent challenge letters under the Hatch-Waxman Act from Cipla, Dr. Reddy’s Labs and Apotex for Triumeq Tivicay Triumeq Tivicay Tivicay Triumeq On 7 February 2017, ViiV Healthcare filed patent infringement suits against all the generic companies in the US District Court for the District of Delaware. Additionally, ViiV Healthcare also filed suit against certain of the generic companies in the US District Court for the District of New Jersey, and the US District Court for the District of West Virginia. The case against Mylan is now proceeding in the Northern District of West Virginia. The court has set the case against Mylan for trial in June 2020. The cases against the other defendants are proceeding in the District of Delaware. The District of Delaware has not yet set a trial date for the cases. On 7 February 2018, ViiV Healthcare filed patent infringement litigation against Gilead Sciences Inc. (Gilead) over bictegravir in the US District Court for the District of Delaware (U.S. Patent No. 8,129,385) and the Canadian Federal Court (Canadian patent No. 2,606,282). ViiV Healthcare alleges that Gilead’s triple combination HIV drug containing the HIV integrase inhibitor bictegravir infringes ViiV Healthcare’s patent covering dolutegravir and other compounds that include dolutegravir’s unique chemical scaffold. In both the US and Canada, ViiV Healthcare seeks financial redress rather than injunctive relief. The District of Delaware case is set for trial in September 2020. The Canadian court has not set a trial date for the Canadian action. Kivexa In 2018, ViiV Healthcare reached confidential agreements with each of DOC Generici, Farmoz and Kyowa Pharmaceuticals to settle various challenges to the validity of the Supplementary Protection Certificate (‘SPC’) for the patent covering the combination of lamivudine and abacavir for Kivexa In June 2017, Biogaran commenced proceedings in France seeking revocation of the French SPC covering Kivexa In Q2 2018, ViiV Healthcare commenced proceedings against Sandoz in Switzerland. Sandoz countered challenging the validity of the patent relating to Kivexa Product liability Pre-clinical Notwithstanding these efforts, when drugs and vaccines are introduced into the marketplace, unanticipated safety issues may become, or be claimed by some to be, evident. The Group is currently a defendant in a number of product liability lawsuits related to the Group’s Pharmaceutical, Vaccine and Consumer Healthcare products. The Group has been able to make a reliable estimate of the expected financial effect of the matters discussed in this category and has included a provision, as appropriate, for the matters below in the provision for legal and other disputes. Matters for which the Group has made a provision are also noted in Note 29, ‘Other provisions.’ Avandia The Group has been named in product liability lawsuits on behalf of individuals asserting personal injury claims arising out of the use of Avandia As of February 2019, there are seven remaining US cases. Four are personal injury actions subject to a settlement agreement and will be dismissed once the settlement has been finalised. Two are class actions, brought by third-party payers asserting claims under the Racketeer Influenced and Corrupt Organizations Act (RICO) and state consumer protection laws, and are on appeal from summary judgements granted in favour of the Group. In the last of the seven, the Santa Clara County (California) Action, summary judgement was granted in favour of the Group on all issues except for the civil penalty claims under California’s False Advertising Act. Additionally, there are 13 class actions pending in Canada, but the Group has reached an agreement, subject to court approval, to settle all of them. Seroxat/Paxil and Paxil CR The Group has received numerous lawsuits and claims alleging that use of Paxil Paxil Paxil Paxil – Pregnancy The Group has reached agreements to settle the majority of the US claims relating to the use of Paxil The Singh action in Alberta, Canada, a proposed national class action, seeks to certify a class relating to birth defects generally. The court, after hearing argument in January 2019, has plaintiffs’ class certification motion under consideration. Another Canadian class action, Jensen, alleging claims of Paxil – Acts of violence As of February 2019, there were six pending claims or cases concerning allegations that patients who took paroxetine or Paxil In the one pending Canadian action, Carmichael, the Group has filed a motion for summary judgement based on the statute of limitations. – Discontinuation In the UK, a long-pending group action alleges that Seroxat However, more recently, Fortitude Law was engaged with the purpose of resurrecting the Seroxat On 8 December 2017, the High Court ruled in favour of the Group on its application for an order that the claimants’ litigation funder give security for costs for a sum in excess of the total funding it had committed to the case. The trial of the action is scheduled to commence in April 2019. Zofran Plaintiffs allege that their children suffered birth defects as a result of the mothers’ ingestion of Zofran Zofran Zofran “off-label” As of February 2019, the Group is a defendant in 430 personal injury lawsuits. All but two of the lawsuits are part of a multi-district litigation proceeding (“MDL”) in the US District Court for the District of Massachusetts. In the MDL, the parties are in the process of completing case-specific discovery and selecting cases for potential trials. While the court recently denied the Group’s motion for summary judgment based on a federal preemption argument, the Group continues to seek the dismissal of individual cases on other grounds as appropriate. GSK is also a defendant in four proposed class actions in Canada. There has been no significant activity in these four matters; however, the parties have recently agreed to a schedule for class certification proceedings in the matter pending in Ontario. Sales and marketing and regulation The Group’s marketing and promotion of its Pharmaceutical and Vaccine products are the subject of certain governmental investigations and private lawsuits brought by litigants under various theories of law. The Group has been able to make a reliable estimate of the expected financial effect of the matters discussed in this category and has included a provision for such matters in the provision for legal and other disputes, except as noted below. Matters for which the Group has made a provision are also noted in Note 29, ‘Other provisions’. SFO and SEC/DOJ Anti-corruption enquiries On 27 May 2014, the UK Serious Fraud Office (SFO) began a formal criminal investigation into the Group’s commercial operations in a number of countries, including China. The SFO inquiry followed investigations initiated by China’s Ministry of Public Security in June 2013 (the ‘China Investigations’), which resulted in a ruling in 2014 that, according to Chinese law, GSK China Investment Co. Ltd. (‘GSKCI’) had offered money or property to non-government non-government On 30 September 2016, the Group reached a global resolution with the US Securities and Exchange Commission (SEC) regarding the SEC’s investigation under the US Foreign Corrupt Practices Act (FCPA) into the Group’s commercial practices in countries outside of the US, including China. As part of the resolution, the Group agreed to pay a civil penalty of $20 million to the US Government. The US Department of Justice (DOJ) confirmed that it had concluded its investigation into the Group’s commercial practices and would take no action against the Group. As part of the resolution with the SEC, the Group agreed to certain undertakings, including a period of self-monitoring and reporting. The Group’s obligations under that resolution continued through 30 September 2018 and have now concluded. In the course of its inquiry, the SFO had requested additional information from the Group regarding third-party advisers engaged by the company in the course of the China Investigations. The SEC and DOJ are also investigating these matters following the Group’s reporting of the SFO’s inquiries. The Group is co-operating The Group is unable to make a reliable estimate of the expected financial effect of these investigations, and no provisions have been made for them. US Vaccines subpoena On 25 February 2016, the Group received a subpoena from the US Attorney’s Office for the Southern District of New York requesting documents relating to the Group’s Vaccines business. The Group responded to the subpoena and was informed by the government in 2018 that the government would be closing the matter without further action. Average wholesale price The Attorney General in Illinois filed suit against the Group and a number of other pharmaceutical companies claiming damages and restitution due to average wholesale price (AWP) and/or wholesale acquisition cost (WAC) price reporting for pharmaceutical products covered by the state’s Medicaid programmes. The case alleges that the Group reported or caused to be reported false AWP and WAC prices, which, in turn, allegedly caused the state Medicaid agency to reimburse providers more money for covered medicines than the agency intended. The state has sought recovery on behalf of itself as payer and on behalf of in-state Cidra third-party payer litigation On 25 July 2013, a number of major US healthcare insurers filed suit against the Group in the Philadelphia, Pennsylvania County Court of Common Pleas seeking compensation for reimbursements they made for medicines manufactured at the Group’s former Cidra plant in Puerto Rico. These insurers claim that the Group knowingly and illegally marketed and sold adulterated drugs manufactured under conditions non-compliant Anti-trust/competition Certain governmental actions and private lawsuits have been brought against the Group alleging violation of competition or anti-trust laws. The Group has been able to make a reliable estimate of the expected financial effect of the matters discussed in this category and has included a provision for such matters in the provision for legal and other disputes, except as noted below. Matters for which the Group has made a provision are also noted in Note 29, ‘Other provisions’. UK Competition and Markets Authority investigation On 12 February 2016, the UK Competition and Markets Authority (CMA) issued a decision fining the Group and two other pharmaceutical companies for infringement of the Competition Act. The CMA imposed a fine of £37.6 million on the Group, as well as fines totaling £7.4 million against the other companies. This relates to agreements to settle patent disputes between the Group and potential suppliers of generic paroxetine formulations, entered into between 2001 and 2003. The Group terminated the agreements at issue in 2004. The Group believes it has strong grounds for its appeal of the CMA’s finding to the Competition Appeal Tribunal (CAT) in order to overturn the fine or substantially reduce it. The appeal concluded in April 2017. The CAT delivered its initial judgement on the appeal on 8 March 2018, referring all the principle points at issue to the Court of Justice of the EU for a preliminary ruling. The matter will then return to the CAT for final judgement. No provision has been made for this matter. Lamictal Purported classes of direct and indirect purchasers filed suit in the US District Court for the District of New Jersey alleging that the Group and Teva Pharmaceuticals unlawfully conspired to delay generic competition for Lamictal On 26 June 2015, the Court of Appeals reversed the trial court’s decision to dismiss the case and remanded the action back to the trial court. On 18 May 2016, the trial court denied the indirect purchaser class plaintiffs’ motion for reconsideration of the Court’s dismissal of their claims. As a result, the indirect purchaser class representatives agreed to a settlement to exit the case and resolve their remaining claims. On 13 December 2018, the trial judge granted plaintiffs’ class certification motion, certifying a class of direct purchasers in this action. The Group is pursuing an appeal with the Court of Appeals regarding the class certification. Commercial and corporate The Group is a defendant in certain cases which allege violation of US federal securities and ERISA laws. The Group has been able to make a reliable estimate of the expected financial effect of the matters discussed in this category and has included a provision for such matters in the provision for legal and other disputes. Matters for which the Group has made a provision are also noted in Note 29, ‘Other provisions”. Securities/ERISA class actions – Stiefel On 12 December 2011, the US Securities and Exchange Commission (SEC) filed a formal complaint against Stiefel Laboratories, Inc., and Charles Stiefel in the US District Court for the District of Florida alleging that Stiefel and its principals violated federal securities laws by inducing Stiefel employees to sell their shares in the employee stock plan back to the company at a greatly undervalued price and without disclosing to employees that the company was about to be sold to the Group. The case was stayed while several private actions brought by former Stiefel employees proceeded through the courts but was returned to active status in early summer 2015. It is unclear when the case ultimately will be scheduled for trial. In addition to the SEC case, one private matter (the “Martinolich” case) remains. It is also pending in federal district court in Florida but has been stayed pending the trial of the SEC matter. The allegations in the Martinolich case largely track those in the SEC matter: the plaintiff, a former Stiefel employee, alleges that Stiefel and its officers and directors violated the US Employee Retirement Income Security Act (ERISA) and federal and state securities laws by inducing Stiefel employees to sell their shares in the employee stock plan back to Stiefel at a greatly undervalued price and without disclosing to employees that Stiefel was about to be sold to the Group. Environmental matters The Group has been notified of its potential responsibility relating to past operations and its past waste disposal practices at certain sites, primarily in the US. Some of these matters are the subject of litigation, including proceedings initiated by the US federal or state governments for waste disposal, site remediation costs and tort actions brought by private parties. The Group has been advised that it may be a responsible party at approximately 16 sites, of which nine appear on the National Priority List created by the Comprehensive Environmental Response Compensation and Liability Act (Superfund). These proceedings seek to require the operators of hazardous waste facilities, transporters of waste to the sites and generators of hazardous waste disposed of at the sites to clean up the sites or to reimburse the US Government for cleanup costs. In most instances, the Group is involved as an alleged generator of hazardous waste. Although Superfund provides that the defendants are jointly and severally liable for cleanup costs, these proceedings are frequently resolved on the basis of the nature and quantity of waste disposed of by the generator at the site. The Group’s proportionate liability for cleanup costs has been substantially determined for 18 of the sites referred to above. The Group’s potential liability varies greatly from site to site. The cost of investigation, study and remediation at such sites could, over time, be significant. The Group has made a provision for these matters, as noted in Note 29, ‘Other provisions’.

Post balance sheet events

Post balance sheet events	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Post balance sheet events	46. Post balance sheet events The agreement to acquire Tesaro, Inc. for $5.1 billion in cash, which was signed in December 2018, completed on 22 January 2019. On 31 January 2019, Mylan N.V. announced that the US Food and Drug Administration had approved their therapeutically equivalent generic of Advair Diskus

Presentation of the financial_2

Presentation of the financial statements (Policies)	12 Months Ended
	Dec. 31, 2018
Statement [LineItems]
Implementation of IFRS 9 and IFRS 15	Implementation of IFRS 9 ‘Financial instruments’ The Group has applied IFRS 9 ‘Financial instruments’ with effect from 1 January 2018. IFRS 9 introduces new requirements for the classification and measurement of financial assets and financial liabilities, impairments for financial assets and general hedge accounting. Details of these new requirements as well as their impact on the Group’s consolidated financial statements are described below. The Group has adopted IFRS 9 retrospectively but with certain permitted exceptions as detailed below. Classification and measurement of financial assets The date of initial application was 1 January 2018. The Group has not applied the requirements of IFRS 9 to instruments that were derecognised prior to 1 January 2018 and has not restated prior years. Any difference between the previous carrying amount and the revised carrying amount at 1 January 2018 has been recognised as an adjustment to opening retained earnings at 1 January 2018. All financial assets that are within the scope of IFRS 9 are required to be measured at amortised cost or fair value, with movements through other comprehensive income or the income statement on the basis of GSK’s business model for managing the financial assets and the contractual cash flow characteristics of the financial assets. IFRS 9 had the following impact on the Group’s assets: • The Group has elected to recognise movements in the fair value of equity investments in other comprehensive income under IFRS 9. Investments in equity instruments that were previously classified as available-for-sale • The Group’s investments in limited life funds included in Other investments that were previously classified as available-for-sale • Liquid investments that were classified as available-for-sale • Investments in money market funds included in Cash and cash equivalents that were classified as amortised cost financial assets under IAS 39 have been classified as FVTPL under IFRS 9 as the contractual cash flows are not solely payments of principal and interest on the principal amount outstanding. • The Group’s trade receivables were all classified as financial assets measured at amortised cost under IAS 39. Under IFRS 9, the business model under which each portfolio of trade receivables held has been assessed. The Group has portfolios in each of the three business models under IFRS 9: to collect the contractual cash flows (measured at amortised cost), to sell the contractual cash flows (measured at FVTPL), and both to collect and to sell the contractual cash flows (measured at FVTOCI). • Amounts receivable under insurance contracts included in Other non-current There were no material changes in carrying value of financial assets as a result of these changes in measurement basis. Impairment of financial assets IFRS 9 requires an expected credit loss (ECL) model to be applied to financial assets rather than the incurred credit loss model required under IAS 39. The expected credit loss model requires the Group to account for expected losses as a result of credit risk on initial recognition of financial assets and to recognise changes in those expected credit losses at each reporting date. 12-month reflecting lifetime ECLs using the simplified approach. An additional ECL allowance of £15 million for trade receivables was recognised on transition to IFRS 9. There were no other transition adjustments arising from the change in impairment basis. The additional ECL allowance of £15 million at 1 January 2018 has been recognised against opening retained earnings, together with a related deferred tax impact of £3 million. General hedge accounting The new general hedge accounting requirements retain the three types of hedge accounting which were available under IAS 39: fair value hedges, cash flow hedges and net investment hedges. However, the effectiveness testing requirements have been simplified. The Group has applied the IFRS 9 hedge accounting requirements prospectively from the date of initial application of 1 January 2018. All existing hedging relationships are eligible, and continued to be effective, under IFRS 9. Implementation of IFRS 15 ‘Revenue from contracts with customers’ The Group has applied IFRS 15 ‘Revenue from contracts with customers’ with effect from 1 January 2018. IFRS 15 provides a single, principles-based approach to the recognition of revenue from all contracts with customers. It focuses on the identification of performance obligations in a contract and requires revenue to be recognised when or as those performance obligations are satisfied. GSK adopted IFRS 15 applying the modified retrospective approach. IFRS 15 did not have a material impact on the amount or timing of recognition of reported revenue. At 1 January 2018, a cumulative adjustment to decrease retained earnings of £4 million was recognised. In accordance with the requirements of IFRS 15 where the modified retrospective approach is adopted, prior year results have not been restated. Impact of new standards on each financial statement line item The table below shows the amount of adjustment for each financial statement line item affected by the application of IFRS 9 and IFRS 15 at 1 January 2018. As IFRS 9 IFRS 15 As Trade and other receivables 6,000 (15 ) 0 5,985 Liquid investments 78 1 0 79 Other payables - returns and rebates (3,463 ) 0 (29 ) (3,492 ) Other payables - deferred income (240 ) 0 27 (213 ) Deferred tax assets 3,796 3 (2 ) 3,797 Total effect on net assets 3,489 (11 ) (4 ) 3,474 Fair value reserve 329 (288 ) 0 41 Retained earnings (6,477 ) 277 (4 ) (6,204 ) Total effect on equity 3,489 (11 ) (4 ) 3,474 The £288 million transfer between retained earnings and the fair value reserve resulted from the reclassification of previous impairment losses on equity investments now designated as measured at FVTOCI under IFRS 9 from retained earnings to the fair value reserve. The application of IFRS 9 and IFRS 15 has had no impact on the consolidated cash flows of the Group.
Consolidation	Consolidation The consolidated financial statements include: • the assets and liabilities, and the results and cash flows, of the company and its subsidiaries, including ESOP Trusts • the Group’s share of the results and net assets of associates and joint ventures • the Group’s share of assets, liabilities, revenue and expenses of joint operations. The financial statements of entities consolidated are made up to 31 December each year. Entities over which the Group has the power to direct the relevant activities so as to affect the returns to the Group, generally through control over the financial and operating policies, are accounted for as subsidiaries. Where the Group has the ability to exercise joint control over, and rights to the net assets of, entities, the entities are accounted for as joint ventures. Where the Group has the ability to exercise joint control over an arrangement, but has rights to specified assets and obligations for specified liabilities of the arrangement, the arrangement is accounted for as a joint operation. Where the Group has the ability to exercise significant influence over entities, they are accounted for as associates. The results and assets and liabilities of associates and joint ventures are incorporated into the consolidated financial statements using the equity method of accounting. The Group’s rights to assets, liabilities, revenue and expenses of joint operations are included in the consolidated financial statements in accordance with those rights and obligations. Interests acquired in entities are consolidated from the date the Group acquires control and interests sold are de-consolidated Transactions and balances between subsidiaries are eliminated and no profit before tax is taken on sales between subsidiaries until the products are sold to customers outside the Group. The relevant proportion of profits on transactions with joint ventures, joint operations and associates is also deferred until the products are sold to third parties. Transactions with non-controlling
Business combinations	Business combinations Business combinations are accounted for using the acquisition accounting method. Identifiable assets, liabilities and contingent liabilities acquired are measured at fair value at acquisition date. The consideration transferred is measured at fair value and includes the fair value of any contingent consideration. The fair value of contingent consideration liabilities are re-assessed The part of each payment relating to the original estimate of the fair value of the contingent consideration on acquisition is reported within investing activities in the cash flow statement and the part of each payment relating to the increase in the liability since the acquisition date is reported within operating cash flows. Where the consideration transferred, together with the non-controlling Goodwill is capitalised as a separate item in the case of subsidiaries and as part of the cost of investment in the case of joint ventures and associates. Goodwill is denominated in the currency of the operation acquired. Where the cost of acquisition is below the fair value of the net assets acquired, the difference is recognised directly in the income statement. Where not all of the equity of a subsidiary is acquired the non-controlling non-controlling case-by-case
Foreign currency translation	Foreign currency translation Foreign currency transactions are booked in the functional currency of the Group company at the exchange rate ruling on the date of transaction. Foreign currency monetary assets and liabilities are retranslated into the functional currency at rates of exchange ruling at the balance sheet date. Exchange differences are included in the income statement. On consolidation, assets and liabilities, including related goodwill, of overseas subsidiaries, associates and joint ventures, are translated into Sterling at rates of exchange ruling at the balance sheet date. The results and cash flows of overseas subsidiaries, associates and joint ventures are translated into Sterling using average rates of exchange. Exchange adjustments arising when the opening net assets and the profits for the year retained by overseas subsidiaries, associates and joint ventures are translated into Sterling, less exchange differences arising on related foreign currency borrowings which hedge the Group’s net investment in these operations, are taken to a separate component of equity. When translating into Sterling the assets, liabilities, results and cash flows of overseas subsidiaries, associates and joint ventures which are reported in currencies of hyper-inflationary economies, adjustments are made where material to reflect current price levels. Any loss on net monetary assets is charged to the consolidated income statement.
Revenue	Revenue (applicable from 1 January 2018) The Group receives revenue for supply of goods to external customers against orders received. The majority of contracts that GSK enters into relate to sales orders containing single performance obligations for the delivery of pharmaceutical, vaccine and consumer healthcare products. The average duration of a sales order is less than 12 months. Product revenue is recognised when control of the goods is passed to the customer. The point at which control passes is determined by each customer arrangement, but generally occurs on delivery to the customer. Product revenue represents net invoice value including fixed and variable consideration. Variable consideration arises on the sale of goods as a result of discounts and allowances given and accruals for estimated future returns and rebates. Revenue is not recognised in full until it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur. The methodology and assumptions used to estimate rebates and returns are monitored and adjusted regularly in the light of contractual and legal obligations, historical trends, past experience and projected market conditions. Once the uncertainty associated with the returns and rebates is resolved, revenue is adjusted accordingly. GSK enters into development and marketing collaborations and out-licences Income dependent on the achievement of a development milestone is recognised when it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur, which is usually when the related event occurs. Sales-based milestone income is recognised when it is highly probable that the sales threshold will be reached. Sales-based royalties on a licence of intellectual property are not recognised until the relevant product sale occurs. If the time between the recognition of revenue and payment from the customer is expected to be more than one year and the impact is material, the amount of consideration is discounted using appropriate discount rates. Value added tax and other sales taxes are excluded from revenue.
Expenditure	Expenditure Expenditure is recognised in respect of goods and services received when supplied in accordance with contractual terms. Provision is made when an obligation exists for a future liability in respect of a past event and where the amount of the obligation can be reliably estimated. Manufacturing start-up Restructuring costs are recognised and provided for, where appropriate, in respect of the direct expenditure of a business reorganisation where the plans are sufficiently detailed and well advanced, and where appropriate communication to those affected has been undertaken.
Research and development	Research and development Research and development expenditure is charged to the income statement in the period in which it is incurred. Development expenditure is capitalised when the criteria for recognising an asset are met, usually when a regulatory filing has been made in a major market and approval is considered highly probable. Property, plant and equipment used for research and development is capitalised and depreciated in accordance with the Group’s policy.
Environmental expenditure	Environmental expenditure Environmental expenditure related to existing conditions resulting from past or current operations and from which no current or future benefit is discernible is charged to the income statement. The Group recognises its liability on a site-by-site clean-up
Legal and other disputes	Legal and other disputes Provision is made for the anticipated settlement costs of legal or other disputes against the Group where an outflow of resources is considered probable and a reliable estimate can be made of the likely outcome. In addition, provision is made for legal or other expenses arising from claims received or other disputes. In respect of product liability claims related to certain products, there is sufficient history of claims made and settlements to enable management to make a reliable estimate of the provision required to cover unasserted claims. In certain cases, an incurred but not reported (IBNR) actuarial technique is used to determine this estimate. The Group may become involved in legal proceedings, in respect of which it is not possible to make a reliable estimate of the expected financial effect, if any, that could result from ultimate resolution of the proceedings. In these cases, appropriate disclosure about such cases would be included but no provision would be made. Costs associated with claims made by the Group against third parties are charged to the income statement as they are incurred.
Pensions and other post-employment benefits	Pensions and other post-employment benefits The costs of providing pensions under defined benefit schemes are calculated using the projected unit credit method and spread over the period during which benefit is expected to be derived from the employees’ services, consistent with the advice of qualified actuaries. Pension obligations are measured as the present value of estimated future cash flows discounted at rates reflecting the yields of high-quality corporate bonds. Pension scheme assets are measured at fair value at the balance sheet date. The costs of other post-employment liabilities are calculated in a similar way to defined benefit pension schemes and spread over the period during which benefit is expected to be derived from the employees’ services, in accordance with the advice of qualified actuaries. Actuarial gains and losses and the effect of changes in actuarial assumptions, are recognised in the statement of comprehensive income in the year in which they arise. The Group’s contributions to defined contribution plans are charged to the income statement as incurred.
Employee share plans	Employee share plans Incentives in the form of shares are provided to employees under share option and share award schemes. The fair values of these options and awards are calculated at their grant dates using a Black-Scholes option pricing model and charged to the income statement over the relevant vesting periods. The Group provides finance to ESOP Trusts to purchase company shares to meet the obligation to provide shares when employees exercise their options or awards. Costs of running the ESOP Trusts are charged to the income statement. Shares held by the ESOP Trusts are deducted from other reserves. A transfer is made between other reserves and retained earnings over the vesting periods of the related share options or awards to reflect the ultimate proceeds receivable from employees on exercise.
Property, plant and equipment	Property, plant and equipment Property, plant and equipment (PP&E) is stated at the cost of purchase or construction, less provisions for depreciation and impairment. Financing costs are capitalised within the cost of qualifying assets in construction. Depreciation is calculated to write off the cost less residual value of PP&E, excluding freehold land, using the straight-line basis over the expected useful life. Residual values and lives are reviewed, and where appropriate adjusted annually. The normal expected useful lives of the major categories of PP&E are: Freehold buildings 20 to 50 years Leasehold land and buildings Lease term or 20 to 50 years Plant and machinery 10 to 20 years Equipment and vehicles 3 to 10 years On disposal of PP&E, the cost and related accumulated depreciation and impairments are removed from the financial statements and the net amount, less any proceeds, is taken to the income statement.
Leases	Leases Leasing agreements which transfer to the Group substantially all the benefits and risks of ownership of an asset are treated as finance leases, as if the asset had been purchased outright. The assets are included in PP&E or computer software and the capital elements of the leasing commitments are shown as obligations under finance leases. Assets held under finance leases are depreciated on a basis consistent with similar owned assets or the lease term, if shorter. The interest element of the lease rental is included in the income statement. All other leases are operating leases and the rental costs are charged to the income statement on a straight-line basis over the lease term.
Goodwill	Goodwill Goodwill is stated at cost less impairments. Goodwill is deemed to have an indefinite useful life and is tested for impairment at least annually. Where the fair value of the interest acquired in an entity’s assets, liabilities and contingent liabilities exceeds the consideration paid, this excess is recognised immediately as a gain in the income statement.
Other intangible assets	Other intangible assets Intangible assets are stated at cost less provisions for amortisation and impairments. Licences, patents, know-how non-exclusivity. Contingent milestone payments are recognised at the point that the contingent event becomes probable. Any development costs incurred by the Group and associated with acquired licences, patents, know-how Acquired brands are valued independently as part of the fair value of businesses acquired from third parties where the brand has a value which is substantial and long term and where the brands either are contractual or legal in nature or can be sold separately from the rest of the businesses acquired. Brands are amortised over their estimated useful lives of up to 20 years, except where it is considered that the useful economic life is indefinite. The costs of acquiring and developing computer software for internal use and internet sites for external use are capitalised as intangible fixed assets where the software or site supports a significant business system and the expenditure leads to the creation of a durable asset. ERP systems software is amortised over seven to ten years and other computer software over three to five years.
Impairment of non-current assets	Impairment of non-current The carrying values of all non-current Impairments of goodwill are not reversed. Impairment losses on other non-current
Investments in associates, joint ventures and joint operations	Investments in associates, joint ventures and joint operations Investments in associates and joint ventures are carried in the consolidated balance sheet at the Group’s share of their net assets at date of acquisition and of their post-acquisition retained profits or losses together with any goodwill arising on the acquisition. The Group recognises its rights to assets, liabilities, revenue and expenses of joint operations. Expected credit losses are recognised in the income statement on financial assets measured at amortised cost and at fair value through other comprehensive income apart from equity investments.
Inventories	Inventories Inventories are included in the financial statements at the lower of cost (including raw materials, direct labour, other direct costs and related production overheads) and net realisable value. Cost is generally determined on a first in, first out basis. Pre-launch
Financial assets	Financial assets Financial assets are measured at amortised cost, fair value through other comprehensive income (FVTOCI) or fair value through profit or loss (FVTPL). The measurement basis is determined by reference to both the business model for managing the financial asset and the contractual cash flow characteristics of the financial asset. For financial assets other than trade receivables a 12-month
Other investments	Other investments Other investments comprise equity investments and investments in limited life funds. The Group has elected to designate equity investments as measured at FVTOCI. They are initially recorded at fair value plus transaction costs and then remeasured at subsequent reporting dates to fair value. Unrealised gains and losses are recognised in other comprehensive income. On disposal of the equity investment, gains and losses that have been deferred in other comprehensive Income are transferred directly to retained earnings. Investments in limited life funds are measured at FVTPL. They are initially recorded at fair value and then remeasured at subsequent reporting dates to fair value. Unrealised gains and losses are recognised in the income statement. Dividends on equity investments and distributions from funds are recognised in the income statement when the Group’s right to receive payment is established. Purchases and sales of Other investments are accounted for on the trade date.
Trade receivables	Trade receivables Trade receivables are measured in accordance with the business model under which each portfolio of trade receivables is held. The Group has portfolios in each of the three business models under IFRS 9: to collect the contractual cash flows (measured at amortised cost), to sell the contractual cash flows (measured at FVTPL), and both to collect and to sell the contractual cash flows (measured at FVTOCI). Trade receivables measured at amortised cost are carried at the original invoice amount less allowances for expected credit losses. Expected credit losses are calculated in accordance with the simplified approach permitted by IFRS 9, using a provision matrix applying lifetime historical credit loss experience to the trade receivables. The expected credit loss rate varies depending on whether and the extent to which settlement of the trade receivables is overdue and it is also adjusted as appropriate to reflect current economic conditions and estimates of future conditions. For the purpose of determining credit loss rates, customers are classified into groupings that have similar loss patterns. The key drivers of the loss rate are the nature of the business unit and the location and type of customer. When a trade receivable is determined to have no reasonable expectation of recovery it is written off, firstly against any expected credit loss allowance available and then to the income statement. Subsequent recoveries of amounts previously provided for or written off are credited to the income statement. Long-term receivables are discounted where the effect is material.
Cash and cash equivalents	Cash and cash equivalents Cash held in deposit accounts is measured at amortised cost. Investments in money market funds are held at fair value through profit or loss.
Borrowings	Borrowings All borrowings are initially recorded at the amount of proceeds received, net of transaction costs. Borrowings are subsequently carried at amortised cost, with the difference between the proceeds, net of transaction costs, and the amount due on redemption being recognised as a charge to the income statement over the period of the relevant borrowing.
Derivative financial instruments	Derivative financial instruments Derivative financial instruments are used to manage exposure to market risks. The principal derivative instruments used by GSK are foreign currency swaps, interest rate swaps, foreign exchange forward contracts and options. The Group does not hold or issue derivative financial instruments for trading or speculative purposes. Derivative financial assets and liabilities, including derivatives embedded in host contracts which have been separated from the host contract, are classified as held-for-trading
Hedge accounting	Hedge accounting Derivatives designated as hedging instruments are classified on inception as cash flow hedges, net investment hedges or fair value hedges. Changes in the fair value of derivatives designated as cash flow hedges are recognised in other comprehensive income to the extent that the hedges are effective. Ineffective portions are recognised in profit or loss immediately. Amounts deferred in other comprehensive income are reclassified to the income statement when the hedged item affects profit or loss. Net investment hedges are accounted for in a similar way to cash flow hedges. Changes in the fair value of derivatives designated as fair value hedges are recorded in the income statement, together with the changes in the fair value of the hedged asset or liability.
Taxation	Taxation Current tax is provided at the amounts expected to be paid applying tax rates that have been enacted or substantively enacted by the balance sheet date. Deferred tax is provided in full, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the financial statements. Deferred tax assets are recognised to the extent that it is probable that future taxable profits will be available against which the temporary differences can be utilised. Deferred tax is provided on temporary differences arising on investments in subsidiaries, associates and joint ventures, except where the timing of the reversal of the temporary difference can be controlled and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is provided using rates of tax that have been enacted or substantively enacted by the balance sheet date. Where an uncertain tax position is identified, management will make a judgement as to what the probable outcome will be. Where it is assessed that an economic outflow is probable to arise a provision is made for the best estimate of the liability. In estimating any such liability GSK applies a risk-based approach which takes into account, as appropriate, the probability that the Group would be able to obtain compensatory adjustments under international tax treaties. These estimates take into account the specific circumstances of each dispute and relevant external advice.
Discounting	Discounting Where the time value of money is material, balances are discounted to current values using appropriate discount rates. The unwinding of the discounts is recorded in finance income and finance expense.
Previously stated [member]
Statement [LineItems]
Revenue	Revenue (applicable up to 31 December 2017) Revenue is recognised in the income statement when goods or services are supplied or made available to external customers against orders received, title and risk of loss is passed to the customer, reliable estimates can be made of relevant deductions and all relevant obligations have been fulfilled, such that the earnings process is regarded as being complete. Turnover represents net invoice value after the deduction of discounts and allowances given and accruals for estimated future rebates and returns. The methodology and assumptions used to estimate rebates and returns are monitored and adjusted regularly in the light of contractual and legal obligations, historical trends, past experience and projected market conditions. Market conditions are evaluated using wholesaler and other third-party analyses, market research data and internally generated information. Value added tax and other sales taxes are excluded from revenue. Where the Group co-promotes a product and the counterparty records the sale, the Group records its share of revenue as co-promotion co-promotion Royalty income is recognised on an accruals basis in accordance with the terms of the relevant licensing agreements.
Trade receivables	Trade receivables Trade receivables are carried at original invoice amount less any provisions for doubtful debts. Provisions are made where there is evidence of a risk of non-payment, Subsequent recoveries of amounts previously provided for are credited to the income statement. Long-term receivables are discounted where the effect is material.
Borrowings	Borrowings All borrowings are initially recorded at the amount of proceeds received, net of transaction costs. Borrowings are subsequently carried at amortised cost, with the difference between the proceeds, net of transaction costs, and the amount due on redemption being recognised as a charge to the income statement over the period of the relevant borrowing.
Available-for-sale investments	Available-for-sale Liquid investments and other investments are classified as available-for-sale available-for-sale On disposal or impairment of the investments, any gains and losses that have been deferred in other comprehensive income are reclassified to the income statement. Dividends on equity investments are recognised in the income statement when the Group’s right to receive payment is established. Equity investments are recorded in non-current Purchases and sales of equity investments are accounted for on the trade date and purchases and sales of other available-for-sale
Derivative financial instruments and hedging	Derivative financial instruments and hedging Derivative financial instruments are used to manage exposure to market risks. The principal derivative instruments used by GSK are foreign currency swaps, interest rate swaps, foreign exchange forward contracts and options. The Group does not hold or issue derivative financial instruments for trading or speculative purposes. Derivative financial instruments are classified as held-for-trading Changes in the fair value of derivatives designated as cash flow hedges are recognised in other comprehensive income to the extent that the hedges are effective. Ineffective portions are recognised in profit or loss immediately. Amounts deferred in other comprehensive income are reclassified to the income statement when the hedged item affects profit or loss. Net investment hedges are accounted for in a similar way to cash flow hedges. Changes in the fair value of derivatives designated as fair value hedges are recorded in the income statement, together with the changes in the fair value of the hedged asset or liability. Changes in the fair value of any derivative instruments that do not qualify for hedge accounting are recognised immediately in the income statement.

