Allurion (ALUR) 10-K26 Mar 242023 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2023	Mar. 22, 2024	Dec. 29, 2023
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	Allurion Technologies, Inc.
Entity Central Index Key	0001964979
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Incorporation, State or Country Code	DE
Entity File Number	001-41767
Entity Tax Identification Number	92-2182207
Entity Address, Address Line One	11 Huron Drive
Entity Address, City or Town	Natick
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01760
City Area Code	508
Local Phone Number	647-4000
Entity Public Float			$ 132,269,016
Entity Common Stock, Shares Outstanding		47,852,203
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference [Text Block]	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s definitive proxy statement for its 2024 Annual Meeting of Stockholders are incorporated by reference in Part III of this Annual Report on Form 10-K. Such proxy statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Annual Report on Form 10-K.
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts
Common Stock, par value $0.0001 per share
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	ALUR
Security Exchange Name	NYSE
Warrants to purchase 1.420455 shares of Common Stock for $8.10 per share
Document Information [Line Items]
Title of 12(b) Security	Warrants to purchase 1.420455 shares of Common Stock for $8.10 per share
Trading Symbol	ALUR WS
Security Exchange Name	NYSE

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 38,037	$ 7,685
Accounts receivable, net of allowance of doubtful accounts of $12,671 and $741, respectively	18,194	29,346
Inventory, net	6,171	3,865
Prepaid expenses and other current assets	2,414	2,487
Total current assets	64,816	43,383
Property and equipment, net	3,381	2,382
Right-of-use asset	3,010	2,899
Other long-term assets	505	2,706
Total assets	71,712	51,370
Current liabilities:
Accounts payable	10,379	5,809
Current portion of term loan	38,643	53,360
Current portion of lease liabilities	908	905
Accrued expenses and other current liabilities	15,495	15,793
Total current liabilities	65,425	75,867
Convertible notes payable, net of discounts		3,103
Public warrant liabilities	5,943
Revenue Interest Financing liability	36,200
Earn-out liabilities	23,990
Lease liabilities, net of current portion	2,306	2,163
Other liabilities	8,335	2,551
Total liabilities	142,199	83,684
Commitments and Contingencies (Note 16)
Stockholders' deficit:
Preferred stock, $0.0001 par value - 100,000,000 shares authorized as of December 31, 2023; and no shares issued and outstanding as of December 31, 2023 and December 31, 2022
Common stock, $0.0001 par value - 1,000,000,000 shares authorized as of December 31, 2023; 47,688,096 and 27,079,856 shares issued and outstanding as of December 31, 2023 and 2022, respectively	5	3
Additional paid-in capital	143,007	99,875
Accumulated other comprehensive loss	(700)
Accumulated deficit	(212,799)	(132,192)
Total stockholders' deficit	(70,487)	(32,314)
Total liabilities and stockholders' deficit	$ 71,712	$ 51,370

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Allowance of doubtful accounts	$ 12,671	$ 741
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	47,688,096	27,079,856
Common stock, shares outstanding	47,688,096	27,079,856

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Income Statement [Abstract]
Revenue		$ 53,467	$ 64,211
Cost of revenue		11,970	13,485
Gross profit		41,497	50,726
Operating expenses:
Sales and marketing		46,857	50,405
Research and development		27,694	16,966
General and administrative		46,024	15,365
Total operating expenses:		120,575	82,736
Loss from operations		(79,078)	(32,010)
Other income (expense):
Interest expense		(10,566)	(4,426)
Changes in fair value of warrants		8,364	(821)
Changes in fair value of debt		(3,751)
Change in fair value of Revenue Interest Financing and PIPE Conversion Option		(2,192)
Change in fair value of earn-out liabilities		(29,050)
Termination of convertible note side letters		(17,598)
Loss on extinguishment of debt		(3,929)
Other income (expense), net		(643)	(344)
Total other income (expense):		(1,265)	(5,591)
Loss before income taxes		(80,343)	(37,601)
Provision for income taxes		(264)	(143)
Net loss		(80,607)	(37,744)
Cumulative undeclared preferred dividends		(1,697)	(2,907)
Net loss attributable to common stockholders		$ (82,304)	$ (40,651)
Net loss per share - Basic	[1]	$ (2.31)	$ (1.51)
Net loss per share - diluted	[1]	$ (2.31)	$ (1.51)
Weighted-average shares outstanding - Basic		35,581,656	26,918,484
Weighted-average shares outstanding - diluted		35,581,656	26,918,484

[1] The weighted-average common shares and thus net loss per share calculations and potentially dilutive security amounts for all periods prior to the Business Combination have been retrospectively adjusted to the equivalent number of shares outstanding immediately after the Business Combination to effect the reverse capitalization. See Note 3 for further information.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (80,607)	$ (37,744)
Other comprehensive loss:
Change in fair value of Revenue Interest Financing due to change in credit risk	(700)
Comprehensive loss	$ (81,307)	$ (37,744)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Series A-1 Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Common Stock Series A-1 Convertible Preferred Stock	Common Stock Series B Convertible Preferred Stock	Additional Paid-in Capital	Additional Paid-in Capital Series A-1 Convertible Preferred Stock	Additional Paid-in Capital Series B Convertible Preferred Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning Balance at Dec. 31, 2021	$ 4,837			$ 3			$ 99,282				$ (94,448)
Beginning Balance (in shares) at Dec. 31, 2021				26,807,365
Exercise of stock options	128						128
Exercise of stock options, (in shares)				128,567
Stock-based compensation expense	437						437
Issuance of convertible preferred stock for the exercise of warrant		$ 24	$ 4					$ 24	$ 4
Issuance of convertible preferred stock for the exercise of warrant (in shares)					5,611	1,028
Issuance of common stock for the exercise of warrants (in shares)				137,285
Net Income (Loss)	(37,744)										(37,744)
Ending Balance at Dec. 31, 2022	(32,314)			$ 3			99,875				(132,192)
Ending Balance (in shares) at Dec. 31, 2022				27,079,856
Exercise of stock options	145						145
Exercise of stock options, (in shares)				298,562
Stock-based compensation expense	8,357						8,357
Issuance of convertible preferred stock for the exercise of warrant		$ 6	$ 89					$ 6	$ 89
Issuance of convertible preferred stock for the exercise of warrant (in shares)					492	8,530
Reverse recapitalization, net of transaction costs	58,573			$ 1			58,572
Reverse recapitalization, net of transaction costs (in shares)				13,735,872
Recognition of warrant liabilities in connection with the Merger	(13,762)						(13,762)
Issuance of common stock in connection with vesting of RSU awards				918,412
Issuance of common stock for the conversion of convertible notes	25,570			$ 1			25,569
Issuance of common stock for the conversion of convertible notes (in shares)				3,301,222
Recognition of earn-out liabilities (Note 3)	(53,040)						(53,040)
Reclassification of Legacy Allurion liabilitiy classified warrants to equity classification	929						929
Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and the additional RTW and Fortress shares and issuance of related shares	16,098						16,098
Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and the additional RTW and Fortress shares and issuance of related shares (in shares)				2,287,696
Issuance of common stock for the exercise of warrants	46						46
Issuance of common stock for the exercise of warrants (in shares)				21,943
Issuance of common stock for commitment shares for equity line financing	123						123
Issuance of common stock for commitment shares for equity line financing (in shares)				35,511
Other comprehensive loss	(700)									$ (700)
Net Income (Loss)	(80,607)										(80,607)
Ending Balance at Dec. 31, 2023	$ (70,487)			$ 5			$ 143,007			$ (700)	$ (212,799)
Ending Balance (in shares) at Dec. 31, 2023				47,688,096

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Operating Activities:
Net loss	$ (80,607)	$ (37,744)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash lease expense	824	1,104
Depreciation and amortization	746	895
Stock-based compensation	8,357	437
Provision for uncollectible accounts	12,675	436
Unrealized exchange gain	(180)	(113)
Provision for inventory	1,399
Change in fair value of warrant liabilities	(8,364)	820
Change in fair value of derivative liabilities	1,730	19
Change in fair value of debt	3,751
Change in fair value of Revenue Interest Financing and PIPE Conversion Option	2,192
Change in fair value of earn-out liabilities	(29,050)
Interest paid on debt recorded at fair value	(1,092)
Non-cash interest expense	2,083	953
Non-cash termination of convertible note side letters	16,098
Loss on extinguishment of debt	3,929
Non-cash issuance of common stock for commitment shares	123
Debt issuance costs associated with debt recorded at fair value	1,210
Changes in operating assets and liabilities:
Accounts receivable	(1,318)	(22,817)
Inventory	(3,705)	(1,150)
Prepaid expenses, other current and long-term assets	285	(577)
Lease liabilities	(789)	(733)
Accounts payable	4,664	3,324
Accrued expenses and other current liabilities	1,057	8,165
Net cash used in operating activities	(63,982)	(46,981)
Investing Activities:
Purchases of property and equipment	(1,606)	(1,550)
Net cash used in investing activities	(1,606)	(1,550)
Financing Activities:
Proceeds from issuance of convertible notes - net	28,700	1,103
Proceeds from term loan - net	59,780	29,850
Payment of debt issuance costs	(3,450)	(262)
Proceeds from Business Combination, net of transaction costs	61,652
Proceeds from revenue interest financing	40,000
Repayment of promissory note assumed in Business Combination	(2,500)
Proceeds from option and warrant exercises	213	132
Repayment of convertible notes	(10,750)
Payment of deferred financing costs		(286)
Net cash provided by financing activities	95,986	30,537
Net increase (decrease) in cash and cash equivalents and restricted cash	30,398	(17,994)
Cash and cash equivalents and restricted cash at beginning of period	8,023	26,017
Cash and cash equivalents and restricted cash at end of period	38,421	8,023
Supplemental disclosure of cash flow information
Cash paid for interest	8,035	3,476
Supplemental cash flow information on non-cash investing and financing activities
Purchase of property and equipment included in accounts payable	134	13
Issuance of warrants in connection with financing		834
Deferred financing costs in accounts payable and accrued expenses	580	$ 1,919
Recognition of assumed warrant liability	13,762
Recognition of earn-out liabilities	53,040
Issuance of common stock upon conversion of convertible notes	25,569
Change in fair value of Revenue Interest Financing through OCI	(700)
2021 Term Loan
Financing Activities:
Repayment of Term Loan	(57,659)
Fortress Term Loan
Financing Activities:
Repayment of Term Loan	$ (20,000)

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (80,607)	$ (37,744)