Presentation of the financial_3

Presentation of the financial statements (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Amount of Adjustment for Each Financial Statement Line Item Affected by Application of IFRS 9 and IFRS 15	The table below shows the amount of adjustment for each financial statement line item affected by the application of IFRS 9 and IFRS 15 at 1 January 2018. As IFRS 9 IFRS 15 As Trade and other receivables 6,000 (15 ) 0 5,985 Liquid investments 78 1 0 79 Other payables - returns and rebates (3,463 ) 0 (29 ) (3,492 ) Other payables - deferred income (240 ) 0 27 (213 ) Deferred tax assets 3,796 3 (2 ) 3,797 Total effect on net assets 3,489 (11 ) (4 ) 3,474 Fair value reserve 329 (288 ) 0 41 Retained earnings (6,477 ) 277 (4 ) (6,204 ) Total effect on equity 3,489 (11 ) (4 ) 3,474

Accounting principles and pol_2

Accounting principles and policies (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Expected Useful Lives of Property Plant and Equipment	The normal expected useful lives of the major categories of PP&E are: Freehold buildings 20 to 50 years Leasehold land and buildings Lease term or 20 to 50 years Plant and machinery 10 to 20 years Equipment and vehicles 3 to 10 years

Exchange rates (Tables)

Exchange rates (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Currencies Translations and Relevant Exchange Rates	The currencies which most influence these translations and the relevant exchange rates were: 2018 2017 2016 Average rates: US$/£ 1.33 1.30 1.36 Euro/£ 1.13 1.15 1.23 Yen/£ 147 145 149 2018 2017 2016 Period end rates: US$/£ 1.27 1.35 1.24 Euro/£ 1.11 1.13 1.17 Yen/£ 140 152 144

Turnover and segment informat_2

Turnover and segment information (Tables)	12 Months Ended
	Dec. 31, 2018
Statement [LineItems]
Turnover by Segment	2018 2017 2016 Turnover by segment £m £m £m Pharmaceuticals 17,269 17,276 16,104 Vaccines 5,894 5,160 4,592 Consumer Healthcare 7,658 7,750 7,193 30,821 30,186 27,889
Segment Profit and Operating Profit	2018 2017 2016 Segment profit £m £m £m Pharmaceuticals 8,420 8,667 7,976 Pharmaceuticals R&D (2,676 ) (2,740 ) (2,488 ) Pharmaceuticals, including R&D 5,744 5,927 5,488 Vaccines 1,943 1,644 1,429 Consumer Healthcare 1,517 1,373 1,116 Segment profit 9,204 8,944 8,033 Corporate and other unallocated costs (459 ) (376 ) (362 ) Other reconciling items between segment profit and operating profit (3,262 ) (4,481 ) (5,073 ) Operating profit 5,483 4,087 2,598 Finance income 81 65 72 Finance costs (798 ) (734 ) (736 ) Profit on disposal of interest in associates 3 94 — Share of after tax profits of associates and joint ventures 31 13 5 Profit before taxation 4,800 3,525 1,939 Taxation (754 ) (1,356 ) (877 ) Profit after taxation for the year 4,046 2,169 1,062 2018 2017 2016 Depreciation and amortisation by segment £m £m £m Pharmaceuticals 506 551 440 Pharmaceuticals R&D 123 96 211 Pharmaceuticals, including R&D 629 647 651 Vaccines 395 405 315 Consumer Healthcare 146 135 126 Segment depreciation and amortisation 1,170 1,187 1,092 Corporate and other unallocated depreciation and amortisation 106 144 94 Other reconciling items between segment depreciation and amortisation and total depreciation and amortisation 580 591 588 Total depreciation and amortisation 1,856 1,922 1,774 PP&E, intangible asset and goodwill impairment by segment 2018 £m 2017 2016 Pharmaceuticals 51 38 29 Pharmaceuticals R&D 15 10 88 Pharmaceuticals, including R&D 66 48 117 Vaccines 5 13 34 Consumer Healthcare 4 10 46 Segment impairment 75 71 197 Corporate and other unallocated impairment 14 3 24 Other reconciling items between segment impairment and total impairment 261 995 68 Total impairment 350 1,069 289 PP&E and intangible asset impairment reversals by segment Pharmaceuticals (4 ) (13 ) (15 ) Pharmaceuticals R&D (1 ) (2 ) (10 ) Pharmaceuticals, including R&D (5 ) (15 ) (25 ) Vaccines 0 — (19 ) Consumer Healthcare 0 (1 ) (8 ) Segment impairment reversals (5 ) (16 ) (52 ) Corporate and other unallocated impairment reversals 0 — (26 ) Other reconciling items between segment impairment reversals and total impairment reversals (8 ) (36 ) (9 ) Total impairment reversals (13 ) (52 ) (87 ) Net assets by segment 2018 £m 2017 Pharmaceuticals 869 2,017 Pharmaceuticals R&D 502 522 Pharmaceuticals, including R&D 1,371 2,539 Vaccines 9,966 9,707 Consumer Healthcare 10,559 2,003 Segment net operating assets 21,896 14,249 Corporate and other unallocated net operating assets 1,141 868 Net operating assets 23,037 15,117 Net debt (21,621 ) (13,178 ) Investments in associates and joint ventures 236 183 Derivative financial instruments 129 2 Current and deferred taxation 1,723 1,252 Assets held for sale (excluding cash and cash equivalents) 168 113 Net assets 3,672 3,489
Summary of Geographical Information	Geographical information The UK is regarded as being the Group’s country of domicile. Turnover by location of customer 2018 2017 2016 UK 923 940 1,056 US 11,982 11,263 10,197 Rest of World 17,916 17,983 16,636 External turnover 30,821 30,186 27,889 Non-current 2018 2017 UK 6,118 6,824 US 7,540 6,841 Rest of World 20,768 20,901 Non-current 34,426 34,566
Pharmaceuticals [member]
Statement [LineItems]
Turnover by Product & Service	2018 2017 2016 Pharmaceuticals turnover by therapeutic area £m £m £m Respiratory 6,928 6,991 6,510 HIV 4,722 4,350 3,556 Immuno-inflammation 472 377 340 Established Pharmaceuticals 5,147 5,558 5,698 17,269 17,276 16,104
Vaccines [member]
Statement [LineItems]
Turnover by Product & Service	2018 2017 2016 Vaccines turnover by category £m £m £m Meningitis 881 890 662 Influenza 523 488 414 Shingles 784 22 — Established Vaccines 3,706 3,760 3,516 5,894 5,160 4,592
Consumer Healthcare [member]
Statement [LineItems]
Turnover by Product & Service	2018 2017 2016 Consumer Healthcare turnover by category £m £m £m Wellness 3,940 4,001 3,726 Oral care 2,496 2,466 2,223 Nutrition 643 680 674 Skin health 579 603 570 7,658 7,750 7,193

Other operating income_(expen_2

Other operating income/(expense) (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary Information about Other Operating Income Expense	2018 2017 2016 £m £m £m Fair value remeasurements of equity investments under IFRS 9 16 Disposal of businesses and assets 258 195 283 Fair value remeasurements on contingent consideration recognised in business combinations (1,252 ) (1,012 ) (2,205 ) Remeasurement of ViiV Healthcare put option liabilities and preferential dividends 58 13 (577 ) Remeasurement of Consumer Healthcare put option liability (658 ) (1,186 ) (1,133 ) Fair value adjustments on derivative financial instruments (3 ) 9 (3 ) Other (expense)/income (7 ) 9 23 Impairment of available-for-sale (30 ) (47 ) Disposal of available-for-sale 37 254 (1,588 ) (1,965 ) (3,405 )

Operating profit (Tables)

Operating profit (Tables)	12 Months Ended
	Dec. 31, 2018
Statement [LineItems]
Summary of Information About Profit Loss	The following items have been included in operating profit: 2018 2017 2016 Employee costs (Note 9) 9,440 9,122 8,212 Advertising 1,376 1,351 1,265 Distribution costs 389 405 395 Depreciation of property, plant and equipment 954 988 978 Impairment of property, plant and equipment, net of reversals 203 327 180 Amortisation of intangible assets 902 934 796 Impairment of intangible assets, net of reversals 134 690 22 Net foreign exchange losses 81 215 53 Inventories: Cost of inventories included in cost of sales 8,713 8,526 8,093 Write-down of inventories 695 701 533 Reversal of prior year write-down of inventories (302 ) (352 ) (145 ) Operating lease rentals: Minimum lease payments 188 110 91 Contingent rents 12 4 4 Sub-lease 5 5 4 Fees payable to the company’s auditor and its associates in relation to the Group (see below) 29.8 29.2 29.7
Summary of Auditors Remuneration	Fees payable to the company’s auditor and its associates: 2018 2017 2016 Audit of parent company and consolidated financial statements 6.7 7.0 5.8 Audit of the company’s subsidiaries 12.9 16.2 16.4 Attestation under s.404 of Sarbanes-Oxley Act 2002 6.6 4.5 4.4 Audit and audit-related services 26.2 27.7 26.6 Taxation compliance 0.1 0.2 0.2 Taxation advice 0 0.1 1.8 Other assurance services 3.0 1.0 0.3 All other services 0.5 0.2 0.8 29.8 29.2 29.7
Pension schemes [member]
Statement [LineItems]
Summary of Auditors Remuneration	In addition to the above, fees paid in respect of the GSK pension schemes were: 2018 2017 2016 Audit 0.3 0.3 0.4 Other services 0 0.1 —

Employee costs (Tables)

Employee costs (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Employee Costs	2018 2017 2016 £m £m £m Wages and salaries 7,203 7,116 6,391 Social security costs 795 802 733 Pension and other post-employment costs, including augmentations (Note 28) 586 616 541 Cost of share-based incentive plans 393 347 338 Severance and other costs from integration and restructuring activities 463 241 209 9,440 9,122 8,212
Summary of Cost of Share-based Incentive Plans	The cost of share-based incentive plans is analysed as follows: 2018 2017 2016 £m £m £m Share Value Plan 304 276 271 Performance Share Plan 49 47 39 Share option plans 4 4 4 Cash settled and other plans 36 20 24 393 347 338
Disclosure of Average Monthly Number of Persons Employed by the Group (Including Directors)	The average monthly number of persons employed by the Group (including Directors) during the year was: 2018 Number 2017 2016 Manufacturing 37,296 38,632 38,611 Selling, general and administration 47,887 49,141 49,961 Research and development 11,668 11,576 11,255 96,851 99,349 99,827
Summary of Compensation of the Directors and Senior Management	The compensation of the Directors and Senior Management (members of the CET) in aggregate, was as follows: 2018 2017 2016 Wages and salaries 29 26 25 Social security costs 3 4 4 Pension and other post-employment costs 3 3 2 Cost of share-based incentive plans 20 22 15 55 55 46

Major restructuring costs (Tabl

Major restructuring costs (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Analysis of Costs Charged to Operating Profit	The analysis of the costs charged to operating profit under these programmes was as follows: 2018 2017 2016 Increase in provision for Major restructuring programmes (see Note 29) 450 259 163 Amount of provision reversed unused (see Note 29) (99 ) (43 ) (140 ) Impairment losses recognised 130 278 158 Other non-cash 72 247 108 Other cash costs 256 315 681 809 1,056 970
Summary of Major Restructuring Charges	The analysis of Major restructuring charges by income statement line was as follows: 2018 2017 2016 Cost of sales 443 545 297 Selling, general and administration 315 248 514 Research and development 49 263 159 Other operating income/(expense) 2 — — 809 1,056 970

Finance income (Tables)

Finance income (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Finance Income	2018 2017 2016 Year to 31 December 2018 under IFRS 9 Finance income arising from: Financial assets measured at amortised cost 73 Financial assets measured at fair value through profit or loss 1 Net gains arising from hedge ineffectiveness on net investment hedges 7 Years to 31 December 2017 and 31 December 2016 under IAS 39 Interest income arising from: Cash and cash equivalents 60 67 Available-for-sale 2 1 Loans and receivables 1 2 Fair value adjustments on derivatives at fair value through profit or loss 2 2 81 65 72

Finance expense (Tables)

Finance expense (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Finance Cost	2018 2017 2016 £m £m £m Finance expense arising on: Financial liabilities at amortised cost (677 ) (698 ) (671 ) Derivatives at fair value through profit or loss (38 ) (22 ) (30 ) Net losses arising from: Financial instruments mandatorily measured at fair value through profit or loss 3 (4 ) (3 ) Reclassification of hedges from other comprehensive income (2 ) — (1 ) Unwinding of discounts on provisions (15 ) (16 ) (16 ) Other finance expense (69 ) 6 (15 ) (798 ) (734 ) (736 )

Associates and joint ventures (

Associates and joint ventures (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of After Tax Profits and Losses of Associates and Joint Ventures	The Group’s share of after tax profits and losses of associates and joint ventures is set out below: 2018 2017 2016 Share of after tax profits of associates 28 16 9 Share of after tax profits/(losses) of joint ventures 3 (3 ) (4 ) 31 13 5
Summary of Group Held for Significant Associate	Summarised income statement information in respect of Innoviva is set out below for the periods in which the Group accounted for its investment in Innoviva as an associate. The Group’s 2018 share of after tax profits of associates and other comprehensive income includes a profit of £33 million and other comprehensive income of £nil in respect of Innoviva. 2018 2017 2016 Turnover 183 165 98 Profit after taxation 134 103 44 Other comprehensive income 0 — — Total comprehensive income 134 103 44
Summary of Aggregated Financial Information	Aggregated financial information in respect of GSK’s share of other associated undertakings and joint ventures is set out below: 2018 2017 2016 Share of turnover 242 252 133 Share of after tax (losses)/profits (2 ) (5 ) (1 ) Share of other comprehensive income 0 — — Share of total comprehensive (expense)/income (2 ) (5 ) (1 )

Taxation (Tables)

Taxation (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Taxation Charge Based on Profits	Taxation charge based on profits for the year 2018 2017 2016 UK current year charge 234 199 241 Rest of World current year charge 1,426 1,928 1,326 Credit in respect of prior periods (492 ) (508 ) (149 ) Total current taxation 1,168 1,619 1,418 Total deferred taxation (414 ) (263 ) (541 ) Total tax 754 1,356 877
Summary of Reconciliation of Tax Charge Calculated at the UK Statutory Rate on the Group Profit Before Tax with the Actual Tax Charge	The following table reconciles the tax charge calculated at the UK statutory rate on the Group profit before tax with the actual tax charge for the year. Reconciliation of taxation on Group profits 2018 2018 2017 2017 2016 2016 Profit before tax 4,800 3,525 1,939 UK statutory rate of taxation 912 19.0 679 19.25 388 20.0 Differences in overseas taxation rates 675 14.1 635 18.0 593 30.6 Benefit of intellectual property incentives (522 ) (10.9 ) (458 ) (13.0 ) (321 ) (16.5 ) R&D credits (73 ) (1.5 ) (75 ) (2.1 ) (93 ) (4.8 ) FV remeasurement of non-taxable 221 4.6 227 6.4 340 17.5 Tax losses where no benefit is recognised 24 0.5 28 0.8 (15 ) (0.8 ) Permanent differences on disposals and acquisitions (7 ) (0.1 ) 4 0.1 (21 ) (1.1 ) Other permanent differences 85 1.7 196 5.6 122 6.3 Re-assessments (436 ) (9.1 ) (475 ) (13.5 ) (116 ) (6.0 ) US and Swiss Tax Reform (125 ) (2.6 ) 595 16.9 Tax charge/tax rate 754 15.7 1,356 38.5 877 45.2
Summary of Tax on Items Charged to Equity and Statement of Comprehensive Income	Future tax charges, and therefore the Group’s effective tax rate, may be affected by factors such as acquisitions, disposals, restructuring, the location of research and development activity, tax regime reforms and resolution of open matters as tax affairs are brought up to date around the world. 2018 2017 2016 Tax on items charged to equity and statement of comprehensive income £m £m £m Current taxation Share-based payments 0 — 7 Defined benefit plans (2 ) 26 32 (2 ) 26 39 Deferred taxation Share-based payments 2 (4 ) — Defined benefit plans (144 ) (247 ) 94 Fair value movements on cash flow hedges (2 ) — 2 Fair value movements on equity investments 10 29 51 (134 ) (222 ) 147 Total (charge)/credit to equity and statement of comprehensive income (136 ) (196 ) 186
Summary of Movement in Deferred Tax Assets and Liabilities	Movement in deferred tax assets and liabilities Accelerated Intangible Contingent Intra-Group Pensions & Tax Share Other Total At 1 January 2017 (377 ) (2,324 ) 1,138 1,054 1,262 227 110 1,350 2,440 Exchange adjustments (7 ) 75 — (58 ) (48 ) (5 ) (4 ) (18 ) (65 ) Credit/(charge) to income statement 62 330 (52 ) 256 3 59 (1 ) (88 ) 569 Credit/(charge) to income statement associated with US tax reform 5 116 (218 ) (235 ) (210 ) (20 ) (27 ) (216 ) (805 ) Credit to income statement associated with Swiss tax reform — 483 — — — — — — 483 (Charge)/credit to statement of comprehensive income and equity — — — — (247 ) — (4 ) 29 (222 ) At 1 January 2018 (317 ) (1,320 ) 868 1,017 760 261 74 1,057 2,400 Exchange adjustments (6 ) (4 ) 0 43 38 2 2 9 84 Credit/(charge) to income statement (12 ) 365 (34 ) (31 ) 33 183 (7 ) (101 ) 396 Credit/(charge) to statement of comprehensive income and equity 0 0 0 0 (144 ) 0 2 8 (134 ) Reclassification on disposal 0 0 0 0 7 1 0 (23 ) (15 ) At 31 December 2018 (335 ) (959 ) 834 1,029 694 447 71 950 2,731
Summary of Net Temporary Differences Include Accrued Expenses	Deferred tax asset and liabilities are recognised on the balance sheet as follows: 2018 2017 £m £m Deferred tax assets 3,887 3,796 Deferred tax liabilities (1,156 ) (1,396 ) 2,731 2,400
Summary of Temporary Difference Unused Tax Losses and Unused Tax Credits	Deferred tax assets are recognised on US foreign tax credits only where it is probable that future taxable profits will be available. The net amount of foreign tax credits on which deferred tax has not been provided was £114 million at 31 December 2018 (2017 – £151 million). 2018 2017 Unrecognised Unrecognised deferred tax deferred tax Tax losses asset Tax losses asset Unrecognised tax losses £m £m £m £m Trading losses expiring: Within 10 years 678 148 802 187 More than 10 years 957 93 872 99 Available indefinitely 89 15 86 14 At 31 December 1,724 256 1,760 300 Capital losses expiring: Available indefinitely 2,042 399 1,924 372 At 31 December 2,042 399 1,924 372

Earnings per share (Tables)

Earnings per share (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Basic and Diluted Earnings Per Share	2018 2017 2016 pence pence pence Basic earnings per share 73.7 31.4 18.8 Diluted earnings per share 72.9 31.0 18.6
Schedule of Numbers of Shares Earnings Per Share	The numbers of shares used in calculating basic and diluted earnings per share are reconciled below. 2018 2017 2016 Weighted average number of shares in issue millions millions millions Basic 4,914 4,886 4,860 Dilution for share options and awards 57 55 49 Diluted 4,971 4,941 4,909

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Interim Financial Reporting	2018 2017 2016 Dividend Total Dividend Total Dividend Total per share dividend per share dividend per share dividend Paid/payable (pence) £m Paid (pence) £m Paid (pence) £m First interim 12 July 2018 19 934 13 July 2017 19 928 14 July 2016 19 923 Second interim 11 October 2018 19 934 12 October 2017 19 929 13 October 2016 19 925 Third interim 10 January 2019 19 935 11 January 2018 19 929 12 January 2017 19 925 Fourth interim 11 April 2019 23 1,132 12 April 2018 23 1,130 13 April 2017 23 1,124 Total 80 3,935 80 3,916 80 3,897
Summary of Dividends to Shareholders	The amounts recognised in each year were as follows: 2018 2017 2016 £m £m £m Dividends to shareholders 3,927 3,906 4,850

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Property, Plant and Equipment	Plant, Land and equipment Assets in buildings and vehicles construction Total £m £m £m £m Cost at 1 January 2017 7,761 11,235 3,168 22,164 Exchange adjustments (127 ) (62 ) (45 ) (234 ) Other additions 69 296 1,219 1,584 Capitalised borrowing costs — — 30 30 Disposals and write-offs (376 ) (685 ) (31 ) (1,092 ) Reclassifications 602 1,186 (1,826 ) (38 ) Transfer to assets held for sale (462 ) (219 ) (14 ) (695 ) Cost at 31 December 2017 7,467 11,751 2,501 21,719 Exchange adjustments 150 187 25 362 Other additions 33 190 1,135 1,358 Capitalised borrowing costs 0 0 21 21 Disposals and write-offs (90 ) (440 ) (53 ) (583 ) Reclassifications 403 1,016 (1,486 ) (67 ) Transfer to assets held for sale (152 ) (167 ) (3 ) (322 ) Cost at 31 December 2018 7,811 12,537 2,140 22,488 Depreciation at 1 January 2017 (3,259 ) (7,410 ) — (10,669 ) Exchange adjustments 50 110 — 160 Charge for the year (299 ) (689 ) — (988 ) Disposals and write-offs 158 539 — 697 Transfer to assets held for sale 314 190 — 504 Depreciation at 31 December 2017 (3,036 ) (7,260 ) 0 (10,296 ) Exchange adjustments (61 ) (111 ) 0 (172 ) Charge for the year (268 ) (686 ) 0 (954 ) Disposals and write-offs 77 401 0 478 Transfer to assets held for sale 55 122 0 177 Depreciation at 31 December 2018 (3,233 ) (7,534 ) 0 (10,767 ) Impairment at 1 January 2017 (279 ) (344 ) (64 ) (687 ) Exchange adjustments 8 2 (2 ) 8 Disposals and write-offs 210 104 28 342 Impairment losses (194 ) (138 ) (17 ) (349 ) Reversal of impairments 7 9 1 17 Transfer to assets held for sale 87 8 11 106 Impairment at 31 December 2017 (161 ) (359 ) (43 ) (563 ) Exchange adjustments (8 ) (4 ) (1 ) (13 ) Disposals and write-offs 10 59 22 91 Impairment losses (16 ) (143 ) (46 ) (205 ) Reversal of impairments 1 6 0 7 Transfer to assets held for sale 0 20 0 20 Impairment at 31 December 2018 (174 ) (421 ) (68 ) (663 ) Total depreciation and impairment at 31 December 2017 (3,197 ) (7,619 ) (43 ) (10,859 ) Total depreciation and impairment at 31 December 2018 (3,407 ) (7,955 ) (68 ) (11,430 ) Net book value at 1 January 2017 4,223 3,481 3,104 10,808 Net book value at 31 December 2017 4,270 4,132 2,458 10,860 Net book value at 31 December 2018 4,404 4,582 2,072 11,058

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Changes in Goodwill	2018 2017 £m £m Cost at 1 January 5,734 5,965 Exchange adjustments 199 (228 ) Transfer to assets held for sale (144 ) (3 ) Cost at 31 December 5,789 5,734 Net book value at 1 January 5,734 5,965 Net book value at 31 December 5,789 5,734
Summary of Goodwill Allocated to Segments	Goodwill is allocated to the Group’s segments as follows: 2018 2017 £m £m Pharmaceuticals 3,273 3,172 Vaccines 1,342 1,302 Consumer Healthcare 1,174 1,260 Net book value at 31 December 5,789 5,734
Schedule of Discounted Cash Flow Models Used in Impairment Tests	Details relating to the discounted cash flow models used in the impairment tests of the Pharmaceuticals, Vaccines and Consumer Healthcare cash generating units are as follows: Valuation basis Fair value less costs of disposal Key assumptions Sales growth rates Profit margins Terminal growth rate Discount rate Taxation rate Determination of assumptions Growth rates are internal forecasts based on both internal and external market information. Margins reflect past experience, adjusted for expected changes. Terminal growth rates based on management’s estimate of future long-term average growth rates. Discount rates based on Group WACC, adjusted where appropriate. Taxation rates based on appropriate rates for each region. Period of specific projected cash flows Five years Terminal growth rate and discount rate Terminal growth rate Discount rate Pharmaceuticals 1% p.a. 7.5% Vaccines 1% p.a. 7.5% Consumer Healthcare 2% p.a. 6%

Other intangible assets (Tables

Other intangible assets (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Other Intangible Assets	Computer Licences, Amortised Indefinite life software patents, etc. brands brands Total £m £m £m £m £m Cost at 1 January 2017 2,156 15,143 427 9,375 27,101 Exchange adjustments (37 ) (215 ) (4 ) (272 ) (528 ) Capitalised development costs — 251 — — 251 Capitalised borrowing costs 2 3 — — 5 Other additions 233 221 — — 454 Disposals and asset write-offs (217 ) (38 ) — — (255 ) Transfer to assets held for sale (1 ) (90 ) — (44 ) (135 ) Reclassifications 38 — 66 (66 ) 38 Cost at 31 December 2017 2,174 15,275 489 8,993 26,931 Exchange adjustments 32 235 29 63 359 Capitalised development costs — 203 — — 203 Capitalised borrowing costs 1 — — — 1 Other additions 173 154 — — 327 Disposals and asset write-offs (80 ) (129 ) — — (209 ) Transfer to assets held for sale (2 ) (81 ) (9 ) — (92 ) Reclassifications 67 — — — 67 Cost at 31 December 2018 2,365 15,657 509 9,056 27,587 Amortisation at 1 January 2017 (1,184 ) (4,983 ) (224 ) — (6,391 ) Exchange adjustments 25 141 — — 166 Charge for the year (163 ) (761 ) (10 ) — (934 ) Disposals and asset write-offs 210 25 — — 235 Transfer to assets held for sale 1 25 — — 26 Amortisation at 31 December 2017 (1,111 ) (5,553 ) (234 ) — (6,898 ) Exchange adjustments (24 ) (104 ) (3 ) — (131 ) Charge for the year (240 ) (645 ) (17 ) — (902 ) Disposals and asset write-offs 67 124 — — 191 Transfer to assets held for sale 1 18 1 — 20 Amortisation at 31 December 2018 (1,307 ) (6,160 ) (253 ) — (7,720 ) Impairment at 1 January 2017 (9 ) (1,652 ) (143 ) (130 ) (1,934 ) Exchange adjustments — 110 — 3 113 Impairment losses (2 ) (546 ) — (132 ) (680 ) Disposals and asset write-offs 2 5 — — 7 Transfer to assets held for sale — 19 — 4 23 Impairment at 31 December 2017 (9 ) (2,064 ) (143 ) (255 ) (2,471 ) Exchange adjustments — (69 ) (20 ) — (89 ) Impairment losses (17 ) (51 ) — (69 ) (137 ) Reversal of impairments — 3 — — 3 Disposals and asset write-offs 14 4 — — 18 Transfer to assets held for sale — 11 — — 11 Impairment at 31 December 2018 (12 ) (2,166 ) (163 ) (324 ) (2,665 ) Total amortisation and impairment at 31 December 2017 (1,120 ) (7,617 ) (377 ) (255 ) (9,369 ) Total amortisation and impairment at 31 December 2018 (1,319 ) (8,326 ) (416 ) (324 ) (10,385 ) Net book value at 1 January 2017 963 8,508 60 9,245 18,776 Net book value at 31 December 2017 1,054 7,658 112 8,738 17,562 Net book value at 31 December 2018 1,046 7,331 93 8,732 17,202
Schedule of Amortisation and Impairment Losses, Net of Reversals	Amortisation and impairment losses, net of reversals, have been charged in the income statement as follows: Amortisation Net impairment losses 2018 2017 2018 2017 £m £m £m £m Cost of sales 593 578 69 400 Selling, general and administration 178 116 19 2 Research and development 131 240 46 278 902 934 134 680
Summary of Book Values of Largest Individual Items	Licences, patents, etc. includes a large number of acquired licences, patents, know-how 2018 2017 £m £m Meningitis portfolio 2,363 2,450 Dolutegravir 1,319 1,389 Benlysta 905 965 Fluarix/FluLaval 274 321 HIV assets acquired from BMS 277 277 Selzentry 136 162 Okairos technology platform 205 202 Others 1,852 1,892 7,331 7,658
Summary of Book Values of Major Brands	Indefinite life brands comprise a portfolio of Consumer Healthcare products primarily acquired with the acquisitions of Sterling Winthrop, Inc. in 1994, Block Drug Company, Inc. in 2001, CNS, Inc. in 2006 and the Novartis Consumer Healthcare business in 2015, together with a number of pharmaceutical brands from the acquisition of Stiefel Laboratories, Inc. in 2009. The book values of the major brands are as follows: 2018 2017 £m £m Voltaren 2,735 2,716 Otrivin 1,385 1,380 Fenistil 651 648 Theraflu 449 441 Panadol 388 386 Sensodyne 265 265 Lamisil 293 289 Breathe Right 262 236 Stiefel trade name 236 228 Excedrin 193 185 Physiogel 150 166 Polident 112 112 Others 1,613 1,686 8,732 8,738

Investments in associates and_2

Investments in associates and joint ventures (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Investments in Associates and Joint Ventures	Joint 2018 Joint 2017 ventures Associates Total ventures Associates Total £m £m £m £m £m £m At 1 January 13 170 183 19 244 263 Exchange adjustments 1 11 12 (2 ) (10 ) (12 ) Additions 1 9 10 — 15 15 Disposals 0 0 0 — (92 ) (92 ) Distributions received 0 (40 ) (40 ) (1 ) (1 ) (2 ) Other movements 1 39 40 — (2 ) (2 ) Profit/(loss) after tax recognised in the consolidated income statement 3 28 31 (3 ) 16 13 At 31 December 19 217 236 13 170 183
Summary of Balance Sheet Information	Summarised balance sheet information, based on published information, in respect of Innoviva is set out below: At At 2018 2017 £m £m Non-current 275 124 Current assets 157 148 Current liabilities (4 ) (26 ) Non-current (302 ) (426 ) Net assets/(liabilities) 126 (180 ) 2018 2017 £m £m Interest in associated undertaking 40 (57 ) Goodwill 91 86 Fair value and other adjustments 58 118 Carrying value at 31 December 189 147

Other investments (Tables)

Other investments (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Other Investments	Investments Investments 2018 2017 £m £m £m £m At 1 January 869 49 918 985 Exchange adjustments 48 4 52 (64 ) Additions 363 9 372 80 Net fair value movements through Other comprehensive income 118 0 118 11 Net fair value movements through profit or loss 0 16 16 — Impairment losses 0 0 0 (30 ) Disposals and settlements (89 ) (6 ) (95 ) (64 ) Transfers to Assets held for sale (59 ) 0 (59 ) — At 31 December 1,250 72 1,322 918
Schedule of Carrying Value of Other Investments	The carrying value at 31 December 2017 of Other investments which had been impaired was as follows: 2017 Original cost 475 Cumulative impairments recognised in the income statement (283 ) Subsequent fair value increases 210 Carrying value at 31 December 2017 402

Other non-current assets (Table

Other non-current assets (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Other Non-Current Assets	2018 2017 £m £m Amounts receivable under insurance contracts 675 648 Pension schemes in surplus 760 538 Other receivables 141 227 1,576 1,413

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Inventories	2018 2017 £m £m Raw materials and consumables 1,122 1,193 Work in progress 2,286 2,381 Finished goods 2,068 1,983 5,476 5,557

Trade and other receivables (Ta

Trade and other receivables (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Trade and Other Receivables	2018 2017 £m £m Trade receivables, net of loss allowance 5,176 4,672 Accrued income 9 21 Other prepayments 330 308 Interest receivable 4 10 Employee loans and advances 14 19 Other receivables 890 970 6,423 6,000
Summary of Loss Allowance	Loss allowance 2018 2017 At 1 January 140 207 Implementation of IFRS 9 15 — At 1 January, as adjusted 155 — Exchange adjustments 0 (4 ) Charge for the year 7 31 Subsequent recoveries of amounts provided for (30 ) (79 ) Utilised (4 ) (15 ) At 31 December 128 140

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Cash and Cash Equivalents	2018 2017 £m £m Cash at bank and in hand 569 826 Short-term deposits 3,305 3,007 3,874 3,833

Assets held for sale (Tables)

Assets held for sale (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Assets Held for Sale	2018 2017 £m £m Property, plant and equipment 109 57 Goodwill 144 — Other intangibles 1 49 Inventory 50 7 Cash and cash equivalents 485 — Other (136 ) — 653 113

Trade and other payables (Table

Trade and other payables (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Trade and Other Payables	2018 2017 £m £m Trade payables 3,645 3,528 Wages and salaries 1,355 1,228 Social security 139 166 Consumer Healthcare put option 0 8,606 ViiV Healthcare put option 1,240 1,304 Other payables 401 363 Deferred income 216 240 Customer return and rebate accruals 5,064 3,463 Other accruals 1,977 2,072 14,037 20,970
Summary of Increase/(Decrease) in Financial Liability and Loss/(Gain) in Income Statement	Pfizer’s put option over its shareholding in ViiV Healthcare is currently exercisable. The amount of the liability recognised is derived from several valuation methodologies, including reference to market multiples of comparable companies. The table below shows on an indicative basis the income statement and balance sheet sensitivity of the Pfizer put option to reasonably possible changes in key assumptions. Increase/(decrease) in financial liability and loss/(gain) in Income statement 2018 10% increase in sales forecasts 140 10% decrease in sales forecasts (140 ) 10 cent appreciation of US Dollar 75 10 cent depreciation of US Dollar (64 ) 10 cent appreciation of Euro 44 10 cent depreciation of Euro (37 )

Pensions and other post-emplo_2

Pensions and other post-employment benefits (Tables)	12 Months Ended
	Dec. 31, 2018
Statement [LineItems]
Summary of Analysis of Defined Benefit Pension Obligation	2018 2017 2016 Pension and other post-employment costs £m £m £m UK pension schemes 246 198 205 US pension schemes 100 113 106 Other overseas pension schemes 190 218 140 Unfunded post-retirement healthcare schemes 50 87 90 586 616 541 Analysed as: Funded defined benefit/hybrid pension schemes 369 335 304 Unfunded defined benefit pension schemes 43 55 43 Unfunded post-retirement healthcare schemes 50 87 90 Defined benefit schemes 462 477 437 Defined contribution pension schemes 124 139 104 586 616 541
Summary of Average Life Expectancy Assumed	The average life expectancy assumed now for an individual at the age of 60 and projected to apply in 2038 for an individual then at the age of 60 is as follows: UK US Male Female Male Female Current 27.5 29.1 27.0 28.7 Projected for 2038 29.0 30.6 28.7 30.3
Summary of Financial Assumptions in Assessing Defined Benefit Liabilities	The Group has applied the following financial assumptions in assessing the defined benefit liabilities: UK US Rest of World 2018 2017 2016 2018 2017 2016 2018 2017 2016 Rate of increase of future earnings 2.00 2.00 2.00 4.00 4.00 4.00 2.70 2.80 2.70 Discount rate 2.90 2.50 2.70 4.20 3.60 3.90 1.80 1.60 1.60 Expected pension increases 3.20 3.20 3.20 n/a n/a n/a 2.10 2.20 2.10 Cash balance credit/conversion rate n/a n/a n/a 3.20 2.90 3.20 0.40 0.30 0.30 Inflation rate 3.20 3.20 3.20 2.25 2.25 2.25 1.50 1.70 1.50
Summary of Amounts Recorded in Income Statement and Statement of Comprehensive Income Related to Defined Benefit Pension and Post-retirement Healthcare Schemes	The amounts recorded in the income statement and statement of comprehensive income for the three years ended 31 December 2018 in relation to the defined benefit pension and post-retirement healthcare schemes were as follows: Pensions Post-retirement benefits 2018 UK US Rest of World Group £m Group £m Amounts charged to operating profit Current service cost 75 72 134 281 29 Past service cost/(credit) 93 1 0 94 (27 ) Net interest (income)/cost (3 ) 20 19 36 49 Gains from settlements 0 0 (14 ) (14 ) (1 ) Expenses 8 7 0 15 0 173 100 139 412 50 Remeasurement gains/(losses) recorded in the statement of comprehensive income 495 (108 ) 196 583 145 Pensions Post-retirement 2017 UK US Rest of World Group Group Amounts charged to operating profit Current service cost 79 70 131 280 30 Past service cost/(credit) 37 — — 37 (2 ) Net interest cost 7 31 16 54 59 Expenses 7 12 — 19 — 130 113 147 390 87 Remeasurement gains/(losses) recorded in the statement of comprehensive income 259 240 (14 ) 485 64 Pensions Post-retirement 2016 UK US Rest of World Group Group £m Amounts charged to operating profit Current service cost 70 66 110 246 31 Past service cost 52 1 1 54 3 Net interest cost 9 27 20 56 56 Gains from settlements — — (28 ) (28 ) — Expenses 7 12 — 19 — 138 106 103 347 90 Remeasurement losses recorded in the statement of comprehensive income (165 ) (27 ) (224 ) (416 ) (59 )
Summary of Balance Sheet Presentation of Group Defined Benefit Pension Schemes and Other Post-retirement Benefits	A summarised balance sheet presentation of the Group defined benefit pension schemes and other post-retirement benefits is set out in the table below: 2018 2017 2016 £m £m £m Recognised in Other non-current Pension schemes in surplus 760 538 313 Recognised in Assets held for sale: Post-retirement benefits (9 ) — — Recognised in Pensions and other post-employment benefits: Pension schemes in deficit (1,755 ) (2,043 ) (2,397 ) Post-retirement benefits (1,370 ) (1,496 ) (1,693 ) (3,125 ) (3,539 ) (4,090 )
Summary of Fair Values of Assets and Liabilities of UK and US Defined Benefit Pension Schemes Together with Aggregated Data for Other Defined Benefit Pension Schemes in Group	The fair values of the assets and liabilities of the UK and US defined benefit pension schemes, together with aggregated data for other defined benefit pension schemes in the Group are as follows: UK US Rest of World Group At 31 December 2018 £m £m £m £m Equities: – listed 3,257 1,280 518 5,055 – unlisted 0 0 7 7 Multi-asset funds 2,997 0 0 2,997 Property: – listed 0 0 33 33 – unlisted 423 231 4 658 Corporate bonds: – listed 404 783 111 1,298 – unlisted 306 0 25 331 Government bonds: – listed 3,835 286 795 4,916 Insurance contracts 770 0 831 1,601 Other assets 589 228 66 883 Fair value of assets 12,581 2,808 2,390 17,779 Present value of scheme obligations (12,087 ) (3,474 ) (3,213 ) (18,774 ) Net surplus/(obligation) 494 (666 ) (823 ) (995 ) Included in Other non-current 711 0 49 760 Included in Pensions and other post-employment benefits (217 ) (666 ) (872 ) (1,755 ) 494 (666 ) (823 ) (995 ) Actual return on plan assets (88 ) (123 ) 55 (156 ) The multi-asset funds comprise investments in pooled investment vehicles that are invested across a range of asset classes, increasing diversification within the growth portfolio. The ‘Other assets’ category comprises cash and mark to market values of derivative positions. In previous years, index-linked gilts held as part of a UK repo programme were included in government bonds. The related loan was included within ‘Other assets’ at a value of £(773) million at 31 December 2017 (2016 – £(1,686) million). This programme was cancelled during 2018. At 31 December 2017 UK US Rest of World Group Equities: – listed 4,902 1,448 544 6,894 – unlisted — — 13 13 Multi-asset funds 2,517 — — 2,517 Property: – unlisted 352 209 32 593 Corporate bonds: – listed 297 820 103 1,220 – unlisted 326 — 20 346 Government bonds: – listed 5,127 239 762 6,128 Insurance contracts 849 — 707 1,556 Other assets (1,216 ) 158 71 (987 ) Fair value of assets 13,154 2,874 2,252 18,280 Present value of scheme obligations (13,101 ) (3,445 ) (3,239 ) (19,785 ) Net surplus/(obligation) 53 (571 ) (987 ) (1,505 ) Included in Other non-current 470 — 68 538 Included in Pensions and other post-employment benefits (417 ) (571 ) (1,055 ) (2,043 ) 53 (571 ) (987 ) (1,505 ) Actual return on plan assets 893 394 82 1,369 At 31 December 2016 UK US Rest of World Group Equities: – listed 5,357 1,358 486 7,201 – unlisted — — 14 14 Multi-asset funds 1,545 — — 1,545 Property: – unlisted 314 216 28 558 Corporate bonds: – listed 292 213 96 601 – unlisted 321 — 24 345 Government bonds: – listed 6,165 815 739 7,719 Insurance contracts 856 — 637 1,493 Other assets (2,267 ) 288 73 (1,906 ) Fair value of assets 12,583 2,890 2,097 17,570 Present value of scheme obligations (12,884 ) (3,752 ) (3,018 ) (19,654 ) Net obligation (301 ) (862 ) (921 ) (2,084 ) Included in Other non-current 276 — 37 313 Included in Pensions and other post-employment benefits (577 ) (862 ) (958 ) (2,397 ) (301 ) (862 ) (921 ) (2,084 ) Actual return on plan assets 2,473 153 99 2,725
Summary of Movements in Fair Values of Assets	Post-retirement Pensions benefits UK US Rest of World Group Group Movements in fair values of assets £m £m £m £m £m Assets at 1 January 2016 10,284 2,501 1,750 14,535 — Exchange adjustments — 459 305 764 — Interest income 385 108 37 530 — Expenses (7 ) (12 ) — (19 ) — Settlements and curtailments — — (110 ) (110 ) — Remeasurement 2,088 45 62 2,195 — Employer contributions 319 31 131 481 91 Scheme participants’ contributions 4 — 14 18 17 Benefits paid (490 ) (242 ) (92 ) (824 ) (108 ) Assets at 31 December 2016 12,583 2,890 2,097 17,570 — Exchange adjustments — (244 ) 24 (220 ) — Interest income 333 104 33 470 — Expenses (7 ) (12 ) — (19 ) — Settlements and curtailments — — (4 ) (4 ) — Remeasurement 560 290 49 899 — Employer contributions 225 103 116 444 101 Scheme participants’ contributions 4 — 17 21 17 Benefits paid (544 ) (257 ) (80 ) (881 ) (118 ) Assets at 31 December 2017 13,154 2,874 2,252 18,280 0 Exchange adjustments 0 171 53 224 0 Interest income 323 102 29 454 0 Expenses (8 ) (7 ) 0 (15 ) 0 Settlements and curtailments 0 0 (14 ) (14 ) 0 Remeasurement (411 ) (225 ) 26 (610 ) 0 Employer contributions 119 150 117 386 93 Scheme participants’ contributions 4 0 16 20 16 Benefits paid (600 ) (257 ) (89 ) (946 ) (109 ) Assets at 31 December 2018 12,581 2,808 2,390 17,779 0
Summary of Movements in Defined Benefit Obligations	Post-retirement Pensions benefits UK US Rest of World Group Group Movements in defined benefit obligations £m £m £m £m £m Obligations at 1 January 2016 (10,601 ) (3,134 ) (2,384 ) (16,119 ) (1,387 ) Exchange adjustments — (586 ) (396 ) (982 ) (248 ) Service cost (70 ) (66 ) (110 ) (246 ) (31 ) Past service cost (52 ) (1 ) (1 ) (54 ) (3 ) Interest cost (394 ) (135 ) (57 ) (586 ) (56 ) Settlements and curtailments — — 138 138 — Remeasurement (2,253 ) (72 ) (286 ) (2,611 ) (59 ) Scheme participants’ contributions (4 ) — (14 ) (18 ) (17 ) Benefits paid 490 242 92 824 108 Obligations at 31 December 2016 (12,884 ) (3,752 ) (3,018 ) (19,654 ) (1,693 ) Exchange adjustments — 305 (45 ) 260 119 Service cost (79 ) (70 ) (131 ) (280 ) (30 ) Past service cost/(credit) (37 ) — — (37 ) 2 Interest cost (340 ) (135 ) (49 ) (524 ) (59 ) Settlements and curtailments — — 4 4 — Remeasurement (301 ) (50 ) (63 ) (414 ) 64 Scheme participants’ contributions (4 ) — (17 ) (21 ) (17 ) Benefits paid 544 257 80 881 118 Obligations at 31 December 2017 (13,101 ) (3,445 ) (3,239 ) (19,785 ) (1,496 ) Exchange adjustments 0 (208 ) (63 ) (271 ) (71 ) Service cost (75 ) (72 ) (134 ) (281 ) (29 ) Past service cost (93 ) (1 ) 0 (94 ) 27 Interest cost (320 ) (122 ) (48 ) (490 ) (49 ) Settlements and curtailments 0 0 28 28 1 Remeasurement 906 117 170 1,193 145 Scheme participants’ contributions (4 ) 0 (16 ) (20 ) (16 ) Benefits paid 600 257 89 946 109 Obligations at 31 December 2018 (12,087 ) (3,474 ) (3,213 ) (18,774 ) (1,379 )
Summary of Net Defined Benefit Liability	The movement in the net defined benefit liability is as follows: 2018 2017 2016 £m £m £m At 1 January (1,505 ) (2,084 ) (1,584 ) Exchange adjustments (47 ) 40 (218 ) Service cost (281 ) (280 ) (246 ) Past service cost (94 ) (37 ) (54 ) Interest cost (36 ) (54 ) (56 ) Settlements and curtailments 14 — 28 Remeasurements: Return on plan assets, excluding amounts included in interest (610 ) 899 2,195 Gain from change in demographic assumptions 131 209 85 Gain/(loss) from change in financial assumptions 1,149 (555 ) (2,770 ) Experience (losses)/gains (87 ) (68 ) 74 Employer contributions 386 444 481 Expenses (15 ) (19 ) (19 ) At 31 December (995 ) (1,505 ) (2,084 )
Summary of Defined Benefit Pension Obligation Analysed by Membership Category	The defined benefit pension obligation analysed by membership category is as follows: 2018 2017 2016 Active 4,427 4,611 4,576 Retired 9,542 9,805 9,574 Deferred 4,805 5,369 5,504 18,774 19,785 19,654
Summary of Post-Retirement Benefit Obligation Analysed By Membership Category	The post-retirement benefit obligation analysed by membership category is as follows: 2018 2017 2016 £m £m £m Active 499 514 594 Retired 879 981 1,099 Deferred 1 1 — 1,379 1,496 1,693
Summary of Weighted Average Duration of Defined Benefit Obligation	The weighted average duration of the defined benefit obligation is as follows: 2018 2017 2016 Pension benefits 15 16 16 Post-retirement benefits 11 11 12
Summary of Changes In Assumptions Used on Benefit Obligations, Defined Benefit Pension and Post Retirement Costs	The effect of changes in assumptions used on the benefit obligations and on the 2019 annual defined benefit pension and post-retirement costs are detailed below. This information has been determined by taking into account the duration of the liabilities and the overall profile of the plan memberships. £m A 0.25% decrease in discount rate would have the following approximate effect: Increase in annual pension cost 28 Decrease in annual post-retirement benefits cost (1 ) Increase in pension obligation 707 Increase in post-retirement benefits obligation 34 A one-year Increase in annual pension cost 21 Increase in annual post-retirement benefits cost 2 Increase in pension obligation 592 Increase in post-retirement benefits obligation 33 A 1% increase in the rate of future healthcare inflation would have the following approximate effect: Increase in annual post-retirement benefits cost 1 Increase in post-retirement benefits obligation 38 A 0.25% increase in inflation would have the following approximate effect: Increase in annual pension cost 18 Increase in pension obligation 447
Defined benefit pension and post-retirement healthcare scheme. [member]
Statement [LineItems]
Summary of Analysis of Defined Benefit Pension Obligation	The costs of the defined benefit pension and post-retirement healthcare schemes are charged in the income statement as follows: 2018 2017 2016 £m £m £m Cost of sales 160 162 135 Selling, general and administration 228 238 221 Research and development 74 77 81 462 477 437
Defined Benefit Pension Obligation [member]
Statement [LineItems]
Summary of Analysis of Defined Benefit Pension Obligation	The defined benefit pension obligation is analysed as follows: 2018 2017 2016 £m £m £m Funded (18,025 ) (19,052 ) (18,974 ) Unfunded (749 ) (733 ) (680 ) (18,774 ) (19,785 ) (19,654 )
Post-retirement benefits [member]
Statement [LineItems]
Summary of Net Defined Benefit Liability	The remeasurements included within post-retirement benefits are detailed below: 2018 2017 2016 £m £m £m Gain from change in demographic assumptions 6 47 — Gain/(loss) from change in financial assumptions 100 (1 ) (81 ) Experience gains 39 18 22 145 64 (59 )