Insider Trading Arrangements

Insider Trading Arrangements	12 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
Organization and Basis of Presentation	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Organization Allurion Technologies, Inc. (“Allurion” or the “Company”) is a vertically integrated medical device company that is developing, manufacturing, and commercializing innovative weight loss experiences centered around its Allurion Balloon. The Allurion Balloon is the world’s first and only swallowable, procedure-less intragastric balloon for weight loss that does not require surgery, endoscopy, or anesthesia for placement or removal. Allurion sells the Allurion Balloon and related hardware accessories through distributors or directly to health care providers. The Company currently also provides, free of charge, artificial intelligence ("AI")-powered remote patient monitoring tools, a mobile app for patients and a clinic dashboard for providers, referred to as the Allurion Virtual Care Suite (“VCS”) and, collectively with the Allurion Balloon referred to as the “Allurion Program”. Allurion currently markets the Allurion Program in over 50 countries, and the Company operates subsidiaries in the United States, France, the United Arab Emirates, Hong Kong, the United Kingdom, Italy, Spain, Australia and Mexico. Business Combination Agreement On February 9, 2023, Allurion Technologies Opco, Inc. (formerly Allurion Technologies, Inc., “Legacy Allurion”) and Allurion Technologies, Inc. (formerly Allurion Technologies Holdings, Inc.), entered into the Business Combination Agreement (as subsequently amended on May 2, 2023, the “Business Combination Agreement”) with Compute Health Acquisition Corp. (“CPUH” or "Compute Health"), Compute Health Corp. (“Merger Sub I”) and Compute Health LLC (“Merger Sub II” and, together with Merger Sub I, the “Merger Subs”). Pursuant to the Business Combination Agreement, on August 1, 2023 (the “Closing Date”), the Mergers (as defined below) were consummated in three steps: (a) Compute Health merged with and into Allurion (the “CPUH Merger”), with Allurion surviving the CPUH Merger as a publicly listed entity (the time at which the CPUH Merger became effective, the “CPUH Merger Effective Time”) and becoming the sole owner of the Merger Subs; (b) three hours following the consummation of the CPUH Merger, Merger Sub I merged with and into Legacy Allurion (the “Intermediate Merger” and the time at which the Intermediate Merger became effective, the “Intermediate Merger Effective Time”), with Legacy Allurion surviving the Intermediate Merger and becoming a direct, wholly-owned subsidiary of Allurion; and (c) thereafter, Legacy Allurion merged with and into Merger Sub II (the “Final Merger” and, collectively with the CPUH Merger and the Intermediate Merger, the “Mergers”, and together with all other transactions contemplated by the Business Combination Agreement, the “Business Combination”), with Merger Sub II surviving the Final Merger and remaining a direct, wholly-owned subsidiary of Allurion (the time at which the Final Merger became effective, the “Final Merger Effective Time”). Allurion shares began trading on the New York Stock Exchange ("NYSE") under the ticker symbol “ALUR” on August 2, 2023. Upon completion of the Business Combination, Legacy Allurion's business operations continued as our business operations. The Business Combination was accounted for as a reverse capitalization in accordance with accounting principles generally accepted in the United States of America. Under this method of accounting, Compute Health was treated as the “acquired” company for financial reporting purposes and Legacy Allurion was the accounting “acquirer”. Accordingly, the Business Combination was treated as the equivalent of Legacy Allurion issuing stock for the net assets of Compute Health, accompanied by a recapitalization. As a result of the reverse recapitalization, the assets and liabilities of the Company are presented at their historical carrying values, and the assets and liabilities of Compute Health are recognized on the acquisition date and measured on the basis of the net proceeds from the capital transaction, with no goodwill or other intangible assets recorded. This determination is primarily based on the fact that, immediately following the Business Combination, Legacy Allurion stockholders had a majority of the voting power of Allurion, Legacy Allurion controlled the majority of the board seats of Allurion, and Legacy Allurion senior management comprised all of the senior management of Allurion. The equity structure has been restated in all comparative periods up to the Closing Date to reflect the number of shares of the Company's common stock, $ 0.0001 par value per share (“Allurion Common Stock” or the “Company’s Common Stock”), issued to Legacy Allurion stockholders in connection with the Business Combination. As such, the shares and corresponding capital amounts and earnings per share related to Legacy Allurion's convertible preferred stock and Legacy Allurion common stock prior to the Business Combination have been retroactively restated as shares reflecting the exchange ratio of approximately 0.9780 (the "Exchange Ratio") established in the Business Combination. As a result of this retrospective application, certain prior period balances within the consolidated financial statements have changed. Refer to Note 3, Business Combination , for further discussion regarding the closing of the Business Combination with Compute Health. Unless otherwise indicated, references in this Annual Report on Form 10-K to the "Company", "our", and "Allurion" refer to the consolidated operations of Allurion Technologies, Inc. and its subsidiaries. References to CPUH and Compute Health refer to Compute Health Acquisition Corp. and its subsidiaries prior to the consummation of the Business Combination and references to "Legacy Allurion" refer to Allurion Technologies, Inc. prior to the consummation of the Business Combination. Basis of Presentation The accompanying consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“US GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”). Any reference in these notes to the applicable accounting guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification ("ASC"), and Accounting Standards Update ("ASU"), of the Financial Accounting Standards Board ("FASB"). In connection with the Business Combination, the Company's equity structure has been restated in prior periods to reflect the number of shares of the Allurion Common Stock, $ 0.0001 par value per share, issued to Legacy Allurion stockholders. As such, the shares and corresponding capital amounts presented in the consolidated balance sheet and consolidated statement of redeemable convertible preferred stock and stockholders' deficit have been retroactively restated as shares reflecting the Exchange Ratio established in the Business Combination. All then-existing Legacy Allurion redeemable convertible preferred stock and Legacy Allurion convertible preferred stock were converted into shares of Allurion Common Stock at the closing of the Business Combination. The consolidated financial statements include Allurion; and its consolidated subsidiaries, Allurion France SAS, and Allurion Middle East, LLC, which were both incorporated in 2017; Allurion Hong Kong Ltd., which was incorporated in 2019; Allurion UK Ltd., which was incorporated in 2021; Allurion Italy, Srl, Allurion Spain, Srl, Allurion Australia Pty Ltd. and Allurion Mexico S. de R.L de C.V, which were incorporated in 2022; and Allurion Technologies, LLC, which was incorporated in 2023. The Company’s operations are located in Europe, the Middle East, Africa, Latin America, Canada and the Asia-Pacific region, and it operates in one business segment. Our foreign operations are subject to exchange rate fluctuations and foreign currency transaction costs. The functional currency for all of our foreign subsidiaries is the United States dollar except Allurion Australia Pty Ltd., which uses the Australian dollar. When remeasuring from a local currency to the functional currency, assets and liabilities are remeasured into U.S. dollars at exchange rates in effect at the balance sheet dates and results of operations transacted in local currency are remeasured into U.S. dollars using average exchange rates for the period presented. Gains (losses) from remeasurement of $ 0.1 million and $( 0.7 ) million for the years ended December 31, 2023 and 2022, respectively, are recorded in the statements of operations and comprehensive loss within other expense, net. The Company translates the foreign functional currency financial statements to U.S. dollars for Allurion Australia Pty Ltd. using the exchange rates at the balance sheet date for assets and liabilities, the period average exchange rates for revenues and expenses, and the historical exchange rates for equity transactions. The effects of foreign currency translation adjustments were immaterial for the years ended December 31, 2023 and 2022. Going Concern The Company has evaluated whether there are certain events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. The Company has incurred recurring losses since inception and anticipates net losses and negative operating cash flows for the near future and may be unable to remain in compliance with certain financial covenants required under the Fortress Term Loan. Through December 31, 2023, the Company has funded its operations primarily with proceeds from the sale of its convertible preferred stock, issuance of convertible notes, issuance of term loans and funds received upon consummation of the Business Combination. The Company has incurred recurring losses and cash outflows from operating activities since its inception, including net losses of $ 80.6 million and $ 37.7 million and cash outflows from operating activities of $ 64.0 million and $ 47.0 million for the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, the Company had an accumulated deficit of $ 212.8 million. The Company expects to continue to generate significant operating losses for the foreseeable future. Based on the Company's recurring losses from operations incurred since inception, its expectation of continuing operating losses for the foreseeable future, the potential need to raise additional capital to finance its future operations and debt service payments, and the potential of being unable to remain in compliance with certain financial covenants under the Fortress Term Loan, the Company has concluded that there is substantial doubt about its ability to continue as a going concern for a period of one year from the date that these consolidated financial statements are issued. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. Due to the substantial doubt about the Company's ability to continue operating as a going concern for twelve months from the issuance date of these financial statements and the liquidity and revenue covenant clauses within the Fortress Term Loan, the amounts due as of December 31, 2023, have been classified as current liabilities in the consolidated financial statements. The lender under the Fortress Term Loan has not invoked the material adverse change clause and the Company has met the liquidity covenant as of the date of issuance of these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP 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 consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Management considers many factors in selecting appropriate financial accounting policies and controls in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Actual results could differ from those estimates. Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations. Adjustments have been made to the consolidated statement of operations and comprehensive loss for the year ended December 31, 2022 to present the change in fair value of derivative liabilities as part of Other income (expense), net, and to present the change in fair value of warrants as its own line item. The change in fair value of derivative liabilities was a separate line item in prior years and the change in fair value of warrants was part of Other income (expense), net in prior years. Risk of Concentration of Credit, Significant Customers and Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash equivalents and accounts receivable, net. The Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company maintains its cash, cash equivalents and restricted cash with financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Significant customers are those which represent more than 10 % of the Company’s total revenue for the years ended December 31, 2023 and 2022 or accounts receivable, net balance as of December 31, 2023 and 2022. The following table presents customers that represent 10% or more of the Company’s total revenue and accounts receivable, net: Revenue Accounts Receivable Years Ended December 31 December 31, 2023 2022 2023 2022 Customer A 10 % N/A 16 % N/A Customer B N/A 11 % N/A N/A Customer C N/A N/A N/A 13 % Customer D N/A N/A N/A 12 % The Company relies on third parties for the supply of parts and components for its products as well as third-party logistics providers. In instances where these parties fail to perform their obligations, the Company may be unable to find alternative suppliers of parts and components to satisfactorily deliver its products to its customers on time, if at all, which could have a material adverse effect on the Company’s operating results, financial condition and cash flows and damage its customer relationships. Leases Effective January 1, 2022, the Company adopted ASC 842, Leases (“ASC 842"). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease. A contract is or contains a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. At the lease commencement date, when control of the underlying asset is transferred from the lessor to the Company, the Company classifies a lease as either an operating or finance lease and recognizes a right-of-use (“ROU”) asset and a current and non-current lease liability as applicable, in the consolidated balance sheets if the lease has a term greater than one year. As permitted under ASC 842, the Company has made an accounting policy election, for all classes of underlying assets, to not recognize ROU assets and lease liabilities for leases having an original term of twelve months or less. When it determines the appropriate classification and accounting for a lease arrangement, the Company typically only considers the committed lease term. Options to extend a lease are not included in the Company’s assessment unless there is reasonable certainty that the Company will either renew or not cancel the lease. At the lease commencement date, operating lease liabilities and their corresponding ROU assets are recorded at the present value of future lease payments over the expected remaining lease term using the discount rate implicit in the lease, if it is readily determinable, or the Company’s incremental borrowing rate. The Company’s incremental borrowing rate reflects the fixed rate at which the Company could borrow the amount of the lease payments in the same currency on a collateralized basis, for a similar term in a similar economic environment. Lease cost for operating leases is recognized on a straight-line basis over the lease term as an operating expense. In addition, certain adjustments to the ROU asset may be required for items such as lease prepayments, incentives received or initial direct costs. The Company enters into contracts that contain both lease and non-lease components. Non-lease components include costs that do not provide a right to use a leased asset but instead provide a service, such as maintenance costs. Variable costs associated with the lease, such as maintenance and utilities, are not included in the measurement of right-of-use assets and lease liabilities but rather are expensed when the events determining the amount of variable consideration to be paid have occurred. Cash and Cash Equivalents and Restricted Cash Cash consists of amounts held in bank savings and checking accounts. Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase. Cash equivalents consist of money market funds. The Company’s restricted cash consists of cash that the Company is contractually obligated to maintain and deposits of cash collateral held in accordance with the terms of various corporate credit cards. Restricted cash is included within other long-term assets on the consolidated balance sheets. A reconciliation of the amounts of cash and cash equivalents and restricted cash in the consolidated balance sheets to the amount in the consolidated statements of cash flows is as follows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 38,037 $ 7,685 Restricted cash included in other long-term assets 384 338 Cash and cash equivalents and restricted cash shown in the statement of cash flows $ 38,421 $ 8,023 Segment Reporting The Company operates in a single operating and reportable segment. Operating segments are defined as components of an enterprise for which discrete financial information is available and is regularly reviewed by the chief operating decision maker (“CODM”) in order to make decisions regarding resource allocation and performance assessment. The Company has determined that its CODM is its Chief Executive Officer. The Company’s CODM reviews financial information presented on a regular basis at the consolidated level for purposes of allocating resources and evaluating financial performance. Since the Company operates as one operating segment, all required financial segment information can be found in the consolidated financial statements. The Company’s products include the Allurion Balloon and related accessories. See Note 4, Revenue below for financial information about sales in geographic areas. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The carrying value of the Company’s financial instruments such as cash and cash equivalents, accounts payable, and accrued expenses approximate their fair values due to their short-term maturity. The carrying value of the Company’s term loan approximates its fair value as the interest rate and other terms are that which are currently available to the Company. The Company’s assets and liabilities recorded at fair value have been categorized based upon a fair value hierarchy, which is distinguished between observable and unobservable inputs in accordance with authoritative accounting guidance: Level 1 inputs: Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date Level 2 inputs: Other than quoted prices included in Level 1, inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability Level 3 inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that the observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset. Inventories Inventories, which include the costs of material, labor, and overhead, are stated at the lower of cost or net realizable value, with cost generally computed using the first-in, first out method. Estimated losses from obsolete and slow-moving inventories are recorded to reduce inventory values to their estimated net realizable value and are charged to cost of sales. At the point of loss recognition, a new cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in a recovery in carrying value. Property and Equipment Property and equipment include computers, laboratory equipment, machinery, and leasehold improvements. Property and equipment are recorded at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, except for leasehold improvements, which are depreciated on a straight-line basis over the shorter of the estimated life or the lease term. Expenditures for repairs and maintenance are expensed as incurred. Capitalized Internal-Use Software Software development costs consist of certain consulting costs and compensation expenses for employees who devote time to the development projects of our internal-use software, as well as certain upgrades and enhancements that are expected to result in enhanced functionality. The Company amortizes these development costs over the estimated useful life, which is determined based on our best estimate of the useful life of the internal-use software after considering factors such as continuous developments in the technology, obsolescence, and anticipated life of the service offering before significant upgrades. Management evaluates the useful lives of these assets and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. The Company determined the amount of internal software costs to be capitalized based on the amount of time spent by our developers on projects in the application stage of development. There is judgment in estimating the time allocated to a particular project in the application stage. A significant change in the time spent on each project could have a material impact on the amount capitalized and related amortization expense in subsequent periods. As of December 31, 2023 and 2022, capitalized internal-use software was immaterial. Impairment of Long-Lived Assets The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. To date, no impairments have occurred. Debt Issuance Costs The Company defers costs directly associated with acquiring third-party financing. Fees incurred to issue debt are generally deferred and amortized as a component of interest expense over the estimated term of the related debt using the effective interest rate method. Fees incurred in connection with a modification are deferred and amortized as a component of interest expense over the remaining life of the loan if due to the creditor. Third-party fees incurred in connection with a modification are expensed as incurred. Deferred Offering Costs Deferred offering costs include certain legal, accounting, consulting and other third-party fees incurred directly related to the Business Combination. The Company deferred offering costs classified as a long-term asset until the closing or termination of the transaction. At the closing of the Business Combination, these costs were recorded in stockholders’ deficit as a reduction of additional paid-in capital. Deferred offering costs are included in other long-term assets. As of December 31, 2023 and 2022, there were zero and $ 2.3 million of deferred offering costs recorded within other long-term assets on the consolidated balance sheet, respectively. Warrants The Company determines the accounting classification of warrants it issues, as either liability or equity classified, by first assessing whether the warrants meet liability classification in accordance with ASC 480-10, Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity (“ASC 480-10”), then in accordance with ASC 815-40, Accounting for Derivative Financial Instruments Indexed to, and Potentially Settled in, a Company’s Own Stock (“ASC 815-40”). Under ASC 480-10, warrants are considered liability classified if the warrants are mandatorily redeemable, obligate the Company to settle the warrants or the underlying shares by paying cash or other assets, or are warrants that must or may require settlement by issuing a variable number of shares. If warrants do not meet liability classification under ASC 480-10, the Company assesses the requirements under ASC 815-40, which states that contracts that require or may require the issuer to settle the contract for cash are liabilities recorded at fair value, irrespective of the likelihood of the transaction occurring that triggers the net cash settlement feature. If the warrants do not require liability classification under ASC 815-40, and in order to conclude equity classification, the Company also assesses whether the warrants are indexed to its common stock and whether the warrants are classified as equity under ASC 815-40 or other applicable GAAP. After all relevant assessments, the Company concludes whether the warrants are classified as liability or equity. Liability classified warrants require fair value accounting at issuance and subsequent to initial issuance, with all changes in fair value after the issuance date recorded in the consolidated statements of operations. Equity classified warrants only require fair value accounting at issuance with no changes recognized subsequent to the issuance date. Derivative Liabilities The Company evaluates its convertible instruments and other contracts, including warrants, to determine if those contracts or embedded components of those contracts are required to be accounted for as derivatives, either in whole or in part. If an embedded derivative is bifurcated from a debt host contract, changes in the fair value of the bifurcated derivative are recorded in the accompanying consolidated statements of operations. 2023 Convertible Notes The Company accounted for the convertible notes issued between February 2023 and August 2023 (the "2023 Convertible Notes") under the fair value option (“FVO”) election of ASC Topic 825, Financial Instruments (“ASC 825”). The convertible notes accounted for under the FVO election were each debt host financial instruments containing embedded features wherein the entire financial instrument was initially measured at its issue-date estimated fair value and then subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. Changes in the estimated fair value of the convertible notes were recorded as a component of Other (expense) income in the consolidated statements of operations. As a result of electing the FVO, direct costs and fees related to the 2023 Convertible Notes were expensed as incurred. The convertible notes issued in 2020, 2021 and 2022 are accounted for as disclosed in Note 8, Debt . In connection with the closing of the Business Combination on August 1, 2023, a portion of the 2023 convertible notes was repaid, with the remaining balance converted to shares of our Common Stock. Earn-Out Liabilities In connection with the Business Combination, certain holders of Legacy Allurion common stock and Legacy Allurion preferred stock and holders of vested options, warrants and restricted stock units exercisable or convertible into Legacy Allurion capital stock received the contingent right to receive up to 9,000,000 additional shares of Allurion Common Stock (the “Earn-Out Shares”) upon the achievement of certain earn-out targets. The contingent earn-out consideration contains a settlement provision that in the event of a change in control, the number of Earn-Out Shares issued may vary. This settlement provision precludes the earn-out liability from being indexed to the Company's Common Stock as a change in control event is not an input into the pricing of a fixed-for-fixed forward or option on equity shares. As such, it is classified as a liability under ASC 480, Distinguishing Liabilities from Equity ("ASC 480"). The fair value of the earn-out consideration is remeasured on a quarterly basis over the earn-out period with changes in the estimated fair value of the contingent earn-out consideration recorded in Other (expense) income in the consolidated statements of operations, and are reflected in the period in which they are identified. Changes in the estimated fair value of the contingent earn-out consideration may materially impact or cause volatility in our operating results. Revenue Interest Financing and PIPE Conversion Option In connection with the Business Combination, the Company entered into a revenue interest financing agreement, dated as of February 9, 2023 (the "Revenue Interest Financing Agreement") with certain entities that have engaged RTW Investments, LP as investment manager (collectively, “RTW”), under which the Company received $ 40.0 million upfront (the "Revenue Interest Financing"). In exchange, the Company is obligated to remit to RTW certain revenue interest payments on all current and future products, digital solutions and services developed, imported, manufactured, marketed, offered for sale, promoted, sold, tested or otherwise distributed by Allurion and its subsidiaries at a rate up to 6.0 % of annual net sales prior to December 31, 2026. On or after January 1, 2027, the Company will remit revenue interest payments at a rate up to 10.0 % of annual net sales, and it will continue to make revenue interest payments to RTW until December 31, 2030. The Company accounts for the Revenue Interest Financing Agreement under the fair value option election of ASC 825. The Revenue Interest Financing Agreement accounted for under the FVO election is a debt host financial instrument that contains embedded features. The embedded features include requirements to settle the Revenue Interest Financing prior to maturity upon the occurrence of certain contingent events, a change in royalty rates upon the occurrence of certain contingent events, and the Company's ability to prepay the Revenue Interest Financing. As the Company has elected the FVO, these embedded features would not meet the criteria for bifurcation and separate accounting as the entire financial instrument is initially measured at its issue-date estimated fair value and then subsequently remeasured at estimated fair value on a recurring basis on each reporting period date. Changes in the estimated fair value of the Revenue Interest Financing Agreement are recorded as a component of Other (expense) income in the consolidated statements of operations. A portion of the estimated change in fair value must be reported in other comprehensive loss to the extent that it is attributable to instrument-specific credit risk. As a result of electing the FVO, direct costs and fees related to the Revenue Interest Financing are expensed as incurred. In connection with the Company entering in the Revenue Interest Financing, the Company and RTW entered into the RTW side letter under which RTW may elect to convert up to $ 7.5 million of its initial PIPE (as defined in Note 3, Business Combination below) subscription into an additional revenue interest financing by forfeiting a number of shares of Allurion Common Stock acquired by the PIPE subscription (the "PIPE Conversion Option"). The Company accounts for the PIPE Conversion Option as a freestanding financial instrument that qualifies for derivative liability accounting in accordance with ASC 815, Derivatives and Hedging ("ASC 815"). The PIPE Conversion Option is initially measured at its fair value within Other liabilities on the consolidated balance sheets with corresponding recognition of expense at inception as there is no right received by the Company that meets the definition of an asset and the transaction did not involve a distribution or a dividend. Subsequent changes in fair value of the derivative liability are recognized as a gain or loss as a component of Other (expense) income in the consolidated statements of operations. Accounts Receivable Accounts receivable are unsecured and are carried at net realizable value, including an allowance for doubtful accounts. Trade credit is generally extended on a short-term basis; trade receivables do not bear interest, although a finance charge may be applied to such receivables that are past due. The allowance for doubtful accounts is based on the Company’s assessment of the collectability of customer accounts. The Company regularly reviews the allowance by considering factors that may affect a customer’s ability to pay, such as historical expense, credit quality, the age of the account receivable balances, and current economic conditions. Amounts determined to be uncollectible are charged or written off against the allowance. The following table summarizes activity in the allowance for doubtful accounts: Year Ended December 31, 2023 2022 Balance at beginning of period $ ( 741 ) $ ( 354 ) Provision for uncollectible accounts ( 12,675 ) ( 436 ) Uncollectible accounts written off 745 49 Balance at end of period $ ( 12,671 ) $ ( 741 ) Revenue Recognition The Company recognizes revenue under ASU No. 2014-09, Revenue from Contracts with Customers (“Topic 606” or “ASC 606”). In general, the Company’s sales contracts fall under its standard sales agreement whereby control transfers to the customer upon shipment, satisfying the performance obligations of the contract. The Company recognizes revenue when control of its products is transferred to customers at an amount that reflects the consideration it expects to receive in exchange for those products. The Company’s revenue recognition process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the transaction price, allocating the transaction price to the distinct performance obligations in the contract, and recognizing revenue as performance obligations are satisfied. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. Performance obligations are considered satisfied once the Company has transferred control of a good or service to the customer, meaning that such customer has the ability to use and obtain the benefit of the good or service. The Company has provided customers purchasing the Allurion Balloon with an implied license for access to its VCS software. This implied software license was given to customers for no additional consideration and was not negotiated as part of the customer’s contracts. Further, the customer contracts and related purchase orders do not include nor specify rights or obligations associated with the VCS software. Based on this assessment, the Company determined the implied license to be immaterial in the context of the contract with customers purchasing the Allurion Balloon, and as such did not allocate any value to the implied VCS license. The Company generates revenue from sales of its Allurion Balloon to distributors and health care providers. Customers typically purchase the Allurion Balloon, including the gastric balloon and related accessories together, although customers can purchase the gastric balloon and its accessories separately. Therefore, each component of the Allurion Balloon and accessories represents a distinct performance obligation and is separately identifiable. In arrangements with multiple performance obligations, the transaction price is allocated to each performance obligation using the relative standalone selling price. The Company determines standalone selling prices based on the price at which the performance obligation is sold separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price taking into account internally approved pricing guidelines and market conditions. Revenue is generally recognized upon shipment of the product because at that point, the customer obtains control of the product and has the ability to direct the use and obtain the benefit of the product. Components of the Allurion Balloon are typically shipped to the customer together, resulting in the performance obligations in the contract being satisfied at the same time. Components shipped separately are recognized upon shipment at their relative standalone selling price. The Company recognizes revenue at the transaction price, which reflects the consideration it believes it is entitled to receive. Transaction price includes estimates of variable consideration for promotions and prompt pay discounts, which are recorded as a reduction of transaction price in the period the related product revenue is recognized. The Company may also make payments to customers for marketing programs. Payments to customers for a distinct good or service that reasonably estimate the fair value of the distinct benefit received, such as marketing programs, are recorded as a marketing expense on the consolidated statement of operations and comprehensive loss. Shipping and logistics costs inclusive of these payments to customers and other costs included in sales and marketing expense for the years ended December 31, 2023 and 2022 were $ 3.3 million and $ 3.6 million , respectively. The Company expenses incremental costs of obtaining a contract, such as sales commissions, when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses in the Company’s consolidated statement of operations and comprehensive loss. The Company has also elected the sales tax practical expedient; therefore, sales and other taxes assessed by a governmental authority that are collected concurrently with revenue-producing activities are excluded from the transaction price. The Company has also elected the significant financing component practical expedient, which allows management to not assess whether the contract has a significant financing component in circumstances where, at contract inception, the expected contract duration is less than one year. Product Warranty The Company does not provide general rights of return of products sold to its customers. However, the Company does provide for rights of exchange to its distributors and end-use customers for products that fail to conform to the Company’s specifications for a limited time following delivery. These performance specifications include that the Allurion Balloon (i) is successfully filled upon initial placement when used according to the instructions for use provided by the Company and/or (ii) remains in the patient’s body for 90 days or more once placed. Customers may exchange product within 30 calendar days if they discover product nonconformities through a reasonable inspection and within 30 calendar days after discovery of any hidden or latent product nonconformities that could not have been discovered by a reasonable inspection. These instances of nonconformity have been immaterial, and the Company’s management expects instances of nonconformity to be extremely rare. Research and Development Costs The Company expenses research and development costs as incurred. Research and development expenses consist of costs associated with performing research and development activities, including salaries and benefits, stock-based compensation, product development costs, materials and supplies, clinical trial activities, depreciation of equipment, and contract and other outside services. Payments for activities that are provided by outside vendors are based upon the terms of the individual arrangements with each vendor. Costs of certain of these activities are expensed based upon an evaluation of the progress to completion of specific tasks and actual costs incurred, using information provided to the Company by its vendors. As payments for these activities may differ from the pattern of costs actually incurred, additional costs are reflected in the consolidated financial statements as prepaid or accrued research and development expenses. Advertising and Marketing Costs The Company expenses advertising and marketing costs as incurred. Advertising and marketing expenses are included in sales and marketing operating expenses. Advertising and marketing costs for the years ended December 31, 2023 and 2022 were $ 10.8 million and $ 16.0 million, respectively. Intellectual Property Prosecution Costs The Company incurs registration and prosecution costs related to its intellectual property. The related costs are expensed as incurred and are classified as a component of general and administrative expenses. Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company’s consolidated financial statements and tax returns. Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for net operating loss and tax credit carryforwards, using enacted tax rates expected to be in effect in the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that these assets may not be realized. The Company determines whether a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. As of December 31, 2023 and 2022, the Company has no t identified any uncertain tax positions for which reserves would be re