Other provisions (Tables)

Other provisions (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Other Provisions	Legal Major Employee Other Total At 1 January 2018 186 504 304 271 1,265 Exchange adjustments 13 17 9 5 44 Charge for the year 119 450 105 50 724 Reversed unused (2 ) (99 ) (25 ) (46 ) (172 ) Unwinding of discount 2 4 0 9 15 Utilised (98 ) (226 ) (41 ) (79 ) (444 ) Reclassifications and other movements (1 ) 12 (2 ) 3 12 Transfer to Pension obligations 0 (21 ) 0 0 (21 ) At 31 December 2018 219 641 350 213 1,423 To be settled within one year 156 362 145 69 732 To be settled after one year 63 279 205 144 691 At 31 December 2018 219 641 350 213 1,423

Other non-current liabilities (

Other non-current liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Other Noncurrent Liabilities	2018 2017 £m £m Accruals 71 82 Deferred Income 19 22 Other payables 848 877 938 981

Net debt (Tables)

Net debt (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Current Assets, Short and Long Term Borrowings	Listing exchange 2018 £m 2017 Current assets: Liquid investments 84 78 Cash and cash equivalents 3,874 3,833 Cash and cash equivalents reported in Assets held for sale 485 — 4,443 3,911 Short-term borrowings: Commercial paper (630 ) (529 ) Bank loans and overdrafts (290 ) (236 ) Obligations under finance leases (24 ) (23 ) Drawn bank facility (3,500 ) — 5.650% US$ US Medium Term Note 2018 New York Stock Exchange 0 (2,037 ) 0.625% € European Medium Term Note 2019 London Stock Exchange (1,349 ) — (5,793 ) (2,825 ) Long-term borrowings: 0.625% € European Medium Term Note 2019 London Stock Exchange 0 (1,324 ) EURIBOR +0.20% € European Medium Term Note 2020 London Stock Exchange (677 ) — 0.000% € European Medium Term Note 2020 London Stock Exchange (1,079 ) (1,060 ) 3.125% US$ US Medium Term Note 2021 New York Stock Exchange (980 ) — LIBOR +0.35% US$ US Medium Term Note 2021 New York Stock Exchange (589 ) — 2.850% US$ US Medium Term Note 2022 New York Stock Exchange (1,568 ) (1,474 ) 2.800% US$ US Medium Term Note 2023 New York Stock Exchange (978 ) (919 ) 3.375% US$ US Medium Term Note 2023 New York Stock Exchange (977 ) — 1.375% € European Medium Term Note 2024 London Stock Exchange (893 ) (876 ) 4.000% € European Medium Term Note 2025 London Stock Exchange (670 ) (659 ) 3.625% US$ US Medium Term Note 2025 New York Stock Exchange (780 ) — 1.000% € European Medium Term Note 2026 London Stock Exchange (629 ) (617 ) 1.250% € European Medium Term Note 2026 London Stock Exchange (897 ) — 3.375% £ European Medium Term Note 2027 London Stock Exchange (593 ) (593 ) 3.875% US$ US Medium Term Note 2028 New York Stock Exchange (1,372 ) — 1.375% € European Medium Term Note 2029 London Stock Exchange (447 ) (439 ) 1.750% € European Medium Term Note 2030 London Stock Exchange (673 ) — 5.250% £ European Medium Term Note 2033 London Stock Exchange (982 ) (986 ) 5.375% US$ US Medium Term Note 2034 New York Stock Exchange (390 ) (368 ) 6.375% US$ US Medium Term Note 2038 New York Stock Exchange (2,143 ) (2,021 ) 6.375% £ European Medium Term Note 2039 London Stock Exchange (694 ) (695 ) 5.250% £ European Medium Term Note 2042 London Stock Exchange (986 ) (989 ) 4.200% US$ US Medium Term Note 2043 New York Stock Exchange (386 ) (363 ) 4.250% £ European Medium Term Note 2045 London Stock Exchange (788 ) (789 ) Obligations under finance leases (44 ) (43 ) Other long-term borrowings (56 ) (49 ) (20,271 ) (14,264 ) Net debt (21,621 ) (13,178 )
Schedule of Finance Lease Obligations	Finance lease obligations 2018 2017 £m £m Rental payments due within one year 29 25 Rental payments due between one and two years 20 29 Rental payments due between two and three years 13 9 Rental payments due between three and four years 7 3 Rental payments due between four and five years 4 2 Rental payments due after five years 11 10 Total future rental payments 84 78 Future finance charges (16 ) (12 ) Total finance lease obligations 68 66

Share capital and share premi_2

Share capital and share premium account (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Share Capital and Share Premium	Ordinary Shares of 25p each Share Number £m £m Share capital authorised At 31 December 2016 10,000,000,000 2,500 At 31 December 2017 10,000,000,000 2,500 At 31 December 2018 10,000,000,000 2,500 Share capital issued and fully paid At 1 January 2016 5,361,307,647 1,340 2,831 Issued under employee share schemes 7,008,415 2 87 Ordinary shares acquired by ESOP Trusts — — 36 At 31 December 2016 5,368,316,062 1,342 2,954 Issued under employee share schemes 4,237,758 1 55 Ordinary shares acquired by ESOP Trusts — — 10 At 31 December 2017 5,372,553,820 1,343 3,019 Issued under employee share schemes 6,513,804 2 72 At 31 December 2018 5,379,067,624 1,345 3,091
Summary of Share Capital	31 December 2018 31 December 2017 000 000 Number of shares issuable under employee share schemes 56,723 38,647 Number of unissued shares not under option 4,564,209 4,588,799

Movements in equity (Tables)

Movements in equity (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Cumulative Translation Exchange in Equity	The cumulative translation exchange in equity is as follows: Net translation exchange included in: Non- Total Retained Fair value controlling translation earnings reserve interests exchange £m £m £m £m At 1 January 2016 (761 ) 10 (109 ) (860 ) Exchange movements on overseas net assets 633 13 603 1,249 At 31 December 2016 (128 ) 23 494 389 Exchange movements on overseas net assets 462 — (149 ) 313 Reclassification of exchange on liquidation or disposal of overseas subsidiaries 109 — — 109 At 31 December 2017 443 23 345 811 Exchange movements on overseas net assets (458 ) (22 ) (1 ) (481 ) At 31 December 2018 (15 ) 1 344 330 The analysis of other comprehensive income by equity category is as follows: Non- Retained Other controlling earnings reserves interests Total 2018 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges (458 ) (22 ) 0 (480 ) Fair value movements on cash flow hedges 0 140 0 140 Reclassification of cash flow hedges on income and expense 0 (175 ) 0 (175 ) Deferred tax on fair value movements on cash flow hedges 0 (22 ) 0 (22 ) Deferred tax reversed on reclassification of cash flow hedges 0 20 0 20 Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling 0 0 (1 ) (1 ) Fair value movements on equity investments 0 180 0 180 Deferred tax on fair value movements on equity investments 0 10 0 10 Remeasurement gains on defined benefit plans 728 0 0 728 Tax on remeasurement gains in defined benefit plans (146 ) 0 0 (146 ) Other comprehensive income/(expense) for the year 124 131 (1 ) 254 Non- Retained Other controlling earnings reserves interests Total 2017 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges 462 — — 462 Reclassification of exchange on liquidation or disposal of overseas subsidiaries 109 — — 109 Fair value movements on available-for-sale — (14 ) — (14 ) Reclassification of fair value movements on available-for-sale — (42 ) — (42 ) Deferred tax on fair value movements on available-for-sale — 47 — 47 Deferred tax reversed on reclassification of available-for-sale — (18 ) — (18 ) Fair value movements on cash flow hedges — (10 ) — (10 ) Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling — — (149 ) (149 ) Remeasurement gains on defined benefit plans 549 — — 549 Tax on remeasurement gains in defined benefit plans (221 ) — — (221 ) Other comprehensive income/(expense) for the year 899 (37 ) (149 ) 713 Non- Retained Other controlling earnings reserves interests Total 2016 £m £m £m £m Items that may be subsequently reclassified to income statement: Exchange movements on overseas net assets and net investment hedges 633 13 — 646 Fair value movements on available-for-sale — 251 — 251 Reclassification of fair value movements on available-for-sale — (245 ) — (245 ) Deferred tax reversed on reclassification of available-for-sale — 51 — 51 Reclassification of cash flow hedges to income statement — 1 — 1 Fair value movements on cash flow hedges — 2 — 2 Deferred tax on fair value movements on cash flow hedges — 2 — 2 Items that will not be reclassified to income statement: Exchange movements on overseas net assets of non-controlling — — 603 603 Remeasurement losses on defined benefit plans (475 ) — — (475 ) Tax on remeasurement losses in defined benefit plans 126 — — 126 Other comprehensive income for the year 284 75 603 962
Summary of Analysis of Other Reserves	The analysis of other reserves is as follows: ESOP Trust Fair value Cash flow Other shares reserve hedge reserve reserves Total £m £m £m £m £m At 1 January 2016 (75 ) 295 (9 ) 2,129 2,340 Exchange adjustments (16 ) — — — (16 ) Transferred to income and expense in the year on disposals — (268 ) — — (268 ) Transferred to income and expense in the year on impairments — 23 — — 23 Net fair value movement in the year — 330 6 — 336 Ordinary shares acquired by ESOP Trusts (576 ) — — — (576 ) Write-down of shares held by ESOP Trusts 381 — — — 381 At 31 December 2016 (286 ) 380 (3 ) 2,129 2,220 Exchange adjustments 22 — — — 22 Transferred to income and expense in the year on disposals — (42 ) — — (42 ) Net fair value movement in the year — (9 ) (8 ) — (17 ) Ordinary shares acquired by ESOP Trusts (656 ) — — — (656 ) Write-down of shares held by ESOP Trusts 520 — — — 520 At 31 December 2017 (400 ) 329 (11 ) 2,129 2,047 Implementation of IFRS 9 — (288 ) — — (288 ) At 31 December, as adjusted (400 ) 41 (11 ) 2,129 1,759 Exchange adjustments (26 ) 0 0 0 (26 ) Transferred to Retained earnings in the year on disposal of equity investments 0 (94 ) 0 0 (94 ) Net fair value movement in the year 0 193 (36 ) 0 157 Write-down of shares held by ESOP Trusts 265 0 0 0 265 At 31 December 2018 (161 ) 140 (47 ) 2,129 2,061

Adjustments reconciling profi_2

Adjustments reconciling profit after tax to operating cash flows (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Cash Generated from Operations	2018 2017 2016 £m £m £m Profit after tax 4,046 2,169 1,062 Tax on profits 754 1,356 877 Share of after tax profits of associates and joint ventures (31 ) (13 ) (5 ) Finance expense net of finance income 717 669 664 Depreciation 954 988 978 Amortisation of intangible assets 902 934 796 Impairment and assets written off 350 1,061 226 Profit on sale of businesses (63 ) (157 ) (5 ) Profit on sale of intangible assets (201 ) (46 ) (178 ) Profit on sale of investments in associates (3 ) (94 ) — Profit on sale of equity investments (4 ) (37 ) (254 ) Gain on Consumer Healthcare Joint Venture put hedging (513 ) — — Business acquisition costs 47 — — Changes in working capital: Decrease/(increase) in inventories 51 (461 ) 70 Increase in trade receivables (429 ) (287 ) (188 ) Increase in trade payables 131 11 96 Decrease in other receivables 18 74 381 Contingent consideration paid (see Note •) (984 ) (594 ) (358 ) Other non-cash 1,250 961 2,281 Increase in other payables 2,362 1,741 1,989 Increase/(decrease) in pension and other provisions 102 (255 ) (621 ) Share-based incentive plans 360 333 319 Fair value adjustments (7 ) — (3 ) Other (62 ) (95 ) (21 ) 5,701 6,089 7,044 Cash generated from operations 9,747 8,258 8,106

Reconciliation of net cash fl_2

Reconciliation of net cash flow to movement in net debt (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Net Debt	2018 2017 2016 £m £m £m Net debt at beginning of year (13,178 ) (13,804 ) (10,727 ) Increase/(decrease) in cash and bank overdrafts 479 (905 ) (1,164 ) Decrease in liquid investments 0 (4 ) — Net increase in long-term loans (10,138 ) (2,233 ) — Repayment of short-term Notes 2,067 2,636 865 (Increase in)/repayment of other short-term loans (81 ) 564 (1,013 ) Net repayment of obligations under finance leases 28 23 18 Exchange adjustments (776 ) 585 (1,781 ) Other non-cash (22 ) (40 ) (2 ) Movement in net debt (8,443 ) 626 (3,077 ) Net debt at end of year (21,621 ) (13,178 ) (13,804 )
Summary of Analysis of Changes in Net Debt	At 1 January Profit Reclass- At 31 December Analysis of changes in net debt 2018 Exchange Other and loss ifications Cash flow 2018 £m £m £m £m £m £m £m Liquid investments 78 5 1 0 0 0 84 Cash and cash equivalents 3,833 4 0 0 (485 ) 522 3,874 Cash and cash equivalents – AHFS 0 485 485 Overdrafts (233 ) 4 0 0 0 (43 ) (272 ) 3,600 8 0 0 0 479 4,087 Debt due within one year: Commercial paper (529 ) (36 ) 0 0 0 (65 ) (630 ) European/US Medium Term Notes and bank facilities (2,037 ) (55 ) 0 0 (4,824 ) 2,067 (4,849 ) Other (26 ) (1 ) (11 ) 0 (16 ) 12 (42 ) (2,592 ) (92 ) (11 ) 0 (4,840 ) 2,014 (5,521 ) Debt due after one year: European/US Medium Term Notes and bank facilities (14,221 ) (696 ) 0 4 4,824 (10,138 ) (20,227 ) Other (43 ) (1 ) (16 ) 0 16 0 (44 ) (14,264 ) (697 ) (16 ) 4 4,840 (10,138 ) (20,271 ) Net debt (13,178 ) (776 ) (26 ) 4 0 (7,645 ) (21,621 ) Analysis of changes in liabilities from financing activities Debt due within one year (2,592 ) (92 ) (11 ) 0 (4,840 ) 2,014 (5,521 ) Debt due after one year (14,264 ) (697 ) (16 ) 4 4,840 (10,138 ) (20,271 ) Hedge of borrowings: Derivative financial instruments 2 1 130 (10 ) 0 6 129 Other financing items 0 (19 ) 0 0 0 19 0 Interest payable (203 ) (2 ) 2 (802 ) 0 766 (239 ) Total liabilities from financing activities (17,057 ) (809 ) 105 (808 ) 0 (7,333 ) (25,902 )

Acquisitions and disposals (Tab

Acquisitions and disposals (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Cash Flows from Business Combinations	Cash flows Associates Associates Business and joint and joint venture venture disposals investments disposals £m £m £m Cash consideration 2 (10 ) 3 Net deferred consideration received 24 0 0 Cash and cash equivalents divested 0 0 0 Cash inflow 26 (10 ) 3 Cash flows Associates Associates Business and joint and joint venture venture disposals investments disposals £m £m £m Cash consideration 256 (15 ) 198 Net deferred consideration received 39 — — Cash and cash equivalents divested (6 ) — — Transaction costs paid (7 ) — (2 ) Cash inflow 282 (15 ) 196
Summary of Profit on Disposal of Businesses	The profit on disposal was determined as follows: Total £m Consideration including currency forwards and purchase adjustments 342 Net assets sold: Goodwill (16 ) Intangible assets (21 ) Property, plant and equipment (18 ) Inventory (11 ) Cash and cash equivalents (6 ) Other net assets (5 ) (77 ) Transaction costs (8 ) Reclassification of exchange from other comprehensive income (100 ) Profit on disposal 157
Summary of Investment in Associates and Joint Ventures	Total £m Cash consideration 198 Net book value of shares (92 ) Reclassification of exchange from other comprehensive income (7 ) Transaction costs (5 ) Profit on disposal 94

Contingent consideration liab_2

Contingent consideration liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Summary of Fair Value of Contingent Consideration Liabilities	The consideration for certain acquisitions includes amounts contingent on future events such as development milestones or sales performance. The Group has provided for the fair value of this contingent consideration as follows: Shionogi- ViiV Novartis Healthcare Vaccines Other Total £m £m £m £m At 1 January 2016 3,409 405 41 3,855 Additions through business combinations 154 — 40 194 Remeasurement through income statement 2,162 152 (33 ) 2,281 Cash payments: operating cash flows (351 ) (5 ) (2 ) (358 ) Cash payments: investing activities (66 ) (7 ) — (73 ) Other movements (4 ) — 1 (3 ) At 31 December 2016 5,304 545 47 5,896 Remeasurement through income statement 909 53 (1 ) 961 Cash payments: operating cash flows (587 ) (7 ) — (594 ) Cash payments: investing activities (84 ) (7 ) — (91 ) At 31 December 2017 5,542 584 46 6,172 Remeasurement through income statement 1,188 56 7 1,251 Cash payments: operating cash flows (703 ) (281 ) 0 (984 ) Cash payments: investing activities (90 ) (63 ) 0 (153 ) At 31 December 2018 5,937 296 53 6,286
Summary of Possible Changes in key Inputs to Valuation of Contingent Consideration Liabilities	The table below shows on an indicative basis the income statement and balance sheet sensitivity to reasonably possible changes in key inputs to the valuations of the contingent consideration liabilities. Shionogi- Novartis ViiV Healthcare Vaccines Increase/(decrease) in financial liability and loss/(gain) in Income statement £m £m 10% increase in sales forecasts 569 62 10% decrease in sales forecasts (569 ) (62 ) 1% increase in discount rate (238 ) (22 ) 1% decrease in discount rate 256 26 5% increase in probability of milestone success 7 5% decrease in probability of milestone success (7 ) 10 cent appreciation of US Dollar 367 (13 ) 10 cent depreciation of US Dollar (313 ) 11 10 cent appreciation of Euro 114 29 10 cent depreciation of Euro (95 ) (25 )

Non-controlling interests (Tabl

Non-controlling interests (Tables)	12 Months Ended
	Dec. 31, 2018
ViiV healthcare [member]
Statement [LineItems]
Summarised Financial Information of Joint Venture	ViiV Healthcare The ViiV Healthcare subgroup has a material non-controlling 2018 2017 2016 Turnover 4,665 4,269 3,527 Profit/(loss) after taxation 560 825 (1,249 ) Other comprehensive income 19 20 36 Total comprehensive income/(expense) 579 845 (1,213 ) 2018 2017 Non-current 2,787 2,736 Current assets 2,643 2,533 Total assets 5,430 5,269 Current liabilities (2,638 ) (2,409 ) Non-current (8,895 ) (8,011 ) Total liabilities (11,533 ) (10,420 ) Net liabilities (6,103 ) (5,151 ) 2018 2017 2016 Net cash inflow from operating activities 2,212 2,132 1,750 Net cash outflow from investing activities (237 ) (207 ) (326 ) Net cash outflow from financing activities (1,982 ) (1,820 ) (1,023 ) (Decrease)/increase in cash and bank overdrafts in the year (7 ) 105 401
Schedule of Amount Attributable to Joint Venture Included in GSK's Consolidated Statement of Comprehensive Income, Consolidated Statement of Changes in Equity and Consolidated Balance Sheet	The following amounts attributable to the ViiV Healthcare group are included in GSK’s Consolidated statement of comprehensive income, Consolidated statement of changes in equity and Consolidated balance sheet: 2018 2017 2016 Total comprehensive income/(expense) for the year attributable to non-controlling 254 187 (83 ) Dividends paid to non-controlling 332 316 152 Non-controlling (543 ) (476 )
Consumer health care joint venture [member]
Statement [LineItems]
Summarised Financial Information of Joint Venture	Consumer Healthcare Joint Venture During 2018, the Group acquired Novartis’ interest in the Consumer Healthcare Joint Venture to obtain 100% ownership. The acquisition became unconditional on 3 May 2018 and completed on 1 June 2018. Summarised financial information in respect of the Consumer Healthcare Joint Venture is as follows: Period ended 3 May 2018 2017 2016 £m £m £m Turnover 2,306 7,003 6,530 Profit after taxation 7 1,211 660 Other comprehensive (expense)/income (79 ) (387 ) 1,640 Total comprehensive (expense)/income (72 ) 824 2,300 2017 £m Non-current 12,771 Current assets 3,282 Total assets 16,053 Current liabilities (2,675 ) Non-current (1,537 ) Total liabilities (4,212 ) Net assets 11,841 Period ended 3 May 2018 2017 2016 £m £m £m Net cash inflow from operating activities 65 883 1,496 Net cash inflow/(outflow) from investing activities 442 270 (537 ) Net cash outflow from financing activities (504 ) (1,194 ) (980 ) Increase/(decrease) in cash and bank overdrafts in the year 3 (41 ) (21 )
Schedule of Amount Attributable to Joint Venture Included in GSK's Consolidated Statement of Comprehensive Income, Consolidated Statement of Changes in Equity and Consolidated Balance Sheet	The following amounts attributable to the Consumer Healthcare Joint Venture are included in GSK’s Consolidated statement of comprehensive income, Consolidated statement of changes in equity and Consolidated balance sheet: 2018 2017 2016 £m £m £m Total comprehensive income for the year attributable to non-controlling 111 296 730 Dividends paid to non-controlling 183 420 346 Non-controlling 0 3,631

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Contractual Obligations and Commitments	2018 2017 Contractual obligations and commitments £m £m Contracted for but not provided in the financial statements: Intangible assets 4,762 5,254 Property, plant and equipment 665 584 Investments 82 107 Purchase commitments 561 346 Pensions 238 738 Other commitments 0 38 Interest on loans 9,418 8,510 Finance lease charges 16 12 15,742 15,589
Summary of Commitments Under Non-Cancellable Operating Leases	Commitments under non-cancellable 2018 2017 Commitments under non-cancellable £m £m Rental payments due within one year 223 186 Rental payments due between one and two years 173 149 Rental payments due between two and three years 143 122 Rental payments due between three and four years 123 107 Rental payments due between four and five years 105 94 Rental payments due after five years 371 387 Total commitments under non-cancellable 1,138 1,045

Financial instruments and rel_2

Financial instruments and related disclosures (Tables)	12 Months Ended
	Dec. 31, 2018
Statement [LineItems]
Summary of External Credit Exposure	2018 AAA/Aaa AA/Aa A/A BBB/Baa BB+/Ba1 Total Bank balances and deposits 0 662 1,275 381 20 2,338 US Treasury and Treasury repo only money market funds 449 0 0 0 0 449 Liquidity funds 1,572 0 0 0 0 1,572 Government securities 0 83 0 1 0 84 3rd party financial derivatives 0 19 127 4 0 150 Total 2,021 764 1,402 386 20 4,593 2017 AAA/Aaa AA/Aa A/A BBB/Baa BB+/Ba1 Total Bank balances and deposits — 423 1,167 80 45 1,715 US Treasury and Treasury repo only money market funds 1,715 — — — — 1,715 Liquidity funds 403 — — — — 403 Government securities — 77 — 1 — 78 3rd party financial derivatives — 26 42 — — 68 Total 2,118 526 1,209 81 45 3,979
Summary of Financial Assets and Liabilities	2018 Notes Carrying Fair Financial assets measured at fair value through other comprehensive income (FVTOCI): Other investments designated at FVTOCI a 1,250 1,250 Trade and other receivables a,b 1,687 1,687 Financial assets measured at amortised cost: Other non-current b 49 49 Trade and other receivables b 3,761 3,761 Liquid investments 84 84 Cash and cash equivalents 2,338 2,338 Other items in Assets held for sale b 47 47 Financial assets mandatorily measured at fair value through profit or loss (FVTPL): Other investments a 72 72 Other non-current a,b 716 716 Trade and other receiveables a,b 120 120 Derivatives designated and effective as hedging instruments a,d,e 69 69 Held for trading derivatives that are not in a designated and effective hedging relationship a,d,e 188 188 Cash and cash equivalents a 2,021 2,021 Total financial assets 12,402 12,402 Financial liabilities measured at amortised cost: Borrowings excluding obligations under finance leases: – bonds in a designated hedging relationship d (8,213 ) (8,279 ) – other bonds (13,307 ) (15,475 ) – bank loans and overdrafts (290 ) (290 ) – commercial paper (630 ) (630 ) – other borrowings (3,556 ) (3,556 ) Total borrowings excluding obligations under finance leases f (25,996 ) (28,230 ) Obligations under finance leases (68 ) (68 ) Total borrowings (26,064 ) (28,298 ) Trade and other payables c (13,338 ) (13,338 ) Other provisions c (58 ) (58 ) Other non-current c (149 ) (149 ) Other items in Assets held for sale c (167 ) (167 ) Financial liabilities mandatorily at fair value through profit or loss (FVTPL): Contingent consideration liabilities a,c (6,286 ) (6,286 ) Derivatives designated and effective as hedging instruments a,d,e (105 ) (105 ) Held for trading derivatives that are not in a designated and effective hedging relationship a,d,e (23 ) (23 ) Total financial liabilities (46,190 ) (48,424 ) Net financial assets and financial liabilities (33,788 ) (36,022 ) 2017 Notes Carrying Fair Available-for-sale Liquid investments (Government bonds) a 78 78 Other investments a 918 918 Loans and receivables: Cash and cash equivalents 3,833 3,833 Trade and other receivables and Other non-current b 5,495 5,495 Financial assets at fair value through profit or loss: Trade and other receivables and Other non-current a,b 506 506 Derivatives designated as at fair value through profit or loss a,d,e 5 5 Derivatives classified as held for trading under IAS 39 a,d,e 71 71 Total financial assets 10,906 10,906 Financial liabilities measured at amortised cost: Borrowings excluding obligations under finance leases: – bonds in a designated hedging relationship d (4,315 ) (4,405 ) – other bonds (11,894 ) (14,743 ) – bank loans and overdrafts (236 ) (236 ) – commercial paper (529 ) (529 ) – other borrowings (49 ) (49 ) Total borrowings excluding obligations under finance leases f (17,023 ) (19,962 ) Obligations under finance leases (66 ) (66 ) Total borrowings (17,089 ) (20,028 ) Trade and other payables, Other provisions and certain Other non-current c (20,325 ) (20,325 ) Financial liabilities at fair value through profit or loss: Contingent consideration liabilities a,c (6,172 ) (6,172 ) Derivatives designated as at fair value through profit or loss a,d,e (26 ) (26 ) Derivatives classified as held for trading under IAS 39 a,d,e (48 ) (48 ) Total financial liabilities (43,660 ) (46,599 ) Net financial assets and financial liabilities (32,754 ) (35,693 )
Summary of Fair Value of Financial Instruments	At 31 December 2018 Level 1 Level 2 Level 3 Total Financial assets at fair value Financial assets at fair value through other comprehensive income (FVTOCI): Other investments designated at FVTOCI 656 0 594 1,250 Trade and other receivables 0 1,687 0 1,687 Financial assets mandatorily measured at fair value through profit or loss (FVTPL): Other investments 0 0 72 72 Other non-current 0 675 41 716 Trade and other receivables 0 79 41 120 Derivatives designated and effective as hedging instruments 0 69 0 69 Held for trading derivatives that are not in a designated and effective hedging relationship 0 182 6 188 Cash and cash equivalents 2,021 0 0 2,021 2,677 2,692 754 6,123 Financial liabilities at fair value Financial liabilities mandatorily at fair value through profit or loss (FVTPL): Contingent consideration liabilities 0 0 (6,286 ) (6,286 ) Derivatives designated and effective as hedging instruments 0 (105 ) 0 (105 ) Held for trading derivatives that are not in a designated and effective hedging relationship 0 (23 ) 0 (23 ) 0 (128 ) (6,286 ) (6,414 ) At 31 December 2017 Level 1 Level 2 Level 3 Total Financial assets at fair value Available-for-sale Liquid investments 77 1 — 78 Other investments 535 — 383 918 Other non-current — — 38 38 Financial assets at fair value through profit or loss: Other non-current — 382 44 426 Trade and other receivables — — 42 42 Derivatives designated as at fair value through profit or loss — 5 — 5 Derivatives classified as held for trading under IAS 39 — 62 9 71 612 450 516 1,578 Financial liabilities at fair value Financial liabilities at fair value through profit or loss: Contingent consideration liabilities — — (6,172 ) (6,172 ) Derivatives designated as at fair value through profit or loss — (26 ) — (26 ) Derivatives classified as held for trading under IAS 39 — (47 ) (1 ) (48 ) — (73 ) (6,173 ) (6,246 )
Summary of Financial and Non Financial Assets	2018 2017 At FVTPL At FVTOCI Amortised Financial Non- Total At FVTPL Loans and Financial Non-financial Total Trade and other receivables (Note 24) 120 1,687 3,761 5,568 855 6,423 42 5,148 5,190 810 6,000 Other non-current 716 0 49 765 811 1,576 464 347 811 602 1,413 Other items in Assets held for sale (Note 26) 0 0 47 47 37 84 — — — — — 836 1,687 3,857 6,380 1,703 8,083 506 5,495 6,001 1,412 7,413
Summary of Ageing of Financial Assets Which are Past Due and for Which No Provision for Bad or Doubtful Debts Has Been Made	The following table shows the ageing of financial assets which were past due at 31 December 2017 and for which no provision for bad or doubtful debts had been made at that date under IAS 39: 2017 Past due by 1–30 days 142 Past due by 31–90 days 70 Past due by 91–180 days 64 Past due by 181–365 days 27 Past due by more than 365 days 108 411
Reconciliation of Financial Instruments Within Trade and Other Payables, Other Provisions, Other Non-current Liabilities and Contingent Consideration Liabilities	2018 2017 Amortised Financial Non-financial Amortised Financial Non-financial At FVTPL cost instruments instruments Total At FVTPL cost instruments instruments Total £m £m £m £m £m £m £m £m £m £m Trade and other payables (Note 27) 0 (13,338 ) (13,338 ) (699 ) (14,037 ) — (20,129 ) (20,129 ) (841 ) (20,970 ) Other provisions (Note 29) 0 (58 ) (58 ) (1,365 ) (1,423 ) — (117 ) (117 ) (1,148 ) (1,265 ) Other non-current 0 (149 ) (149 ) (789 ) (938 ) — (79 ) (79 ) (902 ) (981 ) Contingent consideration liabilities (Note 39) (6,286 ) 0 (6,286 ) 0 (6,286 ) (6,172 ) — (6,172 ) — (6,172 ) Other items in Assets held for sale (Note 26) 0 (167 ) (167 ) (53 ) (220 ) — — — — — (6,286 ) (13,712 ) (19,998 ) (2,906 ) (22,904 ) (6,172 ) (20,325 ) (26,497 ) (2,891 ) (29,388 )
Summary of Fair Values of Derivatives Held	2018 Fair value 2017 Assets Liabilities Assets Liabilities Non-current Cash flow hedges – Interest rate swap contracts (principal amount – £1,266 million (2017 – £nil)) 0 (1 ) — — Net investment hedges – Cross currency swaps (principal amount – £1,575 million (2017 – £nil)) 64 0 — — Current Cash flow hedges – Foreign exchange contracts (principal amount – £1,809 million (2017 – £38 million)) 1 (56 ) — (1 ) Net investment hedges – Foreign exchange contracts (principal amount – £7,316 million (2017 – £6,333 million)) 4 (48 ) 5 (25 ) Derivatives designated and effective as hedging instruments 69 (105 ) 5 (26 ) Non-current Embedded and other derivatives 4 0 8 — Current Foreign exchange contracts (principal amount – £18,537 million (2017 – £14,449 million)) 82 (23 ) 62 (47 ) Embedded and other derivatives 102 0 1 (1 ) Derivatives classified as held for trading 188 (23 ) 71 (48 ) Total derivative instruments 257 (128 ) 76 (74 )
Summary of Effectiveness of Hedging Relationships and Amounts Reclassified from Hedging Reserve to Profit or Loss	The following table details the effectiveness of the hedging relationships and the amounts reclassified from the hedging reserve to profit or loss: 2018 Amount reclassified to profit or loss Hedging Amount Line item Hedged As hedged Line item Cash flow hedges Variability in cash flows from a highly probable forecast transaction 127 0 Other 0 (176 ) Other Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued 1 0 Finance (expense ) 0 0 Finance Net investment hedges Net investment in European foreign operations 286 7 Finance 0 0 Finance
Summary of Offsetting of Financial Assets and Liabilities	The following tables set out the financial assets and liabilities that are offset, or subject to enforceable master netting arrangements and other similar agreements but not offset, as at 31 December 2018 and 31 December 2017. The column ‘Net amount’ shows the impact on the Group’s balance sheet if all offset rights were exercised. At 31 December 2018 Gross Financial Net Related Net Financial assets Trade and other receivables 5,568 0 5,568 (37 ) 5,531 Derivative financial instruments 257 0 257 (62 ) 195 Financial liabilities Trade and other payables (13,338 ) 0 (13,338 ) 37 (13,301 ) Derivative financial instruments (128 ) 0 (128 ) 62 (66 ) At 31 December 2017 Gross Financial Net financial Related Net Financial assets Trade and other receivables 5,191 (1 ) 5,190 (31 ) 5,159 Derivative financial instruments 76 — 76 (64 ) 12 Financial liabilities Trade and other payables (20,130 ) 1 (20,129 ) 31 (20,098 ) Derivative financial instruments (74 ) — (74 ) 64 (10 )
Summary of Debt Interest Rate Repricing	The following table sets out the exposure of the Group to interest rates on debt, including commercial paper. The maturity analysis of fixed rate debt is stated by contractual maturity and of floating rate debt by interest rate repricing dates. For the purpose of this table, debt is defined as all classes of borrowings other than obligations under finance leases. 2018 2017 Total £m Total Floating and fixed rate debt less than one year (5,769 ) (2,802 ) Between one and two years (1,757 ) (1,340 ) Between two and three years (1,570 ) (1,076 ) Between three and four years (1,568 ) (16 ) Between four and five years (2,010 ) (1,475 ) Between five and ten years (5,833 ) (3,664 ) Greater than ten years (7,489 ) (6,650 ) Total (25,996 ) (17,023 ) Original issuance profile: Fixed rate interest (20,322 ) (16,209 ) Floating rate interest (5,635 ) (765 ) Total interest bearing (25,957 ) (16,974 ) Non-interest (39 ) (49 ) (25,996 ) (17,023 )
Summary of Anticipated Contractual Cash Flows Including Interest Payable for the Non-Derivative Financial Liabilities on Undiscounted Basis	At 31 December 2018 Debt Interest Obligations Finance charge Trade payables Total £m Due in less than one year (5,771 ) (714 ) (24 ) (5 ) (14,278 ) (20,792 ) Between one and two years (1,775 ) (708 ) (18 ) (2 ) (1,107 ) (3,610 ) Between two and three years (1,592 ) (675 ) (11 ) (2 ) (902 ) (3,182 ) Between three and four years (1,592 ) (620 ) (6 ) (1 ) (851 ) (3,070 ) Between four and five years (1,970 ) (567 ) (3 ) (1 ) (826 ) (3,367 ) Between five and ten years (5,875 ) (2,370 ) (6 ) (5 ) (3,748 ) (12,004 ) Greater than ten years (7,579 ) (3,764 ) 0 0 (1,468 ) (12,811 ) Gross contractual cash flows (26,154 ) (9,418 ) (68 ) (16 ) (23,180 ) (58,836 ) At 31 December 2017 Debt Interest Obligations Finance charge Trade payables Total Due in less than one year (2,802 ) (555 ) (23 ) (2 ) (21,521 ) (24,903 ) Between one and two years (1,344 ) (497 ) (27 ) (2 ) (853 ) (2,723 ) Between two and three years (1,078 ) (488 ) (8 ) (1 ) (813 ) (2,388 ) Between three and four years (16 ) (488 ) (2 ) (1 ) (784 ) (1,291 ) Between four and five years (1,483 ) (468 ) (1 ) (1 ) (752 ) (2,705 ) Between five and ten years (3,694 ) (2,018 ) (5 ) (5 ) (3,609 ) (9,331 ) Greater than ten years (6,720 ) (3,996 ) — — (1,471 ) (12,187 ) Gross contractual cash flows (17,137 ) (8,510 ) (66 ) (12 ) (29,803 ) (55,528 )
Summary of Anticipated Contractual Cash Flows for Derivative Instruments, Excluding Embedded Derivatives and Equity Options, Using Undiscounted Cash Flows	The table below provides an analysis of the anticipated contractual cash flows for the Group’s derivative instruments excluding equity options which do not give rise to cash flows, and other embedded derivatives, which are not material, using undiscounted cash flows. Cash flows in foreign currencies are translated using spot rates at 31 December. The gross cash flows of foreign exchange contracts are presented for the purpose of this table although, in practice, the Group uses standard settlement arrangements to reduce its liquidity requirements on these instruments. 2018 2017 Receivables Payables Receivables Payables Interest Foreign Interest Foreign Interest Foreign Interest Foreign Due in less than one year 49 26,680 (3 ) (26,802 ) — 20,319 — (20,326 ) Between one and two years 48 1,575 (3 ) (1,513 ) — — — — Between two and three years 24 0 (2 ) 0 — — — — Gross contractual cash flows 121 28,255 (8 ) (28,315 ) — 20,319 — (20,326 )
Interest rate risk [member]
Statement [LineItems]
Sensitivity Analysis for Each Type of Market Risk	The table below hypothetically shows the Group’s sensitivity to changes in interest rates in relation to Sterling, US Dollar and Euro floating rate financial assets and liabilities. If the interest rates applicable to floating rate financial assets and liabilities were to have increased by 1% (100 basis points), and assuming other variables had remained constant, it is estimated that the Group’s finance income for 2018 would have decreased by approximately £13 million (2017 – £5 million increase). A 1% (100 basis points) movement in interest rates is not deemed to have a material effect on equity. 2018 2017 Income statement impact of interest rate movements Increase/(decrease) £m Increase/(decrease) 1% (100 basis points) increase in Sterling interest rates (2 ) 24 1% (100 basis points) increase in US Dollar interest rates 1 (24 ) 1% (100 basis points) increase in Euro interest rates (12 ) 5
Currency risk [member]
Statement [LineItems]
Sensitivity Analysis for Each Type of Market Risk	2018 2017 Income statement impact of non-functional Increase/(decrease) in £m Increase/(decrease) in 10 cent appreciation of the US Dollar 36 76 10 cent appreciation of the Euro (7 ) (5 ) 10 yen appreciation of the Yen 15 9 2018 2017 Income statement impact of non-functional Increase/(decrease) in £m Increase/(decrease) in 10 cent depreciation of the US Dollar (30 ) (66 ) 10 cent depreciation of the Euro 6 4 10 yen depreciation of the Yen (13 ) (8 ) The equity impact, shown below, for foreign exchange sensitivity relates to derivative and non-derivative 2018 2017 Equity impact of non-functional Increase/(decrease) £m Increase/(decrease) 10 cent appreciation of the US Dollar 0 1 10 cent appreciation of the Euro (1,307 ) (1,028 ) 2018 2017 Equity impact of non-functional Increase/(decrease) £m Increase/(decrease) 10 cent depreciation of the US Dollar 0 (1 ) 10 cent depreciation of the Euro 1,091 861 The tables below present the Group’s sensitivity to a weakening and strengthening of Sterling against the relevant currency based on the composition of net debt as shown in Note 31 adjusted for the effects of foreign exchange derivatives that are not part of net debt but affect future foreign currency cash flows. 2018 2017 Impact of foreign exchange movements on net debt (Increase)/decrease £m (Increase)/decrease 10 cent appreciation of the US Dollar (714 ) (637 ) 10 cent appreciation of the Euro (60 ) 197 10 yen appreciation of the Yen 15 (4 ) 2018 2017 Impact of foreign exchange movements on net debt (Increase)/decrease £m (Increase)/decrease 10 cent depreciation of the US Dollar 610 549 10 cent depreciation of the Euro 50 (165 ) 10 yen depreciation of the Yen (13 ) 4
Level 3 [member]
Statement [LineItems]
Summary of Fair Value of Financial Instruments	Movements in the year for financial instruments measured using Level 3 valuation methods are presented below: 2018 2017 £m £m At 1 January (5,657 ) (5,486 ) Net losses recognised in the income statement (1,233 ) (970 ) Net gains recognised in other comprehensive income 123 22 Contingent consideration for businesses divested/acquired during the year 0 80 Payment of contingent consideration liabilities 1,095 685 Additions 381 117 Disposals and settlements (27 ) (52 ) Transfers from Level 3 (241 ) (24 ) Exchange adjustments 27 (29 ) At 31 December (5,532 ) (5,657 )
Interest rate swap contract [member]
Statement [LineItems]
Summary of Detailed Information of Foreign Exchange Forward Contracts, Swaps Outstanding and Related Hedged Items	The following tables provide information regarding interest rate swap contracts outstanding and the related hedged items at 31 December 2018. Interest rate swap contract assets and liabilities are presented in the line ‘Derivative financial instruments’ (either as assets or liabilities) on the Consolidated balance sheet. 2018 Hedging instruments Average Notional Change in fair Fair value Less than 1 year 0 0 0 0 1 to 2 years 0.11 676 0 (1 ) 2 to 5 years 0.16 591 0 23 Over 5 years 0 0 0 0 2018 Hedged items Change in Balance in Variable rate borrowings 3 (3 )
Summary of Effectiveness of Hedging Relationships and Amounts Reclassified from Hedging Reserve to Profit or Loss	The following table details the effectiveness of the hedging relationships and the amounts reclassified from the hedging reserve to profit or loss: 2018 Amount reclassified to profit or loss Hedging Amount Line item in loss in which hedge Hedged As hedged Line item Cash flow hedges Variability in cash flows (3 ) 0 Finance income/ (expense) 0 (2 ) Finance income/ (expense) Pre-hedging 15 0 Finance income/ (expense) 0 3 Finance income/ (expense)
Foreign Exchange Forward Contracts and Swaps [member]
Statement [LineItems]
Summary of Detailed Information of Foreign Exchange Forward Contracts, Swaps Outstanding and Related Hedged Items	2018 Hedging instruments Average exchange Foreign Notional Fair Cash flow hedges Foreign exchange contracts Buy foreign currency: Less than 3 months 0 0 0 0 3 to 6 months 1.13 Euro 26 1 Over 6 months 0 0 0 0 Sell foreign currency: Less than 3 months 0 0 0 0 3 to 6 months 0 0 0 0 Over 6 months 96.40 Indian Rupee 1,783 (56 ) 1,809 (55 ) Net investment hedges Foreign exchange contracts Sell foreign currency: Less than 3 months 1.11 Euro 6,933 (40 ) 3 to 6 months 0 0 0 0 Over 6 months 1.11 Euro 383 (4 ) 7,316 (44) 2018 Hedged items Change in value for Balance in cash flow hedge Cash flow hedges Variability in cash flows from a highly probable forecast transaction 56 (49 ) Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued (1 ) 1 Net investment hedges Investment in European foreign operations 50 286

Employee share schemes (Tables)

Employee share schemes (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Number of Shares and ADS Issuable	Shares Weighted ADS Weighted Number of shares and ADS issuable Number (000) fair value Number (000) fair value At 1 January 2016 32,577 17,520 Awards granted 12,983 £ 14.97 6,589 $ 39.18 Awards exercised (11,198 ) (6,214 ) Awards cancelled (1,507 ) (812 ) At 31 December 2016 32,855 17,083 Awards granted 13,018 £ 13.68 6,610 $ 35.63 Awards exercised (10,596 ) (5,674 ) Awards cancelled (1,352 ) (627 ) At 31 December 2017 33,925 17,392 Awards granted 12,751 £ 13.74 6,503 $ 35.28 Awards exercised (11,089 ) (5,583 ) Awards cancelled (1,519 ) (925 ) At 31 December 2018 34,068 17,387
Summary of Valuation Model Used to Valuing Saving - Related Option to Arrive at the Share Based Payment Charge	The assumptions used in the model are as follows: 2018 Grant 2017 Grant 2016 Grant Risk-free interest rate 0.76 % 0.54 % 0.32 % Dividend yield 5.3 % 5.9 % 4.9 % Volatility 21 % 23 % 23 % Expected life 3 years 3 years 3 years Savings-related options grant price (including 20% discount) £ 12.09 £ 10.86 £ 12.95
Summary of Option Outstanding	Share option Share option Savings-related Options outstanding schemes – shares schemes – ADS share option schemes Weighted Weighted Weighted Number exercise Number exercise Number exercise 000 price 000 price 000 price At 31 December 2018 1,796 £ 11.96 1,216 $ 36.19 5,929 £ 11.70 Range of exercise prices on options outstanding at year end £ 11.60 – £ 12.21 $ 33.42 – $ 38.14 £ 10.13 – £ 12.95 Weighted average market price on exercise during year £ 14.43 $ 39.77 £ 15.13 Weighted average remaining contractual life 0.9 years 0.9 years 2.6 years
Summary of Shares Held for Share Award Schemes	Shares held for share award schemes 2018 2017 Number of shares (000) 41,391 66,558 £m £m Nominal value 10 17 Carrying value 160 399 Market value 617 880 Shares held for share option schemes 2018 2017 Number of shares (000) 139 139 £m £m Nominal value 0 — Carrying value 1 1 Market value 2 2

Principal Group companies (Tabl

Principal Group companies (Tables)	12 Months Ended
	Dec. 31, 2018
Text block [abstract]
Schedule of Principal Subsidiaries and Their Countries of Incorporation	The following represent the principal subsidiaries and their countries of incorporation of the Group at 31 December 2018. The equity share capital of these entities is wholly owned by the Group except where its percentage interest is shown otherwise. All companies are incorporated in their principal country of operation except where stated. England US Glaxo Group Limited Block Drug Company, Inc. Glaxo Operations UK Limited Corixa Corporation GlaxoSmithKline Capital plc GlaxoSmithKline Capital Inc. GlaxoSmithKline Consumer Healthcare Holdings Limited GlaxoSmithKline Consumer Healthcare Holdings (US) LLC GlaxoSmithKline Consumer Healthcare (UK) Trading Limited GlaxoSmithKline Consumer Healthcare, L.P. (88%) GlaxoSmithKline Consumer Trading Services Limited GlaxoSmithKline Holdings (Americas) Inc. GlaxoSmithKline Export Limited GlaxoSmithKline LLC GlaxoSmithKline Finance plc Human Genome Sciences, Inc. GlaxoSmithKline Holdings Limited * GSK Consumer Health, Inc. (formerly Novartis Consumer Health, Inc.) GlaxoSmithKline Research & Development Limited S.R. One, Limited GlaxoSmithKline Services Unlimited * Stiefel Laboratories, Inc. GlaxoSmithKline UK Limited ViiV Healthcare Company (78.3%) Setfirst Limited SmithKline Beecham Limited ViiV Healthcare Limited (78.3%) ViiV Healthcare UK Limited (78.3%) Europe Others GlaxoSmithKline Biologicals SA (Belgium) GlaxoSmithKline Argentina S.A. (Argentina) GlaxoSmithKline Pharmaceuticals SA (Belgium) GlaxoSmithKline Australia Pty Ltd (Australia) GlaxoSmithKline Biologicals S.A.S. (France) GlaxoSmithKline Consumer Healthcare Australia Pty Ltd (Australia) GlaxoSmithKline Sante Grand Public SAS (France) GlaxoSmithKline Brasil Limitada (Brazil) Laboratoire GlaxoSmithKline (France) GlaxoSmithKline Consumer Healthcare Inc. (Canada) ViiV Healthcare SAS (France) (78.3%) GlaxoSmithKline Inc. (Canada) GlaxoSmithKline Consumer Healthcare GmbH & Co. KG (Germany) ID Biomedical Corporation of Quebec (Canada) GlaxoSmithKline GmbH & Co. KG (Germany) GlaxoSmithKline Limited (China (Hong Kong)) GSK Vaccines GmbH (Germany) GlaxoSmithKline (Tianjin) Co. Ltd (China) (90%) GlaxoSmithKline Consumer Healthcare S.p.A. (Italy) Sino-American Tianjin Smith Kline & French Laboratories Ltd (China) (55%) GlaxoSmithKline S.p.A. (Italy) GlaxoSmithKline Consumer Healthcare Limited (India) (72.5%) GSK Vaccines S.r.l. (Italy) GlaxoSmithKline Pharmaceuticals Limited (India) (75%) GlaxoSmithKline B.V. (Netherlands) GlaxoSmithKline Consumer Healthcare Japan K.K. (Japan) GlaxoSmithKline Consumer Healthcare Sp.z.o.o. (Poland) GlaxoSmithKline K.K. (Japan) GSK Services Sp z o.o. (Poland) ViiV Healthcare Kabushiki Kaisha (Japan) (78.3%) GlaxoSmithKline Trading Services Limited (Republic of Ireland) (i) GlaxoSmithKline Pakistan Limited (Pakistan) (82.6%) GlaxoSmithKline Healthcare AO (Russia) Glaxo Wellcome Manufacturing Pte Ltd. (Singapore) GlaxoSmithKline S.A. (Spain) GlaxoSmithKline Korea Limited (Republic of Korea) Laboratorios ViiV Healthcare, S.L. (Spain) (78.3%) GlaxoSmithKline llaclari Sanayi ve Ticaret A.S. (Turkey) GSK Consumer Healthcare S.A. (Switzerland) (i) Exempt from the provisions of section 347 and 348 of the Companies Act 2014 (Ireland), in accordance with the exemptions noted in Section 357 of that Act. Further subsidiaries, as disclosed on pages 260 to 270, are exempt from these provisions as they are also consolidated in the group financial statements. * Directly held wholly owned subsidiary of GlaxoSmithKline plc.

Presentation of the Financial_4

Presentation of the Financial Statements - Additional Information (Detail) - GBP (£)	Jan. 01, 2018	Dec. 31, 2018
Presentation Of The Financial Statements [abstract]
Additional ECL allowance for trade receivables	£ 15,000,000	£ 15,000,000
Other transition adjustments arising from change in impairment basis		£ 0
Deferred tax impact, retained earnings	3,000,000
Cumulative adjustment to decrease retained earnings	4,000,000
Transfer between retained earnings and fair value reserve	£ 288,000,000

Presentation of the Financial_5

Presentation of the Financial Statements - Summary of Amount of Adjustment for Each Financial Statement Line Item Affected by Application of IFRS 9 and IFRS 15 (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of adjustment for each financial statement line item affected by application IFRS 9 and IFRS 15 [line items]
Trade and other receivables	£ 6,423	£ 5,985	£ 6,000
Liquid investments	84	79	78
Other payables - returns and rebates		(3,492)
Other payables - deferred income		(213)
Deferred tax assets	2,731	3,797	2,400	£ 2,440
Total effect on net assets	3,672	3,474	3,489
Fair value reserve	2,061	41	2,047	2,220	£ 2,340
Retained earnings	(2,137)	(6,204)	(6,477)
Total effect on equity	£ 3,672	3,474	3,489	£ 4,963	£ 8,878
Previously stated [member]
Disclosure of adjustment for each financial statement line item affected by application IFRS 9 and IFRS 15 [line items]
Trade and other receivables		6,000
Liquid investments		78
Other payables - returns and rebates		(3,463)
Other payables - deferred income		(240)
Deferred tax assets		3,796
Total effect on net assets		3,489
Fair value reserve		329
Retained earnings		(6,477)
Total effect on equity		3,489	3,489
IFRS 9 adjustments [member]
Disclosure of adjustment for each financial statement line item affected by application IFRS 9 and IFRS 15 [line items]
Trade and other receivables		(15)
Liquid investments		1
Other payables - returns and rebates		0
Other payables - deferred income		0
Deferred tax assets		3
Total effect on net assets		(11)
Fair value reserve		(288)
Retained earnings		277
Total effect on equity		(11)	(11)
IFRS 15 adjustments [member]
Disclosure of adjustment for each financial statement line item affected by application IFRS 9 and IFRS 15 [line items]
Trade and other receivables		0
Liquid investments		0
Other payables - returns and rebates		(29)
Other payables - deferred income		27
Deferred tax assets		(2)
Total effect on net assets		(4)
Fair value reserve		0
Retained earnings		(4)
Total effect on equity		£ (4)	£ (4)

Accounting Principles and Pol_3

Accounting Principles and Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018GBP (£)
Disclosure of accounting principles and policies [line items]
Provisions related to legal and other disputes	£ 0
Licences and franchises [member] | Top of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	20 years
Amortised brands [member] | Top of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	20 years
ERP software systems [member] | Top of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	Ten years
ERP software systems [member] | Bottom of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	Seven years
Other computer software [member] | Top of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	Five years
Other computer software [member] | Bottom of range [member]
Disclosure of accounting principles and policies [line items]
Estimated useful lives	Three years

Accounting Principles and Pol_4

Accounting Principles and Policies - Summary of Expected Useful Lives of Property Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2018
Freehold buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives of property plant and equipment	20 to 50 years
Leasehold land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives of property plant and equipment	Lease term or 20 to 50 years
Plant and machinery [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives of property plant and equipment	10 to 20 years
Equipment and vehicles [member]
Disclosure of detailed information about property, plant and equipment [line items]
Useful lives of property plant and equipment	3 to 10 years

Key Accounting Judgements and_2

Key Accounting Judgements and Estimates - Additional Information (Detail) £ in Millions, $ in Billions	1 Months Ended	12 Months Ended
	Jun. 30, 2018GBP (£)	Dec. 31, 2018GBP (£)	Dec. 31, 2017GBP (£)	Dec. 31, 2016GBP (£)	Jun. 30, 2018USD ($)	Dec. 31, 2015GBP (£)
Disclosure of changes in accounting estimates [line items]
Turnover		£ 30,821	£ 30,186	£ 27,889
Tax charge for the year		754	1,356	877
Tax payable, current		965	995
Tax recoverable, current		229	258
Tax payable, non-current		272	411
Uncertain tax position charge		1,082	1,175
Legal costs		117	166
Provision for legal and other disputes		219	186
Contingent consideration and put option liabilities		1,851	2,134
Contingent consideration liabilities		6,286	6,172	5,896		£ 3,855
Surplus on defined benefit schemes		£ 711	470
Percentage of decrease in discount rate		0.25%
Net pension deficit		£ 707
Increased annual pension cost		28
Shionogi ViiV healthcare joint venture [member] | Trade and other payable [member] | Written put options [member]
Disclosure of changes in accounting estimates [line items]
Put option recognised		1,240
Shionogi ViiV healthcare joint venture [member]
Disclosure of changes in accounting estimates [line items]
Contingent consideration liabilities		5,937	5,542	£ 5,304		£ 3,409
Business combinations [member]
Disclosure of changes in accounting estimates [line items]
Contingent consideration liabilities		6,286	6,172
Novartis [member]
Disclosure of changes in accounting estimates [line items]
Contingent consideration liabilities		£ 296	£ 584
Acquisition cost | $					$ 13
Acquisition related net charge	£ 658

New Accounting Requirements - A

New Accounting Requirements - Additional Information (Detail) - GBP (£)	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Description Of New Accounting Requirements [line items]
IFRS 16, description		IFRS 16 'Leases' was issued in January 2016 and will be implemented by the Group from 1 January 2019. The Standard will replace IAS 17 'Leases' and will require lease liabilities and 'right of use' assets to be recognised on the balance sheet for almost all leases.
Lease liability		£ 68	£ 66
Events After Reporting Period [member] | IFRS 16 leases [member]
Description Of New Accounting Requirements [line items]
Right of use of assets	£ 1,100,000,000
Lease liability	1,300,000,000
Reduction in net assets	(100,000,000)
Reduction in total equity	£ (100,000,000)

Exchange Rates - Summary of Cur

Exchange Rates - Summary of Currencies Translations and Relevant Exchange Rates (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
USD [member]
Disclosure of foreign exchange rates [line items]
Average rates	1.33	1.30	1.36
Period end rates	1.27	1.35	1.24
Euro [member]
Disclosure of foreign exchange rates [line items]
Average rates	1.13	1.15	1.23
Period end rates	1.11	1.13	1.17
Yen [member]
Disclosure of foreign exchange rates [line items]
Average rates	147	145	149
Period end rates	140	152	144

Turnover and Segment Informat_3

Turnover and Segment Information - Additional Information (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)SegmentsWholesalers	Dec. 31, 2017GBP (£)	Dec. 31, 2016GBP (£)	Dec. 31, 2015GBP (£)
Disclosure of operating segments [line items]
Number of reportable operating segments | Segments	4
Description of factors used to identify entity's reportable segments	Operating segments are reported based on the financial information provided to the Chief Executive Officer and the responsibilities of the Corporate Executive Team (CET). GSK reports results under four segments: Pharmaceuticals; Pharmaceuticals R&D; Vaccines and Consumer Healthcare, and individual members of the CET are responsible for each segment.
Revenue recognised in year from performance obligations satisfied in previous periods	£ 426
Turnover from changes to estimates of RAR accruals	122
Royalty income	299	£ 356	£ 398
Turnover	30,821	30,186	27,889
Contingent consideration liability	6,286	6,172	5,896	£ 3,855
Shionogi-ViiV Healthcare [member]
Disclosure of operating segments [line items]
Contingent consideration liability	5,937	5,542
Pfizer put option	1,240	1,304
Consumer Healthcare [member]
Disclosure of operating segments [line items]
Turnover	7,658	7,750	7,193
Put option liability	£ 0	8,606
US [member] | Pharmaceuticals and Vaccines [member]
Disclosure of operating segments [line items]
Number of wholesalers | Wholesalers	3
Wholesalers 1 [member] | US [member] | Pharmaceuticals and Vaccines [member]
Disclosure of operating segments [line items]
Turnover	£ 2,709	2,449	2,139
Wholesalers 2 [member] | US [member] | Pharmaceuticals and Vaccines [member]
Disclosure of operating segments [line items]
Turnover	2,962	3,043	2,691
Wholesalers 3 [member] | US [member] | Pharmaceuticals and Vaccines [member]
Disclosure of operating segments [line items]
Turnover	£ 2,656	£ 2,356	£ 2,129

Turnover and Segment Informat_4

Turnover and Segment Information - Turnover by Segment (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of operating segments [line items]
Turnover	£ 30,821	£ 30,186	£ 27,889
Operating Segments [member]
Disclosure of operating segments [line items]
Turnover	30,821	30,186	27,889
Pharmaceuticals [member]
Disclosure of operating segments [line items]
Turnover	17,269	17,276	16,104
Pharmaceuticals [member] | Operating Segments [member]
Disclosure of operating segments [line items]
Turnover	17,269	17,276	16,104
Vaccines [member]
Disclosure of operating segments [line items]
Turnover	5,894	5,160	4,592
Vaccines [member] | Operating Segments [member]
Disclosure of operating segments [line items]
Turnover	5,894	5,160	4,592
Consumer Healthcare [member]
Disclosure of operating segments [line items]
Turnover	7,658	7,750	7,193
Consumer Healthcare [member] | Operating Segments [member]
Disclosure of operating segments [line items]
Turnover	£ 7,658	£ 7,750	£ 7,193

Turnover and Segment Informat_5

Turnover and Segment Information - Turnover by Product & Service (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of products and services [line items]
Turnover	£ 30,821	£ 30,186	£ 27,889
Consumer Healthcare [member]
Disclosure of products and services [line items]
Turnover	7,658	7,750	7,193
Consumer Healthcare [member] | Wellness [member]
Disclosure of products and services [line items]
Turnover	3,940	4,001	3,726
Consumer Healthcare [member] | Oral Care [member]
Disclosure of products and services [line items]
Turnover	2,496	2,466	2,223
Consumer Healthcare [member] | Nutrition [member]
Disclosure of products and services [line items]
Turnover	643	680	674
Consumer Healthcare [member] | Skin Health [member]
Disclosure of products and services [line items]
Turnover	579	603	570
Pharmaceuticals [member]
Disclosure of products and services [line items]
Turnover	17,269	17,276	16,104
Pharmaceuticals [member] | Respiratory [member]
Disclosure of products and services [line items]
Turnover	6,928	6,991	6,510
Pharmaceuticals [member] | HIV [member]
Disclosure of products and services [line items]
Turnover	4,722	4,350	3,556
Pharmaceuticals [member] | Immuno inflammation [member]
Disclosure of products and services [line items]
Turnover	472	377	340
Pharmaceuticals [member] | Established Pharmaceuticals [member]
Disclosure of products and services [line items]
Turnover	5,147	5,558	5,698
Vaccines [member]
Disclosure of products and services [line items]
Turnover	5,894	5,160	4,592
Vaccines [member] | Meningitis [member]
Disclosure of products and services [line items]
Turnover	881	890	662
Vaccines [member] | Influenza [member]
Disclosure of products and services [line items]
Turnover	523	488	414
Vaccines [member] | Shingles [member]
Disclosure of products and services [line items]
Turnover	784	22
Vaccines [member] | Established vaccines [member]
Disclosure of products and services [line items]
Turnover	£ 3,706	£ 3,760	£ 3,516

Turnover and Segment Informat_6

Turnover and Segment Information - Segment Profit and Operating Profit (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Segment profit
Operating profit	£ 5,483	£ 4,087	£ 2,598
Finance income	81	65	72
Finance costs	(798)	(734)	(736)
Profit on disposal of interest in associates	3	94
Share of after tax profits of associates and joint ventures	31	13	5
Profit before taxation	4,800	3,525	1,939
Taxation	(754)	(1,356)	(877)
Profit after taxation for the year	4,046	2,169	1,062
Depreciation and amortisation by segment
Total depreciation and amortisation	1,856	1,922	1,774
PP&E, intangible asset and goodwill impairment by segment
Total impairment	350	1,069	289
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(13)	(52)	(87)
Net operating assets	23,037	15,117
Net debt	(21,621)	(13,178)
Investments in associates and joint ventures	236	183	263
Derivative financial instruments	129	2
Current and deferred taxation	1,723	1,252
Assets held for sale (excluding cash and cash equivalents)	168	113
Net assets	3,672	3,489		£ 3,474
Operating Segments [member]
Segment profit
Operating profit	9,204	8,944	8,033
Depreciation and amortisation by segment
Total depreciation and amortisation	1,170	1,187	1,092
PP&E, intangible asset and goodwill impairment by segment
Total impairment	75	71	197
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(5)	(16)	(52)
Net operating assets	21,896	14,249
Corporate and Other Unallocated [member]
Segment profit
Operating profit	(459)	(376)	(362)
Depreciation and amortisation by segment
Total depreciation and amortisation	106	144	94
PP&E, intangible asset and goodwill impairment by segment
Total impairment	14	3	24
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	0		(26)
Net operating assets	1,141	868
Other Reconciling Items between Segment Profit and Operating Profit [member]
Segment profit
Operating profit	(3,262)	(4,481)	(5,073)
Depreciation and amortisation by segment
Total depreciation and amortisation	580	591	588
PP&E, intangible asset and goodwill impairment by segment
Total impairment	261	995	68
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(8)	(36)	(9)
Pharmaceuticals [member] | Operating Segments [member]
Segment profit
Operating profit	8,420	8,667	7,976
Depreciation and amortisation by segment
Total depreciation and amortisation	506	551	440
PP&E, intangible asset and goodwill impairment by segment
Total impairment	51	38	29
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(4)	(13)	(15)
Net operating assets	869	2,017
Pharmaceuticals Research and Development [member] | Operating Segments [member]
Segment profit
Operating profit	(2,676)	(2,740)	(2,488)
Depreciation and amortisation by segment
Total depreciation and amortisation	123	96	211
PP&E, intangible asset and goodwill impairment by segment
Total impairment	15	10	88
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(1)	(2)	(10)
Net operating assets	502	522
Pharmaceuticals Including Research and Development [member] | Operating Segments [member]
Segment profit
Operating profit	5,744	5,927	5,488
Depreciation and amortisation by segment
Total depreciation and amortisation	629	647	651
PP&E, intangible asset and goodwill impairment by segment
Total impairment	66	48	117
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	(5)	(15)	(25)
Net operating assets	1,371	2,539
Vaccines [member] | Operating Segments [member]
Segment profit
Operating profit	1,943	1,644	1,429
Depreciation and amortisation by segment
Total depreciation and amortisation	395	405	315
PP&E, intangible asset and goodwill impairment by segment
Total impairment	5	13	34
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	0		(19)
Net operating assets	9,966	9,707
Consumer Healthcare [member] | Operating Segments [member]
Segment profit
Operating profit	1,517	1,373	1,116
Depreciation and amortisation by segment
Total depreciation and amortisation	146	135	126
PP&E, intangible asset and goodwill impairment by segment
Total impairment	4	10	46
PP&E and intangible asset impairment reversals by segment
Total impairment reversals	0	(1)	£ (8)
Net operating assets	£ 10,559	£ 2,003

Turnover and Segment Informat_7

Turnover and Segment Information - Summary of Geographical Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of geographical areas [line items]
Turnover	£ 30,821	£ 30,186	£ 27,889
Non-current assets	34,426	34,566
UK [member]
Disclosure of geographical areas [line items]
Non-current assets	6,118	6,824
US [member]
Disclosure of geographical areas [line items]
Non-current assets	7,540	6,841
Rest of World. [member]
Disclosure of geographical areas [line items]
Non-current assets	20,768	20,901
Customer [member]
Disclosure of geographical areas [line items]
Turnover	30,821	30,186	27,889
Customer [member] | UK [member]
Disclosure of geographical areas [line items]
Turnover	923	940	1,056
Customer [member] | US [member]
Disclosure of geographical areas [line items]
Turnover	11,982	11,263	10,197
Customer [member] | Rest of World. [member]
Disclosure of geographical areas [line items]
Turnover	£ 17,916	£ 17,983	£ 16,636

Other Operating Income_(Expen_3

Other Operating Income/(Expense) - Information about Other Operating Income Expense (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of other operating income expense [abstract]
Fair value remeasurements of equity investments under IFRS 9	£ 16
Disposal of businesses and assets	258	£ 195	£ 283
Fair value remeasurements on contingent consideration recognised in business combinations	(1,252)	(1,012)	(2,205)
Remeasurement of ViiV Healthcare put option liabilities and preferential dividends	58	13	(577)
Remeasurement of Consumer Healthcare put option liability	(658)	(1,186)	(1,133)
Fair value adjustments on derivative financial instruments	(3)	9	(3)
Other (expense)/income	(7)	9	23
Impairment of available-for-sale equity investments under IAS 39		(30)	(47)
Disposal of available-for-sale equity investments under IAS 39		37	254
Other operating income expense	£ (1,588)	£ (1,965)	£ (3,405)

Other Operating Income_(Expen_4

Other Operating Income/(Expense) - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of other operating income expense [line items]
Disposal of businesses and assets	£ 258	£ 195	£ 283
Fair value remeasurements on contingent consideration	(1,252)	£ (1,012)	£ (2,205)
Vaccines business acquisition [member]
Disclosure of other operating income expense [line items]
Fair value remeasurements on contingent consideration	56
Shionogi ViiV healthcare joint venture [member]
Disclosure of other operating income expense [line items]
Fair value remeasurements on contingent consideration	1,188
Tapinarof [member]
Disclosure of other operating income expense [line items]
Disposal of businesses and assets	119
Consumer Tail Brands [member]
Disclosure of other operating income expense [line items]
Disposal of businesses and assets	£ 33

Operating Profit - Summary of I

Operating Profit - Summary of Information About Profit Loss (Detail) - GBP (£)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Profit or loss [abstract]
Employee costs (Note 9)	£ 9,440,000,000	£ 9,122,000,000	£ 8,212,000,000
Advertising	1,376,000,000	1,351,000,000	1,265,000,000
Distribution costs	389,000,000	405,000,000	395,000,000
Depreciation of property, plant and equipment	954,000,000	988,000,000	978,000,000
Impairment of property, plant and equipment, net of reversals	203,000,000	327,000,000	180,000,000
Amortisation of intangible assets	902,000,000	934,000,000	796,000,000
Impairment of intangible assets, net of reversals	134,000,000	690,000,000	22,000,000
Net foreign exchange losses	81,000,000	215,000,000	53,000,000
Inventories:
Cost of inventories included in cost of sales	8,713,000,000	8,526,000,000	8,093,000,000
Write-down of inventories	695,000,000	701,000,000	533,000,000
Reversal of prior year write-down of inventories	(302,000,000)	(352,000,000)	(145,000,000)
Operating lease rentals:
Minimum lease payments	188,000,000	110,000,000	91,000,000
Contingent rents	12,000,000	4,000,000	4,000,000
Sub-lease payments	5,000,000	5,000,000	4,000,000
Fees payable to the company's auditor and its associates in relation to the Group	£ 29,800,000	£ 29,200,000	£ 29,700,000

Operating Profit - Additional I

Operating Profit - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Operating Profit [line items]
Net foreign exchange losses	£ 81	£ 215	£ 53
Major restructuring costs	809	1,056	970
Liquidation Or Disposal Of Overseas Subsidiary [member]
Disclosure of Operating Profit [line items]
Net foreign exchange losses	£ 0	£ 109	£ 0

Operating Profit - Summary of A

Operating Profit - Summary of Auditors Remuneration (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Auditor's remuneration [abstract]
Audit	£ 26.2	£ 27.7	£ 26.6
Taxation compliance	0.1	0.2	0.2
Taxation advice	0	0.1	1.8
Other assurance services	3	1	0.3
All other services	0.5	0.2	0.8
Auditors remuneration	29.8	29.2	29.7
Pension schemes [member]
Auditor's remuneration [abstract]
Audit	0.3	0.3	0.4
All other services	0	0.1
GLAXOSMITHKLINE PLC [member]
Auditor's remuneration [abstract]
Audit	6.7	7	5.8
Subsidiaries [member]
Auditor's remuneration [abstract]
Audit	12.9	16.2	16.4
Attestation under s.404 of Sarbanes-Oxley Act 2002 [member]
Auditor's remuneration [abstract]
Audit	£ 6.6	£ 4.5	£ 4.4

Employee Costs - Summary of Emp

Employee Costs - Summary of Employee Costs (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-term employee benefits expense [abstract]
Wages and salaries	£ 7,203	£ 7,116	£ 6,391
Social security costs	795	802	733
Pension and other post-employment costs, including augmentations (Note 28)	586	616	541
Cost of share-based incentive plans	393	347	338
Severance and other costs from integration and restructuring activities	463	241	209
Employee benefits expense	£ 9,440	£ 9,122	£ 8,212

Employee Costs - Summary of Cos

Employee Costs - Summary of Cost of Share-based Incentive Plans (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expense from share based payment transactions with employees [line items]
Cost of share-based incentive plans	£ 393	£ 347	£ 338
Share Value Plan [member]
Expense from share based payment transactions with employees [line items]
Cost of share-based incentive plans	304	276	271
Performance Share Plan [member]
Expense from share based payment transactions with employees [line items]
Cost of share-based incentive plans	49	47	39
Share option plans [member]
Expense from share based payment transactions with employees [line items]
Cost of share-based incentive plans	4	4	4
Cash settled and other plans [member]
Expense from share based payment transactions with employees [line items]
Cost of share-based incentive plans	£ 36	£ 20	£ 24

Employee Costs - Disclosure of

Employee Costs - Disclosure of Average Monthly Number of Persons Employed by the Group (Including Directors) (Detail) - Employee	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of employee costs and numbers [line items]
Average number of employees	96,851	99,349	99,827
Manufacturing [member]
Disclosure of employee costs and numbers [line items]
Average number of employees	37,296	38,632	38,611
Selling, general and administration [member]
Disclosure of employee costs and numbers [line items]
Average number of employees	47,887	49,141	49,961
Research and development [member]
Disclosure of employee costs and numbers [line items]
Average number of employees	11,668	11,576	11,255

Employee Costs - Summary of Com

Employee Costs - Summary of Compensation of the Directors and Senior Management (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employees Benefit [abstract]
Wages and salaries	£ 29	£ 26	£ 25
Social security costs	3	4	4
Pension and other post-employment costs	3	3	2
Cost of share-based incentive plans	20	22	15
Key management personnel compensation	£ 55	£ 55	£ 46

Major Restructuring Costs - Add

Major Restructuring Costs - Additional Information (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Major Restructuring Costs [abstract]
Total restructuring costs	£ 809

Major Restructuring Costs - Sum

Major Restructuring Costs - Summary of Analysis of Costs Charged to Operating Profit (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Major Restructuring Costs [abstract]
Increase in provision for Major restructuring programmes	£ 450	£ 259	£ 163
Amount of provision reversed unused	(99)	(43)	(140)
Impairment losses recognised	130	278	158
Other non-cash charges	72	247	108
Other cash costs	256	315	681
Cost charged to operating profit	£ 809	£ 1,056	£ 970

Major Restructuring Costs - S_2

Major Restructuring Costs - Summary of Major Restructuring Charges (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of restructuring costs [line items]
Cost of sales	£ 10,241	£ 10,342	£ 9,290
Selling, general and administration	9,915	9,672	9,366
Other operating income/(expense)	1,588	1,965	3,405
Cost charged to operating profit	809	1,056	970
Cost of major restructuring [member]
Disclosure of restructuring costs [line items]
Cost of sales	443	545	297
Selling, general and administration	315	248	514
Research and development	49	263	159
Other operating income/(expense)	2
Cost charged to operating profit	£ 809	£ 1,056	£ 970

Finance Income - Summary of Fin

Finance Income - Summary of Finance Income (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Financial Income and Expense [line items]
Fair value adjustments on derivatives at fair value through profit or loss	£ (3)	£ 9	£ (3)
Finance income	81	65	72
IFRS9 [member]
Disclosure Of Financial Income and Expense [line items]
Financial assets measured at amortised cost	73
Financial assets measured at fair value through profit or loss	1
Net gains arising from hedge ineffectiveness on net investment hedges	7
IAS 39 [member]
Disclosure Of Financial Income and Expense [line items]
Cash and cash equivalents		60	67
Available-for-sale investments		2	1
Loans and receivables		1	2
Fair value adjustments on derivatives at fair value through profit or loss		2	2
Finance income	£ 81	£ 65	£ 72

Finance Expense - Summary of Fi

Finance Expense - Summary of Finance Cost (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finance expense arising on:
Financial liabilities at amortised cost	£ (677)	£ (698)	£ (671)
Derivatives at fair value through profit or loss	(38)	(22)	(30)
Net losses arising from: Financial instruments mandatorily measured at fair value through profit or loss	3	(4)	(3)
Reclassification of hedges from other comprehensive income	(2)		(1)
Unwinding of discounts on provisions	(15)	(16)	(16)
Other finance expense	(69)	6	(15)
Finance Costs	£ (798)	£ (734)	£ (736)

Finance Expense - Additional In

Finance Expense - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of finance expense [abstract]
Description of financial instrument	All derivatives accounted for at fair value through profit or loss, other than designated and effective hedging instruments (see Note 42, 'Financial instruments and related disclosures'), are classified as held-for-trading financial instruments. Interest expense arising on derivatives at fair value through profit or loss relates to swap interest expense.
Interest paid relating to income taxes	£ 39
Interest received relating to income taxes		£ 24

Associates and Joint Ventures -

Associates and Joint Ventures - Summary of After Tax Profits and Losses of Associates and Joint Ventures (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial information of associates and joint ventures [line items]
Share of after tax profits and losses of associates and joint ventures	£ 31	£ 13	£ 5
Joint ventures [member]
Disclosure of financial information of associates and joint ventures [line items]
Share of after tax profits and losses of associates and joint ventures	3	(3)	(4)
Associates [member]
Disclosure of financial information of associates and joint ventures [line items]
Share of after tax profits and losses of associates and joint ventures	£ 28	£ 16	£ 9

Associates and joint ventures_2

Associates and joint ventures - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of joint ventures and associates [line items]
Profit after taxation for the year	£ 31	£ 13	£ 5
Other comprehensive income	254	713	962
Sales to associates and joint ventures	43	£ 41	£ 43
Innoviva Inc [member]
Disclosure of joint ventures and associates [line items]
Profit after taxation for the year	33
Other comprehensive income	£ 0

Associates and Joint Ventures_3

Associates and Joint Ventures - Summary of Group Held for Significant Associate (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial information of associates and joint ventures [line items]
Turnover	£ 30,821	£ 30,186	£ 27,889
Profit after taxation	4,046	2,169	1,062
Other comprehensive income	254	713	962
Total comprehensive income	4,300	2,882	2,024
Innoviva Inc [member]
Disclosure of financial information of associates and joint ventures [line items]
Turnover	183	165	98
Profit after taxation	134	103	44
Other comprehensive income	0
Total comprehensive income	£ 134	£ 103	£ 44

Associates and Joint Ventures_4

Associates and Joint Ventures - Summary of Aggregated Financial Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial information of associates and joint ventures [line items]
Share of turnover	£ 30,821	£ 30,186	£ 27,889
Share of after tax (losses)/profits	4,046	2,169	1,062
Share of other comprehensive income	254	713	962
Share of total comprehensive (expense)/income	4,300	2,882	2,024
Other associates [member]
Disclosure of financial information of associates and joint ventures [line items]
Share of turnover	242	252	133
Share of after tax (losses)/profits	(2)	(5)	(1)
Share of other comprehensive income	0
Share of total comprehensive (expense)/income	£ (2)	£ (5)	£ (1)

Taxation - Summary of Taxation

Taxation - Summary of Taxation Charge Based on Profits (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current tax expense (income) and adjustments for current tax of prior periods [abstract]
Credit in respect of prior periods	£ (492)	£ (508)	£ (149)
Total current taxation	1,168	1,619	1,418
Total deferred taxation	(414)	(263)	(541)
Total tax	754	1,356	877
UK [member]
Current tax expense (income) and adjustments for current tax of prior periods [abstract]
Current tax expense (income)	234	199	241
Rest of World [member]
Current tax expense (income) and adjustments for current tax of prior periods [abstract]
Current tax expense (income)	£ 1,426	£ 1,928	£ 1,326

Taxation - Additional Informati

Taxation - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax expense benefits [line items]
Average effective tax rate	15.70%	38.50%	45.20%
Provisions For Uncertain Tax Position	£ 1,082	£ 1,175
Provision for deferred tax liabilities	1,156	1,396
Unremitted profits	18,000	17,000
Unremitted profits for which deferred tax not provided	231	0
Deferred tax expense (income) recognised in profit or loss	396
Research and development incentives recognised in operating profit	18
Deferred tax assets recognized on trading losses	447	261
Foreign tax credits for which deferred tax has not been provided	114	151
Overseas [Member]
Income tax expense benefits [line items]
Provision for deferred tax liabilities	185	£ 209
UK [member]
Income tax expense benefits [line items]
Payments of corporation tax	113
US [member]
Income tax expense benefits [line items]
Reassessment of prior year estimate of US Tax Reform	£ 125

Taxation - Summary of Reconcili

Taxation - Summary of Reconciliation of Tax Charge Calculated at the UK Statutory Rate on the Group Profit Before Tax with the Actual Tax Charge (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure - Taxation - Summary of Reconciliation of Tax Charge Calculated at the UK Statutory Rate on the Group Profit Before Tax with the Actual Tax Charge [Abstract]
Profit before tax	£ 4,800	£ 3,525	£ 1,939
UK statutory rate of taxation	912	679	388
Differences in overseas taxation rates	675	635	593
Benefit of intellectual property incentives	(522)	(458)	(321)
R&D credits	(73)	(75)	(93)
FV remeasurement of non-taxable put options	221	227	340
Tax losses where no benefit is recognised	24	28	(15)
Permanent differences on disposals and acquisitions	(7)	4	(21)
Other permanent differences	85	196	122
Re-assessments of prior year estimates	(436)	(475)	(116)
US and Swiss Tax Reform	(125)	595
Tax charge/tax rate	£ 754	£ 1,356	£ 877
UK statutory rate of taxation	19.00%	19.25%	20.00%
Differences in overseas taxation rates	14.10%	18.00%	30.60%
Benefit of intellectual property incentives	(10.90%)	(13.00%)	(16.50%)
R&D credits	(1.50%)	(2.10%)	(4.80%)
FV remeasurement of non-taxable put options	4.60%	6.40%	17.50%
Tax losses where no benefit is recognised	0.50%	0.80%	(0.80%)
Permanent differences on disposals and acquisitions	(0.10%)	0.10%	(1.10%)
Other permanent differences	1.70%	5.60%	6.30%
Re-assessments of prior year estimates	(9.10%)	(13.50%)	(6.00%)
US and Swiss Tax Reform	(2.60%)	16.90%
Tax charge/tax rate	15.70%	38.50%	45.20%

Taxation - Summary of Tax on It

Taxation - Summary of Tax on Items Charged to Equity and Statement of Comprehensive Income (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred taxation
Share-based payments	£ 2	£ (4)
Defined benefit plans	(144)	(247)	£ 94
Fair value movements on cash flow hedges	(2)		2
Fair value movements on equity investments	10	29	51
Total equity and comprehensive income	(134)	(222)	147
Total (charge)/credit to equity and statement of comprehensive income	(136)	(196)	186
Share-based payments	0		7
Defined benefit plans	(2)	26	32
Total equity and comprehensive income	£ (2)	£ 26	£ 39

Taxation - Summary of Movement

Taxation - Summary of Movement in Deferred Tax Assets and Liabilities (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	£ 2,400	£ 2,440
Exchange adjustments	84	(65)
Credit/(charge) to income statement	396
(Charge)/credit to statement of comprehensive income and equity	(134)	(222)
Reclassification on disposal	(15)
At 31 December 2017	2,731	2,400
Share option and award schemes [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	74	110
Exchange adjustments	2	(4)
(Charge)/credit to statement of comprehensive income and equity	2	(4)
Reclassification on disposal	0
At 31 December 2017	71	74
Contingent Consideration [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	868	1,138
Exchange adjustments	0
(Charge)/credit to statement of comprehensive income and equity	0
Reclassification on disposal	0
At 31 December 2017	834	868
Intangible assets [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	(1,320)	(2,324)
Exchange adjustments	(4)	75
(Charge)/credit to statement of comprehensive income and equity	0
Reclassification on disposal	0
At 31 December 2017	(959)	(1,320)
Accelerated capital allowances [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	(317)	(377)
Exchange adjustments	(6)	(7)
(Charge)/credit to statement of comprehensive income and equity	0
Reclassification on disposal	0
At 31 December 2017	(335)	(317)
Tax losses [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	261	227
Exchange adjustments	2	(5)
(Charge)/credit to statement of comprehensive income and equity	0
Reclassification on disposal	1
At 31 December 2017	447	261
Other temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	1,057	1,350
Exchange adjustments	9	(18)
(Charge)/credit to statement of comprehensive income and equity	8	29
Reclassification on disposal	(23)
At 31 December 2017	950	1,057
Origination and reversal of temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	396	569
Origination and reversal of temporary differences [member] | Share option and award schemes [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	(7)	(1)
Origination and reversal of temporary differences [member] | Contingent Consideration [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	(34)	(52)
Origination and reversal of temporary differences [member] | Intangible assets [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	365	330
Origination and reversal of temporary differences [member] | Accelerated capital allowances [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	(12)	62
Origination and reversal of temporary differences [member] | Tax losses [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	183	59
Origination and reversal of temporary differences [member] | Other temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	(101)	(88)
US tax reform [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(805)
US tax reform [member] | Share option and award schemes [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(27)
US tax reform [member] | Contingent Consideration [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(218)
US tax reform [member] | Intangible assets [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		116
US tax reform [member] | Accelerated capital allowances [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		5
US tax reform [member] | Tax losses [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(20)
US tax reform [member] | Other temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(216)
Swiss tax reform [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		483
Swiss tax reform [member] | Intangible assets [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		483
Pensions and other post-employment benefits [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	760	1,262
Exchange adjustments	38	(48)
(Charge)/credit to statement of comprehensive income and equity	(144)	(247)
Reclassification on disposal	7
At 31 December 2017	694	760
Pensions and other post-employment benefits [member] | Origination and reversal of temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	33	3
Pensions and other post-employment benefits [member] | US tax reform [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		(210)
Intra group profit [member]
Changes in deferred tax liability (asset) [abstract]
At 1 January 2017	1,017	1,054
Exchange adjustments	43	(58)
(Charge)/credit to statement of comprehensive income and equity	0
Reclassification on disposal	0
At 31 December 2017	1,029	1,017
Intra group profit [member] | Origination and reversal of temporary differences [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement	£ (31)	256
Intra group profit [member] | US tax reform [member]
Changes in deferred tax liability (asset) [abstract]
Credit/(charge) to income statement		£ (235)

Taxation - Summary of Net Defer

Taxation - Summary of Net Deferred Tax Asset (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Major components of tax expense (income) [abstract]
Deferred tax assets	£ 3,887		£ 3,796
Deferred tax liabilities	(1,156)		(1,396)
Total	£ 2,731	£ 3,797	£ 2,400	£ 2,440

Taxation - Summary of Temporary

Taxation - Summary of Temporary Difference Unused Tax Losses and Unused Tax Credits (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses	£ 1,724	£ 1,760
Unrecognised deferred tax asset	256	300
Tax losses	2,042	1,924
Capital losses	399	372
Within 10 years [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses	678	802
Unrecognised deferred tax asset	148	187
Greater Than Ten Years [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses	957	872
Unrecognised deferred tax asset	93	99
Available indefinitely [member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Tax losses	89	86
Unrecognised deferred tax asset	15	14
Tax losses	2,042	1,924
Capital losses	£ 399	£ 372

Earnings per share - Summary of

Earnings per share - Summary of Basic and Diluted Earnings Per Share (Detail) - £ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings per share [abstract]
Basic earnings per share	£ 0.737	£ 0.314	£ 0.188
Diluted earnings per share	£ 0.729	£ 0.310	£ 0.186

Earnings per share - Schedule o

Earnings per share - Schedule of Numbers of Shares Earnings Per Share (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted average number of shares in issue
Basic	4,914	4,886	4,860
Dilution for share options and awards	57	55	49
Diluted	4,971	4,941	4,909

Dividends - Summary of Interim

Dividends - Summary of Interim Financial Reporting (Detail) - GBP (£) £ / shares in Units, £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of dividends [line items]
Dividend per share (pence)	£ 0.80	£ 0.80	£ 0.80
Total dividend	£ 3,935	£ 3,916	£ 3,897
First interim [member]
Disclosure of dividends [line items]
Paid	Jul. 12, 2018	Jul. 13, 2017	Jul. 14, 2016
Dividend per share (pence)	£ 0.19	£ 0.19	£ 0.19
Total dividend	£ 934	£ 928	£ 923
Second interim [member]
Disclosure of dividends [line items]
Paid	Oct. 11, 2018	Oct. 12, 2017	Oct. 13, 2016
Dividend per share (pence)	£ 0.19	£ 0.19	£ 0.19
Total dividend	£ 934	£ 929	£ 925
Third interim [member]
Disclosure of dividends [line items]
Paid	Jan. 10, 2019	Jan. 11, 2018	Jan. 12, 2017
Dividend per share (pence)	£ 0.19	£ 0.19	£ 0.19
Total dividend	£ 935	£ 929	£ 925
Fourth interim [member]
Disclosure of dividends [line items]
Paid	Apr. 11, 2019	Apr. 12, 2018	Apr. 13, 2017
Dividend per share (pence)	£ 0.23	£ 0.23	£ 0.23
Total dividend	£ 1,132	£ 1,130	£ 1,124

Dividends - Additional Informat

Dividends - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Disclosure of Dividends [abstract]
Description of compliance with IFRSs applied For interim financial report	Under IFRS interim dividends are only recognised in the financial statements when paid and not when declared. GSK normally pays a dividend two quarters after the quarter to which it relates and one quarter after it is declared. The 2018 financial statements recognise those dividends paid in 2018, namely the third and fourth interim dividends for 2017, and the first and second interim dividends for 2018.