Business Combination

Business Combination	12 Months Ended
Business Combination	Dec. 31, 2023
Business Combinations [Abstract]
Business Combination	3. Business Combination As discussed in Note 1, Organization and Basis of Presentation , on August 1, 2023 the Company consummated the Business Combination with Compute Health pursuant to the Business Combination Agreement. The Business Combination was accounted for as a reverse capitalization in accordance with U.S. GAAP. Under this method of accounting, Compute Health, which was the legal acquirer, was treated as the “acquired” company for financial reporting purposes. Accordingly, the Business Combination was treated as the equivalent of Allurion issuing stock for the net assets of Compute Health, accompanied by a recapitalization. Upon the closing of the Business Combination, (a) holders of Legacy Allurion common stock received shares of Allurion Common Stock in an amount determined by application of the Exchange Ratio of approximately 0.9780 , (b) each then-outstanding share of Legacy Allurion preferred stock was converted into the right to receive shares of Allurion Common Stock equal to the number of shares of Allurion Common Stock that would be issued upon conversion of such outstanding share of Legacy Allurion preferred stock based on the applicable conversion ratio multiplied by the Exchange Ratio, (c) each then-outstanding and unexercised Legacy Allurion option was converted into a new Allurion option on the same terms and conditions as were applicable to such Legacy Allurion option based on the Exchange Ratio ("Rollover Option"), (d) each then-outstanding Legacy Allurion warrant was converted into a new Allurion warrant based on the Exchange Ratio ("Rollover Warrant"), (e) each then-outstanding Legacy Allurion restricted stock unit was converted into a rollover restricted stock unit based on the Exchange Ratio, and (f) certain amounts of loans made by Compute Health Sponsor LLC (the "Sponsor") to CPUH, which balance was $ 3.7 million at the time of the Business Combination (the "Sponsor Loan Excess"), was converted into 525,568 shares of Allurion Common Stock (the "Sponsor Loan Equity Issuance"). For periods prior to the Business Combination, the reported share and per share amounts have been retroactively converted by applying the Exchange Ratio. The consolidated assets, liabilities, and results of operations prior to the Business Combination are those of Legacy Allurion. Further, upon the closing of the Business Combination, each then-outstanding share of Compute Health Class A common stock was canceled and extinguished and was converted into the right to receive 1.420455 shares of Allurion Common Stock. Additionally, the Company assumed 13,206,922 outstanding public warrants to purchase an aggregate 18,759,838 shares of Allurion Common Stock at $ 8.10 per share. In connection with the Business Combination, the Company incurred approximately $ 22.7 million of transaction costs, consisting of legal and other professional fees, $ 15.2 million of which were recorded to additional paid-in capital as a reduction of proceeds, $ 2.5 million of which were recorded as debt issuance costs in connection with the Fortress Term Loan (as defined below), and $ 5.0 million of which were recorded as an expense in general and administrative expenses on the consolidated statement of operations and comprehensive loss. Of the $ 5.0 million recorded as expense, $ 3.6 million relates to a one-time insurance payment related to any potential matters that might arise from the period prior to the Business Combination, and as such is not capitalized as an asset. An additional $ 1.2 million relates to direct costs and fees incurred as part of the Revenue Interest Financing with RTW. The following table reconciles the elements of the Business Combination to the consolidated statement of cash flows and the consolidated statement of changes in equity: December 31, 2023 Cash – CPUH trust (net of redemptions) $ 38,395 Cash – PIPE Investors 37,922 Gross Proceeds 76,317 Less: transaction costs paid ( 14,665 ) Net proceeds from the Business Combination (1) 61,652 Less: warrant liabilities assumed (2) ( 13,762 ) Less: repayment of note assumed in the Business Combination (1) ( 2,500 ) Less: accrued transaction costs at December 31, 2023 (1) ( 580 ) Business Combination, net of transaction costs $ 44,810 (1) The Net proceeds from the Business Combination, less the repayment of note assumed in the Business Combination, less the accrued transaction costs at December 31, 2023 are presented net in the consolidated statements of stockholders deficit within line "Reverse recapitalization, net of transaction costs (Note 3)". (2) The warrant liabilities assumed are presented separately from the "Reverse recapitalization, net of transaction costs (Note 3)" line within the consolidated statements of stockholders deficit. The number of shares of Allurion Common Stock outstanding immediately following the consummation of the Business Combination was as follows: Common Stock Legacy Allurion Equityholders (1) 27,897,387 CPUH Stockholders (2) 5,165,698 Shares Issued to PIPE Investors (2) 5,386,695 Shares issued to RTW and Fortress (3) 1,900,000 Shares issued to convertible note holders 3,301,222 CPUH Sponsor Shares (2) 3,262,711 Side Letter Termination Shares (3) 387,696 Total shares of Common Stock immediately after Business Combination 47,301,409 (1) Consists of Legacy Allurion common stock and Legacy Allurion preferred stockholders, plus the issuance of common stock in connection with the vesting of RSUs at closing, less the Gaur Contributed Shares (as defined below). (2) The CPUH Stockholders shares, PIPE shares, and CPUH Sponsor shares are presented combined within the consolidated statements of redeemable convertible preferred stock and stockholders deficit on the "Reverse recapitalization, net of transaction costs" line, which is less the Gaur Contributed Shares (as defined below). (3) The shares issued to RTW and Fortress and the Side Letter Termination shares are presented combined within the consolidated statements of redeemable convertible preferred stock and stockholders deficit on the "Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and additional RTW and Fortress shares and issuance of related shares" line. PIPE Investment In connection with the execution of the Business Combination Agreement, Allurion and Compute Health entered into subscription agreements, each dated February 9, 2023 (the “PIPE Subscription Agreements”), with certain accredited investors and qualified institutional buyers (the “PIPE Investors”), pursuant to which, upon the terms and subject to the conditions set forth therein, the PIPE Investors, among other things, purchased an aggregate of 5,386,695 shares of Allurion Common Stock at a purchase price of $ 7.04 per share (other than as set forth in the Amended and Restated RTW Side Letter, as defined below), for an aggregate purchase price of $ 37.9 million, following the CPUH Merger Effective Time (the "PIPE Investment"). Revenue Interest Financing Agreement, Side Letter and PIPE Conversion Option On February 9, 2023, concurrently with the execution of the Business Combination Agreement, the Company entered into the Revenue Interest Financing Agreement with RTW. Pursuant to the Revenue Interest Financing Agreement, at the closing of the Business Combination, RTW paid Allurion an aggregate of $ 40.0 million (the “Investment Amount”). In exchange for the Investment Amount, Allurion will remit revenue interest payments on all current and future products, digital solutions and services developed, imported, manufactured, marketed, offered for sale, promoted, sold, tested or otherwise distributed by Allurion and its subsidiaries at a rate up to 6.0 % of annual net sales prior to December 31, 2026. On or after January 1, 2027, the Company will remit revenue interest payments at a rate up to 10.0 % of annual net sales, and it will continue to make revenue interest payments to RTW until December 31, 2030. Additionally, in connection with the Company entering in the Revenue Interest Financing, the Company, Compute Health, Legacy Allurion, Merger Sub II and RTW entered into a side letter (the "RTW Side Letter") on February 9, 2023 under which RTW may elect to convert up to $ 7.5 million of its initial PIPE subscription into an additional revenue interest financing by forfeiting a number of shares of Allurion common stock acquired by its PIPE Investment. Refer to Note 9, Revenue Interest Financing, Side Letter, and PIPE Conversion Option below for further discussion on the Revenue Interest Financing. On May 2, 2023, the parties amended and restated the RTW Side Letter (as amended, the "Amended and Restated RTW Side Letter"), in connection with the Backstop Agreement (defined below), pursuant to which, among other things, Allurion issued 250,000 shares of Allurion Common Stock to RTW immediately prior to the Intermediate Merger Effective Time. Fortress Credit Agreement In connection with the closing of the Business Combination, the Company entered into a term loan facility (the “Fortress Term Loan”) pursuant to a credit agreement and guaranty, dated as of August 1, 2023 (the “Fortress Credit Agreement”), with Fortress Credit Corp. (“Fortress”), as administrative agent for the lenders party thereto from time to time (the “Lenders”). Under the terms of the Fortress Term Loan, we borrowed $ 60.0 million which was used to repay the outstanding principal, accrued and unpaid interest, and other obligations with respect to the 2021 Term Loan (as defined below). Additionally, per the terms of the Fortress Term Loan and Backstop Agreement, Allurion issued an aggregate of 950,000 shares of Allurion Common Stock to an affiliate of Fortress pursuant to a subscription agreement between Allurion and such affiliate. Refer to Note 8, Debt for further discussion on the Fortress Term Loan. Backstop Agreement On May 2, 2023, CFIP2 ALLE LLC, an affiliate of Fortress Credit Corp., and RTW (collectively, the “Backstop Purchasers”), Legacy Allurion, Allurion and Hunter Ventures Limited (“HVL”) entered into the backstop agreement (the “Backstop Agreement”). Pursuant to the Backstop Agreement, immediately prior to the Intermediate Merger Closing (a) each Backstop Purchaser purchased $ 2 million of the aggregate principal amount outstanding of HVL's Legacy Allurion convertible note issued in February 2023, (b) Allurion canceled the existing HVL Legacy Allurion Convertible Note and issued a new Allurion Convertible Note to HVL for the remaining balance together with all unpaid interest accrued since the date of issuance thereof, (c) Allurion issued new Allurion Convertible Notes to each Backstop Purchaser with an issuance date of August 1, 2023 and an original principal amount of $ 2 million each and (d) Allurion issued 700,000 shares of Allurion Common Stock to each Backstop Purchaser. Refer to Note 8, Debt for further discussion around the Backstop Agreement. HVL Termination Agreement On May 2, 2023, HVL and Legacy Allurion entered into a letter agreement (the “HVL Termination Agreement”), terminating the side letter agreement entered into between Legacy Allurion and HVL in connection with the issuance of HVL’s Legacy Allurion convertible note on February 15, 2023. Pursuant to the HVL Termination Agreement, among other things, at the closing of the Business Combination, upon the terms and subject to the conditions set forth therein, Allurion issued to HVL 387,696 shares of Allurion Common Stock. Refer to Note 8, Debt for further discussion regarding the HVL Termination Agreement. Gaur Contribution Agreement On May 2, 2023, Shantanu K. Gaur and Neha Gaur, trustees of The Shantanu K. Gaur Revocable Trust of 2021 (the “Gaur Trust”) and Allurion entered into a contribution agreement (the “Gaur Contribution Agreement”), pursuant to which, among other things, upon the terms and subject to the conditions set forth therein, the Gaur Trust contributed to Allurion, as a contribution of capital, 79,232 shares of Allurion Common Stock (the “Gaur Trust Contributed Shares”). The Gaur Trust’s contribution of the Gaur Trust Contributed Shares was effective immediately following the consummation of the Business Combination and the issuance of shares of Allurion Common Stock to the Gaur Trust pursuant to the terms of the Business Combination Agreement. RSU Forfeiture Agreement On May 2, 2023, Krishna Gupta, a member of our Board of Directors, entered into a letter agreement with Legacy Allurion (the “RSU Forfeiture Agreement”), pursuant to which, among other things, upon the terms and subject to the conditions set forth therein, Mr. Gupta agreed to forfeit 79,232 restricted stock units of Allurion (the “Forfeited RSUs”). The Forfeited RSUs were terminated and cancelled without consideration therefore immediately following the closing of the Business Combination Agreement. Sponsor Contribution Agreement On May 2, 2023, the Sponsor and Compute Health entered into a letter agreement (the "Sponsor Contribution Agreement") pursuant to which, among other things, upon the terms and subject to the conditions set forth therein, the Sponsor agreed to contribute to Compute Health, as a contribution of capital, 161,379 shares of Compute Health Class A Common Stock (“Sponsor Contributed Shares”). The Sponsor’s contribution of the Sponsor Contributed Shares was made immediately following the CPUH Recapitalization (defined below) and immediately prior to the CPUH Merger Effective Time. Sponsor Support Agreement On February 9, 2023, Allurion entered into a support agreement (the "Sponsor Support Agreement"), pursuant to which immediately prior to the CPUH Merger Effective time, (a) the Sponsor recapitalized each of the Sponsor’s 21,442,500 shares of Compute Health Class B Common Stock, and all 12,833,333 of the Sponsor’s warrants to purchase shares of Class A Common Stock, into 2,088,327 shares of Compute Health Class A Common Stock and (b) the additional Class B Holders set forth on Schedule I of the Sponsor Support Agreement (the "Additional Class B Holders") recapitalized his or her 30,000 shares of Compute Health Class B Common Stock into 21,120 shares of Compute Health Class A Common Stock (the "CPUH Recapitalization"). Subsequently, at the CPUH Merger Effective Time, each such share of Compute Health Class A Common Stock was converted into shares of Allurion Common Stock at an exchange ratio of 1.420455 (the "CPUH Exchange Ratio"). Conversion of Convertible Notes In connection with the closing of the Business Combination, outstanding Legacy Allurion Convertible Notes with an aggregate principal amount together with accrued but unpaid interest of approximately $ 21.8 million were converted into 3,301,222 shares of Allurion Common Stock with a corresponding recognition of additional paid-in capital ("APIC") of $ 25.6 million provided for under the terms of such Legacy Allurion Convertible Notes, and are no longer outstanding. Refer to Note 8, Debt for further information on the Company's convertible notes. Public Warrants and Warrant Amendment In connection with the closing of the Business Combination, the Company assumed 13,206,922 outstanding Public Warrants (defined below) to purchase an aggregate 18,759,838 shares of Allurion Common Stock at $ 8.10 per share following the Warrant Amendment (defined below). The total value of the liability associated with the Public Warrants was $ 13.8 million measured at fair value based on the public warrant quoted price. The Company concluded the warrants met the definition of a liability based on the settlement provision that allows the warrant holders to net-share settle their warrants in the event of a failed registration statement within 60 days of the Business Combination or any time a registration is not effective. As such, they have been classified as a liability on the balance sheet. See Note 12, Capital Stock and Stockholders' Deficit and Note 10, Fair Value Measurements for further information on the Public Warrants and Warrant Amendment. Earn-Out Liabilities In connection with the closing of the Business Combination, Legacy Allurion equity holders are entitled to receive additional shares of Allurion Common Stock if the shares price achieves certain targets. The Company accounts for the potential issuance of the Earn-Out Shares as a contingent consideration arrangement, which was initially valued and recorded at $ 53.0 million. See Note 10, Fair Value Measurements for further information on the earn-out liabilities.

Revenue

Revenue	12 Months Ended
Revenue	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue	4. Revenue Revenue by geographic region is based on the country in which our customer is domiciled and is summarized by geographic area as follows (in thousands): Year Ended December 31, 2023 2022 France $ 5,569 $ 6,032 Turkey 5,494 4,079 Spain 4,618 6,852 Chile 2,708 5,008 All other countries 35,078 42,240 Total Revenues $ 53,467 $ 64,211 There is currently no revenue generated in the United States. For the year ended December 31, 2023, $ 13.3 million of revenue was generated in four countries included within All other countries in the table above, representing approximately 25 % of Total Revenues, with each country responsible for approximately 5 %- 9 % of the total. The remaining revenue was generated by sales in 55 other countries included within All other countries. For the year ended Dece mber 31, 2022, $ 16.0 million of revenue was generated in four countries included within All other countries, representing approximately 25 % of Total Revenues, with each country responsible for approximately 6 %- 7 % of the total. Remaining revenue was generated by sales in 50 other countries included within All other countries.

Inventory

Inventory	12 Months Ended
Inventory	Dec. 31, 2023
Disclosure Text Block [Abstract]
Inventory	5. Inventory Inventory consists of the following (in thousands): December 31, 2023 2022 Finished goods $ 3,427 $ 2,096 Work in progress 967 213 Raw materials 1,777 1,556 Total Inventory $ 6,171 $ 3,865 Inventory is stated net of less than $ 0.1 million and zero for the provision of excess and obsolete inventory as of December 31, 2023 and 2022, respectively.

Property and Equipment, net

Property and Equipment, net	12 Months Ended
Property and Equipment, net	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, net	6. Property and Equipment, net Property and equipment consist of the following (in thousands): December 31, Estimates Useful Life (in Years) 2023 2022 Computers and purchased software 3 $ 618 $ 575 Leasehold improvements Shorter of useful life 1,943 1,822 Furniture and fixtures 5 291 251 Machinery and equipment 3 - 5 2,893 2,002 Property and equipment—at cost 5,745 4,650 Less accumulated depreciation and amortization ( 3,559 ) ( 2,851 ) Construction in progress 1,195 583 Property and equipment—net $ 3,381 $ 2,382 Depreciation expense was $ 0.7 million and $ 0.9 million for the years ended December 31, 2023 and 2022, respectively, recorded as follows (in thousands): Year Ended December 31, 2023 2022 Cost of revenue $ 367 $ 568 Research and development 179 90 General and administrative 138 160 Sales and marketing 62 57 Total depreciation and amortization expense $ 746 $ 875

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
Accrued Expenses and Other Current Liabilities	Dec. 31, 2023
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses and Other Current Liabilities	7. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2023 2022 Distributor fees and marketing reimbursements $ 2,834 $ 6,348 Accrued compensation 1,687 3,453 Accrued clinical trials and R&D 3,694 228 Accrued selling and marketing 1,110 481 Accrued professional fees 1,505 2,105 Accrued interest — 489 Accrued warranty 44 48 Accrued restructuring 655 — Other accrued expenses 3,966 2,641 Total accrued expenses and other current liabilities $ 15,495 $ 15,793 In connection with strategic initiatives implemented during the period ended December 31, 2023, the Company's management approved and initiated plans to reduce its cost structure. The Company recorded $ 1.0 million of restructuring charges during the year ended December 31, 2023, of which $ 0.4 million has been paid as of December 31, 2023. The restructuring charges are included in operating expenses in the statement of operations. Substantially all of this charge represents the severance cost of terminated employees.