Dividends - Summary of Dividend

Dividends - Summary of Dividends to Shareholders (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Dividends [abstract]
Dividends to shareholders	£ 3,927	£ 3,906	£ 4,850

Property, Plant and Equipment -

Property, Plant and Equipment - Summary of Property, Plant and Equipment (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	£ 10,860	£ 10,808
Charge for the year	(954)	(988)	£ (978)
Impairment losses	(203)	(327)	(180)
Property, plant and equipment at end of period	11,058	10,860	10,808
Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	21,719	22,164
Exchange adjustments	362	(234)
Other additions	1,358	1,584
Capitalised borrowing costs	21	30
Disposals and write-offs	(583)	(1,092)
Reclassifications	(67)	(38)
Transfer to assets held for sale	(322)	(695)
Property, plant and equipment at end of period	22,488	21,719	22,164
Depreciation and amortisation [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(10,296)	(10,669)
Exchange adjustments	(172)	160
Charge for the year	(954)	(988)
Disposals and write-offs	478	697
Transfer to assets held for sale	177	504
Property, plant and equipment at end of period	(10,767)	(10,296)	(10,669)
Impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(563)	(687)
Exchange adjustments	(13)	8
Disposals and write-offs	91	342
Impairment losses	(205)	(349)
Reversal of impairments	7	17
Transfer to assets held for sale	20	106
Property, plant and equipment at end of period	(663)	(563)	(687)
Depreciation, amortisation, and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(10,859)
Property, plant and equipment at end of period	(11,430)	(10,859)
Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	4,270	4,223
Property, plant and equipment at end of period	4,404	4,270	4,223
Land and buildings [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	7,467	7,761
Exchange adjustments	150	(127)
Other additions	33	69
Capitalised borrowing costs	0
Disposals and write-offs	(90)	(376)
Reclassifications	403	602
Transfer to assets held for sale	(152)	(462)
Property, plant and equipment at end of period	7,811	7,467	7,761
Land and buildings [member] | Depreciation and amortisation [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(3,036)	(3,259)
Exchange adjustments	(61)	50
Charge for the year	(268)	(299)
Disposals and write-offs	77	158
Transfer to assets held for sale	55	314
Property, plant and equipment at end of period	(3,233)	(3,036)	(3,259)
Land and buildings [member] | Impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(161)	(279)
Exchange adjustments	(8)	8
Disposals and write-offs	10	210
Impairment losses	(16)	(194)
Reversal of impairments	1	7
Transfer to assets held for sale	0	87
Property, plant and equipment at end of period	(174)	(161)	(279)
Land and buildings [member] | Depreciation, amortisation, and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(3,197)
Property, plant and equipment at end of period	(3,407)	(3,197)
Plant, equipment and vehicles [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	4,132	3,481
Property, plant and equipment at end of period	4,582	4,132	3,481
Plant, equipment and vehicles [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	11,751	11,235
Exchange adjustments	187	(62)
Other additions	190	296
Capitalised borrowing costs	0
Disposals and write-offs	(440)	(685)
Reclassifications	1,016	1,186
Transfer to assets held for sale	(167)	(219)
Property, plant and equipment at end of period	12,537	11,751	11,235
Plant, equipment and vehicles [member] | Depreciation and amortisation [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(7,260)	(7,410)
Exchange adjustments	(111)	110
Charge for the year	(686)	(689)
Disposals and write-offs	401	539
Transfer to assets held for sale	122	190
Property, plant and equipment at end of period	(7,534)	(7,260)	(7,410)
Plant, equipment and vehicles [member] | Impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(359)	(344)
Exchange adjustments	(4)	2
Disposals and write-offs	59	104
Impairment losses	(143)	(138)
Reversal of impairments	6	9
Transfer to assets held for sale	20	8
Property, plant and equipment at end of period	(421)	(359)	(344)
Plant, equipment and vehicles [member] | Depreciation, amortisation, and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(7,619)
Property, plant and equipment at end of period	(7,955)	(7,619)
Assets in construction [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	2,458	3,104
Property, plant and equipment at end of period	2,072	2,458	3,104
Assets in construction [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	2,501	3,168
Exchange adjustments	25	(45)
Other additions	1,135	1,219
Capitalised borrowing costs	21	30
Disposals and write-offs	(53)	(31)
Reclassifications	(1,486)	(1,826)
Transfer to assets held for sale	(3)	(14)
Property, plant and equipment at end of period	2,140	2,501	3,168
Assets in construction [member] | Depreciation and amortisation [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	0
Exchange adjustments	0
Charge for the year	0
Disposals and write-offs	0
Transfer to assets held for sale	0
Property, plant and equipment at end of period	0	0
Assets in construction [member] | Impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(43)	(64)
Exchange adjustments	(1)	(2)
Disposals and write-offs	22	28
Impairment losses	(46)	(17)
Reversal of impairments	0	1
Transfer to assets held for sale	0	11
Property, plant and equipment at end of period	(68)	(43)	£ (64)
Assets in construction [member] | Depreciation, amortisation, and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment at beginning of period	(43)
Property, plant and equipment at end of period	£ (68)	£ (43)

Property, Plant and Equipment_2

Property, Plant and Equipment - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about property, plant and equipment [line items]
Weighted average interest rate for capitalised borrowing costs	3.00%	4.00%
Property, plant and equipment	£ 11,058	£ 10,860	£ 10,808
Weighted average cost of capital post tax discount rate percentage	7.00%
Weighted average cost of capital pre-tax discount rate percentage	9.00%
Impairment loss recognised in profit or loss, property, plant and equipment	£ 203	327	£ 180
Impairments charged or reversed	95	33
Computer software [member]
Disclosure of detailed information about property, plant and equipment [line items]
Assets in construction reclassified to intangible assets	67	38
Cost of sales [member]
Disclosure of detailed information about property, plant and equipment [line items]
Impairment loss recognised in profit or loss, property, plant and equipment	142	198
Research and development [member]
Disclosure of detailed information about property, plant and equipment [line items]
Impairment loss recognised in profit or loss, property, plant and equipment	9	93
Selling general and administrative expenses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Impairment loss recognised in profit or loss, property, plant and equipment	54	36
Major restructuring programmes [member]
Disclosure of detailed information about property, plant and equipment [line items]
Impairment loss recognised in profit or loss, property, plant and equipment	138	278
Land and buildings under operating leases [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	24	27
Plant, equipment and vehicles under operating leases [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment	£ 59	£ 55

Goodwill - Summary of Changes i

Goodwill - Summary of Changes in Goodwill (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill Beginning balance	£ 5,734	£ 5,965
Goodwill Ending Balance	5,789	5,734
Cost [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill Beginning balance	5,734	5,965
Exchange adjustments	199	(228)
Transfer to assets held for sale	(144)	(3)
Goodwill Ending Balance	£ 5,789	£ 5,734

Goodwill - Summary of Goodwill

Goodwill - Summary of Goodwill Allocated to Segments (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 5,789	£ 5,734	£ 5,965
Pharmaceuticals [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	3,273	3,172
Vaccines [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	1,342	1,302
Consumer Healthcare [member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	£ 1,174	£ 1,260

Goodwill - Additional Informati

Goodwill - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of reconciliation of changes in goodwill [line items]
Description of basis on which unit's recoverable amount has been determined	The recoverable amounts of the cash generating units are assessed using a fair value less costs of disposal model. Fair value less costs of disposal is calculated using a discounted cash flow approach, with a post-tax discount rate applied to the projected risk-adjusted post-tax cash flows and terminal value.
Discount rate applied to cash flow projections	7.00%
Pharmaceuticals [member]
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	7.50%
Carrying value of assets with indefinite lives	£ 236	£ 228
Consumer Healthcare [member]
Disclosure of reconciliation of changes in goodwill [line items]
Discount rate applied to cash flow projections	6.00%
Carrying value of assets with indefinite lives	£ 8,500	£ 8,500

Goodwill - Schedule of Discount

Goodwill - Schedule of Discounted Cash Flow Models Used in Impairment Tests (Detail)	12 Months Ended
	Dec. 31, 2018
Disclosure of reconciliation of changes in goodwill [line items]
Valuation basis	Fair value less costs of disposal
Key assumptions	Sales growth rates Profit margins Terminal growth rate Discount rate Taxation rate
Determination of assumptions	Growth rates are internal forecasts based on both internal and external market information. Margins reflect past experience, adjusted for expected changes. Terminal growth rates based on management's estimate of future long-term average growth rates. Discount rates based on Group WACC, adjusted where appropriate. Taxation rates based on appropriate rates for each region.
Period of specific projected cash flows	Five years
Discount rate	7.00%
Pharmaceuticals [member]
Disclosure of reconciliation of changes in goodwill [line items]
Terminal growth rate	1.00%
Discount rate	7.50%
Vaccines [member]
Disclosure of reconciliation of changes in goodwill [line items]
Terminal growth rate	1.00%
Discount rate	7.50%
Consumer Healthcare [member]
Disclosure of reconciliation of changes in goodwill [line items]
Terminal growth rate	2.00%
Discount rate	6.00%

Other Intangible Assets - Summa

Other Intangible Assets - Summary of Other Intangible Assets (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	£ 17,562	£ 18,776
Charge for the year	(902)	(934)	£ (796)
Impairment losses	(134)	(690)	(22)
Ending Balance	17,202	17,562	18,776
Brands with indefinite useful life [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	8,738	9,245
Ending Balance	8,732	8,738	9,245
Cost [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	26,931	27,101
Exchange adjustments	359	(528)
Capitalised development costs	203	251
Capitalised borrowing costs	1	5
Other additions	327	454
Disposals and asset write-offs	(209)	(255)
Transfer to assets held for sale	(92)	(135)
Reclassifications	67	38
Ending Balance	27,587	26,931	27,101
Cost [member] | Brands with indefinite useful life [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	8,993	9,375
Exchange adjustments	63	(272)
Transfer to assets held for sale		(44)
Reclassifications		(66)
Ending Balance	9,056	8,993	9,375
Depreciation and amortisation [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(6,898)	(6,391)
Exchange adjustments	(131)	166
Charge for the year	(902)	(934)
Disposals and asset write-offs	191	235
Transfer to assets held for sale	20	26
Ending Balance	(7,720)	(6,898)	(6,391)
Impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(2,471)	(1,934)
Exchange adjustments	(89)	113
Impairment losses	(137)	(680)
Reversal of impairments	3
Disposals and asset write-offs	18	7
Transfer to assets held for sale	11	23
Ending Balance	(2,665)	(2,471)	(1,934)
Impairment [member] | Brands with indefinite useful life [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(255)	(130)
Exchange adjustments		3
Impairment losses	(69)	(132)
Transfer to assets held for sale		4
Ending Balance	(324)	(255)	(130)
Depreciation, amortisation, and impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(9,369)
Ending Balance	(10,385)	(9,369)
Depreciation, amortisation, and impairment [member] | Brands with indefinite useful life [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(255)
Ending Balance	(324)	(255)
Computer software [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	1,054	963
Ending Balance	1,046	1,054	963
Computer software [member] | Cost [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	2,174	2,156
Exchange adjustments	32	(37)
Capitalised borrowing costs	1	2
Other additions	173	233
Disposals and asset write-offs	(80)	(217)
Transfer to assets held for sale	(2)	(1)
Reclassifications	67	38
Ending Balance	2,365	2,174	2,156
Computer software [member] | Depreciation and amortisation [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(1,111)	(1,184)
Exchange adjustments	(24)	25
Charge for the year	(240)	(163)
Disposals and asset write-offs	67	210
Transfer to assets held for sale	1	1
Ending Balance	(1,307)	(1,111)	(1,184)
Computer software [member] | Impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(9)	(9)
Impairment losses	(17)	(2)
Disposals and asset write-offs	14	2
Ending Balance	(12)	(9)	(9)
Computer software [member] | Depreciation, amortisation, and impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(1,120)
Ending Balance	(1,319)	(1,120)
Licences and franchises [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	7,658	8,508
Ending Balance	7,331	7,658	8,508
Licences and franchises [member] | Cost [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	15,275	15,143
Exchange adjustments	235	(215)
Capitalised development costs	203	251
Capitalised borrowing costs		3
Other additions	154	221
Disposals and asset write-offs	(129)	(38)
Transfer to assets held for sale	(81)	(90)
Ending Balance	15,657	15,275	15,143
Licences and franchises [member] | Depreciation and amortisation [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(5,553)	(4,983)
Exchange adjustments	(104)	141
Charge for the year	(645)	(761)
Disposals and asset write-offs	124	25
Transfer to assets held for sale	18	25
Ending Balance	(6,160)	(5,553)	(4,983)
Licences and franchises [member] | Impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(2,064)	(1,652)
Exchange adjustments	(69)	110
Impairment losses	(51)	(546)
Reversal of impairments	3
Disposals and asset write-offs	4	5
Transfer to assets held for sale	11	19
Ending Balance	(2,166)	(2,064)	(1,652)
Licences and franchises [member] | Depreciation, amortisation, and impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(7,617)
Ending Balance	(8,326)	(7,617)
Amortised brands [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	112	60
Ending Balance	93	112	60
Amortised brands [member] | Cost [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	489	427
Exchange adjustments	29	(4)
Transfer to assets held for sale	(9)
Reclassifications		66
Ending Balance	509	489	427
Amortised brands [member] | Depreciation and amortisation [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(234)	(224)
Exchange adjustments	(3)
Charge for the year	(17)	(10)
Transfer to assets held for sale	1
Ending Balance	(253)	(234)	(224)
Amortised brands [member] | Impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(143)	(143)
Exchange adjustments	(20)
Ending Balance	(163)	(143)	£ (143)
Amortised brands [member] | Depreciation, amortisation, and impairment [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Beginning Balance	(377)
Ending Balance	£ (416)	£ (377)

Other Intangible Assets - Addit

Other Intangible Assets - Additional information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about intangible assets [line items]
Weighted average interest rate for capitalised borrowing costs	3.00%	4.00%
Intangible assets, for which impairments have been charged or reversed	£ 73	£ 300
Discount rate equal to post-tax WACC	7.00%
Bottom of range [member]
Disclosure of detailed information about intangible assets [line items]
Terminal growth rate, estimates of future long-term average growth rate	0.00%
Top of range [member]
Disclosure of detailed information about intangible assets [line items]
Terminal growth rate, estimates of future long-term average growth rate	3.00%
Internally generated [member]
Disclosure of detailed information about intangible assets [line items]
Net book value of computer software	£ 578	£ 669

Other Intangible Assets - Sched

Other Intangible Assets - Schedule of Amortisation and Impairment Losses, Net of Reversals (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Amortisation of intangible assets	£ 902	£ 934	£ 796
Impairment of intangible assets, net of reversals	134	690	£ 22
Cost of sales [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Amortisation of intangible assets	593	578
Impairment of intangible assets, net of reversals	69	400
Selling general and administrative expenses [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Amortisation of intangible assets	178	116
Impairment of intangible assets, net of reversals	19	2
Research and development [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Amortisation of intangible assets	131	240
Impairment of intangible assets, net of reversals	£ 46	£ 278

Other Intangible Assets - Sum_2

Other Intangible Assets - Summary of Book Values of Largest Individual Items (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	£ 17,202	£ 17,562	£ 18,776
Licences and franchises [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	7,331	7,658	£ 8,508
Licences and franchises [member] | Meningitis Portfolio [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	2,363	2,450
Licences and franchises [member] | Dolutegravir [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	1,319	1,389
Licences and franchises [member] | Benlysta [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	905	965
Licences and franchises [member] | Fluarix FluLaval [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	274	321
Licences and franchises [member] | HIV assets acquired from BMS [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	277	277
Licences and franchises [member] | Selzentry [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	136	162
Licences and franchises [member] | Okairos technology platform [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	205	202
Licences and franchises [member] | Others products [member]
Disclosure of reconciliation of changes in intangible assets and goodwill [line items]
Other intangible assets	£ 1,852	£ 1,892

Other Intangible Assets - Sum_3

Other Intangible Assets - Summary of Book Values of Major Brands (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	£ 8,732	£ 8,738
Voltaren [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	2,735	2,716
Otrivin [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	1,385	1,380
Fenistil [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	651	648
Theraflu [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	449	441
Panadol [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	388	386
Sensodyne [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	265	265
Lamisil [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	293	289
Breathe Right [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	262	236
Stiefel trade name [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	236	228
Excedrin [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	193	185
Physiogel [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	150	166
Polident [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	112	112
Other Brands [member]
Disclosure of detailed information about intangible assets [line items]
Indefinite life brands	£ 1,613	£ 1,686

Investments in Associates and_3

Investments in Associates and Joint Ventures - Summary of Investments in Associates and Joint Ventures (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Investments in Associates and Joint Ventures [line items]
Beginning of investments	£ 183	£ 263
Exchange adjustments	12	(12)
Additions	10	15
Disposals	0	(92)
Distributions received	(40)	(2)
Other movements	40	(2)
Profit/(loss) after tax recognised in the consolidated income statement	31	13	£ 5
Ending of investments	236	183	263
Joint ventures [member]
Disclosure of Investments in Associates and Joint Ventures [line items]
Beginning of investments	13	19
Exchange adjustments	1	(2)
Additions	1
Disposals	0
Distributions received	0	(1)
Other movements	1
Profit/(loss) after tax recognised in the consolidated income statement	3	(3)	(4)
Ending of investments	19	13	19
Associates [member]
Disclosure of Investments in Associates and Joint Ventures [line items]
Beginning of investments	170	244
Exchange adjustments	11	(10)
Additions	9	15
Disposals	0	(92)
Distributions received	(40)	(1)
Other movements	39	(2)
Profit/(loss) after tax recognised in the consolidated income statement	28	16
Ending of investments	£ 217	£ 170	£ 244

Investments in Associates and_4

Investments in Associates and Joint Ventures - Additional Information (Detail) £ in Millions, shares in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)Associateshares	Dec. 31, 2017GBP (£)
Innoviva Inc [member]
Disclosure of Investments in Associates and Joint Ventures [line items]
Significant associate | Associate	1
Number of shares owned | shares	32
Percentage of shares owned	31.70%
Percentage of interest in royalty	15.00%
Market value of investment | £	£ 440	£ 336
Theravance Biopharma Inc [member]
Disclosure of Investments in Associates and Joint Ventures [line items]
Percentage of interest in royalty	85.00%
Percentage of common stock	17.40%

Investments in Associates and_5

Investments in Associates and Joint Ventures - Summary of Balance Sheet Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018	Dec. 31, 2016
Disclosure of Investments in Associates and Joint Ventures [line items]
Non-current assets	£ 41,139	£ 40,474
Current assets	16,927	15,907
Current liabilities	(22,491)	(26,569)
Non-current liabilities	(31,903)	(26,323)
Net assets/(liabilities)	3,672	3,489	£ 3,474
Goodwill	5,789	5,734		£ 5,965
Innoviva Inc [member]
Disclosure of Investments in Associates and Joint Ventures [line items]
Non-current assets	275	124
Current assets	157	148
Current liabilities	(4)	(26)
Non-current liabilities	(302)	(426)
Net assets/(liabilities)	126	(180)
Interest in associated undertaking	40	(57)
Goodwill	91	86
Fair value and other adjustments	58	118
Carrying value at 31 December	£ 189	£ 147

Other Investments - Schedule of

Other Investments - Schedule of Other Investments (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other investments [line items]
Beginning of other investments	£ 918	£ 985
Exchange adjustments	52	(64)
Additions	372	80
Net fair value movements through Other comprehensive income	118	11
Net fair value movements through profit or loss	16
Impairment losses	0	(30)
Disposals and settlements	(95)	(64)
Transfers to Assets held for sale	(59)
Ending of other investments	1,322	918
Investments designated as measured at FVTOCI [member]
Other investments [line items]
Beginning of other investments	869
Exchange adjustments	48
Additions	363
Net fair value movements through Other comprehensive income	118
Net fair value movements through profit or loss	0
Impairment losses	0
Disposals and settlements	(89)
Transfers to Assets held for sale	(59)
Ending of other investments	1,250	869
Investments measured a FVTPL [member]
Other investments [line items]
Beginning of other investments	49
Exchange adjustments	4
Additions	9
Net fair value movements through Other comprehensive income	0
Net fair value movements through profit or loss	16
Impairment losses	0
Disposals and settlements	(6)
Transfers to Assets held for sale	0
Ending of other investments	£ 72	£ 49

Other Investments - Additional

Other Investments - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other investments [line items]
Listed investments	£ 656	£ 535
Equity investments measured at fair value through other comprehensive income (FVTOCI) [member]
Other investments [line items]
Fair value of investment disposed during the year	148
Cumulative gain loss on disposal of investments	56
Equity investments measured at fair value through profit or loss (FVTPL) [member]
Other investments [line items]
Fair value of investment disposed during the year	0
Cumulative gain loss on disposal of investments	£ 0
Theravance Biopharma Inc [member]
Other investments [line items]
Percentage of common stock held	17.40%
Investment fair value	£ 194	£ 199
Tandem [member]
Other investments [line items]
Percentage of common stock held	0.00%
Orchard [member]
Other investments [line items]
Percentage of common stock held	14.50%
23 and Me [member]
Other investments [line items]
Percentage of common stock held	14.50%

Other Investments - Schedule _2

Other Investments - Schedule of Carrying Value of Other Investments (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2017GBP (£)
Other investments 1 [abstract]
Carrying value at original cost	£ 475
Cumulative impairments recognised in the income statement	(283)
Subsequent fair value increases	210
Carrying value, ending balance	£ 402

Other Non-Current Assets - Summ

Other Non-Current Assets - Summary of Other Non-Current Assets (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Miscellaneous non-current assets [abstract]
Amounts receivable under insurance contracts	£ 675	£ 648
Pension schemes in surplus	760	538
Other receivables	141	227
Total	£ 1,576	£ 1,413

Other Non-Current Assets - Addi

Other Non-Current Assets - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Other Non Current Assets [line items]
Other receivables	£ 141	£ 227
Financial assets	12,402	£ 10,906
Other Non Current Receivables [member]
Disclosure Of Other Non Current Assets [line items]
Financial assets	89
Other Non Current Receivables [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure Of Other Non Current Assets [line items]
Financial assets	41
Other Non Current Receivables [member] | Remaining Balance [member]
Disclosure Of Other Non Current Assets [line items]
Financial assets	£ 48

Inventories - Summary of Invent

Inventories - Summary of Inventories (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Classes of current inventories [abstract]
Raw materials and consumables	£ 1,122	£ 1,193
Work in progress	2,286	2,381
Finished goods	2,068	1,983
Total	£ 5,476	£ 5,557

Trade and Other Receivables - S

Trade and Other Receivables - Summary of Trade and Other Receivables (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Trade and other receivables [abstract]
Trade receivables, net of loss allowance	£ 5,176	£ 4,672
Accrued income	9	21
Other prepayments	330	308
Interest receivable	4	10
Employee loans and advances	14	19
Other receivables	890	970
Total trade and other receivables	£ 6,423	£ 6,000

Trade and Other Receivables - A

Trade and Other Receivables - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Disclosure of trade and other receivables [line items]
Trade receivables	£ 5,176		£ 4,672
Other receivables	890		970
Trade receivables	6,423		6,000
Financial assets	12,402		10,906
Expected credit loss allowance	15	£ 15
Trade and other receivables [member]
Disclosure of trade and other receivables [line items]
Expected credit loss allowance on trade receivables credit impaired	7
Financial assets	376
Expected credit loss allowance	5
Trade and other receivables [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of trade and other receivables [line items]
Financial assets	41
Trade and other receivables [member] | Remaining Balance [member]
Disclosure of trade and other receivables [line items]
Financial assets	335
Financial instruments credit-impaired [member] | Trade and other receivables [member]
Disclosure of trade and other receivables [line items]
Trade receivables	71
Associates and joint ventures [member]
Disclosure of trade and other receivables [line items]
Trade receivables	15		11
Other receivables	£ 0		£ 7

Trade and Other Receivables -_2

Trade and Other Receivables - Summary of Loss Allowance (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of trade and other receivables [line items]
Implementation of IFRS 9	£ 15
Beginning balance	155
Exchange adjustments	0	£ (4)
Charge for the year	7	31
Subsequent recoveries of amounts provided for	(30)	(79)
Utilised	(4)	(15)
Ending balance	128	155
Previously stated [member]
Disclosure of trade and other receivables [line items]
Beginning balance	£ 140	207
Ending balance		£ 140

Cash and cash equivalents - Sum

Cash and cash equivalents - Summary of Cash and Cash Equivalents (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and cash equivalents [abstract]
Cash at bank and in hand	£ 569	£ 826
Short-term deposits	3,305	3,007
Total cash and cash equivalents	£ 3,874	£ 3,833	£ 4,897

Cash and cash equivalents - Add

Cash and cash equivalents - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents [abstract]
Cash and cash equivalents reported in assets held for sale	£ 485
Cash and cash equivalents not available for general use	£ 200	£ 800

Assets Held for Sale - Summary

Assets Held for Sale - Summary of Assets Held for Sale (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets Held For Sale [line items]
Property, plant and equipment	£ 11,058	£ 10,860	£ 10,808
Goodwill	5,789	5,734	5,965
Inventory	5,476	5,557
Cash and cash equivalents	3,874	3,833	£ 4,897
Total assets held for sale	168	113
Assets held for sale [member]
Assets Held For Sale [line items]
Property, plant and equipment	109	57
Goodwill	144
Other intangibles	1	49
Inventory	50	7
Cash and cash equivalents	485
Other	(136)
Total assets held for sale	£ 653	£ 113

Assets Held for Sale - Addition

Assets Held for Sale - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about intangible assets [line items]
Financial assets written down to fair value	£ 12,402	£ 10,906
Assets held for sale [member] | Level 3 [member]
Disclosure of detailed information about intangible assets [line items]
Financial assets written down to fair value	£ 51	£ 63

Trade and Other Payables - Summ

Trade and Other Payables - Summary of Trade and Other Payables (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of trade and other payables [line items]
Trade payables	£ 3,645	£ 3,528
Wages and salaries	1,355	1,228
Social security	139	166
Other payables	401	363
Deferred income	216	240
Customer return and rebate accruals	5,064	3,463
Other accruals	1,977	2,072
Total trade and other payables	14,037	20,970
Consumer Healthcare [member]
Disclosure of trade and other payables [line items]
Put option payable	0	8,606
Shionogi-ViiV Healthcare [member]
Disclosure of trade and other payables [line items]
Put option payable	£ 1,240	£ 1,304

Trade and Other Payables - Addi

Trade and Other Payables - Additional Information (Detail) - GBP (£) £ in Millions	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017
Disclosure of trade and other payables [line items]
Trade and other current payables		£ 14,037	£ 20,970
Revenue recognized in deferred income	£ 66
Customer return and rebate accruals		5,064	3,463
India [member]
Disclosure of trade and other payables [line items]
Revenue recognized related to proceeds from a site disposal		64
Estimated rebates, discounts or allowances payable to customers [member] | US Pharmaceuticals and vaccines [member]
Disclosure of trade and other payables [line items]
Customer return and rebate accruals		4,356	2,837
Associates and joint ventures [member]
Disclosure of trade and other payables [line items]
Trade and other current payables		£ 64	£ 53

Trade and Other Payables - Su_2

Trade and Other Payables - Summary of Increase/(Decrease) in Financial Liability and Loss/(Gain) in Income Statement (Detail) - Pfizer put option [member] £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
10% increase in sales forecasts or sales multiple applied [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	£ 140
Loss/(gain) in Income statement	140
10% decrease in sales forecasts or sales multiple applied [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	(140)
Loss/(gain) in Income statement	(140)
10 cent appreciation of the US Dollar [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	75
Loss/(gain) in Income statement	75
10 cent depreciation of US Dollar [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	(64)
Loss/(gain) in Income statement	(64)
10 cent appreciation of the Euro [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	44
Loss/(gain) in Income statement	44
10 cent depreciation of Euro [member]
Disclosure of information about activities subject to rate regulation [line items]
Increase/(decrease) in financial liability	(37)
Loss/(gain) in Income statement	£ (37)

Pensions and Other Post-emplo_3

Pensions and Other Post-employment Benefits - Summary of Pension and Other Post-employment Costs (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of pension and other post employment plan [line items]
Cost of sales	£ 10,241	£ 10,342	£ 9,290
Selling, general and administration	9,915	9,672	9,366
Research and development	3,893	4,476	3,628
Pension and other post-employment cost	586	616	541
UK Defined Benefit Plans [member]
Disclosure of pension and other post employment plan [line items]
Defined benefit pension and post retirement cost	246	198	205
US Defined Benefit Plans [member]
Disclosure of pension and other post employment plan [line items]
Defined benefit pension and post retirement cost	100	113	106
Other overseas pension schemes [member]
Disclosure of pension and other post employment plan [line items]
Pension and other post-employment cost	190	218	140
Unfunded post retirement healthcare schemes [member]
Disclosure of pension and other post employment plan [line items]
Defined benefit pension and post retirement cost	50	87	90
Pension and other post-employment cost Analysed	50	87	90
Funded defined benefit pension plans [member]
Disclosure of pension and other post employment plan [line items]
Pension and other post-employment cost Analysed	369	335	304
Unfunded defined benefit pension plan [member]
Disclosure of pension and other post employment plan [line items]
Pension and other post-employment cost Analysed	43	55	43
Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure of pension and other post employment plan [line items]
Cost of sales	160	162	135
Selling, general and administration	228	238	221
Research and development	74	77	81
Defined benefit pension and post retirement cost	462	477	437
Defined benefit schemes [member]
Disclosure of pension and other post employment plan [line items]
Pension and other post-employment cost Analysed	462	477	437
Defined contribution pension scheme [member]
Disclosure of pension and other post employment plan [line items]
Pension and other post-employment cost Analysed	£ 124	£ 139	£ 104

Pensions and Other Post-emplo_4

Pensions and Other Post-employment Benefits - Additional Information (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Pensions and Other Post-employment Benefits [line items]
Long term rate of improvement per year		1.25%
GMP costs included in past service costs		£ 40
Augmentation costs included in past service costs		43	£ 37	£ 52
Augmentation costs arising from major restructuring programmes		21
Special contributions		£ 386	444	481
Pension schemes [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Employer contributions	£ 420
Post-retirement benefits [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Employer contributions	100
UK [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Percentage allocated to return seeking assets		55.00%
Percentage allocated to liability matching assets		45.00%
Special contributions		£ 0	136	191
UK [member] | Pension schemes [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Payment due, 2019	£ 75
UK [member] | Other assets [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Loans on structured debt amount contributed to fair value of plan assets			(773)	(1,686)
US [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Percentage allocated to return seeking assets		55.00%
Percentage allocated to liability matching assets		45.00%
Special contributions		£ 125	£ 78	0
Assumption for future medical inflation		6.50%	6.75%
US [member] | 2026 and thereafter [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
Assumption for future medical inflation		5.00%
US [member] | Unfunded [member]
Disclosure of Pensions and Other Post-employment Benefits [line items]
US post retirement healthcare scheme obligation		£ 1,179	£ 1,254	£ 1,463

Pensions and Other Post-emplo_5

Pensions and Other Post-employment Benefits - Summary of Average Life Expectancy Assumed (Detail)	12 Months Ended
	Dec. 31, 2018
UK [member] | Current. [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Male Years	27 years 6 months
Female Years	29 years 1 month 6 days
UK [member] | Projected at 2038 [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Male Years	29 years
Female Years	30 years 7 months 6 days
US [member] | Current. [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Male Years	27 years
Female Years	28 years 8 months 12 days
US [member] | Projected at 2038 [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Male Years	28 years 8 months 12 days
Female Years	30 years 3 months 18 days

Pensions and Other Post-emplo_6

Pensions and Other Post-employment Benefits - Summary of Financial Assumptions in Assessing Defined Benefit Liabilities (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
UK [member]
Disclosure Of Defined Benefit Plan Actuarial Assumptions [line items]
Rate of increase of future earnings	2.00%	2.00%	2.00%
Discount rate	2.90%	2.50%	2.70%
Expected pension increases	3.20%	3.20%	3.20%
Inflation rate	3.20%	3.20%	3.20%
US [member]
Disclosure Of Defined Benefit Plan Actuarial Assumptions [line items]
Rate of increase of future earnings	4.00%	4.00%	4.00%
Discount rate	4.20%	3.60%	3.90%
Cash balance credit/conversion rate	3.20%	2.90%	3.20%
Inflation rate	2.25%	2.25%	2.25%
Rest of World. [member]
Disclosure Of Defined Benefit Plan Actuarial Assumptions [line items]
Rate of increase of future earnings	2.70%	2.80%	2.70%
Discount rate	1.80%	1.60%	1.60%
Expected pension increases	2.10%	2.20%	2.10%
Cash balance credit/conversion rate	0.40%	0.30%	0.30%
Inflation rate	1.50%	1.70%	1.50%

Pensions and Other Post-emplo_7

Pensions and Other Post-employment Benefits - Summary of Amounts Recorded in Income Statement and Statement of Comprehensive Income Related to Defined Benefit Pension and Post-retirement Healthcare Schemes (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	£ 281	£ 280	£ 246
Past service cost/(credit)	(94)	(37)	(54)
Net interest (income)/cost	36	54	56
Gains from settlements	(14)		(28)
Remeasurement gains/(losses) recorded in the statement of comprehensive income	728	549	(475)
Pension schemes [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	281	280	246
Past service cost/(credit)	(94)	(37)	(54)
Net interest (income)/cost	(490)	(524)	(586)
Gains from settlements	28	4	138
Pension schemes [member] | Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	281	280	246
Past service cost/(credit)	94	37	54
Net interest (income)/cost	36	54	56
Gains from settlements	(14)		(28)
Expenses	15	19	19
Net operating cost	412	390	347
Remeasurement gains/(losses) recorded in the statement of comprehensive income	583	485	(416)
Post-retirement benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	29	30	31
Past service cost/(credit)	27	2	(3)
Net interest (income)/cost	(49)	(59)	(56)
Gains from settlements	1
Post-retirement benefits [member] | Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	29	30	31
Past service cost/(credit)	(27)	(2)	3
Net interest (income)/cost	49	59	56
Gains from settlements	(1)
Expenses	0
Net operating cost	50	87	90
Remeasurement gains/(losses) recorded in the statement of comprehensive income	145	64	(59)
UK [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	75	79	70
Past service cost/(credit)	(93)	(37)	(52)
Net interest (income)/cost	(320)	(340)	(394)
Gains from settlements	0
UK [member] | Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	75	79	70
Past service cost/(credit)	93	37	52
Net interest (income)/cost	(3)	7	9
Gains from settlements	0
Expenses	8	7	7
Net operating cost	173	130	138
Remeasurement gains/(losses) recorded in the statement of comprehensive income	495	259	(165)
US [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	72	70	66
Past service cost/(credit)	(1)		(1)
Net interest (income)/cost	(122)	(135)	(135)
Gains from settlements	0
US [member] | Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	72	70	66
Past service cost/(credit)	1		1
Net interest (income)/cost	20	31	27
Gains from settlements	0
Expenses	7	12	12
Net operating cost	100	113	106
Remeasurement gains/(losses) recorded in the statement of comprehensive income	(108)	240	(27)
Rest of World. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	134	131	110
Past service cost/(credit)	0		(1)
Net interest (income)/cost	(48)	(49)	(57)
Gains from settlements	28	4	138
Rest of World. [member] | Defined benefit pension and post-retirement healthcare scheme. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Current service cost	134	131	110
Past service cost/(credit)	0		1
Net interest (income)/cost	19	16	20
Gains from settlements	(14)		(28)
Expenses	0
Net operating cost	139	147	103
Remeasurement gains/(losses) recorded in the statement of comprehensive income	£ 196	£ (14)	£ (224)