Debt

Debt	12 Months Ended
Debt	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt	8. Debt The components of the Company’s third-party debt consisted of the following (in thousands): December 31, 2023 2022 Fortress Term Loan $ 43,100 $ — 2021 Term Loan — 55,000 Convertible Notes — 3,103 Total principal amounts of debt 43,100 58,103 Plus: Accretion 148 213 Less: current portion of long-term debt, net of discounts ( 38,643 ) ( 53,360 ) Less: unamortized deferred financing costs and debt discounts ( 4,605 ) ( 1,853 ) Long-term debt, net of current portion and discounts $ — $ 3,103 As of December 31, 2023 and 2022, the fair value for the Company’s Fortress Term Loan and 2021 Term Loan approximated the respective carrying amounts. Term Loans 2021 Term Loan In March 2021, the Company entered into a loan and security agreement (as amended, the “2021 Term Loan” and the “2021 Term Loan Agreement”) with Runway Growth Credit Fund, Inc. (“Runway”) that provided initial cash proceeds of $ 15.0 million, all of which was drawn down in March 2021 and provided for additional borrowings of up to $ 10.0 million, in $ 5.0 million increments, based upon the achievement of certain revenue thresholds within specified time periods, as defined in the 2021 Term Loan Agreement. In December 2021, the 2021 Term Loan Agreement was amended (the “Amendment”) to extend the maturity date of the 2021 Term Loan to December 30, 2025 and provide for an additional $ 20.0 million of borrowings, of which $ 15.0 million (the “Term C Loan”) was available based upon the achievement of certain revenue thresholds within specified time periods as defined in 2021 Term Loan Agreement as amended. The agreement provided for equal monthly principal payments to commence on December 30, 2024 such that the borrowed principal amounts would be repaid in full on December 30, 2025. However, if certain revenue thresholds were achieved prior to April 15, 2023, the borrowed principal amounts would be repaid in full on December 30, 2025. The revenue thresholds were achieved in June 2022 . In connection with the 2021 Term Loan, the Company paid issuance costs of $ 0.7 million which were amortized over the remaining life of the loan. In December 2021, the Company issued warrants exercisable for 132,979 shares of Legacy Allurion Series C preferred stock as consideration for the Amendment and the draw down related to the 2021 Term Loan Agreement. The fair value of these warrants was determined to be $ 0.3 million upon issuance and are classified as a warrant liability on the consolidated balance sheet as of December 31, 2023 and 2022 (see Note 10, Fair Value Measurements ). Upon the closing of the Business Combination, these warrants were converted into warrants exercisable for 130,053 shares of Allurion Common Stock. In June 2022, the 2021 Term Loan Agreement was amended to revise definitional terms for certain milestone events, the final payment amount and financial covenant. In September 2022, the 2021 Term Loan Agreement was further amended to, among other things: (1) change the interest rate to the higher of the prime rate or 3.25 % plus the applicable margin of 6.44186 %, (2) extend the maturity date of its outstanding term loans from December 30, 2025 to December 30, 2026 , and (3) increase additional borrowing up to $ 15.0 million (the “Term D Loan”). During June through September of 2022, the Company drew an additional $ 15.0 million of the Term C Loan based upon the achievement of certain revenue thresholds under the amended and restated provisions of the 2021 Term Loan. In connection with the Term C Loan under the 2021 Term Loan, the Company paid issuance costs of $ 0.3 million, which were amortized over the remaining life of the loan. Upon the additional $ 15.0 million draw on the Term C Loan, warrants exercisable for 44,220 shares of Series D-1 preferred stock were issued. In 2022, the Company recorded a warrant liability of $ 0.4 million in connection with the Term C Loan on the consolidated balance sheets. In September 2022, in connection with the amendment of the 2021 Term Loan, the Company committed to issue warrants exercisable for an additional 44,220 shares of Series D-1 preferred stock if the Company drew on the entire Term D Loan. The fair value of these warrants was determined to be $ 0.4 million upon issuance and are classified as a warrant liability on the consolidated balance sheets as of December 31, 2023 and 2022 (see Note 10, Fair Value Measurements ). Upon the closing of the Business Combination, the warrants exercisable for 88,440 shares of Series D-1 preferred stock were converted into warrants exercisable for 90,476 shares of Allurion Common Stock. During October through December of 2022, the Company drew an additional $ 15.0 million of the Term D Loan based upon the achievement of certain revenue thresholds under the amended and restated provisions of the 2021 Term Loan. On August 1, 2023, the 2021 Term Loan was paid off using the proceeds from the Fortress Term Loan (see below). The total payoff amount was $ 58.0 million, consisting of $ 55.0 million repayment of principal, a $ 1.1 million prepayment fee, and a $ 1.6 million final payment fee. The prepayment fee was calculated as 2 % of the outstanding principal balance as of August 1, 2023. The final payment fee was calculated as 3 % of the outstanding principal balance as of August 1, 2023 less the original final payment of $ 0.1 million. The Company recorded a $ 3.9 million loss on extinguishment of debt in connection with the 2021 Term Loan repayment. Interest expense for the year ended December 31, 2023 related to the 2021 Term Loan was $ 5.0 million, consisting of $ 4.7 million of contractual interest, $ 0.1 million amortization of debt discount, $ 0.1 million amortization of warrant, and $ 0.1 million term loan accretion. Interest expense for the year ended December 31, 2022 was $ 4.3 million, consisting of $ 3.8 million of contractual interest, $ 0.2 million amortization of debt discount, $ 0.1 million amortization of warrant, and $ 0.2 million term loan accretion. Fortress Term Loan On August 1, 2023, the Company entered into the Fortress Term Loan pursuant to the Fortress Credit Agreement with Fortress that provided gross proceeds of $ 60 million. The Fortress Term Loan has a maturity date of June 30, 2027 and accrues interest per annum at a rate of 6.44 % plus the greater of (i) the Wall Street Journal Prime Rate and (ii) 3.0 %, which interest is payable in arrears on a monthly basis. An exit payment equal to 3.0 % of the Fortress Term Loan (the "Exit Fee") is due upon prepayment or the maturity date of the Fortress Term Loan, in addition to any early prepayment fee. The Exit Fee is treated as additional interest expense and is accreted over the life of the loan using the effective interest method. Proceeds of the Fortress Term Loan were used, in part, to repay all amounts outstanding under the 2021 Term Loan. In connection with the issuance of the Fortress Term Loan, the Company paid issuance costs of $ 2.5 million, which were recorded as a debt discount and will be amortized over the remaining life of the loan. On December 29, 2023, the Company entered into an amendment to the Fortress Credit Agreement (the "Fortress Amendment"). The Fortress Amendment waived the December 31, 2023 minimum revenue covenant under the Fortress Credit Agreement and modified the minimum liquidity covenant by increasing the minimum liquidity amount from $ 12.5 million to $ 33.5 million until March 31, 2024, $ 23.5 million from April 1, 2024 to June 30, 2024, $ 16.9 million from July 1, 2024 to September 30, 2024 and $ 12.5 million on October 1, 2024 and thereafter. The Fortress Amendment also provides that at any time after March 31, 2024, each lender will have the right to convert a portion of the outstanding principal amount, not to exceed the lender's proportionate share of a maximum of $ 20.0 million in aggregate outstanding principal amount, into shares of Common Stock of the Company at a conversion price based on the 30-day volume weighted average price ("VWAP") of the Common Stock on the NYSE ending on the trading day immediately preceding the date of exercise of the lender's conversion right (the "Fortress Conversion Option"). As part of the Fortress Amendment , the Company prepaid $ 20.0 million of the principal outstanding under the Fortress Credit Agreement. Additionally, $ 3.1 million of fees were incurred and considered paid-in-kind and capitalized as an additional debt discount and added to the outstanding principal amount of the loans under the Fortress Amendment. The fees will be amortized through interest expense over the remaining life of the loan. The Fortress Amendment was accounted for as a modification under ASC 470. In connection with the modification and related prepayment, the Company wrote off $ 0.8 million of the unamortized debt issuance costs which was recorded within Interest expense on the consolidated statement of operations. The Fortress Credit Agreement contains certain financial reporting and other covenants, including the maintenance of a minimum liquidity amount and maintenance of minimum product revenues over trailing twelve-month periods. Upon the occurrence of an event of default, the Lenders may declare all outstanding obligations immediately due and payable as well as increase the interest rate 3.0 % above the rate that is otherwise applicable. The Company has determined that there is substantial doubt about the Company's ability to continue as a going concern (see Note 1, Organization and Basis of Presentation ) and there is a risk that it may not meet its covenants under the Fortress Term Loan in the future. Therefore, the amounts due as of December 31, 2023 have been classified as a current liability in the consolidated financial statements. The Company is in compliance with all covenants as of December 31, 2023. The Company assessed the terms and features of the Fortress Credit Agreement in order to identify any potential embedded features that would require bifurcation or any beneficial conversion features. The terms and features assessed include, under certain circumstances, a default interest rate of 3 % which will apply to all outstanding obligations during the occurrence and continuance of an event of default. In accordance with ASC 815, the Company concluded that this feature is not clearly and closely related to the host instrument and represents an embedded derivative (the "Term Loan Derivative Liability") that is required to be re-remeasured at fair value on a quarterly basis. At the inception of the Fortress Term Loan, the fair value of the embedded derivative was determined to be immaterial. The fair value of the Term Loan Derivative Liability was $ 1.9 million as of December 31, 2023, with a corresponding recognition of Other income (expense), net in the consolidated statement of operations. The Company classified the Term Loan Derivative Liability as a non-current liability within Other liabilities on the balance sheet as of December 31, 2023. Interest expense from August 1, 2023 through December 31, 2023 related to the Fortress Term Loan was $ 4.1 million, consisting of $ 3.8 million of contractual interest, $ 0.2 million amortization of the debt discount, and term loan accretion of $ 0.1 million. The average interest rate of the Fortress Term Loan during the year ended December 31, 2023 was 14.94 %. Scheduled future maturities of the Fortress Term Loan for years subsequent to December 31, 2023 are as follows (in thousands): December 31, 2024 — December 31, 2025 — December 31, 2026 8,979 December 31, 2027 34,121 $ 43,100 Convertible Notes 2021 Convertible Notes In December 2021, the Company entered into a convertible note agreement with an investor for gross proceeds of $ 2.0 million with a stated interest rate of 5.0 % per annum (the “2021 Convertible Notes”) and a maturity date 36 months from the date of issuance unless previously converted pursuant to their terms of the agreement. No issuance costs were incurred. The 2021 Convertible Notes provided that, effective upon either a Special Purpose Acquisition Company (i.e. “deSPAC”) transaction, closing of a qualified financing, or closing of a non-qualified financing, all of the outstanding principal and interest would automatically convert into common shares or shares of the same class or series of capital stock issued in the qualified financing in an amount equal to the balance of the 2021 Convertible Notes on the date of conversion divided by the capped conversion price, which is calculated by dividing $ 600.0 million by the fully diluted capitalization of the Company immediately prior to the conversion of the 2021 Convertible Notes. Interest expense for the years ended December 31, 2023 and 2022 related to the 2021 Convertible Notes was $ 0.1 million, consisting entirely of contractual interest . Interest expense related to the 2021 Convertible Notes is recorded within Interest expense on the consolidated statement of operations and comprehensive loss. On August 1, 2023, in connection with the closing of the Business Combination, the outstanding 2021 Convertible Notes were converted into an aggregate 133,617 shares of Allurion Common Stock with a corresponding recognition of APIC of $ 2.2 million, and are no longer outstanding. 2022 Convertible Notes In January 2022, the Company entered into a convertible note agreement with investors for gross proceeds of $ 1.1 million with a stated interest rate of 5.0 % per annum (the “2022 Convertible Notes”). The 2022 Convertible Notes mature 36 months from the issuance date unless previously converted pursuant to their terms of the agreement. Issuance costs were de minimis. The 2022 Convertible Notes had the same terms as the 2021 Convertible notes. Interest expense for the years ended December 31, 2023 and 2022 related to the 2022 Convertible Notes wa s less than $ 0.1 million and $ 0.2 million, respectively, consisting entirely of contractual interest. Interest expense related to the 2022 Convertible Notes is recorded within Interest expense on the consolidated statement of operations and comprehensive loss. On August 1, 2023, in connection with the closing of the Business Combination, the outstanding 2022 Convertible Notes were converted into an aggregate 83,216 shares of Allurion Common Stock with a corresponding recognition of APIC of $ 1.2 million, and are no longer outstanding. 2023 Convertible Notes Between February and August 2023, the Company entered into a convertible note purchase agreement, and related side letters, for the sale of the 2023 Convertible Notes to certain investors for gross proceeds of $ 28.7 million, with a stated interest rate of 7.0 % per annum. The 2023 Convertible Notes provided that they would mature on December 31, 2026 unless previously converted pursuant to the terms of their agreement. The 2023 Convertible Notes also provided that, effective upon a deSPAC transaction, all of the outstanding principal and interest would automatically convert into a number of shares of common stock equal to the balance of the 2023 Convertible Notes on the date of conversion divided by the discounted capped conversion price, which is calculated by dividing $ 217.3 million by the fully diluted capitalization of the Company immediately prior to the conversion of the 2023 Convertible Notes. Additionally, the 2023 Convertible Notes provide that, effective upon the closing of a qualified financing, holders of the 2023 Convertible Notes could optionally accelerate repayment of the principal and interest of the 2023 Convertible Notes or convert all of the outstanding principal and interest into common shares or shares of the same class or series of capital stock issued in the qualified financing equal to the balance of the 2023 Convertible Notes on the date of conversion divided by the greater of the capped price or the discounted price. The capped price is calculated by dividing $ 260.0 million by the fully diluted capitalization of the Company immediately prior to the conversion of the 2023 Convertible Notes, and the discounted price is calculated as 85 % of the cash price of the same class or series of capital stock issued in the qualified financing. The 2023 Convertible Notes are accounted for under the FVO election of ASC 825 as the notes contain embedded derivatives including the automatic conversion upon a deSPAC transaction prior to the deSPAC deadline, voluntary conversion upon a qualified financing, automatic repayment upon a sale event, and conversion rate adjustment, which would require bifurcation and separate accounting. These convertible notes are initially measured at their issue-date estimated fair value and subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. Interest expense for the year ended December 31, 2023 related to the 2023 Convertible Notes was $ 0.5 million, consisting entirely of contractual interest. Interest expense related to the 2023 Convertible Notes is recorded within Interest expense on the consolidated statement of operations and comprehensive loss. On May 2, 2023 the Company entered into termination agreements (the “Termination Agreements”) with respect to side letters entered into with certain holders of Legacy Allurion Convertible Notes. With respect to the Termination Agreement with one of the side letter holders (the “Side Letter Holder”), the Company had the right to prepay, in one or more transactions, all or a portion of the outstanding principal amount, plus accrued interest, under the 2023 Convertible Note (the “Side Letter Holder Bridge Note”), including by way of (a) a $ 2 million payment in cash by the Company to the Side Letter Holder on May 2, 2023, $ 1.5 million of which is deemed a prepayment penalty and recorded as other expense on the income statement, with the remaining $ 0.5 million recorded as a reduction of the principal amount, (b) immediately prior to the consummation of the transactions contemplated by the Business Combination Agreement, an additional payment of at least $ 6 million, up to the then-outstanding principal amount, plus accrued interest, under the Side Letter Holder Bridge Note by way of (i) payment in cash by the Company and/or (ii) the sale and transfer of all or any portion of the Side Letter Holder Bridge Note, equivalent in value to the portion of the additional payment to be repaid pursuant to this clause (b)(ii), to any person or persons designated in writing by the Company. The Termination Agreements were accounted for as a modification of debt and the modified convertible notes continued to be accounted for under the FVO with any change in fair value recognized in other expense on the income statement. In addition, under the Termination Agreement executed with the Side Letter Holder, the Company agreed to issue to the Side Letter Holder a number of shares of Allurion Common Stock (“PubCo Additional Shares”) equal to (a) the outstanding principal and accrued interest under the Side Letter Holder Bridge Note immediately prior to the consummation of the transactions contemplated by the Business Combination Agreement (after giving effect to the payment of the repayments) divided by $ 5.00 , plus (b) 300,000 shares of Allurion Common Stock. The PubCo Additional Shares were accounted for as a freestanding financing liability. The liability for the PubCo Additional Shares is initially measured at its issue-date estimated fair value and subsequently remeasured at fair value at each reporting period with changes in fair value reflected in earnings until the PubCo Additional Shares are issued. A $ 3.4 million liability was recorded at issuance for the PubCo Additional Shares as Other liabilities on the consolidated balance sheet and the related expense recorded through Other income (expense) on the consolidated statement of operations and comprehensive loss for the year ended December 31, 2023. On August 1, 2023, upon closing of the Business Combination, the Side Letter Holder was issued 387,696 PubCo Additional Shares with a corresponding recognition of APIC of $ 2.7 million, and the liability is no longer outstanding. Further on May 2, 2023, RTW and Fortress (the “Backstop Purchasers”) entered into the Backstop Agreement with the Company, Legacy Allurion and the Side Letter Holder. Pursuant to the Backstop Agreement, each Backstop Purchaser agreed that to the extent any Side Letter Holder Bridge Notes remain outstanding prior to the consummation of the Business Combination, such Backstop Purchaser will, at the closing of the Business Combination, purchase up to $ 2.0 million of the Side Letter Holder Bridge Notes from the Side Letter Holder in exchange for shares of Allurion Common Stock (the “Base PubCo Shares”, “Backstop Shares” and “Conditional Additional PubCo Shares”). The Base PubCo Shares and Backstop Shares were accounted for as a freestanding financing liability. The Base PubCo Shares and Backstop Shares liability is initially measured at its issue-date estimated fair value and subsequently remeasured at fair value at each reporting period with changes in fair value reflected in earnings until the Base PubCo Shares and Backstop Shares are issued. A $ 3.3 million liability was recorded at issuance for the Base PubCo Shares and Backstop Shares liability as Other liabilities on the consolidated balance sheet. On August 1, 2023, upon closing of the Business Combination, per the terms of the Fortress Term Loan, the Amended and Restated RTW Side Letter and the Backstop Agreement, the Backstop Purchasers were each issued 950,000 shares of Allurion Common Stock with a corresponding recognition of APIC of $ 13.4 million, and the liability is no longer outstanding. On August 1, 2023, immediately prior to the closing of the Business Combination, the Company repaid $ 6.3 million of the Side Letter Holder Bridge Note, leaving a principal balance of $ 6.3 million. Each Backstop Purchaser then purchased $ 2.0 million principal amount of the outstanding portion of the Side Letter Holder Bridge Note, Allurion canceled the existing Side Letter Holder Bridge Note and issued a new convertible note to the Side Letter Holder for the remaining balance together with all unpaid interest accrued since the date of issuance of $ 2.7 million, Allurion issued convertible notes to each Backstop Purchaser with an issuance date of the Closing Date (August 1, 2023) and an original principal amount of $ 2.0 million each and Allurion issued 700,000 shares of Allurion Common Stock to each Backstop Purchaser. Additionally, the outstanding 2023 Convertible Notes were converted into an aggregate 3,084,389 shares of Allurion Common Stock with a corresponding recognition of APIC of $ 22.2 million, and are no longer outstanding.

Revenue Interest Financing, Sid

Revenue Interest Financing, Side Letter, and PIPE Conversion Option	12 Months Ended
	Dec. 31, 2023
Contract with Customer, Liability [Abstract]
Revenue Interest Financing, Side Letter, and PIPE Conversion Option	9. Revenue Interest Financing, Side Letter, and PIPE Conversion Option On February 9, 2023, Legacy Allurion entered into the Revenue Interest Financing Agreement. Pursuant to the Revenue Interest Financing, at the closing of the Business Combination, RTW paid Allurion an aggregate of $ 40.0 million Investment Amount. In exchange for the Investment Amount, Allurion will remit revenue interest payments on all current and future products, digital solutions and services developed, imported, manufactured, marketed, offered for sale, promoted, sold, tested or otherwise distributed by Allurion and its subsidiaries at a rate up to 6.0 % of annual net sales prior to December 31, 2026. On or after January 1, 2027, the Company will remit revenue interest payments at a rate up to 10.0 % of annual net sales, and it will continue to make revenue interest payments to RTW until December 31, 2030. If RTW has not received aggregate revenue interest payments equal to at least 100 % of the Investment Amount by December 31, 2027, the Company must make a cash payment in an amount sufficient to catch RTW up to 100 % of the Investment Amount. If RTW has not received revenue interest payments equal to at least 240 % of the Investment Amount by December 31, 2030, the Company must make a cash payment in an amount sufficient to catch RTW up to 240 % of the Investment Amount. In any event, RTW shall not receive aggregated revenue interest payments in excess of 260 % of the Investment Amount (the "Hard Cap"). In addition, prior to December 31, 2025, the Company may prepay a pre-specified payment amount (the "Prepayment Amount") and terminate the Revenue Interest Financing Agreement. The Prepayment Amount shall be an amount equal to 165 % of the Investment Amount less the sum of all revenue interest payments made to RTW prior to such date of prepayment. The Revenue Interest Financing is accounted for under the FVO election of ASC 825 as the Revenue Interest Financing contains embedded derivatives, including the requirements to settle the Revenue Interest Financing prior to maturity upon the occurrence of certain contingent events and our ability to prepay the Revenue Interest Financing, which would require bifurcation and separate accounting. The Revenue Interest Financing is initially measured at its issue-date estimated fair value and subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. Changes in fair value are recorded as a component of Other (expense) income in the consolidated statements of operations. A portion of the estimated change in fair value must be reported in other comprehensive loss to the extent that it is attributable to instrument-specific credit risk. For the year ended December 31, 2023, the Company recorded a $ 3.4 million gain and a $ 0.7 million loss through the consolidated statements of operations and other comprehensive loss, respectively. In connection with the issuance of the Investment Amount, we paid $ 1.2 million in issuance costs, which were directly expensed through general and administrative expense due to the FVO election. As of December 31, 2023, the Company has made $ 1.1 million in royalty payments to RTW. Concurrently and in connection with the Revenue Interest Financing and PIPE Subscription Agreement (as discussed in Note 3, Business Combination ), on February 9, 2023, Legacy Allurion entered into the RTW Side Letter with RTW, subsequently amended on May 2, 2023. The Amended and Restated RTW Side Letter amended and restated the existing RTW Side Letter in its entirety, in order to reflect that any conditional additional shares issuable to RTW would be calculated net of any Backstop Shares issuable to RTW under the Backstop Agreement. Refer to Note 8, Debt for discussion around the additional shares issued to RTW in connection with the Amended and Restated RTW Side Letter and Backstop Agreement. In connection with the Company entering into the Revenue Interest Financing, if, at any time beginning 12 months and ending 24 months following the closing of the Mergers, the VWAP per share of Allurion Common Stock is less than $ 7.04 for the average of 20 trading days within any 30 trading day period (“Stock Price Drop”); and the absolute value of the percentage decrease of such Stock Price Drop measured from a reference price of $ 10.00 per share of Allurion Common Stock is greater than the absolute value of the percentage decrease in the VWAP of a comparable publicly traded peer index as defined in the Amended and Restated RTW Side Letter over the same time period, then RTW may elect to convert up to $ 7.5 million of its initial PIPE subscription into additional revenue interest financing to be added to the Investment Amount by forfeiting a number of shares of Allurion Common Stock acquired in the PIPE subscription. Such additions to the Investment Amount would result in proportional increases to the minimum aggregate revenue interest payments described above. The PIPE Conversion Option is accounted for as a derivative under ASC 815. The PIPE Conversion Option was initially measured at its issue-date estimated fair value of $ 3.3 million within Other liabilities on the consolidated balance sheet with corresponding recognition of expense at inception as there is no right received by the Company that meets the definition of an asset and the transaction did not involve a distribution or a dividend. The PIPE Conversion Option liability is subsequently remeasured at its estimated fair value on a recurring basis at each reporting period date, with a gain or loss recognized within Other income (expense). The components of the Company’s Revenue Interest Financing consist of the following (in thousands): December 31, 2023 Revenue Interest Financing liability $ 40,000 Total principal amounts of debt 40,000 Less: Royalty payments ( 1,092 ) Less: Change in fair value of debt ( 2,708 ) Long-term Revenue Interest Financing liability $ 36,200