Pensions and Other Post-emplo_8

Pensions and Other Post-employment Benefits - Summary of Balance Sheet Presentation of Group Defined Benefit Pension Schemes and Other Post-retirement Benefits (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Post-retirement benefits/Pension schemes in deficit and surplus	£ 760	£ 538
Benefit plans	(3,125)	(3,539)	£ (4,090)
Other Noncurrent Assets [member] | Pension schemes [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Post-retirement benefits/Pension schemes in deficit and surplus	760	538	313
Assets classified as held for sale [member] | Post-retirement benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Post-retirement benefits/Pension schemes in deficit and surplus	(9)
Pensions and other post-employment benefits [member] | Pension schemes [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Post-retirement benefits/Pension schemes in deficit and surplus	(1,755)	(2,043)	(2,397)
Pensions and other post-employment benefits [member] | Post-retirement benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Post-retirement benefits/Pension schemes in deficit and surplus	£ (1,370)	£ (1,496)	£ (1,693)

Pensions and Other Post-emplo_9

Pensions and Other Post-employment Benefits - Fair Values of Assets and Liabilities of UK and US Defined Benefit Pension Schemes Together with Aggregated Data for Other Defined Benefit Pension Schemes in Group (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Present value of scheme obligations	£ (18,774)	£ (19,785)	£ (19,654)
Actual return on plan assets	610	(899)	(2,195)
Group [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Equities, listed	5,055	6,894	7,201
Equity, unlisted	7	13	14
Multi-asset funds	2,997	2,517	1,545
Property, listed	33
Property, unlisted	658	593	558
Corporate bonds, listed	1,298	1,220	601
Corporate bonds, unlisted	331	346	345
Government bonds, listed	4,916	6,128	7,719
Insurance contracts	1,601	1,556	1,493
Other assets	883	(987)	(1,906)
Fair value of assets	17,779	18,280	17,570
Present value of scheme obligations	(18,774)	(19,785)	(19,654)
Net surplus/(obligation)	(995)	(1,505)	(2,084)
Actual return on plan assets	(156)	1,369	2,725
Group [member] | Other Noncurrent Assets [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	760	538	313
Group [member] | Pensions and other post-employment benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	(1,755)	(2,043)	(2,397)
UK [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Equities, listed	3,257	4,902	5,357
Equity, unlisted	0
Multi-asset funds	2,997	2,517	1,545
Property, listed	0
Property, unlisted	423	352	314
Corporate bonds, listed	404	297	292
Corporate bonds, unlisted	306	326	321
Government bonds, listed	3,835	5,127	6,165
Insurance contracts	770	849	856
Other assets	589	(1,216)	(2,267)
Fair value of assets	12,581	13,154	12,583
Present value of scheme obligations	(12,087)	(13,101)	(12,884)	£ (10,601)
Net surplus/(obligation)	494	53	(301)
Actual return on plan assets	(88)	893	2,473
UK [member] | Other Noncurrent Assets [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	711	470	276
UK [member] | Pensions and other post-employment benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	(217)	(417)	(577)
US [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Equities, listed	1,280	1,448	1,358
Equity, unlisted	0
Multi-asset funds	0
Property, listed	0
Property, unlisted	231	209	216
Corporate bonds, listed	783	820	213
Corporate bonds, unlisted	0
Government bonds, listed	286	239	815
Insurance contracts	0
Other assets	228	158	288
Fair value of assets	2,808	2,874	2,890
Present value of scheme obligations	(3,474)	(3,445)	(3,752)	(3,134)
Net surplus/(obligation)	(666)	(571)	(862)
Actual return on plan assets	(123)	394	153
US [member] | Other Noncurrent Assets [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	0
US [member] | Pensions and other post-employment benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	(666)	(571)	(862)
Rest of World. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Equities, listed	518	544	486
Equity, unlisted	7	13	14
Multi-asset funds	0
Property, listed	33
Property, unlisted	4	32	28
Corporate bonds, listed	111	103	96
Corporate bonds, unlisted	25	20	24
Government bonds, listed	795	762	739
Insurance contracts	831	707	637
Other assets	66	71	73
Fair value of assets	2,390	2,252	2,097
Present value of scheme obligations	(3,213)	(3,239)	(3,018)	£ (2,384)
Net surplus/(obligation)	(823)	(987)	(921)
Actual return on plan assets	55	82	99
Rest of World. [member] | Other Noncurrent Assets [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	49	68	37
Rest of World. [member] | Pensions and other post-employment benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Net surplus/(obligation)	£ (872)	£ (1,055)	£ (958)

Pensions and Other Post-empl_10

Pensions and Other Post-employment Benefits - Summary of Movements in Fair Values of Assets (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Obligations beginning balance	£ (19,785)	£ (19,654)
Exchange adjustments	47	(40)	£ 218
Service cost	(281)	(280)	(246)
Past service cost/(credit)	(94)	(37)	(54)
Interest cost	36	54	56
Settlements and curtailments	(14)		(28)
Employer contributions	(386)	(444)	(481)
Obligations ending balance	(18,774)	(19,785)	(19,654)
UK [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	13,154	12,583
Obligations beginning balance	(13,101)	(12,884)	(10,601)
Exchange adjustments	0
Service cost	(75)	(79)	(70)
Past service cost/(credit)	(93)	(37)	(52)
Interest cost	(320)	(340)	(394)
Settlements and curtailments	0
Remeasurement	906	(301)	(2,253)
Employer contributions	0	(136)	(191)
Scheme participants' contributions	(4)	(4)	(4)
Benefits paid	600	544	490
Assets, ending balance	12,581	13,154	12,583
Obligations ending balance	(12,087)	(13,101)	(12,884)
UK [member] | Plan Assets [Member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	13,154	12,583	10,284
Exchange adjustments	0
Interest cost	323	333	385
Expenses	(8)	(7)	(7)
Settlements and curtailments	0
Remeasurement	(411)	560	2,088
Employer contributions	119	225	319
Scheme participants' contributions	4	4	4
Benefits paid	(600)	(544)	(490)
Assets, ending balance	12,581	13,154	12,583
US [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	2,874	2,890
Obligations beginning balance	(3,445)	(3,752)	(3,134)
Exchange adjustments	(208)	305	(586)
Service cost	(72)	(70)	(66)
Past service cost/(credit)	(1)		(1)
Interest cost	(122)	(135)	(135)
Settlements and curtailments	0
Remeasurement	117	(50)	(72)
Employer contributions	(125)	(78)	0
Scheme participants' contributions	0
Benefits paid	257	257	242
Assets, ending balance	2,808	2,874	2,890
Obligations ending balance	(3,474)	(3,445)	(3,752)
US [member] | Plan Assets [Member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	2,874	2,890	2,501
Exchange adjustments	171	(244)	459
Interest cost	102	104	108
Expenses	(7)	(12)	(12)
Settlements and curtailments	0
Remeasurement	(225)	290	45
Employer contributions	150	103	31
Scheme participants' contributions	0
Benefits paid	(257)	(257)	(242)
Assets, ending balance	2,808	2,874	2,890
Rest of World. [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	2,252	2,097
Obligations beginning balance	(3,239)	(3,018)	(2,384)
Exchange adjustments	(63)	(45)	(396)
Service cost	(134)	(131)	(110)
Past service cost/(credit)	0		(1)
Interest cost	(48)	(49)	(57)
Settlements and curtailments	28	4	138
Remeasurement	170	(63)	(286)
Scheme participants' contributions	(16)	(17)	(14)
Benefits paid	89	80	92
Assets, ending balance	2,390	2,252	2,097
Obligations ending balance	(3,213)	(3,239)	(3,018)
Rest of World. [member] | Plan Assets [Member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	2,252	2,097	1,750
Exchange adjustments	53	24	305
Interest cost	29	33	37
Expenses	0
Settlements and curtailments	(14)	(4)	(110)
Remeasurement	26	49	62
Employer contributions	117	116	131
Scheme participants' contributions	16	17	14
Benefits paid	(89)	(80)	(92)
Assets, ending balance	2,390	2,252	2,097
Pension schemes [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Obligations beginning balance	(19,785)	(19,654)	(16,119)
Exchange adjustments	(271)	260	(982)
Service cost	(281)	(280)	(246)
Past service cost/(credit)	(94)	(37)	(54)
Interest cost	(490)	(524)	(586)
Settlements and curtailments	28	4	138
Remeasurement	1,193	(414)	(2,611)
Scheme participants' contributions	(20)	(21)	(18)
Benefits paid	946	881	824
Obligations ending balance	(18,774)	(19,785)	(19,654)
Pension schemes [member] | Plan Assets [Member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	18,280	17,570	14,535
Exchange adjustments	224	(220)	764
Interest cost	454	470	530
Expenses	(15)	(19)	(19)
Settlements and curtailments	(14)	(4)	(110)
Remeasurement	(610)	899	2,195
Employer contributions	386	444	481
Scheme participants' contributions	20	21	18
Benefits paid	(946)	(881)	(824)
Assets, ending balance	17,779	18,280	17,570
Post-retirement benefits [member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Obligations beginning balance	(1,496)	(1,693)	(1,387)
Exchange adjustments	(71)	119	(248)
Service cost	(29)	(30)	(31)
Past service cost/(credit)	27	2	(3)
Interest cost	(49)	(59)	(56)
Settlements and curtailments	1
Remeasurement	145	64	(59)
Scheme participants' contributions	(16)	(17)	(17)
Benefits paid	109	118	108
Obligations ending balance	(1,379)	(1,496)	(1,693)
Post-retirement benefits [member] | Plan Assets [Member]
Disclosure Of Defined Benefit Pension And Post Retirement [line items]
Assets, beginning balance	0
Exchange adjustments	0
Interest cost	0
Expenses	0
Settlements and curtailments	0
Remeasurement	0
Employer contributions	93	101	91
Scheme participants' contributions	16	17	17
Benefits paid	(109)	(118)	£ (108)
Assets, ending balance	£ 0	£ 0

Pensions and Other Post-empl_11

Pensions and Other Post-employment Benefits - Summary of Analysis of Defined Benefit Pension Obligation (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [line items]
Defined benefit obligation	£ (18,774)	£ (19,785)	£ (19,654)
Funded [member]
Disclosure of defined benefit plans [line items]
Defined benefit obligation	(18,025)	(19,052)	(18,974)
Unfunded [member]
Disclosure of defined benefit plans [line items]
Defined benefit obligation	£ (749)	£ (733)	£ (680)

Pensions and Other Post-empl_12

Pensions and Other Post-employment Benefits - Summary of Movement in Net Defined Benefit Liability (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [abstract]
Beginning of net defined benefit liability	£ (1,505)	£ (2,084)	£ (1,584)
Exchange adjustments	(47)	40	(218)
Service cost	(281)	(280)	(246)
Past service cost	(94)	(37)	(54)
Interest cost	(36)	(54)	(56)
Settlements and curtailments	14		28
Remeasurements:
Return on plan assets, excluding amounts included in interest	(610)	899	2,195
Gain/(loss) from change in demographic assumptions	131	209	85
Gain/(loss) from change in financial assumptions	1,149	(555)	(2,770)
Experience (losses)/gains	(87)	(68)	74
Employer contributions	386	444	481
Expenses	(15)	(19)	(19)
Ending of net defined benefit liability	£ (995)	£ (1,505)	£ (2,084)

Pensions and Other Post-Empl_13

Pensions and Other Post-Employment Benefits - Summary of Remeasurements Within Post-Retirement Benefits (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of net defined benefit liability (asset) [line items]
Gain from change in demographic assumptions	£ (131)	£ (209)	£ (85)
Gain/(loss) from change in financial assumptions	(1,149)	555	2,770
Experience gains	87	68	(74)
Post-retirement benefits [member]
Disclosure of net defined benefit liability (asset) [line items]
Gain from change in demographic assumptions	6	47
Gain/(loss) from change in financial assumptions	100	(1)	(81)
Experience gains	39	18	22
Total	£ 145	£ 64	£ (59)

Pensions and Other Post-Empl_14

Pensions and Other Post-Employment Benefits - Summary of Defined Benefit Pension Obligation Analysed by Membership Category (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [line items]
Defined benefit pension obligation analysed by membership category	£ 18,774	£ 19,785	£ 19,654
Pension schemes [member]
Disclosure of defined benefit plans [line items]
Defined benefit pension obligation analysed by membership category	18,774	19,785	19,654	£ 16,119
Active [member] | Pension schemes [member]
Disclosure of defined benefit plans [line items]
Defined benefit pension obligation analysed by membership category	4,427	4,611	4,576
Retired [member] | Pension schemes [member]
Disclosure of defined benefit plans [line items]
Defined benefit pension obligation analysed by membership category	9,542	9,805	9,574
Deferred [member] | Pension schemes [member]
Disclosure of defined benefit plans [line items]
Defined benefit pension obligation analysed by membership category	£ 4,805	£ 5,369	£ 5,504

Pensions and Other Post-Empl_15

Pensions and Other Post-Employment Benefits - Summary of Post-Retirement Benefit Obligation Analysed by Membership Category (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [line items]
Post-retirement benefit obligation analysed by membership category	£ 18,774	£ 19,785	£ 19,654
Post-retirement benefits [member]
Disclosure of defined benefit plans [line items]
Post-retirement benefit obligation analysed by membership category	1,379	1,496	1,693	£ 1,387
Active [member] | Post-retirement benefits [member]
Disclosure of defined benefit plans [line items]
Post-retirement benefit obligation analysed by membership category	499	514	594
Retired [member] | Post-retirement benefits [member]
Disclosure of defined benefit plans [line items]
Post-retirement benefit obligation analysed by membership category	879	981	£ 1,099
Deferred [member] | Post-retirement benefits [member]
Disclosure of defined benefit plans [line items]
Post-retirement benefit obligation analysed by membership category	£ 1	£ 1

Pensions and Other Post-Empl_16

Pensions and Other Post-Employment Benefits - Summary of Weighted Average Duration Defined Benefit Obligation (Detail) - yr	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension schemes [member]
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [line items]
Weighted average duration of the defined benefit obligation	15	16	16
Post retirement benefit [Member]
Disclosure of Information About Maturity Profile of Defined Benefit Obligation [line items]
Weighted average duration of the defined benefit obligation	11	11	12

Pensions and Other Post-Empl_17

Pensions and Other Post-Employment Benefits - Summary of Changes in Assumptions Used on Benefit Obligations, Defined Benefit Pension and Post Retirement Costs (Details) (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in annual pension cost	£ 28
Actuarial assumption of discount rates [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in annual pension cost	28
Increase/Decrease in annual post-retirement benefits cost	(1)
Increase in pension obligation	707
Increase in post-retirement benefits obligation	34
Actuarial assumption of life expectancy rates [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in annual pension cost	21
Increase/Decrease in annual post-retirement benefits cost	2
Increase in pension obligation	592
Increase in post-retirement benefits obligation	33
Actuarial assumption for future healthcare inflation [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase/Decrease in annual post-retirement benefits cost	1
Increase in post-retirement benefits obligation	38
Actuarial assumption of expected rates of inflation [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in annual pension cost	18
Increase in pension obligation	£ 447

Pensions and Other Post-Empl_18

Pensions and Other Post-Employment Benefits - Summary of Changes in Assumptions Used on Benefit Obligations, Defined Benefit Pension and Post Retirement Costs (Details) (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018
Actuarial assumption of discount rates [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Decrease in discount rate	0.25%
Actuarial assumption of life expectancy rates [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in life expectancy	1 year
Actuarial assumption for future healthcare inflation [member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in rate of future healthcare inflation	1.00%
Actuarial assumption of expected rates of inflation [Member]
Disclosure of Sensitivity Analysis for Actuarial Assumptions [Line Items]
Increase in inflation	0.25%

Other Provisions - Summary of O

Other Provisions - Summary of Other Provisions (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Disclosure of other provisions [line items]
Other provisions, beginning balance	£ 1,265
Exchange adjustments	44
Charge for the year	724
Reversed unused	(172)
Unwinding of discount	15
Utilised	(444)
Reclassifications and other movements	12
Transfer to Pension obligations	(21)
Other provisions, ending balance	1,423
To be settled within one year		£ 732	£ 629
To be settled after one year		691	636
Other provisions	1,265	1,423	1,265
Legal and other disputes [member]
Disclosure of other provisions [line items]
Other provisions, beginning balance	186
Exchange adjustments	13
Charge for the year	119
Reversed unused	(2)
Unwinding of discount	2
Utilised	(98)
Reclassifications and other movements	(1)
Transfer to Pension obligations	0
Other provisions, ending balance	219
To be settled within one year		156
To be settled after one year		63
Other provisions	186	219	186
Major Restructuring Programmes [Member]
Disclosure of other provisions [line items]
Other provisions, beginning balance	504
Exchange adjustments	17
Charge for the year	450
Reversed unused	(99)
Unwinding of discount	4
Utilised	(226)
Reclassifications and other movements	12
Transfer to Pension obligations	(21)
Other provisions, ending balance	641
To be settled within one year		362
To be settled after one year		279
Other provisions	504	641	504
Employee Related Provisions [Member]
Disclosure of other provisions [line items]
Other provisions, beginning balance	304
Exchange adjustments	9
Charge for the year	105
Reversed unused	(25)
Unwinding of discount	0
Utilised	(41)
Reclassifications and other movements	(2)
Transfer to Pension obligations	0
Other provisions, ending balance	350
To be settled within one year		145
To be settled after one year		205
Other provisions	304	350	304
Other Provision [Member]
Disclosure of other provisions [line items]
Other provisions, beginning balance	271
Exchange adjustments	5
Charge for the year	50
Reversed unused	(46)
Unwinding of discount	9
Utilised	(79)
Reclassifications and other movements	3
Transfer to Pension obligations	0
Other provisions, ending balance	213
To be settled within one year		69
To be settled after one year		144
Other provisions	£ 271	£ 213	£ 271

Other provisions - Additional I

Other provisions - Additional Information (Detail) - GBP (£)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of other provisions [line items]
Discount on the provisions	£ 2,000,000	£ 2,000,000
Short term legal proceedings	156,000,000
Legal proceedings and other disputes provision estimated	37,000,000	0
Pension augmentations arising from staff redundancies	£ 21,000,000	18,000,000
Period for amounts provided are expected to be utilised	2 years
Provision for employee benefits	£ 7,000,000	6,000,000
Onerous property lease provisions	6,000,000	38,000,000
Disabled employees [member]
Disclosure of other provisions [line items]
Provision for employee benefits	87,000,000	£ 108,000,000
Legal and other disputes [member]
Disclosure of other provisions [line items]
Charges on other provisions	£ 117,000,000

Other Non-current Liabilities -

Other Non-current Liabilities - Summary of Other Noncurrent Liabilities (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Other non-current liabilities [abstract]
Accruals	£ 71	£ 82
Deferred Income	19	22
Other payables	848	877
Other noncurrent liabilities	£ 938	£ 981

Net Debt - Schedule of Current

Net Debt - Schedule of Current Assets, Short and Long Term Borrowings (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Liquid investments	£ 84	£ 79	£ 78
Cash and cash equivalents	3,874		3,833	£ 4,897
Cash and cash equivalents reported in assets held for sale	485
Current assets	16,927		15,907
Short-term borrowings:
Commercial paper	(630)		(529)
Bank loans and overdrafts	(290)		(236)
Drawn bank facility	(3,500)
Short-term borrowings	(5,793)		(2,825)
Long-term borrowings:
Long-term borrowings	(20,271)		(14,264)
Net debt	(21,621)		(13,178)	£ (13,804)	£ (10,727)
Short-term borrowings [member]
Short-term borrowings:
Obligations under finance leases	(24)		(23)
Long Term Borrowings [Member]
Long-term borrowings:
Obligations under finance leases	(44)		(43)
Other LongTerm Borrowings [member]
Long-term borrowings:
Long-term borrowings	(56)		(49)
New York Stock Exchange [member] | 5.650% US$ US Medium Term Note 2018 [member]
Short-term borrowings:
Short-term borrowings	0		(2,037)
New York Stock Exchange [member] | 3.125% US$ US Medium Term Note 2021 [member]
Long-term borrowings:
Long-term borrowings	(980)
New York Stock Exchange [member] | LIBOR +0.35% US$ US Medium Term Note 2021 [member]
Long-term borrowings:
Long-term borrowings	(589)
New York Stock Exchange [member] | 2.850% US$ US Medium Term Note 2022 [Member]
Long-term borrowings:
Long-term borrowings	(1,568)		(1,474)
New York Stock Exchange [member] | 2.800% US$ US Medium Term Note 2023 [member]
Long-term borrowings:
Long-term borrowings	(978)		(919)
New York Stock Exchange [member] | 3.375% US$ US Medium Term Note 2023 [member]
Long-term borrowings:
Long-term borrowings	(977)
New York Stock Exchange [member] | 3.625% US$ US Medium Term Note 2025 [member]
Long-term borrowings:
Long-term borrowings	(780)
New York Stock Exchange [member] | 3.875% US$ US Medium Term Note 2028 [member]
Long-term borrowings:
Long-term borrowings	(1,372)
New York Stock Exchange [member] | 5.375% US Medium Term Note 2034 [Member]
Long-term borrowings:
Long-term borrowings	(390)		(368)
New York Stock Exchange [member] | 6.375% US Medium Term Note 2038 [Member]
Long-term borrowings:
Long-term borrowings	(2,143)		(2,021)
New York Stock Exchange [member] | 4.200% US$ US Medium Term Note 2043 [Member]
Long-term borrowings:
Long-term borrowings	(386)		(363)
London Stock Exchange [member] | 0.625% European Medium Term Notes 2019 [member]
Short-term borrowings:
Short-term borrowings	(1,349)
Long-term borrowings:
Long-term borrowings	0		(1,324)
London Stock Exchange [member] | EURIBOR +0.20% European Medium Term Note 2020 [member]
Long-term borrowings:
Long-term borrowings	(677)
London Stock Exchange [member] | 0.000% European Medium Term Note 2020 [member]
Long-term borrowings:
Long-term borrowings	(1,079)		(1,060)
London Stock Exchange [member] | 1.375% European Medium Term Notes 2024 [Member]
Long-term borrowings:
Long-term borrowings	(893)		(876)
London Stock Exchange [member] | 4.000% European Medium Term Note 2025 [Member]
Long-term borrowings:
Long-term borrowings	(670)		(659)
London Stock Exchange [member] | 1.000% European Medium Term Note 2026 [Member]
Long-term borrowings:
Long-term borrowings	(629)		(617)
London Stock Exchange [member] | 1.250% European Medium Term Note 2026 [member]
Long-term borrowings:
Long-term borrowings	(897)
London Stock Exchange [member] | 3.375% European Medium Term Note 2027 [Member]
Long-term borrowings:
Long-term borrowings	(593)		(593)
London Stock Exchange [member] | 1.375% European Medium Term Notes Two Thousand twenty nine [Member]
Long-term borrowings:
Long-term borrowings	(447)		(439)
London Stock Exchange [member] | 1.750% European Medium Term Note 2030 [member]
Long-term borrowings:
Long-term borrowings	(673)
London Stock Exchange [member] | 5.250% European Medium Term Note 2033 [Member]
Long-term borrowings:
Long-term borrowings	(982)		(986)
London Stock Exchange [member] | 6.375% European Medium Term Note 2039 [Member]
Long-term borrowings:
Long-term borrowings	(694)		(695)
London Stock Exchange [member] | 5.250% European Medium Term Note 2042 [Member]
Long-term borrowings:
Long-term borrowings	(986)		(989)
London Stock Exchange [member] | 4.250% European Medium Term Note 2045 [Member]
Long-term borrowings:
Long-term borrowings	(788)		(789)
Net debt [member]
Current assets:
Liquid investments	84		78
Cash and cash equivalents	3,874		3,833
Cash and cash equivalents reported in assets held for sale	485
Current assets	£ 4,443		£ 3,911

Net Debt - Additional Informati

Net Debt - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018GBP (£)Transactions	Dec. 31, 2018USD ($)Transactions	Dec. 31, 2017GBP (£)	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Jun. 30, 2018GBP (£)	Dec. 31, 2017USD ($)
Disclosure of debt [line items]
Effective Interest rate on liquid investment	1.00%		1.00%		1.00%		1.00%
Effective Interest rate on cash and cash equivalents	1.90%	1.90%	1.30%	1.30%
Non-interest bearing holdings	£ 263,000,000
Commercial paper issued	630,000,000		£ 529,000,000
Drawn bank facility	£ 3,500,000,000
Weighted average interest rate on current bank loans and overdrafts	12.00%		4.70%		12.00%		4.70%
Average effective pre-swap interest rate notes as short	0.80%		5.90%		0.80%		5.90%
Long-term borrowings	£ 20,271,000,000		£ 14,264,000,000
Average effective pre-swap interest rate notes	4.40%	4.40%	3.60%	3.60%
Other non current assets	£ 1,576,000,000		£ 1,413,000,000
Argentina [member]
Disclosure of debt [line items]
Weighted average interest rate on short-term loan	60.00%				60.00%
Disproportionate Effect on Weighted Average Rate [member]
Disclosure of debt [line items]
Weighted average interest rate on current bank loans and overdrafts	4.40%				4.40%
US commercial paper program [member]
Disclosure of debt [line items]
Commercial paper authorized	£ 7,900,000,000				$ 10,000,000,000
Commercial paper issued	£ 600,000,000		500,000,000		800,000,000		$ 700,000,000
Bottom of range [member]
Disclosure of debt [line items]
Repayment dates	2024	2024
Top of range [member]
Disclosure of debt [line items]
Repayment dates	2045	2045
Floating interest rate [member]
Disclosure of debt [line items]
Liquid investment	£ 84,000,000		78,000,000
Interest income	4,094,000,000		3,832,000,000
Fixed interest rate [member]
Disclosure of debt [line items]
Liquid investment	0		0
Interest income	£ 2,000,000		£ 1,000,000
Commercial paper [member]
Disclosure of debt [line items]
Weighted average interest rate of borrowings	2.50%	2.50%	1.50%	1.50%
Letter of credit 1 [member]
Disclosure of debt [line items]
Pledged investments value	£ 39,000,000	$ 50,000,000	£ 78,000,000	$ 105,000,000
Other non current assets			20,000,000
364 day committed facilities [member] | US commercial paper program [member]
Disclosure of debt [line items]
Credit Facility available amount	£ 2,000,000,000				2,500,000,000
Number of transactions active | Transactions	2	2
364 day committed facilities [member] | US commercial paper program [member] | Novartis [member]
Disclosure of debt [line items]
Drawn bank facility						£ 3,500,000,000
364 day committed facilities [member] | US commercial paper program [member] | Tesaro [member]
Disclosure of debt [line items]
Undrawn bank facility | $					$ 5,000,000,000
Five -year commitment facility [member] | US commercial paper program [member]
Disclosure of debt [line items]
Credit Facility available amount	£ 1,900,000,000
Later than 5 years [member]
Disclosure of debt [line items]
Long-term borrowings	£ 13,300,000,000		£ 10,300,000,000
Later than 5 years [member] | Bottom of range [member]
Disclosure of debt [line items]
Interest at effective rates	1.10%	1.10%
Later than 5 years [member] | Top of range [member]
Disclosure of debt [line items]
Interest at effective rates	6.40%	6.40%
Matured in May 2018 [member]
Disclosure of debt [line items]
Coupon note interest rate	5.65%				5.65%
Matures in December 2019 [member]
Disclosure of debt [line items]
Coupon note interest rate	0.625%				0.625%

Net Debt - Schedule of Finance

Net Debt - Schedule of Finance Lease Obligations (Detail) - GBP (£)	Dec. 31, 2018	Dec. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	£ 84	£ 78
Future finance charges	(16)	(12)
Total finance lease obligations	68	66
Not later than 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	29	25
Between 1 and 2 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	20	29
Between 2 and 3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	13	9
Between 3 and 4 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	7	3
Between 4 and 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	4	2
Later than 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Total future rental payments	£ 11	£ 10

Contingent Liabilities - Additi

Contingent Liabilities - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of contingent liabilities [abstract]
Contingent liabilities, comprising guarantees, discounted bills and other items	£ 93	£ 434
Financial assets were pledged as collateral for contingent liabilities	£ 0	£ 2

Share Capital and Share Premi_3

Share Capital and Share Premium Account - Summary of Share Capital and Share Premium (Detail) - GBP (£)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Share capital issued and fully paid beginning balance	5,372,553,820	5,368,316,062	5,361,307,647
Shares Authorised	10,000,000,000	10,000,000,000	10,000,000,000
Issued under employee share schemes	6,513,804	4,237,758	7,008,415
Ordinary shares acquired by ESOP Trusts		0	0
Share capital issued and fully paid ending balance	5,379,067,624	5,372,553,820	5,368,316,062
Equity at beginning of period	£ 3,489,000,000	£ 4,963,000,000	£ 8,878,000,000
Issued under employee share schemes	74,000,000	56,000,000	89,000,000
Issued under employee share schemes	74,000,000	56,000,000	89,000,000
Equity at end of period	3,672,000,000	3,489,000,000	4,963,000,000
Share premium [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Equity at beginning of period	3,019,000,000	2,954,000,000	2,831,000,000
Issued under employee share schemes	72,000,000	55,000,000	87,000,000
Ordinary shares acquired by ESOP Trusts		10,000,000	36,000,000
Issued under employee share schemes	72,000,000	55,000,000	87,000,000
Ordinary shares acquired by ESOP Trusts		10,000,000	36,000,000
Equity at end of period	3,091,000,000	3,019,000,000	2,954,000,000
Share capital [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Equity at beginning of period		1,342,000,000	1,340,000,000
Issued under employee share schemes	2,000,000	1,000,000	2,000,000
Issued under employee share schemes	2,000,000	1,000,000	2,000,000
Equity at end of period	1,345,000,000		1,342,000,000
Share capital [member] | Ordinary shares [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Shares Authorised, value	2,500,000,000	2,500,000,000	2,500,000,000
Equity at beginning of period	1,343,000,000	1,342,000,000	1,340,000,000
Issued under employee share schemes	2,000,000	1,000,000	2,000,000
Issued under employee share schemes	2,000,000	1,000,000	2,000,000
Equity at end of period	£ 1,345,000,000	£ 1,343,000,000	£ 1,342,000,000

Share Capital and Share Premi_4

Share Capital and Share Premium Account - Summary of Share Capital and Share Premium (Parenthetical) (Detail)	Dec. 31, 2018£ / shares
Disclosure Of Classes Of Share Capital And Share Premium [abstract]
Ordinary price per share	£ 0.25

Share Capital and Share Premi_5

Share Capital and Share Premium Account - Summary of Share Capital (Detail)	12 Months Ended
	Dec. 31, 2018shares	Dec. 31, 2017shares
Disclosure Of Classes Of Share Capital And Share Premium [abstract]
Number of shares issuable under employee share schemes	56,723	38,647
Number of unissued shares not under option	4,564,209	4,588,799

Share Capital and Share Premi_6

Share Capital and Share Premium Account - Additional Information (Detail)	Dec. 31, 2018shares
Employee share ownership plan [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Share capital issued	41,530,909
Treasury shares [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Share capital issued	414,605,950
Free issue [member]
Disclosure Of Classes Of Share Capital And Share Premium [line items]
Share capital issued	4,922,930,765

Movements in Equity - Additiona

Movements in Equity - Additional Information (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retained losses and other reserves	£ 76		£ (4,430)	£ (3,172)
Other reserve	2,061	£ 41	2,047	2,220	£ 2,340
Associates and joint ventures [member]
Retained losses and other reserves	337		334	329
Merger and premerger reserves [member]
Other reserve	1,849		1,849	1,849
Capital redemption reserve [member]
Other reserve	£ 280		£ 280	£ 280

Movements in Equity - Summary o

Movements in Equity - Summary of Cumulative Translation Exchange in Equity (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Beginning balance	£ 811	£ 389	£ (860)
Exchange movements on overseas net assets	(481)	313	1,249
Reclassification of exchange on liquidation or disposal of overseas subsidiaries	0	109
Ending balance	330	811	389
Retained earnings [member]
Beginning balance	443	(128)	(761)
Exchange movements on overseas net assets	(458)	462	633
Reclassification of exchange on liquidation or disposal of overseas subsidiaries		109
Ending balance	(15)	443	(128)
Fair value reserve [member]
Beginning balance	23	23	10
Exchange movements on overseas net assets	(22)		13
Ending balance	1	23	23
Non- controlling interests [member]
Beginning balance	345	494	(109)
Exchange movements on overseas net assets	(1)	(149)	603
Ending balance	£ 344	£ 345	£ 494

Movements in Equity - Analysis

Movements in Equity - Analysis of Other Comprehensive Income by Equity Category (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Items that may be subsequently reclassified to income statement:
Exchange movements on overseas net assets and net investment hedges	£ (480)	£ 462	£ 646
Reclassification of exchange on liquidation or disposal of overseas subsidiaries	0	109
Fair value movements on available-for-sale investments		(14)	251
Reclassification of fair value movements on available-for-sale investments		(42)	(245)
Deferred tax on fair value movements on available-for-sale investments		47
Deferred tax reversed on reclassification of available-for-sale investments		(18)	51
Reclassification of cash flow hedges to income statement			1
Fair value movements on cash flow hedges	140	(10)	2
Reclassification of cash flow hedges on income and expense	(175)		1
Deferred tax on fair value movements on cash flow hedges	(22)		2
Deferred tax reversed on reclassification of cash flow hedges	20
Items that will not be reclassified to income statement:
Exchange movements on overseas net assets of non-controlling interests	(1)	(149)	603
Fair value movements on equity investments	180
Deferred tax on fair value movements on equity investments	10
Remeasurement gains (losses) on defined benefit plans	728	549	(475)
Tax on remeasurement gains (losses) in defined benefit plans	(146)	(221)	126
Other comprehensive income for the year	254	713	962
Retained earnings [member]
Items that may be subsequently reclassified to income statement:
Exchange movements on overseas net assets and net investment hedges	(458)	462	633
Reclassification of exchange on liquidation or disposal of overseas subsidiaries		109
Fair value movements on cash flow hedges	0
Reclassification of cash flow hedges on income and expense	0
Deferred tax on fair value movements on cash flow hedges	0
Deferred tax reversed on reclassification of cash flow hedges	0
Items that will not be reclassified to income statement:
Exchange movements on overseas net assets of non-controlling interests	0
Fair value movements on equity investments	0
Deferred tax on fair value movements on equity investments	0
Remeasurement gains (losses) on defined benefit plans	728	549	(475)
Tax on remeasurement gains (losses) in defined benefit plans	(146)	(221)	126
Other comprehensive income for the year	124	899	284
Other reserves [member]
Items that may be subsequently reclassified to income statement:
Exchange movements on overseas net assets and net investment hedges	(22)		13
Fair value movements on available-for-sale investments		(14)	251
Reclassification of fair value movements on available-for-sale investments		(42)	(245)
Deferred tax on fair value movements on available-for-sale investments		47
Deferred tax reversed on reclassification of available-for-sale investments		(18)	51
Reclassification of cash flow hedges to income statement			1
Fair value movements on cash flow hedges	140	(10)	2
Reclassification of cash flow hedges on income and expense	(175)
Deferred tax on fair value movements on cash flow hedges	(22)		2
Deferred tax reversed on reclassification of cash flow hedges	20
Items that will not be reclassified to income statement:
Exchange movements on overseas net assets of non-controlling interests	0
Fair value movements on equity investments	180
Deferred tax on fair value movements on equity investments	10
Remeasurement gains (losses) on defined benefit plans	0
Tax on remeasurement gains (losses) in defined benefit plans	0
Other comprehensive income for the year	131	(37)	75
Non- controlling interests [member]
Items that may be subsequently reclassified to income statement:
Exchange movements on overseas net assets and net investment hedges	0
Fair value movements on cash flow hedges	0
Reclassification of cash flow hedges on income and expense	0
Deferred tax on fair value movements on cash flow hedges	0
Deferred tax reversed on reclassification of cash flow hedges	0
Items that will not be reclassified to income statement:
Exchange movements on overseas net assets of non-controlling interests	(1)	(149)	603
Fair value movements on equity investments	0
Deferred tax on fair value movements on equity investments	0
Remeasurement gains (losses) on defined benefit plans	0
Tax on remeasurement gains (losses) in defined benefit plans	0
Other comprehensive income for the year	£ (1)	£ (149)	£ 603

Movements in Equity - Analysi_2

Movements in Equity - Analysis of Other Reserves (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other reserves, beginning balance	£ 2,047	£ 2,220	£ 2,340
Implementation of IFRS 9	(288)
At 31 December, as adjusted	1,759
Exchange adjustments	(26)	22	(16)
Transferred to income and expense in the year on disposals		(42)	(268)
Transferred to Retained earnings in the year on disposal of equity investments	(94)
Transferred to income and expense in the year on impairments			23
Net fair value movement in the year	157	(17)	336
Ordinary shares acquired by ESOP Trusts		(656)	(576)
Write-down of shares held by ESOP Trusts	265	520	381
Other reserves, ending balance	2,061	2,047	2,220
ESOP trust shares [member]
Other reserves, beginning balance	(400)	(286)	(75)
At 31 December, as adjusted	(400)
Exchange adjustments	(26)	22	(16)
Transferred to Retained earnings in the year on disposal of equity investments	0
Net fair value movement in the year	0
Ordinary shares acquired by ESOP Trusts		(656)	(576)
Write-down of shares held by ESOP Trusts	265	520	381
Other reserves, ending balance	(161)	(400)	(286)
Fair value reserve [member]
Other reserves, beginning balance	329	380	295
Implementation of IFRS 9	(288)
At 31 December, as adjusted	41
Exchange adjustments	0
Transferred to income and expense in the year on disposals		(42)	(268)
Transferred to Retained earnings in the year on disposal of equity investments	(94)
Transferred to income and expense in the year on impairments			23
Net fair value movement in the year	193	(9)	330
Write-down of shares held by ESOP Trusts	0
Other reserves, ending balance	140	329	380
Cash Flow Hedges Reserve [Member]
Other reserves, beginning balance	(11)	(3)	(9)
At 31 December, as adjusted	(11)
Exchange adjustments	0
Transferred to Retained earnings in the year on disposal of equity investments	0
Net fair value movement in the year	(36)	(8)	6
Write-down of shares held by ESOP Trusts	0
Other reserves, ending balance	(47)	(11)	(3)
Other reserves [member]
Other reserves, beginning balance	2,129	2,129	2,129
At 31 December, as adjusted	2,129
Exchange adjustments	0
Transferred to Retained earnings in the year on disposal of equity investments	0
Net fair value movement in the year	0
Write-down of shares held by ESOP Trusts	0
Other reserves, ending balance	£ 2,129	£ 2,129	£ 2,129

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - GBP (£) shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of transactions between related parties [line items]
Liability	£ 54,394,000,000	£ 52,892,000,000
Japan Vaccine Company Limited [member]
Disclosure of transactions between related parties [line items]
Sale of vaccine product	43,000,000	41,000,000
Trading balance receivable	15,000,000	11,000,000
Trading balance payable	£ 0	0
Innoviva incorporation [member]
Disclosure of transactions between related parties [line items]
Number of shares owned	32
Percentage of shares owned	31.70%
Royalty charge	£ 209,000,000	173,000,000
Royalty payable	£ 64,000,000	£ 53,000,000
Joint ventures where entity is venturer [member] | Japan Vaccine Company Limited [member]
Disclosure of transactions between related parties [line items]
Ownership interest	50.00%
Medicxi Ventures I Limited Partner [member]
Disclosure of transactions between related parties [line items]
Loans outstanding	£ 5,000,000
Index ventures life VI [member]
Disclosure of transactions between related parties [line items]
Loans outstanding	6,000,000
Kurma Biofund II, FCPR [member]
Disclosure of transactions between related parties [line items]
Increase in equity investment	3,000,000
Apollo Therapeutics LLP [member]
Disclosure of transactions between related parties [line items]
Increase in equity investment	2,000,000
Longwood Founders Fund LP [member]
Disclosure of transactions between related parties [line items]
Increase in equity investment	200,000
Qura Therapeutics LLC [member]
Disclosure of transactions between related parties [line items]
Decrease in liability	3,000,000
Liability	£ 4,000,000

Adjustments Reconciling Profi_3

Adjustments Reconciling Profit After Tax to Operating Cash Flows - Summary of Cash Generated from Operations (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Adjustments to reconcile profit (loss) [abstract]
Profit after tax	£ 4,046	£ 2,169	£ 1,062
Tax on profits	754	1,356	877
Share of after tax profits of associates and joint ventures	(31)	(13)	(5)
Finance expense net of finance income	717	669	664
Depreciation	954	988	978
Amortisation of intangible assets	902	934	796
Impairment and assets written off	350	1,061	226
Profit on sale of businesses	(63)	(157)	(5)
Profit on sale of intangible assets	(201)	(46)	(178)
Profit on sale of investments in associates	(3)	(94)
Profit on sale of equity investments	(4)	(37)	(254)
Gain on Consumer Healthcare Joint Venture put hedging	(513)
Business acquisition costs	47
Changes in working capital:
Decrease/(increase) in inventories	51	(461)	70
Increase in trade receivables	(429)	(287)	(188)
Increase in trade payables	131	11	96
Decrease in other receivables	18	74	381
Contingent consideration paid (see Note •)	(984)	(594)	(358)
Other non-cash increase in contingent consideration liabilities	1,250	961	2,281
Increase in other payables	2,362	1,741	1,989
Increase/(decrease) in pension and other provisions	102	(255)	(621)
Share-based incentive plans	360	333	319
Fair value adjustments	(7)		(3)
Other	(62)	(95)	(21)
Adjustments reconciling profit after tax to operating cash flows	5,701	6,089	7,044
Cash generated from operations	£ 9,747	£ 8,258	£ 8,106

Reconciliation of Net Cash Fl_3

Reconciliation of Net Cash Flow to Movement in Net Debt - Summary of Net Debt (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of net debt [abstract]
Net debt at beginning of year	£ (13,178)	£ (13,804)	£ (10,727)
Increase/(decrease) in cash and bank overdrafts	479	(905)	(1,164)
Decrease in liquid investments	0	(4)
Net increase in long-term loans	(10,138)	(2,233)
Repayment of short-term Notes	2,067	2,636	865
(Increase in)/repayment of other short-term loans	(81)	564	(1,013)
Net repayment of obligations under finance leases	28	23	18
Exchange adjustments	(776)	585	(1,781)
Other non-cash movements	(22)	(40)	(2)
Movement in net debt	(8,443)	626	(3,077)
Net debt at end of year	£ (21,621)	£ (13,178)	£ (13,804)

Reconciliation of Net Cash Fl_4

Reconciliation of Net Cash Flow to Movement in Net Debt - Summary of Analysis of Changes in Net Debt (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	£ (17,057)
Exchange	(809)
Other	105
Profit and loss	(808)
Reclassification	0
Cash flow	(7,333)
Ending balance	(25,902)
Short-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(2,592)
Exchange	(92)
Other	(11)
Profit and loss	0
Reclassification	(4,840)
Cash flow	2,014
Ending balance	(5,521)
Long Term Borrowings [Member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(14,264)
Exchange	(697)
Other	(16)
Profit and loss	4
Reclassification	4,840
Cash flow	(10,138)
Ending balance	(20,271)
Total Debt [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(13,178)
Exchange	(776)
Other	(26)
Profit and loss	4
Reclassification	0
Cash flow	(7,645)
Ending balance	(21,621)
Accrued interest [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(203)
Exchange	(2)
Other	2
Profit and loss	(802)
Reclassification	0
Cash flow	766
Ending balance	(239)
Commercial paper [member] | Short-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(529)
Exchange	(36)
Other	0
Profit and loss	0
Reclassification	0
Cash flow	(65)
Ending balance	(630)
European/US Medium Term Notes and Bank Facilities [member] | Short-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(2,037)
Exchange	(55)
Other	0
Profit and loss	0
Reclassification	(4,824)
Cash flow	2,067
Ending balance	(4,849)
Other [member] | Short-term borrowings [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(26)
Exchange	(1)
Other	(11)
Profit and loss	0
Reclassification	(16)
Cash flow	12
Ending balance	(42)
European/US Medium Term Notes and Bank Facilities Non-current [member] | Long Term Borrowings [Member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(14,221)
Exchange	(696)
Other	0
Profit and loss	4
Reclassification	4,824
Cash flow	(10,138)
Ending balance	(20,227)
Other non-current debt [member] | Long Term Borrowings [Member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(43)
Exchange	(1)
Other	(16)
Profit and loss	0
Reclassification	16
Cash flow	0
Ending balance	(44)
Liquid Investments [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	78
Exchange	5
Other	1
Profit and loss	0
Reclassification	0
Cash flow	0
Ending balance	84
Cash and cash equivalents [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	3,833
Exchange	4
Other	0
Profit and loss	0
Reclassification	(485)
Cash flow	522
Ending balance	3,874
Cash and cash equivalents - AHFS [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	0
Exchange	0
Other	0
Profit and loss	0
Reclassification	485
Cash flow	0
Ending balance	485
Overdrafts [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	(233)
Exchange	4
Other	0
Profit and loss	0
Reclassification	0
Cash flow	(43)
Ending balance	(272)
Cash and cash equivalents and overdrafts [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	3,600
Exchange	8
Other	0
Profit and loss	0
Reclassification	0
Cash flow	479
Ending balance	4,087
Derivative financial instruments [member] | Assets held to hedge liabilities arising from financing activities [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	2
Exchange	1
Other	130
Profit and loss	(10)
Reclassification	0
Cash flow	6
Ending balance	129
Other financing items [member] | Assets held to hedge liabilities arising from financing activities [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	0
Exchange	(19)
Other	0
Profit and loss	0
Reclassification	0
Cash flow	19
Ending balance	£ 0

Acquisitions and Disposals - 20

Acquisitions and Disposals - 2016 Acquisitions - Additional Information (Detail) £ in Millions, $ in Billions	12 Months Ended
	Dec. 31, 2018GBP (£)Acquisition	Dec. 31, 2017GBP (£)Acquisition	Dec. 31, 2016GBP (£)Acquisitions	Jan. 22, 2019USD ($)	Dec. 31, 2018USD ($)Acquisition
Disclosure of detailed information about business combination [line items]
Fair value assets	£ 12,402	£ 10,906
Cash investment in associates and joint ventures		15	£ 11
Goodwill	5,789	5,734	£ 5,965
Embedded Derivative [member]
Disclosure of detailed information about business combination [line items]
Fair value assets	£ 100
Major business combination [member] | Pfizer [member] | Pfizer's Consumer Health Business [member]
Disclosure of detailed information about business combination [line items]
Percentage of holding in joint venture	32.00%
2017 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration		342
Cash consideration		6
Deferred consideration receivable		86
2018 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration	£ 2
Disposal groups classified as held for sale [member] | GSK Consumer Healthcare Limited [member]
Disclosure of detailed information about business combination [line items]
Percentage of ownership	72.50%
Disposal groups classified as held for sale [member] | Other disposals of assets [member] | GSK Consumer Healthcare Limited [member]
Disclosure of detailed information about business combination [line items]
Percentage of ownership	5.70%
Associates [member]
Disclosure of detailed information about business combination [line items]
Cash consideration paid		£ 198
Number of investment holdings sold		2
2018 Acquisition [member]
Disclosure of detailed information about business combination [line items]
Number of acquisitions | Acquisition	0				0
2017 acquisition [member]
Disclosure of detailed information about business combination [line items]
Number of acquisitions | Acquisition		0
2016 acquisitions [member]
Disclosure of detailed information about business combination [line items]
Number of acquisitions | Acquisitions			2
2016 acquisitions [member] | 2016 business disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration			£ 72
Deferred consideration receivable			43
HIV R&D preclinical and discovery stage portfolio [member]
Disclosure of detailed information about business combination [line items]
Cash consideration			24
Initial estimate of recognised for contingent consideration			40
Intangible assets			57
Goodwill			7
Galvani Bioelectronics Limited [member]
Disclosure of detailed information about business combination [line items]
Intangible assets			45
Cash and cash equivalents			£ 41
Proportion of non-controlling interest			45.00%
Fair value of shareholdings			£ 47
Non controlling interest			£ 39
GSK Consumer Healthcare Limited With Hindustan Unilever Limited [member] | Disposal groups classified as held for sale [member] | Other disposals of assets [member]
Disclosure of detailed information about business combination [line items]
Total consideration value	£ 3,100
Tesaro, Inc.[member]
Disclosure of detailed information about business combination [line items]
Percentage acquired	100.00%				100.00%
Tesaro, Inc.[member] | Major business combination [member]
Disclosure of detailed information about business combination [line items]
Cash consideration	£ 4,000			$ 5.1	$ 5.1

Acquisitions and Disposals - Su

Acquisitions and Disposals - Summary of Investment in Associates and Joint Ventures (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about business combination [line items]
Cash inflow	£ (1,553)	£ (1,443)	£ (1,269)
Associates and joint ventures 2018 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration	3
Net deferred consideration received	0
Cash and cash equivalents divested	0
Cash inflow	3
Associates and joint ventures 2017 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration		198
Transaction costs paid		(2)
Cash inflow		196
Business combinations [member] | 2018 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration	2
Net deferred consideration received	24
Cash and cash equivalents divested	0
Cash inflow	26
Business combinations [member] | 2017 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration		256
Net deferred consideration received		39
Cash and cash equivalents divested		(6)
Transaction costs paid		(7)
Cash inflow		282
Associates and JV investments [member] | 2018 investments [member]
Disclosure of detailed information about business combination [line items]
Cash consideration	(10)
Net deferred consideration received	0
Cash and cash equivalents divested	0
Cash inflow	£ (10)
Associates and JV investments [member] | 2017 investments [member]
Disclosure of detailed information about business combination [line items]
Cash consideration		(15)
Cash inflow		£ (15)

Acquisitions and Disposals - _2

Acquisitions and Disposals - Summary of Profit on Disposal of Businesses (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net assets sold:
Reclassification of exchange from other comprehensive income	£ 0	£ 109
2017 disposals [member]
Disclosure of detailed information about business combination [line items]
Consideration including currency forwards and purchase adjustments		342
Net assets sold:
Goodwill		(16)
Intangible assets		(21)
Property, plant and equipment		(18)
Inventory		(11)
Cash and cash equivalents		(6)
Other net assets		(5)
Net assets sold		(77)
Transaction costs		(8)
Reclassification of exchange from other comprehensive income		(100)
Profit on disposal		£ 157

Acquisitions and Disposals - _3

Acquisitions and Disposals - Summary of Disposal of Associates (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about business combination [line items]
Profit on disposal	£ 0
Investment associates and joint ventures [member] | 2017 disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration		£ 198
Net book value of shares		(92)
Reclassification of exchange from other comprehensive income		(7)
Transaction costs		(5)
Profit on disposal		£ 94

Acquisitions and Disposals - _4

Acquisitions and Disposals - Summary of Cash Flows from Business Combinations (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2016GBP (£)
Business acquisitions [member]
Disclosure of detailed information about business combination [line items]
Cash consideration (paid)/received after purchase adjustments	£ (24)
Cash and cash equivalents acquired	41
Cash inflow	17
Business disposals [member]
Disclosure of detailed information about business combination [line items]
Cash consideration (paid)/received after purchase adjustments	72
Cash inflow	£ 72

Contingent consideration liab_3

Contingent consideration liabilities - Summary of Fair Value Contingent Consideration (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of contingent liabilities in business combination [line items]
Beginning balance	£ 6,172	£ 5,896	£ 3,855
Additions through business combinations			194
Remeasurement through income statement	1,251	961	2,281
Cash payments: operating cash flows	(984)	(594)	(358)
Cash payments: investing activities	(153)	(91)	(73)
Other movements			(3)
Ending balance	6,286	6,172	5,896
Shionogi ViiV healthcare joint venture [member]
Disclosure of contingent liabilities in business combination [line items]
Beginning balance	5,542	5,304	3,409
Additions through business combinations			154
Remeasurement through income statement	1,188	909	2,162
Cash payments: operating cash flows	(703)	(587)	(351)
Cash payments: investing activities	(90)	(84)	(66)
Other movements			(4)
Ending balance	5,937	5,542	5,304
Novartis [member]
Disclosure of contingent liabilities in business combination [line items]
Beginning balance	584	545	405
Remeasurement through income statement	56	53	152
Cash payments: operating cash flows	(281)	(7)	(5)
Cash payments: investing activities	(63)	(7)	(7)
Ending balance	296	584	545
Other [member]
Disclosure of contingent liabilities in business combination [line items]
Beginning balance	46	47	41
Additions through business combinations			40
Remeasurement through income statement	7	(1)	(33)
Cash payments: operating cash flows	0		(2)
Cash payments: investing activities	0
Other movements			1
Ending balance	£ 53	£ 46	£ 47

Contingent Consideration Liab_4

Contingent Consideration Liabilities - Additional Information (Detail) £ in Millions	1 Months Ended
	Jan. 31, 2018USD ($)	Dec. 31, 2018GBP (£)	Dec. 31, 2017GBP (£)
Disclosure of fair value of contingent consideration [line items]
Contingent consideration payable | £		£ 837	£ 1,076
Novartis [member]
Disclosure of fair value of contingent consideration [line items]
Contingent consideration settled | $	$ 450
Novartis [member] | Bottom of range [member]
Disclosure of fair value of contingent consideration [line items]
Contingent consideration liability discount percentage		8.00%
Novartis [member] | Top of range [member]
Disclosure of fair value of contingent consideration [line items]
Contingent consideration liability discount percentage		9.00%
Shionogi ViiV healthcare joint venture [member]
Disclosure of fair value of contingent consideration [line items]
Contingent consideration liability discount percentage		8.50%

Contingent consideration liab_5

Contingent consideration liabilities - Summary of Possible Changes in key Inputs to Valuation of Contingent Consideration Liabilities (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Shionogi ViiV healthcare joint venture [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10% increase in sales forecasts	£ 569
10% decrease in sales forecasts	(569)
1% increase in discount rate	(238)
1% decrease in discount rate	256
Shionogi ViiV healthcare joint venture [member] | 10 cent appreciation of the US Dollar [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent appreciation of US Dollar	367
Shionogi ViiV healthcare joint venture [member] | 10 cent depreciation of US Dollar [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent depreciation of US Dollar	(313)
Shionogi ViiV healthcare joint venture [member] | 10 cent appreciation of the Euro [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent appreciation of Euro	114
Shionogi ViiV healthcare joint venture [member] | 10 cent depreciation of Euro [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent depreciation of Euro	(95)
Novartis vaccines [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10% increase in sales forecasts	62
10% decrease in sales forecasts	(62)
1% increase in discount rate	(22)
1% decrease in discount rate	26
5% increase in probability of milestone success	7
5% decrease in probability of milestone success	(7)
Novartis vaccines [member] | 10 cent appreciation of the US Dollar [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent appreciation of US Dollar	(13)
Novartis vaccines [member] | 10 cent depreciation of US Dollar [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent depreciation of US Dollar	11
Novartis vaccines [member] | 10 cent appreciation of the Euro [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent appreciation of Euro	29
Novartis vaccines [member] | 10 cent depreciation of Euro [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
10 cent depreciation of Euro	£ (25)

Contingent consideration liab_6

Contingent consideration liabilities - Summary of Possible Changes in key Inputs to Valuation of Contingent Consideration Liabilities (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018
Shionogi ViiV healthcare joint venture [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
Increase in sales forecasts	10.00%
Decrease in sales forecasts	10.00%
increase in discount rate	1.00%
Decrease in discount rate	1.00%
Novartis vaccines [member]
Disclosure of valuation techniques and key model inputs used to measure contingent consideration [line items]
Increase in sales forecasts	10.00%
Decrease in sales forecasts	10.00%
increase in discount rate	1.00%
Decrease in discount rate	1.00%
Increase in probability of milestone success	5.00%
Decrease in probability of milestone success	5.00%

Non-controlling interests - Sum

Non-controlling interests - Summarised Financial Information of ViiV Healthcare Group and GSK Consumer Healthcare Joint Venture (Detail) - GBP (£) £ in Millions	May 03, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Disclosure of noncontrolling interests [line items]
Total comprehensive income/(expense) for the year attributable to non-controlling interests		£ 4,300	£ 2,882	£ 2,024
Non-controlling interests in the Consolidated balance sheet		(688)	3,557
Turnover		30,821	30,186	27,889
Profit/(loss) after taxation		423	637	150
Other comprehensive (expense)/income		254	713	962
Total comprehensive (expense)/income		422	488	753
Non-current assets		41,139	40,474
Current assets		16,927	15,907
Total assets		58,066	56,381
Current liabilities		(22,491)	(26,569)
Non-current liabilities		(31,903)	(26,323)
Total liabilities		(54,394)	(52,892)
Net assets		3,672	3,489		£ 3,474
Net cash inflow from operating activities		8,421	6,918	6,497
Net cash inflow/(outflow) from investing activities		(1,553)	(1,443)	(1,269)
Net cash outflow from financing activities		(6,389)	(6,380)	(6,392)
ViiV healthcare [member]
Disclosure of noncontrolling interests [line items]
Total comprehensive income/(expense) for the year attributable to non-controlling interests		254	187	(83)
Dividends paid to non-controlling interests		332	316	152
Non-controlling interests in the Consolidated balance sheet		(543)	(476)
Turnover		4,665	4,269	3,527
Profit/(loss) after taxation		560	825	(1,249)
Other comprehensive (expense)/income		19	20	36
Total comprehensive (expense)/income		579	845	(1,213)
Non-current assets		2,787	2,736
Current assets		2,643	2,533
Total assets		5,430	5,269
Current liabilities		(2,638)	(2,409)
Non-current liabilities		(8,895)	(8,011)
Total liabilities		(11,533)	(10,420)
Net assets		(6,103)	(5,151)
Net cash inflow from operating activities		2,212	2,132	1,750
Net cash inflow/(outflow) from investing activities		(237)	(207)	(326)
Net cash outflow from financing activities		(1,982)	(1,820)	(1,023)
(Decrease)/increase in cash and bank overdrafts in the year		(7)	105	401
Consumer health care joint venture [member]
Disclosure of noncontrolling interests [line items]
Total comprehensive income/(expense) for the year attributable to non-controlling interests		111	296	730
Dividends paid to non-controlling interests		183	420	346
Non-controlling interests in the Consolidated balance sheet		£ 0	3,631
Turnover	£ 2,306		7,003	6,530
Profit/(loss) after taxation	7		1,211	660
Other comprehensive (expense)/income	(79)		(387)	1,640
Total comprehensive (expense)/income	(72)		824	2,300
Non-current assets			12,771
Current assets			3,282
Total assets			16,053
Current liabilities			(2,675)
Non-current liabilities			(1,537)
Total liabilities			(4,212)
Net assets			11,841
Net cash inflow from operating activities	65		883	1,496
Net cash inflow/(outflow) from investing activities	442		270	(537)
Net cash outflow from financing activities	(504)		(1,194)	(980)
(Decrease)/increase in cash and bank overdrafts in the year	£ 3		£ (41)	£ (21)

Non-controlling interests - Add

Non-controlling interests - Additional Information (Detail) - GBP (£) £ in Millions	May 03, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of noncontrolling interests [line items]
Profit after taxation		£ 423	£ 637	£ 150
ViiV healthcare [member]
Disclosure of noncontrolling interests [line items]
Profit after taxation		560	825	(1,249)
Shionogi ViiV healthcare joint venture [member]
Disclosure of noncontrolling interests [line items]
Remeasurement of contingent consideration payable for acquisition		£ 1,194	909	2,186
Consumer health care joint venture [member]
Disclosure of noncontrolling interests [line items]
Profit after taxation	£ 7		£ 1,211	£ 660
Joint venture ownership percentage		100.00%

Non-controlling interests - Sch

Non-controlling interests - Schedule of Amount Attributable to VIIV Healthcare Group Included in GSK's Consolidated Statement of Comprehensive Income, Consolidated Statement of Changes in Equity and Consolidated Balance Sheet (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of noncontrolling interests [line items]
Total comprehensive income/(expense) for the year attributable to non-controlling interests	£ 4,300	£ 2,882	£ 2,024
Non-controlling interests in the Consolidated balance sheet	(688)	3,557
Consumer health care joint venture [member]
Disclosure of noncontrolling interests [line items]
Total comprehensive income/(expense) for the year attributable to non-controlling interests	111	296	730
Dividends paid to non-controlling interests	183	420	£ 346
Non-controlling interests in the Consolidated balance sheet	£ 0	£ 3,631

Commitments - Schedule of Contr

Commitments - Schedule of Contractual Obligations and Commitments (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Contractual Obligations And Commitments [abstract]
Intangible assets	£ 4,762	£ 5,254
Property, plant and equipment	665	584
Investments	82	107
Purchase commitments	561	346
Pensions	238	738
Other commitments	0	38
Interest on loans	9,418	8,510
Finance lease charges	16	12
Total contractual obligations and commitments	£ 15,742	£ 15,589

Commitments - Additional Inform

Commitments - Additional Information (Detail) - GBP (£)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of Commitments [abstract]
Payment due, 2019	£ 75,000,000
Payment due, 2020	75,000,000
Payment due, 2021	44,000,000
Payment due, 2022	44,000,000
Ongoing annual funding requirement	140,000,000
Commitments under non-cancellable operating leases	£ 161,000,000	£ 117,000,000

Commitments - Summary of Commit

Commitments - Summary of Commitments Under Non-Cancellable Operating Leases (Detail) - GBP (£)	Dec. 31, 2018	Dec. 31, 2017
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	£ 1,138,000,000	£ 1,045,000,000
Not later than 1 year [member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	223,000,000	186,000,000
Between 1 and 2 years [member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	173,000,000	149,000,000
Between 2 and 3 years [member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	143,000,000	122,000,000
Between 3 and 4 Years [Member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	123,000,000	107,000,000
Between 4 and 5 years [member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	105,000,000	94,000,000
Later than 5 years [member]
Disclosure of operating lease by lessee [line items]
Total commitments under non-cancellable operating leases	£ 371,000,000	£ 387,000,000

Financial instruments and rel_3

Financial instruments and related disclosures - Additional Information (Detail) $ in Billions	12 Months Ended
	Dec. 31, 2018GBP (£)Customer	Dec. 31, 2017GBP (£)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016GBP (£)	Dec. 31, 2015GBP (£)
Disclosure of detailed information about financial instruments [line items]
Borrowings	£ 21,621,000,000	£ 13,178,000,000			£ 13,804,000,000	£ 10,727,000,000
Non-controlling interests	(688,000,000)	3,557,000,000
Total capital	25,300,000,000
Short-term finance through issuance of commercial paper	630,000,000	529,000,000
Maximum exposure to credit risk	11,080,000,000	9,988,000,000
Group trade receivables due from three largest US wholesalers	5,176,000,000	4,672,000,000
Cash and cash equivalents reported in assets held for sale	485,000,000
Carrying value of shares held by trust under employee share ownership plan	161,000,000	400,000,000
Market value of shares held by trust under employee share ownership plan	619,000,000	882,000,000
Treasury shares at cost	5,800,000,000	5,800,000,000
Net gains recognised in other comprehensive income	123,000,000	22,000,000
Net gains (losses) on financial investments held	98,000,000	(6,000,000)
Contingent consideration liabilities	6,286,000,000	6,172,000,000			£ 5,896,000,000	£ 3,855,000,000
Novartis [member]
Disclosure of detailed information about financial instruments [line items]
Contingent consideration liabilities	296,000,000	584,000,000
Increase in anticipated ontractual cashflows for repayment of debt and debt interest	9,900,000,000
Consumer health care joint venture [member]
Disclosure of detailed information about financial instruments [line items]
Non-controlling interests	£ 0	£ 3,631,000,000
PercentageOfDivestmentStake	36.50%	36.50%
Bonds In A Designated Hedging Relationship [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	£ 8,213,000,000	£ 4,315,000,000
Shionogi ViiV healthcare joint venture [member]
Disclosure of detailed information about financial instruments [line items]
Remeasurement through income statement	1,188,000,000	909,000,000
Novartis [member]
Disclosure of detailed information about financial instruments [line items]
Remeasurement through income statement	56,000,000	53,000,000
Level 3 [member]
Disclosure of detailed information about financial instruments [line items]
Net losses recognised in the income statement	1,233,000,000	970,000,000
Level 3 [member] | Equity investments [member]
Disclosure of detailed information about financial instruments [line items]
Net gains (losses) on equity investments held	117,000,000	(6,000,000)
Level 3 [member] | Shionogi ViiV healthcare joint venture [member]
Disclosure of detailed information about financial instruments [line items]
Contingent consideration liabilities	5,937,000,000	5,542,000,000
Level 3 [member] | Novartis [member]
Disclosure of detailed information about financial instruments [line items]
Contingent consideration liabilities	296,000,000	584,000,000
Liquidity risk [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents and liquid investments	4,500,000,000
Cash and cash equivalents and liquid investments held centrally	2,900,000,000
Short-term finance through issuance of commercial paper	£ 1,900,000,000
Description of contractual committed facilities	The five-year committed facility was agreed in September 2015 and was extended by one year to 2021 in September 2016. The 364-day committed facility was agreed in September 2018. These facilities were undrawn at 31 December 2018. GSK considers this level of committed facilities to be adequate, given current liquidity requirements.
Description of maturity date of borrowings	GSK's borrowings mature at dates between 2019 and 2045.
Amount held at European medium term note programme	£ 20,000,000,000
Notes issued at European medium term note programme	11,400,000,000
Notes issued under us shelf registration	10,200,000,000		$ 12.9
Liquidity risk [member] | Novartis [member]
Disclosure of detailed information about financial instruments [line items]
Drawn amount	£ 3,500,000,000
Description of maturity date of borrowings	December 2019
Borrowings maturity extension period	June 2020
Liquidity risk [member] | Not later than 1 year [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings	£ 5,800,000,000
Liquidity risk [member] | Not later than 1 year [member] | Tesaro [member]
Disclosure of detailed information about financial instruments [line items]
Committed facilities during the period | $			5
Liquidity risk [member] | Later than one year and not later than five years [member]
Disclosure of detailed information about financial instruments [line items]
Committed facilities during the period	2,000,000,000		2.5
Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Amount of cash held at unrated counter parties	20,000,000
Cash in transit	1,000,000
Bank balances and deposits held with counter parties	2,338,000,000	1,715,000,000
Cash held by subsidiary	£ 1,700,000,000
Credit risk [member] | Non USA [member]
Disclosure of detailed information about financial instruments [line items]
Number of major customers accounting for more than 5% of trade receivables | Customer	0
Credit risk [member] | Nigeria [member]
Disclosure of detailed information about financial instruments [line items]
Concentration of credit risk	£ 6,000,000
Credit risk [member] | Austria [member]
Disclosure of detailed information about financial instruments [line items]
Concentration of credit risk	3,000,000
Credit risk [member] | Argentina [member]
Disclosure of detailed information about financial instruments [line items]
Concentration of credit risk	2,000,000
Credit risk [member] | Uruquay [member]
Disclosure of detailed information about financial instruments [line items]
Concentration of credit risk	2,000,000
Credit risk [member] | Not later than three months [member]
Disclosure of detailed information about financial instruments [line items]
Cash reserves	2,900,000,000
1% (100 basis points) increase in sterling interest rates [member]
Disclosure of detailed information about financial instruments [line items]
Impact on income through interest rate movements	(2,000,000)	24,000,000
External credit grades [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Concentration of credit risk	700,000,000	500,000,000
BBB/Baa [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Bank balances and deposits held with counter parties	381,000,000	80,000,000
BBB -/ Baa3 Rated [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Bank balances and deposits held with counter parties	£ 22,000,000
Floating interest rate [member]
Disclosure of detailed information about financial instruments [line items]
Percentage of increase in interest rate	1.00%
Floating interest rate [member] | 1% (100 basis points) increase in sterling interest rates [member]
Disclosure of detailed information about financial instruments [line items]
Impact on income through interest rate movements	£ 13,000,000	5,000,000
Top of range [member] | Credit risk [member] | Non USA [member]
Disclosure of detailed information about financial instruments [line items]
Maximum percentage of trade receivables balance held by major customer account	5.00%
HDFC bank [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Balances or deposits with banks	£ 20,000,000
State Bank of India [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Balances or deposits with banks	1,000,000
Global insurance programme [member]
Disclosure of detailed information about financial instruments [line items]
Group trade receivables due from three largest US wholesalers	240,000,000
US commercial paper program [member] | Liquidity risk [member]
Disclosure of detailed information about financial instruments [line items]
Drawn amount	£ 600,000,000		$ 0.8	$ 0.7
Pharmaceuticals and Vaccines [member] | Credit risk [member] | US [member]
Disclosure of detailed information about financial instruments [line items]
Percentage of sales to three largest wholesalers	82.00%
Group trade receivables due from three largest US wholesalers	£ 2,134,000,000	£ 1,265,000,000
ViiV healthcare [member] | Credit risk [member]
Disclosure of detailed information about financial instruments [line items]
Percentage of ownership interest in subsidiary	78.30%

Financial Instruments and Rel_4

Financial Instruments and Related Disclosures - Summary of External Credit Exposure (Detail) - Credit risk [member] - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of external credit grades [line items]
Bank balances and deposits	£ 2,338	£ 1,715
US Treasury and Treasury repo only money market funds	449	1,715
Liquidity funds	1,572	403
Government securities	84	78
3rd party financial derivatives	150	68
Total	4,593	3,979
AAA/Aaa [member]
Disclosure of external credit grades [line items]
Bank balances and deposits	0
US Treasury and Treasury repo only money market funds	449	1,715
Liquidity funds	1,572	403
Government securities	0
3rd party financial derivatives	0
Total	2,021	2,118
AA/Aa [member]
Disclosure of external credit grades [line items]
Bank balances and deposits	662	423
US Treasury and Treasury repo only money market funds	0
Liquidity funds	0
Government securities	83	77
3rd party financial derivatives	19	26
Total	764	526
A/A [member]
Disclosure of external credit grades [line items]
Bank balances and deposits	1,275	1,167
US Treasury and Treasury repo only money market funds	0
Liquidity funds	0
Government securities	0
3rd party financial derivatives	127	42
Total	1,402	1,209
BBB/Baa [member]
Disclosure of external credit grades [line items]
Bank balances and deposits	381	80
US Treasury and Treasury repo only money market funds	0
Liquidity funds	0
Government securities	1	1
3rd party financial derivatives	4
Total	386	81
BB+/Ba1 and Below/Unrated [member]
Disclosure of external credit grades [line items]
Bank balances and deposits	20	45
US Treasury and Treasury repo only money market funds	0
Liquidity funds	0
Government securities	0
3rd party financial derivatives	0
Total	£ 20	£ 45

Financial Instruments and Rel_5

Financial Instruments and Related Disclosures - Summary of Financial Assets and Liabilities (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
Total financial assets	£ 12,402	£ 10,906
Cash and cash equivalents	3,874	3,833	£ 4,897
Total borrowings	(21,621)	(13,178)	(13,804)	£ (10,727)
Total financial liabilities	(46,190)	(46,599)
Net financial assets and financial liabilities	(33,788)	(35,693)
Total financial assets fair value	12,402	10,906
Cash and cash equivalents	3,874	3,833	£ 4,897
Total financial liabilities fair value	(48,424)	(43,660)
Net financial assets and financial liabilities	(36,022)	(32,754)
Financial assets at amortised cost, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets fair value	49
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets fair value	716
Loans and Receivables, Category [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents		3,833
Total financial assets fair value		5,495
Cash and cash equivalents		3,833
Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(28,230)	(17,023)
Obligations under finance leases	(68)	(66)
Total borrowings	(28,298)	(17,089)
Trade and other payables, Other provisions and certain Other non-current liabilities in scope of IAS 39		(20,325)
Borrowings excluding obligations under finance leases:	(25,996)	(19,962)
Obligations under finance leases	(68)	(66)
Total borrowings	(26,064)	(20,028)
Trade and other payables, Other provisions and certain Other non-current liabilities in scope of IAS 39		(20,325)
Other investments [member] | Financial assets at fair value through other comprehensive income, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	1,250
Total financial assets fair value	1,250
Other investments [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	72
Total financial assets fair value	72
Other investments [member] | Financial Assets Available-for-sale, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets		918
Total financial assets fair value		918
Trade and other receivable [member] | Financial assets at fair value through other comprehensive income, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	1,687
Total financial assets fair value	1,687
Trade and other receivable [member] | Financial assets at amortised cost, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	3,761
Total financial assets fair value	3,761
Trade and other receivable [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	120
Total financial assets fair value	120
Liquid Investments [member] | Financial assets at amortised cost, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	84
Total financial assets fair value	84
Cash and cash equivalents [member] | Financial assets at amortised cost, category [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	2,338
Cash and cash equivalents	2,338
Cash and cash equivalents [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	2,021
Cash and cash equivalents	2,021
Other items in Assets held for sale [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	47
Total financial assets fair value	47
Derivatives designated and effective as hedging instruments [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	69
Total financial assets fair value	69
Derivatives designated and effective as hedging instruments [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Financial liabilities at fair value through profit or loss, mandatorily measured at fair value, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(105)
Total financial liabilities fair value	(105)
Held for trading derivatives that are not in a designated and effective hedging relationship [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	188
Total financial assets fair value	188
Held for trading derivatives that are not in a designated and effective hedging relationship [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Financial liabilities at fair value through profit or loss, mandatorily measured at fair value, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(23)
Total financial liabilities fair value	(23)
Other Noncurrent Assets [member] | Financial assets at amortised cost, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	49
Other Noncurrent Assets [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	716
Government bonds [member] | Financial Assets Available-for-sale, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets		78
Total financial assets fair value		78
Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	8,083	7,413
Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member] | Financial assets at fair value through other comprehensive income, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	1,687
Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member] | Loans and Receivables, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets		5,495
Total financial assets fair value		3,833
Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member] | Financial Assets at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets	836	506
Total financial assets fair value		506
Derivatives Financial Assets Designated At Fair Value Through Profit Or Loss [member] | Financial Assets at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets		5
Total financial assets fair value		5
Derivatives Financial Assets Classified As Held For Trading Under IAS39 [member] | Financial Assets at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial assets		71
Total financial assets fair value		71
Financial Liabilities at Amortised Cost, Category [member] | Trade and other payable [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities fair value	(13,338)
Financial Liabilities at Amortised Cost, Category [member] | Other provisions [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities fair value	(58)
Financial Liabilities at Amortised Cost, Category [member] | Other non current liabilities [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities fair value	(149)
Financial Liabilities at Amortised Cost, Category [member] | Other assets classified as held for sale [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities fair value	(167)
Contingent Consideration Liabilities [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities		(6,172)
Total financial liabilities fair value		(6,172)
Contingent Consideration Liabilities [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Financial liabilities at fair value through profit or loss, mandatorily measured at fair value, category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(6,286)
Total financial liabilities fair value	(6,286)
Trade and other payable [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(13,338)
Other provisions [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(58)
Other non current liabilities [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(149)
Other assets classified as held for sale [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities	(167)
Derivatives Financial Liabilities Designated At Fair Value Through Profit Or Loss [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities		(26)
Total financial liabilities fair value		(26)
Derivatives financial liabilities classified as held for trading under IAS39 [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member]
Disclosure of detailed information about financial instruments [line items]
Total financial liabilities		(48)
Total financial liabilities fair value		(48)
Bonds In A Designated Hedging Relationship [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases:	(8,213)	(4,315)
Bonds In A Designated Hedging Relationship [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(8,279)	(4,315)
Borrowings excluding obligations under finance leases:	(8,213)	(4,405)
Other Bonds [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(15,475)	(11,894)
Borrowings excluding obligations under finance leases:	(13,307)	(14,743)
Bank Loans and Overdrafts [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(290)	(236)
Borrowings excluding obligations under finance leases:	(290)	(236)
Commercial paper [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(630)	(529)
Borrowings excluding obligations under finance leases:	(630)	(529)
Other Borrowing [member] | Financial Liabilities at Amortised Cost, Category [member]
Disclosure of detailed information about financial instruments [line items]
Borrowings excluding obligations under finance leases	(3,556)	(49)
Borrowings excluding obligations under finance leases:	£ (3,556)	£ (49)

Financial Instruments and Rel_6

Financial Instruments and Related Disclosures - Summary of Fair Value of Financial Instruments (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	£ 12,402	£ 10,906
Financial liabilities at fair value	(48,424)	(43,660)
Financial assets at fair value through other comprehensive income, category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	1,250
Financial assets at fair value through other comprehensive income, category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	1,687
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	716
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	72
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	120
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	69
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	188
Financial Assets Available-for-sale, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		918
Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Contingent Consideration Liabilities [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value		(6,172)
At Fair Value [Member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	6,123	1,578
Financial liabilities at fair value	(6,414)	(6,246)
At Fair Value [Member] | Financial assets at fair value through other comprehensive income, category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	1,250
At Fair Value [Member] | Financial assets at fair value through other comprehensive income, category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	1,687
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	72
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	120
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	716
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	69
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	188
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash and cash equivalents [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	2,021
At Fair Value [Member] | Financial Assets Available-for-sale, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		918
At Fair Value [Member] | Financial Assets Available-for-sale, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		38
At Fair Value [Member] | Financial Assets Available-for-sale, Category [member] | Liquid Investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		78
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		42
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		426
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives Financial Assets Designated At Fair Value Through Profit Or Loss [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		5
At Fair Value [Member] | Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Derivatives assets held for trading [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		71
At Fair Value [Member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Contingent Consideration Liabilities [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(6,286)	(6,172)
At Fair Value [Member] | Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(105)	(26)
At Fair Value [Member] | Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(23)	(48)
At Fair Value [Member] | Level 1 of fair value hierarchy [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	2,677	612
Financial liabilities at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial assets at fair value through other comprehensive income, category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	656
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial assets at fair value through other comprehensive income, category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash and cash equivalents [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	2,021
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets Available-for-sale, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		535
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Assets Available-for-sale, Category [member] | Liquid Investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		77
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Contingent Consideration Liabilities [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	0
At Fair Value [Member] | Level 1 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	0
At Fair Value [Member] | Level 2 of fair value hierarchy [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	2,692	450
Financial liabilities at fair value	(128)	(73)
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial assets at fair value through other comprehensive income, category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial assets at fair value through other comprehensive income, category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	1,687
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	79
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	675
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	69
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	182
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash and cash equivalents [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets Available-for-sale, Category [member] | Liquid Investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		1
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		382
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives Financial Assets Designated At Fair Value Through Profit Or Loss [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		5
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Derivatives assets held for trading [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		62
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Contingent Consideration Liabilities [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	0
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(105)	(26)
At Fair Value [Member] | Level 2 of fair value hierarchy [member] | Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(23)	(47)
At Fair Value [Member] | Level 3 [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	754	516
Financial liabilities at fair value	(6,286)	(6,173)
At Fair Value [Member] | Level 3 [member] | Financial assets at fair value through other comprehensive income, category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	594
At Fair Value [Member] | Level 3 [member] | Financial assets at fair value through other comprehensive income, category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	72
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	41
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	41
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	6
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash and cash equivalents [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value	0
At Fair Value [Member] | Level 3 [member] | Financial Assets Available-for-sale, Category [member] | Other investments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		383
At Fair Value [Member] | Level 3 [member] | Financial Assets Available-for-sale, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		38
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Trade and other receivable [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		42
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Other Noncurrent Assets [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		44
At Fair Value [Member] | Level 3 [member] | Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Derivatives assets held for trading [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial assets at fair value		9
At Fair Value [Member] | Level 3 [member] | Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Contingent Consideration Liabilities [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	(6,286)	(6,172)
At Fair Value [Member] | Level 3 [member] | Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Derivatives designated and effective as hedging instruments [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	0
At Fair Value [Member] | Level 3 [member] | Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Held for trading derivatives that are not in a designated and effective hedging relationship [member]
Disclosure Of Financial Assets And Liabilities [line items]
Financial liabilities at fair value	£ 0	£ (1)

Financial Instruments and Rel_7

Financial Instruments and Related Disclosures - Summary of Movement in Financial Instruments Measured Using Level 3 Valuation Method (Detail) - Level 3 [member] - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of fair value measurements of assets and liabilities [line items]
Beginning balance	£ (5,657)	£ (5,486)
Net losses recognised in the income statement	(1,233)	(970)
Net gains recognised in other comprehensive income	123	22
Contingent consideration for businesses divested/acquired during the year	0	80
Payment of contingent consideration liabilities	1,095	685
Additions	381	117
Disposals and settlements	(27)	(52)
Transfers from Level 3	(241)	(24)
Exchange adjustments	27	(29)
Ending balance	£ (5,532)	£ (5,657)

Financial instruments and rel_8

Financial instruments and related disclosures - Summary of Financial Assets and Non Financial Assets (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	£ 6,423	£ 6,000
Other non-current assets (Note 22)	1,576	1,413
Financial assets	12,402	10,906
Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	6,423	6,000
Other non-current assets (Note 22)	1,576	1,413
Other items in Assets held for sale (Note 26)	84
Financial assets	8,083	7,413
Financial Assets at Fair Value Through Profit or Loss, Category [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	120	42
Other non-current assets (Note 22)	716	464
Other items in Assets held for sale (Note 26)	0
Financial assets	836	506
Financial assets at fair value through other comprehensive income, category [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	1,687
Other non-current assets (Note 22)	0
Other items in Assets held for sale (Note 26)	0
Financial assets	1,687
Amortised cost [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	3,761
Other non-current assets (Note 22)	49
Other items in Assets held for sale (Note 26)	47
Financial assets	3,857
Financial Instruments [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	5,568	5,190
Other non-current assets (Note 22)	765	811
Other items in Assets held for sale (Note 26)	47
Financial assets	6,380	6,001
Non Financial Instruments [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)	855	810
Other non-current assets (Note 22)	811	602
Other items in Assets held for sale (Note 26)	37
Financial assets	£ 1,703	1,412
Loans and Receivables, Category [member] | Trade and Other Receivables and Certain Other Non-current Assets in Scope of IAS 39 [member]
Disclosure of financial assets and non financial assets [line items]
Trade and other receivables (Note 24)		5,148
Other non-current assets (Note 22)		347
Financial assets		£ 5,495

Financial instruments and rel_9

Financial instruments and related disclosures - Schedule Of Ageing Financial Assets (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets	£ 12,402	£ 10,906
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		411
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member] | 1 - 30 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		142
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member] | 31 - 90 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		70
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member] | 91 - 180 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		64
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member] | 181 - 365 days [member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		27
Financial Assets Past Due and No Provision for Bad and Doubtful Debt [member] | Later Than One Year [Member]
Disclosure of financial assets that are either past due or impaired [line items]
Financial assets		£ 108

Financial instruments and re_10

Financial instruments and related disclosures - Reconciliation of financial instruments within Trade and other payables, Other provisions, Other non-current liabilities and Contingent consideration liabilities (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of financial liabilities [line items]
Other provisions (Note 29)	£ (1,423)	£ (1,265)
Other non-currentliabilities (Note 30)	(938)	(981)
Financial liabilities	(46,190)	(46,599)
Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)	(14,037)	(20,970)
Other provisions (Note 29)	(1,423)	(1,265)
Other non-currentliabilities (Note 30)	(938)	(981)
Contingent consideration liabilities (Note 39)	(6,286)	(6,172)
Other items in Assets held for sale (Note 26)	(220)
Financial liabilities	(22,904)	(29,388)
Financial Liabilities at Fair Value Through Profit or Loss, Category [member] | Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)	0
Other provisions (Note 29)	0
Other non-currentliabilities (Note 30)	0
Contingent consideration liabilities (Note 39)	(6,286)	(6,172)
Other items in Assets held for sale (Note 26)	0
Financial liabilities	(6,286)	(6,172)
Other Liabilities [member] | Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)		(20,129)
Other provisions (Note 29)		(117)
Other non-currentliabilities (Note 30)		(79)
Financial liabilities		(20,325)
Financial Instruments [member] | Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)	(13,338)	(20,129)
Other provisions (Note 29)	(58)	(117)
Other non-currentliabilities (Note 30)	(149)	(79)
Contingent consideration liabilities (Note 39)	(6,286)	(6,172)
Other items in Assets held for sale (Note 26)	(167)
Financial liabilities	(19,998)	(26,497)
Non Financial Instruments [member] | Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)	(699)	(841)
Other provisions (Note 29)	(1,365)	(1,148)
Other non-currentliabilities (Note 30)	(789)	(902)
Contingent consideration liabilities (Note 39)	0
Other items in Assets held for sale (Note 26)	(53)
Financial liabilities	(2,906)	£ (2,891)
Amortised cost [member] | Trade and Other Payables, Other Provisions and Certain Other Non-Current Liabilities in Scope of IFRS9 (2017 - IAS39) [member]
Disclosure of financial liabilities [line items]
Trade and other payables (Note 27)	(13,338)
Other provisions (Note 29)	(58)
Other non-currentliabilities (Note 30)	(149)
Contingent consideration liabilities (Note 39)	0
Other items in Assets held for sale (Note 26)	(167)
Financial liabilities	£ (13,712)

Financial instruments and re_11

Financial instruments and related disclosures - Fair Values of Derivatives Held (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	£ 257	£ 76
Total derivative instruments	(128)	(74)
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	69	5
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash Flow Hedges [member] | Interest rate swap contract [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, Non current	0
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cash Flow Hedges [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	1
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Net Investment Hedges [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	4	5
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Net Investment Hedges [member] | Cross currency swap [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, Non current	64
Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	188	71
Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, current	82	62
Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Embedded and Other Derivatives [member]
Disclosure of detailed information about hedging instruments [line items]
Financial assets, Non current	4	8
Financial assets, current	102	1
Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member]
Disclosure of detailed information about hedging instruments [line items]
Financial Liabilities, current	(105)	(26)
Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Cash Flow Hedges [member] | Interest rate swap contract [member]
Disclosure of detailed information about hedging instruments [line items]
Financial liabilities non current	(1)
Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Cash Flow Hedges [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial Liabilities, current	(56)	(1)
Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Net Investment Hedges [member] | Interest rate swap contract [member]
Disclosure of detailed information about hedging instruments [line items]
Financial liabilities non current	0
Financial Liabilities at Fair Value Through Profit or Loss, Designated Upon Initial Recognition or Subsequently, Category [member] | Net Investment Hedges [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial Liabilities, current	(48)	(25)
Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member]
Disclosure of detailed information about hedging instruments [line items]
Financial Liabilities, current	(23)	(48)
Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Financial Liabilities, current	(23)	(47)
Financial Liabilities at Fair Value Through Profit or Loss That Meet Definition of Held for Trading, Category [member] | Embedded and Other Derivatives [member]
Disclosure of detailed information about hedging instruments [line items]
Financial liabilities non current	0
Financial Liabilities, current	£ 0	£ (1)

Financial instruments and re_12

Financial instruments and related disclosures - Fair Values of Derivatives Held (Parenthetical) (Detail)	Dec. 31, 2018	Dec. 31, 2017
Foreign Exchange Contracts [member] | Cash Flow Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	1,809,000,000
Foreign Exchange Contracts [member] | Net Investment Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	7,316,000,000
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Interest rate swap contract [member] | Cash Flow Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	1,266,000,000	0
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Foreign Exchange Contracts [member] | Cash Flow Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	1,809,000,000	38,000,000
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Foreign Exchange Contracts [member] | Net Investment Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	7,316,000,000	6,333,000,000
Financial Assets at Fair Value Through Profit or Loss, Mandatory Measured at Fair Value, Category [member] | Cross currency swap [member] | Net Investment Hedges [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	1,575,000,000	0
Financial Assets at Fair Value Through Profit or Loss, Classified as Held for Trading, Category [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedging instruments [line items]
Principal amount	18,537,000,000	14,449,000,000

Financial Instruments and Re_13

Financial Instruments and Related Disclosures - Summary of Detailed Information of Foreign Exchange Forward Contracts, Swaps Outstanding and Related Hedged Items (Detail) - Foreign Exchange Contracts [member] £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Cash Flow Hedges [member]
Disclosure of detailed information about hedged items [line items]
Notional value	1,809,000,000
Fair value	£ (55)
Cash Flow Hedges [member] | Buy Foreign Currency Less than 3 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	0
Foreign currency	0
Notional value	0
Fair value	£ 0
Cash Flow Hedges [member] | Buy Foreign Currency 3 to 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	1.13
Foreign currency	Euro
Notional value	26,000,000
Fair value	£ 1
Cash Flow Hedges [member] | Buy Foreign Currency over 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	0
Foreign currency	0
Notional value	0
Fair value	£ 0
Cash Flow Hedges [member] | Sell Foreign Currency Less than 3 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	0
Foreign currency	0
Notional value	0
Fair value	£ 0
Cash Flow Hedges [member] | Sell Foreign Currency 3 to 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	0
Foreign currency	0
Notional value	0
Fair value	£ 0
Cash Flow Hedges [member] | Sell Foreign Currency over 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	96.40
Foreign currency	Indian Rupee
Notional value	1,783,000,000
Fair value	£ (56)
Cash Flow Hedges [member] | Variability in cash flows from a highly probable forecast transaction [member]
Disclosure of detailed information about hedged items [line items]
Change in value for calculating hedge ineffectiveness	56
Balance in cash flow hedge reserve/foreign currency translation reserve for continuing hedges	(49)
Cash Flow Hedges [member] | Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued [member]
Disclosure of detailed information about hedged items [line items]
Change in value for calculating hedge ineffectiveness	(1)
Balance in cash flow hedge reserve/foreign currency translation reserve for continuing hedges	£ 1
Net Investment Hedges [member]
Disclosure of detailed information about hedged items [line items]
Notional value	7,316,000,000
Fair value	£ (44)
Net Investment Hedges [member] | Sell Foreign Currency Less than 3 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	1.11
Foreign currency	Euro
Notional value	6,933,000,000
Fair value	£ (40)
Net Investment Hedges [member] | Sell Foreign Currency 3 to 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	0
Foreign currency	0
Notional value	0
Fair value	£ 0
Net Investment Hedges [member] | Sell Foreign Currency over 6 months [member]
Disclosure of detailed information about hedged items [line items]
Average exchange rate	1.11
Foreign currency	Euro
Notional value	383,000,000
Fair value	£ (4)
Hedges of net investment in foreign operations [member]
Disclosure of detailed information about hedged items [line items]
Change in value for calculating hedge ineffectiveness	50
Balance in cash flow hedge reserve/foreign currency translation reserve for continuing hedges	£ 286

Financial Instruments and Re_14

Financial Instruments and Related Disclosures - Summary of Effectiveness of Hedging Relationships and Amounts Reclassified from Hedging Reserve to Profit or Loss (Detail) £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Variability in cash flows [member]
Disclosure of detailed information about hedged items [line items]
Hedging gains/(losses) recognised in reserves	£ (3)
Amount of hedge ineffectiveness recognised in profit or loss	£ 0
Line item in profit or loss in which hedge ineffectiveness is included	Finance income/ (expense)
Amount reclassified to profit or loss as hedged future cash flows no longer expected to occur	£ 0
Amount reclassified to profit or loss as hedged item affects profit or loss	£ (2)
Amount reclassified to profit or loss line item in which reclassification adjustment is included	Finance income/ (expense)
Pre-hedging of long-term interest rates [member]
Disclosure of detailed information about hedged items [line items]
Hedging gains/(losses) recognised in reserves	£ 15
Amount of hedge ineffectiveness recognised in profit or loss	£ 0
Line item in profit or loss in which hedge ineffectiveness is included	Finance income/ (expense)
Amount reclassified to profit or loss as hedged future cash flows no longer expected to occur	£ 0
Amount reclassified to profit or loss as hedged item affects profit or loss	£ 3
Amount reclassified to profit or loss line item in which reclassification adjustment is included	Finance income/ (expense)
Cash Flow Hedges [member] | Foreign Exchange Contracts [member] | Variability in cash flows from a highly probable forecast transaction [member]
Disclosure of detailed information about hedged items [line items]
Hedging gains/(losses) recognised in reserves	£ 127
Amount of hedge ineffectiveness recognised in profit or loss	£ 0
Line item in profit or loss in which hedge ineffectiveness is included	Other operating income/ (expense)
Amount reclassified to profit or loss as hedged future cash flows no longer expected to occur	£ 0
Amount reclassified to profit or loss as hedged item affects profit or loss	£ (176)
Amount reclassified to profit or loss line item in which reclassification adjustment is included	Other operating income/ (expense)
Cash Flow Hedges [member] | Foreign Exchange Contracts [member] | Variability in cash flows from foreign exchange exposure arising on Euro denominated coupon payments relating to debt issued [member]
Disclosure of detailed information about hedged items [line items]
Hedging gains/(losses) recognised in reserves	£ 1
Amount of hedge ineffectiveness recognised in profit or loss	£ 0
Line item in profit or loss in which hedge ineffectiveness is included	Finance income/ (expense )
Amount reclassified to profit or loss as hedged future cash flows no longer expected to occur	£ 0
Amount reclassified to profit or loss as hedged item affects profit or loss	£ 0
Amount reclassified to profit or loss line item in which reclassification adjustment is included	Finance income/ (expense)
Hedges of net investment in foreign operations [member] | Foreign Exchange Contracts [member]
Disclosure of detailed information about hedged items [line items]
Hedging gains/(losses) recognised in reserves	£ 286
Amount of hedge ineffectiveness recognised in profit or loss	£ 7
Line item in profit or loss in which hedge ineffectiveness is included	Finance income/ (expense)
Amount reclassified to profit or loss as hedged future cash flows no longer expected to occur	£ 0
Amount reclassified to profit or loss as hedged item affects profit or loss	£ 0
Amount reclassified to profit or loss line item in which reclassification adjustment is included	Finance income/ (expense)

Financial Instruments and Re_15

Financial Instruments and Related Disclosures - Summary of Detailed Information of Interest Rate Swap Contracts Outstanding and Related Hedged Items (Detail) - Interest rate swap contract [member] £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)
Variable rate borrowings [member]
Disclosure of detailed information about hedged items [line items]
Change in value used for calculating hedge ineffectiveness	£ 3
Balance in cash flow hedge reserve for continuing hedges	£ (3)
Not later than 1 year [member]
Disclosure of detailed information about hedged items [line items]
Average contracted fixed rate %	0.00%
Notional principal value £m	0
Change in fair value for recognising hedge ineffectiveness £m	£ 0
Fair value assets/ (liabilities) £m	£ 0
Between 1 and 2 years [member]
Disclosure of detailed information about hedged items [line items]
Average contracted fixed rate %	0.11%
Notional principal value £m	676,000,000
Change in fair value for recognising hedge ineffectiveness £m	£ 0
Fair value assets/ (liabilities) £m	£ (1)
Later than 2 years and not later than 5 years [member]
Disclosure of detailed information about hedged items [line items]
Average contracted fixed rate %	0.16%
Notional principal value £m	591,000,000
Change in fair value for recognising hedge ineffectiveness £m	£ 0
Fair value assets/ (liabilities) £m	£ 23
Later than 5 years [member]
Disclosure of detailed information about hedged items [line items]
Average contracted fixed rate %	0.00%
Notional principal value £m	0
Change in fair value for recognising hedge ineffectiveness £m	£ 0
Fair value assets/ (liabilities) £m	£ 0

Financial instruments and re_16

Financial instruments and related disclosures - Schedule of Offsetting of Financial Assets and Liabilities (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Trade and other receivable [member]
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross financial assets/(liabilities)	£ 5,568	£ 5,191
Gross financial (Liabilities)/assets set off	0	(1)
Net financial assets/(liabilities)per balance sheet	5,568	5,190
Related amounts not set off in the balance sheet	(37)	(31)
Net amount	5,531	5,159
Derivative financial assets [member]
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross financial assets/(liabilities)	257	76
Gross financial (Liabilities)/assets set off	0
Net financial assets/(liabilities)per balance sheet	257	76
Related amounts not set off in the balance sheet	(62)	(64)
Net amount	195	12
Trades and other payables [member]
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross financial assets/(liabilities)	(13,338)	(20,130)
Gross financial (Liabilities)/assets set off	0	1
Net financial assets/(liabilities)per balance sheet	(13,338)	(20,129)
Related amounts not set off in the balance sheet	37	31
Net amount	(13,301)	(20,098)
Derivative financial liabilities [member]
Disclosure of offsetting of financial assets and financial liabilities [line items]
Gross financial assets/(liabilities)	(128)	(74)
Gross financial (Liabilities)/assets set off	0
Net financial assets/(liabilities)per balance sheet	(128)	(74)
Related amounts not set off in the balance sheet	62	64
Net amount	£ (66)	£ (10)

Financial instruments and re_17

Financial instruments and related disclosures - Schedule of Debt Interest Rate Repricing (Detail) - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Disclosure of debt interest rate repricing [line items]
Total debt	£ (25,996)	£ (17,023)
Total interest bearing	(25,957)	(16,974)
Non-interest bearing	(39)	(49)
Floating and Fixed Rate Debt [member] | Later Than One Year [Member]
Disclosure of debt interest rate repricing [line items]
Total debt	(5,769)	(2,802)
Floating and Fixed Rate Debt [member] | Between 1 and 2 years [member]
Disclosure of debt interest rate repricing [line items]
Total debt	(1,757)	(1,340)
Floating and Fixed Rate Debt [member] | Between 2 and 3 years [member]
Disclosure of debt interest rate repricing [line items]
Total debt	(1,570)	(1,076)
Floating and Fixed Rate Debt [member] | Between 3 and 4 Years [Member]
Disclosure of debt interest rate repricing [line items]
Total debt	(1,568)	(16)
Floating and Fixed Rate Debt [member] | Between 4 and 5 years [member]
Disclosure of debt interest rate repricing [line items]
Total debt	(2,010)	(1,475)
Floating and Fixed Rate Debt [member] | Between Five and Ten Years [Member]
Disclosure of debt interest rate repricing [line items]
Total debt	(5,833)	(3,664)
Floating and Fixed Rate Debt [member] | Greater Than Ten Years [Member]
Disclosure of debt interest rate repricing [line items]
Total debt	(7,489)	(6,650)
Fixed interest rate [member]
Disclosure of debt interest rate repricing [line items]
Total interest bearing	(20,322)	(16,209)
Floating interest rate [member]
Disclosure of debt interest rate repricing [line items]
Total interest bearing	£ (5,635)	£ (765)

Financial instruments and re_18

Financial instruments and related disclosures - Impact of Non-functional Currency Foreign Exchange Exposures (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
10 cent appreciation of the US Dollar [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	£ 36	£ 76
(Increase)/decrease in net debt	(714)	(637)
10 cent appreciation of the Euro [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	(7)	(5)
(Increase)/decrease in net debt	(60)	197
10 Yen appreciation of the Yen [Member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	15	9
(Increase)/decrease in net debt	15	(4)
10 cent depreciation of US Dollar [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	(30)	(66)
(Increase)/decrease in net debt	610	549
10 cent depreciation of Euro [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	6	4
(Increase)/decrease in net debt	50	(165)
Yen Exchange Rates [Member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	(13)	(8)
10 cent depreciation of Yen [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
(Increase)/decrease in net debt	£ (13)	£ 4

Financial instruments and re_19

Financial instruments and related disclosures - Impact of Interest Rate Currency Movements (Detail) - GBP (£) £ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
1% (100 basis points) increase in sterling interest rates [member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	£ (2)	£ 24
1% (100 Basis Points) Increase in US Dollar Interest Rates [Member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	1	(24)
1% (100 Basis Points) Increase in Euro Interest Rates [Member]
Disclosure of nature and extent of risks arising from financial instruments [line items]
Increase/(decrease) in income	£ (12)	£ 5

Financial instruments and re_20

Financial instruments and related disclosures - Summary of Maturity Analysis for Non-derivative Financial Liabilities (Detail) - GBP (£)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Obligations under finance leases	£ (68)	£ (66)
Finance charge on obligations under finance leases	(16)	(12)
Non Derivatives Financial Liabilities [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(26,154,000,000)	(17,137,000,000)
Interest on debt	(9,418,000,000)	(8,510,000,000)
Obligations under finance leases	(68,000,000)	(66,000,000)
Finance charge on obligations under finance leases	(16,000,000)	(12,000,000)
Trade payables and other liabilities not in net debt	(23,180,000,000)	(29,803,000,000)
Total	(58,836,000,000)	(55,528,000,000)
Non Derivatives Financial Liabilities [member] | Not later than 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(5,771,000,000)	(2,802,000,000)
Interest on debt	(714,000,000)	(555,000,000)
Obligations under finance leases	(24,000,000)	(23,000,000)
Finance charge on obligations under finance leases	(5,000,000)	(2,000,000)
Trade payables and other liabilities not in net debt	(14,278,000,000)	(21,521,000,000)
Total	(20,792,000,000)	(24,903,000,000)
Non Derivatives Financial Liabilities [member] | Between 1 and 2 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(1,775,000,000)	(1,344,000,000)
Interest on debt	(708,000,000)	(497,000,000)
Obligations under finance leases	(18,000,000)	(27,000,000)
Finance charge on obligations under finance leases	(2,000,000)	(2,000,000)
Trade payables and other liabilities not in net debt	(1,107,000,000)	(853,000,000)
Total	(3,610,000,000)	(2,723,000,000)
Non Derivatives Financial Liabilities [member] | Between 2 and 3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(1,592,000,000)	(1,078,000,000)
Interest on debt	(675,000,000)	(488,000,000)
Obligations under finance leases	(11,000,000)	(8,000,000)
Finance charge on obligations under finance leases	(2,000,000)	(1,000,000)
Trade payables and other liabilities not in net debt	(902,000,000)	(813,000,000)
Total	(3,182,000,000)	(2,388,000,000)
Non Derivatives Financial Liabilities [member] | Between 3 and 4 Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(1,592,000,000)	(16,000,000)
Interest on debt	(620,000,000)	(488,000,000)
Obligations under finance leases	(6,000,000)	(2,000,000)
Finance charge on obligations under finance leases	(1,000,000)	(1,000,000)
Trade payables and other liabilities not in net debt	(851,000,000)	(784,000,000)
Total	(3,070,000,000)	(1,291,000,000)
Non Derivatives Financial Liabilities [member] | Between 4 and 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(1,970,000,000)	(1,483,000,000)
Interest on debt	(567,000,000)	(468,000,000)
Obligations under finance leases	(3,000,000)	(1,000,000)
Finance charge on obligations under finance leases	(1,000,000)	(1,000,000)
Trade payables and other liabilities not in net debt	(826,000,000)	(752,000,000)
Total	(3,367,000,000)	(2,705,000,000)
Non Derivatives Financial Liabilities [member] | Between Five and Ten Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(5,875,000,000)	(3,694,000,000)
Interest on debt	(2,370,000,000)	(2,018,000,000)
Obligations under finance leases	(6,000,000)	(5,000,000)
Finance charge on obligations under finance leases	(5,000,000)	(5,000,000)
Trade payables and other liabilities not in net debt	(3,748,000,000)	(3,609,000,000)
Total	(12,004,000,000)	(9,331,000,000)
Non Derivatives Financial Liabilities [member] | Greater Than Ten Years [Member]
Disclosure of maturity analysis for non-derivative financial liabilities [line items]
Debt	(7,579,000,000)	(6,720,000,000)
Interest on debt	(3,764,000,000)	(3,996,000,000)
Obligations under finance leases	0
Finance charge on obligations under finance leases	0
Trade payables and other liabilities not in net debt	(1,468,000,000)	(1,471,000,000)
Total	£ (12,811,000,000)	£ (12,187,000,000)

Financial instruments and re_21

Financial instruments and related disclosures - Summary Anticipated Contractual Cash Flows for Derivative Instruments, Excluding Embedded Derivatives and Equity Options, Using Undiscounted Cash Flows (Detail) - Derivative Instruments [Member] - GBP (£) £ in Millions	Dec. 31, 2018	Dec. 31, 2017
Interest rate swap contract [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	£ 121
Payables, Interest rate swaps	(8)
Foreign Exchange Forward Contracts and Swaps [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	28,255	£ 20,319
Payables, Interest rate swaps	(28,315)	(20,326)
Not later than 1 year [member] | Interest rate swap contract [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	49
Payables, Interest rate swaps	(3)
Not later than 1 year [member] | Foreign Exchange Forward Contracts and Swaps [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	26,680	20,319
Payables, Interest rate swaps	(26,802)	£ (20,326)
Between 1 and 2 years [member] | Interest rate swap contract [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	48
Payables, Interest rate swaps	(3)
Between 1 and 2 years [member] | Foreign Exchange Forward Contracts and Swaps [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	1,575
Payables, Interest rate swaps	(1,513)
Between 2 and 3 years [member] | Interest rate swap contract [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	24
Payables, Interest rate swaps	(2)
Between 2 and 3 years [member] | Foreign Exchange Forward Contracts and Swaps [member]
Disclosure of detailed information about financial instruments [line items]
Receivable, Foreign exchange forward contracts and swaps	0
Payables, Interest rate swaps	£ 0

Employee Share Schemes - Additi

Employee Share Schemes - Additional Information (Detail) £ / shares in Units, shares in Thousands, £ in Millions	12 Months Ended
	Dec. 31, 2018GBP (£)shares£ / shares	Dec. 31, 2018shares£ / shares$ / shares	Dec. 31, 2017GBP (£)shares£ / shares	Dec. 31, 2017$ / shares	Dec. 31, 2016GBP (£)shares£ / shares	Dec. 31, 2016$ / shares
Disclosure of employee share schemes [line items]
Cost of share-based incentive plans | £	£ 393		£ 347		£ 338
Savings-Related Share Option Schemes [member]
Disclosure of employee share schemes [line items]
Share options granted at percentage below market price	20.00%
Number of options granted	2,900
Weighted average fair value of options granted | £ / shares	£ 2.40	£ 2.40
Number share options were not exercisable	5,500	5,500
Share Value Plan [member]
Disclosure of employee share schemes [line items]
Cost of share-based incentive plans | £	£ 304		£ 276		£ 271
Expected future dividend yield percentage share granted	4.80%		4.80%		4.50%
Number of awards granted	12,751		13,018		12,983
Weighted average fair value of awards | £ / shares	£ 13.74		£ 13.68		£ 14.97
Share Value Plan [member] | American Depositary Shares [member]
Disclosure of employee share schemes [line items]
Number of awards granted	6,503		6,610		6,589
Weighted average fair value of awards | $ / shares		£ 35.28		$ 35.63		$ 39.18
Performance Share Plan [member]
Disclosure of employee share schemes [line items]
Cost of share-based incentive plans | £	£ 49		£ 47		£ 39
Number of awards granted	4,700
Weighted average fair value of awards | £ / shares	£ 10.46
Number of outstanding awards	13,100	13,100
Performance Share Plan [member] | American Depositary Shares [member]
Disclosure of employee share schemes [line items]
Number of awards granted	1,300
Weighted average fair value of awards | $ / shares		£ 29.43
Number of outstanding awards	3,400	3,400

Employee Share Schemes - Schedu

Employee Share Schemes - Schedule of Number of Shares and ADS Issuable (Detail) - Share Value Plan [member] shares in Thousands	12 Months Ended
	Dec. 31, 2018shares£ / shares	Dec. 31, 2018shares$ / shares	Dec. 31, 2017shares£ / shares	Dec. 31, 2017shares$ / shares	Dec. 31, 2016shares£ / shares	Dec. 31, 2016shares$ / shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of shares, Beginning balance	33,925	33,925	32,855	32,855	32,577	32,577
Number of shares, Awards granted	12,751	12,751	13,018	13,018	12,983	12,983
Number of shares, Awards exercised	(11,089)	(11,089)	(10,596)	(10,596)	(11,198)	(11,198)
Number of shares, Awards cancelled	(1,519)	(1,519)	(1,352)	(1,352)	(1,507)	(1,507)
Number of shares, Ending balance	34,068	34,068	33,925	33,925	32,855	32,855
Weighted fair value, Awards granted | £ / shares	£ 13.74		£ 13.68		£ 14.97
American Depositary Shares [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of shares, Beginning balance	17,392	17,392	17,083	17,083	17,520	17,520
Number of shares, Awards granted	6,503	6,503	6,610	6,610	6,589	6,589
Number of shares, Awards exercised	(5,583)	(5,583)	(5,674)	(5,674)	(6,214)	(6,214)
Number of shares, Awards cancelled	(925)	(925)	(627)	(627)	(812)	(812)
Number of shares, Ending balance	17,387	17,387	17,392	17,392	17,083	17,083
Weighted fair value, Awards granted | $ / shares		$ 35.28		$ 35.63		$ 39.18

Employee Share Schemes - Summar

Employee Share Schemes - Summary of Valuation Model Used to Valuing Saving - Related Option to Arrive at the Share Based Payment Charge (Detail) - Share Options and Savings-Related Options [member] - £ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of share options and savings related options [line items]
Risk-free interest rate	0.76%	0.54%	0.32%
Dividend yield	5.30%	5.90%	4.90%
Volatility	21.00%	23.00%	23.00%
Expected life	3 years	3 years	3 years
Savings-related options grant price (including 20% discount)	£ 12.09	£ 10.86	£ 12.95

Employee Share Schemes - Summ_2

Employee Share Schemes - Summary of Valuation Model Used to Valuing Saving - Related Option to Arrive at the Share Based Payment Charge (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Options and Savings-Related Options [member]
Disclosure of share options and savings related options [line items]
Savings-related options grant price discount	20.00%	20.00%	20.00%

Employee Share Schemes - Summ_3

Employee Share Schemes - Summary of Option Outstanding (Detail) - Dec. 31, 2018 shares in Thousands	sharesyr£ / shares	sharesyr$ / shares
Share Option Schemes [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of Shares | shares	1,796	1,796
Share option schemes - shares Weighted exercise price	£ 11.96
Weighted average market price on exercise during year	£ 14.43
Weighted average remaining contractual life | yr	0.9	0.9
Share Option Schemes [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end	£ 12.21
Share Option Schemes [member] | Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end	£ 11.60
Share Option Schemes American Depositary Shares [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of Shares | shares	1,216	1,216
Share option schemes - shares Weighted exercise price | $ / shares		$ 36.19
Weighted average market price on exercise during year | $ / shares		$ 39.77
Weighted average remaining contractual life | yr	0.9	0.9
Share Option Schemes American Depositary Shares [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end | $ / shares		$ 38.14
Share Option Schemes American Depositary Shares [member] | Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end | $ / shares		$ 33.42
Savings-Related Share Option Schemes [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Number of Shares | shares	5,929	5,929
Share option schemes - shares Weighted exercise price	£ 11.70
Weighted average market price on exercise during year	£ 15.13
Weighted average remaining contractual life | yr	2.6	2.6
Savings-Related Share Option Schemes [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end	£ 12.95
Savings-Related Share Option Schemes [member] | Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Range of exercise prices on options outstanding at year end	£ 10.13

Employee Share Schemes - Summ_4

Employee Share Schemes - Summary of Shares Held for Share Award Schemes (Detail) - Employee share ownership plan [member] pure in Thousands, £ in Millions	Dec. 31, 2018GBP (£)	Dec. 31, 2017GBP (£)
Disclosure of terms and conditions of share-based payment arrangement [line items]
Shares held for share award schemes, Number of shares	41,391	66,558
Shares held for share award schemes, Nominal value	£ 10	£ 17
Shares held for share award schemes, Carrying value	160	399
Shares held for share award schemes, Market value	£ 617	£ 880
Shares held for share option schemes, Number of shares	139	139
Shares held for share option schemes, Nominal value	£ 0
Shares held for share option schemes, Carrying value	1	£ 1
Shares held for share option schemes, Market value	£ 2	£ 2

Principal Group companies - Sch

Principal Group companies - Schedule of the Subsidiaries and Their Counties of Incorporation and the Equity Share Capital of These Entities wholly owned by the Group (Detail)	12 Months Ended
	Dec. 31, 2018
Glaxo Group Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Glaxo Group Limited
Glaxo Operations UK Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Glaxo Operations UK Limited
GlaxoSmithKline Capital PLC [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Capital plc
GlaxoSmithKline Consumer Healthcare Holdings Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Holdings Limited
GlaxoSmithKline Consumer Healthcare (UK) Trading Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare (UK) Trading Limited
GlaxoSmithKline Consumer Trading Services Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Trading Services Limited
GlaxoSmithKline Export Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Export Limited
GlaxoSmithKline Finance PLC [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Finance plc
GlaxoSmithKline Holdings Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Holdings Limited
GlaxoSmithKline Research and Development Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Research & Development Limited
GlaxoSmithKline Services Unlimited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Services Unlimited
GlaxoSmithKline UK Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline UK Limited
Setfirst Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Setfirst Limited
SmithKline Beecham Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	SmithKline Beecham Limited
ViiV Health Care Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ViiV Healthcare Limited
ViiV Healthcare UK Limited [member] | UK [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ViiV Healthcare UK Limited
Block Drug Company Inc. [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Block Drug Company, Inc.
Corixa Corporation [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Corixa Corporation
GlaxoSmithKline Capital Inc. [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Capital Inc.
GlaxoSmithKline Consumer Healthcare Holdings (US) LLC [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Holdings (US) LLC
GlaxoSmithKline Consumer Health Care L P [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare, L.P.
GlaxoSmithKline Holdings (Americas) Inc. [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Holdings (Americas) Inc.
GlaxoSmithKline LLC [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline LLC
Human Genome Sciences, Inc. [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Human Genome Sciences, Inc.
GSK Consumer Health, Inc [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GSK Consumer Health, Inc. (formerly Novartis Consumer Health, Inc.)
S.R One, Limited [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	S.R. One, Limited
Stiefel Laboratories, Inc. [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Stiefel Laboratories, Inc.
Vii V Health Care Company [member] | US [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ViiV Healthcare Company
GlaxoSmithKline Argentina S.A. [member] | Argentina [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Argentina S.A.
GlaxoSmithKline Australia Pty Ltd [Member] | Australia [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Australia Pty Ltd
GlaxoSmithKline Consumer Healthcare Australia Pty Ltd [member] | Australia [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Australia Pty Ltd
GlaxoSmithKline Brasil Limitada [Member] | Brazil [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Brasil Limitada
GlaxoSmithKline Consumer Healthcare Inc. [Member] | Canada [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Inc.
GlaxoSmithKline Inc. [Member] | Canada [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Inc.
ID Biomedical Corporation of Quebec [Member] | Canada [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ID Biomedical Corporation of Quebec
GlaxoSmithKline Limited [Member] | China [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Limited
GlaxoSmithKline (Tianjin) Co. Ltd [member] | China [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline (Tianjin) Co. Ltd
Sino-American Tianjin Smith Kline and French Laboratories Ltd [Member] | China [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Sino-American Tianjin Smith Kline & French Laboratories Ltd
GlaxoSmithKline Consumer Healthcare Limited [member] | India [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Limited
GlaxoSmithKline Pharmaceuticals Limited [member] | India [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Pharmaceuticals Limited
GlaxoSmithKline Consumer Healthcare Japan K.K. [member] | Japan [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Japan K.K.
GlaxoSmithKline K.K. [member] | Japan [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline K.K.
ViiV Healthcare Kabushiki Kaisha [member] | Japan [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ViiV Healthcare Kabushiki Kaisha
GlaxoSmithKline Pakistan Limited [member] | Pakistan [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Pakistan Limited
Glaxo Wellcome Manufacturing Pte Ltd. [member] | Singapore [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Glaxo Wellcome Manufacturing Pte Ltd.
GlaxoSmithKline Korea Limited [member] | Republic of Korea [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Korea Limited
GlaxoSmithKline llaclari Sanayi ve Ticaret A.S. [member] | Turkey [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline llaclari Sanayi ve Ticaret A.S.
GlaxoSmithKline Biologicals SA [member] | Belgium [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Biologicals SA
GlaxoSmithKline Pharmaceuticals S.A. [member] | Belgium [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Pharmaceuticals SA
GlaxoSmithKline Biologicals S.A.S. [member] | France [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Biologicals S.A.S
GlaxoSmithKline Sante Grand Public SAS [member] | France [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Sante Grand Public SAS
Laboratoire GlaxoSmithKline [member] | France [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Laboratoire GlaxoSmithKline
ViiV Healthcare SAS [member] | France [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	ViiV Healthcare SAS
GlaxoSmithKline Consumer Healthcare GmbH and Co. KG [member] | Germany [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare GmbH & Co. KG
GlaxoSmithKline GmbH and Co. KG [member] | Germany [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline GmbH & Co. KG
GSK Vaccines GmbH [member] | Germany [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GSK Vaccines GmbH
GlaxoSmithKline Consumer Healthcare S.p.A. [member] | Italy [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare S.p.A.
GlaxoSmithKline S.p.A. [member] | Italy [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline S.p.A.
GSK Vaccines S.r.l. [member] | Italy [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GSK Vaccines S.r.l.
GlaxoSmithKline B.V. [member] | Netherlands [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline B.V.
GlaxoSmithKline Consumer Healthcare S p z o o [member] | Poland [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Consumer Healthcare Sp.z.o.o.
GSK Services Sp z o.o. [member] | Poland [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GSK Services Sp z o.o.
GlaxoSmithKline Trading Services Limited [member] | Ireland [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Trading Services Limited
GlaxoSmithKline Healthcare AO [member] | Russia [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline Healthcare AO
GlaxoSmithKline S.A. [member] | Spain [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GlaxoSmithKline S.A.
Laboratorios ViiV Healthcare, S.L. [member] | Spain [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	Laboratorios ViiV Healthcare, S.L.
GSK Consumer Healthcare S.A [member] | Switzerland [member]
Disclosure of subsidiaries [line items]
Name of subsidiary	GSK Consumer Healthcare S.A.

Principal Group companies - S_2

Principal Group companies - Schedule of the Subsidiaries and Their Counties of Incorporation and the Equity Share Capital of These Entities wholly owned by the Group (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018
UK [member] | Glaxo Group Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | Glaxo Operations UK Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Capital PLC [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Consumer Healthcare Holdings Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Consumer Healthcare (UK) Trading Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Consumer Trading Services Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Export Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Finance PLC [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Holdings Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Research and Development Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline Services Unlimited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | GlaxoSmithKline UK Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | Setfirst Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | SmithKline Beecham Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
UK [member] | ViiV Health Care Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
Proportion of ownership interest in subsidiary	78.30%
UK [member] | ViiV Healthcare UK Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	England
Proportion of ownership interest in subsidiary	78.30%
US [member] | Block Drug Company Inc. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | Corixa Corporation [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | GlaxoSmithKline Capital Inc. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | GlaxoSmithKline Consumer Healthcare Holdings (US) LLC [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | GlaxoSmithKline Consumer Health Care L P [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
Proportion of ownership interest in subsidiary	88.00%
US [member] | GlaxoSmithKline Holdings (Americas) Inc. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | GlaxoSmithKline LLC [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | Human Genome Sciences, Inc. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | GSK Consumer Health, Inc [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | S.R One, Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | Stiefel Laboratories, Inc. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
US [member] | Vii V Health Care Company [member]
Disclosure of subsidiaries [line items]
Country of incorporation	US
Proportion of ownership interest in subsidiary	78.30%
Argentina [member] | GlaxoSmithKline Argentina S.A. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Argentina
Australia [member] | GlaxoSmithKline Australia Pty Ltd [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	Australia
Australia [member] | GlaxoSmithKline Consumer Healthcare Australia Pty Ltd [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Australia
Brazil [member] | GlaxoSmithKline Brasil Limitada [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	Brazil
Canada [member] | GlaxoSmithKline Consumer Healthcare Inc. [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	Canada
Canada [member] | GlaxoSmithKline Inc. [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	Canada
Canada [member] | ID Biomedical Corporation of Quebec [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	Canada
China [member] | GlaxoSmithKline Limited [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	China (Hong Kong)
China [member] | GlaxoSmithKline (Tianjin) Co. Ltd [member]
Disclosure of subsidiaries [line items]
Country of incorporation	China
Proportion of ownership interest in subsidiary	90.00%
China [member] | Sino-American Tianjin Smith Kline and French Laboratories Ltd [Member]
Disclosure of subsidiaries [line items]
Country of incorporation	China
Proportion of ownership interest in subsidiary	55.00%
India [member] | GlaxoSmithKline Consumer Healthcare Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	India
Proportion of ownership interest in subsidiary	72.50%
India [member] | GlaxoSmithKline Pharmaceuticals Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	India
Proportion of ownership interest in subsidiary	75.00%
Japan [member] | GlaxoSmithKline Consumer Healthcare Japan K.K. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Japan
Japan [member] | GlaxoSmithKline K.K. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Japan
Japan [member] | ViiV Healthcare Kabushiki Kaisha [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Japan
Proportion of ownership interest in subsidiary	78.30%
Pakistan [member] | GlaxoSmithKline Pakistan Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Pakistan
Proportion of ownership interest in subsidiary	82.60%
Singapore [member] | Glaxo Wellcome Manufacturing Pte Ltd. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Singapore
Republic of Korea [member] | GlaxoSmithKline Korea Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Republic of Korea
Turkey [member] | GlaxoSmithKline llaclari Sanayi ve Ticaret A.S. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Turkey
Belgium [member] | GlaxoSmithKline Biologicals SA [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Belgium
Belgium [member] | GlaxoSmithKline Pharmaceuticals S.A. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Belgium
France [member] | GlaxoSmithKline Biologicals S.A.S. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	France
France [member] | GlaxoSmithKline Sante Grand Public SAS [member]
Disclosure of subsidiaries [line items]
Country of incorporation	France
France [member] | Laboratoire GlaxoSmithKline [member]
Disclosure of subsidiaries [line items]
Country of incorporation	France
France [member] | ViiV Healthcare SAS [member]
Disclosure of subsidiaries [line items]
Country of incorporation	France
Proportion of ownership interest in subsidiary	78.30%
Germany [member] | GlaxoSmithKline Consumer Healthcare GmbH and Co. KG [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Germany
Germany [member] | GlaxoSmithKline GmbH and Co. KG [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Germany
Germany [member] | GSK Vaccines GmbH [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Germany
Italy [member] | GlaxoSmithKline Consumer Healthcare S.p.A. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Italy
Italy [member] | GlaxoSmithKline S.p.A. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Italy
Italy [member] | GSK Vaccines S.r.l. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Italy
Netherlands [member] | GlaxoSmithKline B.V. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Netherlands
Poland [member] | GlaxoSmithKline Consumer Healthcare S p z o o [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Poland
Poland [member] | GSK Services Sp z o.o. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Poland
Ireland [member] | GlaxoSmithKline Trading Services Limited [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Republic of Ireland
Russia [member] | GlaxoSmithKline Healthcare AO [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Russia
Spain [member] | GlaxoSmithKline S.A. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Spain
Spain [member] | Laboratorios ViiV Healthcare, S.L. [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Spain
Proportion of ownership interest in subsidiary	78.30%
Switzerland [member] | GSK Consumer Healthcare S.A [member]
Disclosure of subsidiaries [line items]
Country of incorporation	Switzerland

Legal Proceedings - Additional

Legal Proceedings - Additional Information (Detail) £ in Millions, $ in Millions	Sep. 30, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018GBP (£)	Dec. 31, 2017GBP (£)	Feb. 12, 2016GBP (£)
Disclosure of Legal Proceedings [line items]
Provisions for legal and other disputes			£ 219	£ 186
Legal and other disputes receivable			37
Net exposure on legal proceedings			£ 182
US [member]
Disclosure of Legal Proceedings [line items]
Civil penalty | $	$ 20
Dolin case [member] | US [member]
Disclosure of Legal Proceedings [line items]
Amount of compensation awarded to plaintiff | $		$ 3
UK Competition and Markets Authority [member]
Disclosure of Legal Proceedings [line items]
Fine paid by group					£ 37.6
Fine paid by other companies					£ 7.4

Post Balance Sheet Events - Add

Post Balance Sheet Events - Additional Information (Detail) £ in Billions, $ in Billions	Jan. 22, 2019USD ($)	Dec. 31, 2018GBP (£)	Dec. 31, 2018USD ($)
Major business combination [member] | Tesaro, Inc.[member]
Disclosure of non-adjusting events after reporting period [line items]
Cash consideration	$ 5.1	£ 4	$ 5.1