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	10. Fair Value Measurements The following tables present the fair value hierarchy for assets and liabilities that are measured at fair value at issuance date and on a recurring basis and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value (in thousands): Fair Value Measurement as of December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Cash equivalents Money market funds $ 30,582 $ 30,582 $ — $ — Total assets $ 30,582 $ 30,582 $ — $ — Liabilities: Legacy Allurion Common Stock Warrant Liabilities $ 821 $ — $ — $ 821 Public Warrants 5,943 5,943 — — Revenue Interest Financing 36,200 — — 36,200 PIPE Conversion Option 5,600 — — 5,600 Earn-out Liability 23,990 — — 23,990 Term Loan Derivative Liability 1,895 — — 1,895 Success Fee Derivative Liability 14 — — 14 Total Liabilities $ 74,463 $ 5,943 $ — $ 68,520 Fair Value Measurement as of December 31, 2022 Total Level 1 Level 2 Level 3 Assets: Cash equivalents Money market funds $ 4,925 $ 4,925 $ — $ — Total assets $ 4,925 $ 4,925 $ — $ — Liabilities: Legacy Allurion Series C Common Stock Warrant Liability $ 340 $ — $ — $ 340 Legacy Allurion Series B Preferred Stock Warrant Liability 303 — — 303 Legacy Allurion Series A-1 Preferred Stock Warrant Liability 82 — — 82 Other Common Stock Warrant Liabilities 255 — — 255 Legacy Allurion Series C Preferred Stock Warrant Liability 684 — — 684 Derivative Liability—Success Fee 180 — — 180 Legacy Allurion Series D-1 Preferred Stock Warrant Liability 707 — — 707 Total Liabilities $ 2,551 $ — $ — $ 2,551 Public Warrants As a result of the Business Combination on August 1, 2023, the Company recorded a liability for Public Warrants to purchase the Company's Common Stock. The Public Warrants are traded on the NYSE and are recorded at fair value using the closing price as of December 31, 2023 of $ 0.45 , wh ich is a Level 1 input. Legacy Allurion Warrants The Company has classified the warrants within Level 3 of the hierarchy as the fair value is derived using the Black-Scholes option pricing model, which uses a combination of observable (Level 2) and unobservable (level 3) inputs. See table below for the assumptions used in the pricing model: Measurement Date Interest Exercise Estimated Fair Expected Expected Legacy Allurion Series C Preferred Stock warrants (as converted to Common) December 31, 2023 3.88 % 6.73 3.74 100 % 7.25 Other Common Stock December 31, 2023 3.95 % 1.05 3.74 100 % 3.69 Legacy Allurion Series D-1 Preferred Stock warrants (as converted to Common) December 31, 2023 3.88 % 12.14 3.74 100 % 7.25 - 8.71 Measurement Date Interest Exercise Estimated Fair Expected Expected Legacy Allurion Series A-1 Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 4.42 % $ 1.90 $ 6.75 69 % 0.25 Legacy Allurion Series B Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 4.41 % 2.38 6.91 65 % 2.00 Legacy Allurion Series C Common Stock warrants (as converted to Rollover warrants) December 31, 2022 4.11 % 0.01 4.54 63 % 4.00 Legacy Allurion Series C Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 3.92 % 6.58 7.24 63 % 8.20 Other Common Stock Warrants December 31, 2022 3.99 % 1.02 - 1.10 4.54 63 % 4.6 - 4.7 Legacy Allurion Series D-1 Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 3.88 - 3.92 % 11.87 11.31 63 % 8.2 - 9.7 Expected dividend yield for all calculations is 0.00 %. The following table reconciles the changes in fair value for the years ended December 31, 2023 and 2022 of the warrant liabilities valued using Level 3 inputs: Preferred Stock Warrants (as converted to Common) Common Stock Warrants Total Balance – January 1, 2022 $ 510 $ 231 $ 741 Fair value upon issuance 834 — 834 Change in fair value 456 365 821 Exercise of warrants ( 23 ) — ( 23 ) Balance – December 31, 2022 $ 1,777 $ 596 $ 2,373 Change in fair value ( 720 ) 172 ( 548 ) Exercise of warrants ( 75 ) — ( 75 ) Derecognition of liability to equity ( 340 ) ( 589 ) ( 929 ) Balance – December 31, 2023 $ 642 $ 179 $ 821 2019 Term Loan Success Fee Derivative Liability The derivative liability for the success fee associated with Legacy Allurion's November 2019 loan and security agreement with Western Alliance Bank (the "2019 Term Loan" and such fee, the "Success Fee") was recorded at fair value as of December 31, 2023 using the following assumptions: weighted-average probability for the likelihood of a change in control or liquidity event within four years from the initial valuation date of the derivative liability and a market-based discount rate that will increase or decrease each period based on changes in the probability in the future cash flows. 2023 Convertible Notes The 2023 Convertible Notes were accounted for using the FVO election. Under the FVO election, the financial instrument is initially measured at its issue-date estimated fair value and subsequently re-measured at estimated fair value on a recurring basis at each reporting period date. The fair value was measured as of August 1, 2023, just prior to the conversion of the notes, using the share price at conversion ($ 7.04 per share). Upon the conversion of the notes, the convertible note liability was derecognized. PubCo Additional Shares Liability The PubCo Additional Shares liability was initially recorded at fair value as of May 2, 2023 and revalued as of August 1, 2023, just prior to the close of the Business Combination, using the number of shares issued at the close of the Business Combination of 387,696 and an estimated price of shares at settlement of $ 7.04 . Upon the issuance of shares, the PubCo Additional Shares liability was derecognized. Base PubCo Shares and Backstop Shares Liability The Base PubCo Shares and Backstop Shares liability was initially recorded at fair value as of May 2, 2023 and revalued as of August 1, 2023, just prior to the close of the Business Combination, using the number of shares for each Backstop Purchaser at the close of the Business Combination of 950,000 and an estimated price of shares at settlement of $ 7.04 . Upon the issuance of shares, the Base PubCo Shares and Backstop Shares liability was derecognized. Revenue Interest Financing and PIPE Conversion Option The Revenue Interest Financing was accounted for using the FVO election. Under the FVO election, the financial instrument is initially measured at its issue-date estimated fair value and subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. The fair value of the Revenue Interest Financing was remeasured as of December 31, 2023 using a discounted cash flow ("DCF") method under the income approach utilizing future revenue projections and a discount rate of 24.4 %. The fair value of the PIPE Conversion Option was accounted for as a derivative under ASC 815. The instrument is measured using a Monte Carlo Simulation Method using the number of shares convertible of 1,065,341 and the following assumptions: December 31, 2023 Stock Price 3.74 Risk-free interest rate 4.46 % Expected term (in years) 1.6 Expected volatility 82.5 % Earn-Out Liability Upon the closing of the Business Combination, the Earn-Out Shares were accounted for as a liability because the triggering events that determine the number of shares to be earned included events that were not indexed to Allurion Common Stock, with the change in fair value recognized in Change in the fair value of earn-out liabilities in the consolidated statement of operations. The estimated fair value of the earn-out shares was determined using a Monte Carlo Simulation Method using the following assumptions at the valuation date: December 31, 2023 Stock Price 3.74 Risk-free interest rate 3.9 % Expected term (in years) 4.6 Expected volatility 87.0 % Term Loan Derivative Liability The Term Loan Derivative Liability associated with the Fortress Term Loan was recorded at fair value as of December 31, 2023 using a DCF model that includes default interest payments expected to be made based on future revenue projections and cash flow assumptions and a discount rate of 24.4 %. The changes in the fair values of the Success Fee derivative liability, 2023 Convertible Notes, PubCo Additional Shares liability, Base PubCo Shares and Backstop Shares liability, Revenue Interest Financing, PIPE Conversion Option, Earn-out liability, and Term Loan Derivative Liability categorized with Level 3 inputs for the years ended December 31, 2023 and 2022 were as follows: Success Fee 2023 PubCo Base Revenue PIPE Earn-Out Term Loan Derivative Liability Total Balance – January 1, 2022 $ 159 $ — $ — $ — $ — $ — $ — $ — $ 159 Fair value upon issuance — — — — — — — — — Change in fair value 19 — — — — — — — 19 Exercise of warrants — — — — — — — — — Balance – December 31, 2022 $ 178 $ — $ — $ — $ — $ — $ — $ — $ 178 Fair value upon issuance — $ 28,700 3,370 3,264 40,000 3,340 53,040 1,895 133,609 Change in fair value ( 164 ) 3,751 ( 642 ) 10,106 ( 3,408 ) 2,260 ( 29,050 ) — ( 17,147 ) Change in fair value - OCI — — — — 700 — — — 700 Payments — ( 10,750 ) — — ( 1,092 ) — — — ( 11,842 ) Derecognition of liability to — ( 21,701 ) ( 2,728 ) ( 13,370 ) — — — — ( 37,799 ) Balance – December 31, 2023 $ 14 $ — $ — $ — $ 36,200 $ 5,600 $ 23,990 $ 1,895 $ 67,699 The change in fair value of the Success Fee derivative liability, 2023 Convertible Notes, PubCo Additional Shares liability, Base PubCo Shares and Backstop Shares liability, Revenue Interest Financing, PIPE Conversion Option, Earn-Out liability, and Term Loan Derivative Liability at each period is recorded as a component of Other (expense) income in the consolidated statements of operations, with the exception of the change in fair value associated with the change in credit risk related to the Revenue Interest Financing which is recorded as a component of other comprehensive loss. Assets and Liabilities Not Carried at Fair Value The Company's Fortress term loan is carried at amortized cost. The fair value of the Fortress term loan was estimated to be $ 43.2 million on December 31, 2023. The fair value was determined using a discounted cash flow approach. We classified the fair value disclosures for the Fortress Term Loan within level 3 of the fair value hierarchy because the fair value is derived using a significant unobservable input, which includes a discount rate.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The components of net loss before income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 U.S. $ ( 81,259 ) $ ( 38,267 ) Foreign 916 666 Loss before income taxes $ ( 80,343 ) $ ( 37,601 ) The reconciliation between the effective tax rate and the statutory federal income tax rate for the years ended December 31, 2023 and 2022 is as follows: Year Ended December 31, 2023 2022 U.S. statutory federal income tax rate 21.0 % 21.0 % State income taxes, net of federal income tax benefit 7.1 % 6.9 % Change in fair value of financial instruments 3.0 % 0.0 % Tax credits 0.4 % 1.0 % Valuation allowance ( 30.5 )% ( 29.0 )% Non-deductible expenses ( 0.9 )% 0.0 % Other ( 0.4 )% ( 0.2 )% Effective tax rate ( 0.3 )% ( 0.3 )% Significant components of the Company’s deferred tax assets are as follows (in thousands): December 31, 2023 2022 U.S. federal and state net operating loss carryforwards $ 36,092 $ 25,051 Capitalized start-up and research and development expenses 10,868 5,377 Research and development tax credits 2,275 1,780 Interest expense 3,918 — Lease liability 659 838 Depreciation 203 236 Bad debt reserve 3,461 — Other temporary differences 2,145 994 Total deferred tax assets 59,621 34,276 Valuation allowance ( 57,985 ) ( 33,484 ) Net deferred tax assets 1,636 792 Right of use asset ( 623 ) ( 792 ) Other deferred tax liability ( 1,013 ) — Total deferred tax liabilities ( 1,636 ) ( 792 ) Net deferred tax asset $ — $ — The Company recorded income tax expense of $ 0.3 million during the year ended December 31, 2023 due to foreign operating income. The Company recorded $ 0.1 million of income tax expense during the year ended December 31, 2022. The Company maintains a valuation allowance for the full amount of the net United States deferred tax assets, as the realization of the deferred tax assets is not determined to be more likely than not. The valuation allowance increased for the years ended December 31, 2023 and 2022 by approximately $ 24.5 million and $ 10.9 million, respectively, due to an increase in deferred tax assets having a full valuation allowance primarily due to the operating losses incurred, capitalized research and development expenses and tax credits generated. As of December 31, 2023, the Company had $ 132.2 million and $ 131.7 million of federal and state NOL carryforwards, respectively. Of the federal NOL carryforwards, $ 12.8 million expire between 2030 and 2037 and $ 119.5 million do not expire. The state NOL carryforwards expire between 2030 and 2042 . As of December 31, 2023, the Company had $ 1.5 million and $ 0.9 million of federal and state research and development tax credits, which expire beginning in 2031 and 2028 , respectively. Changes to the Com pany’s valuation allowance are as follows (in thousands): Year Ended December 31, 2023 2022 Beginning balances $ 33,484 $ 22,579 Additions charged to net loss 24,501 10,905 Ending balances $ 57,985 $ 33,484 Realization of the future tax benefits from these assets is dependent on many factors, including the Company’s ability to generate taxable income within the net operating loss carryforward period. Under the provisions of the Internal Revenue Code, certain substantial changes in the Company’s ownership, including a sale of the Company or significant changes in ownership due to sales of equity, may have limited, or may limit in the future, the amount of net operating loss and research and development credit carryforwards that could be used annually to offset future taxable income. The Company has not completed a study to assess whether a change of control has occurred or whether there have been multiple changes of control since the Company’s formation due to the significant complexity and cost associated with such study and because there could be additional changes in control in the future. As a result, the Company is not able to estimate the effect of the change in control, if any, on the Company’s ability to utilize net operating loss and research and development credit carryforwards in the future. The Company is subject to US federal income tax, state income tax in Massachusetts, and income tax in certain foreign jurisdictions. The Company’s historical income taxes in foreign jurisdictions have been immaterial to the consolidated financial statements. The Company is not currently under examination by the Internal Revenue Service (“IRS”) or any other jurisdictions for any tax years; however, all tax years since inception remain open to examination by the major taxing jurisdictions to which the Company is subject, as carryforward attributes generated in years past may still be adjusted upon examination by the U.S. IRS or other authorities if they have, or will be, used in a future period. As of December 31, 2023 and 2022, the unremitted earnings of the Company’s foreign subsidiaries are immaterial. Interpretive guidance on the accounting for global intangible low-taxed income (“GILTI”) states that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred as a period expense. The Company made the accounting policy election to recognize GILTI as a period expense. As of December 31, 2023 and 2022, the Company has no t recorded a tax liability for any uncertain tax positions. Interest and penalties associated with uncertain tax positions are recorded as a component of income tax expense. There are no accrued interest and penalties as of December 31, 2023 and 2022.

Capital Stock and Stockholders'

Capital Stock and Stockholders' Deficit	12 Months Ended
Capital Stock and Stockholders' Deficit	Dec. 31, 2023
Equity [Abstract]
Redeemable Convertible Preferred Stock and Stockholders' Deficit	12. Capital Stock and Stockholders’ Deficit The Allurion certificate of incorporation authorizes the issuance of up to 100,000,000 shares of Allurion preferred stock. As of December 31, 2023, no shares of Allurion preferred stock were outstanding. Legacy Allurion Preferred Equity In connection with the Business Combination, the Legacy Allurion preferred stock was retroactively adjusted, converted into common stock at the Exchange Ratio, and reclassified to permanent equity as a result of the reverse recapitalization. As of December 31, 2023, there is no Legacy Allurion preferred stock authorized, issued, or outstanding. The following table summarizes details of Legacy Allurion Preferred Stock authorized, issued, and outstanding immediately prior to the Business Combination (in thousands, except share amounts): Preferred Stock (1) Preferred Stock Issued Carrying Value Series A Preferred Stock 2,276,786 2,276,786 $ 1,542 Series A-1 Preferred Stock 1,513,028 1,486,048 2,842 Series B Preferred Stock 2,298,929 2,245,515 5,253 Series C Preferred Stock 8,113,616 7,927,446 39,122 Series D-1 Preferred Stock 1,684,565 842,283 9,614 Series D-2 Preferred Stock 3,644,616 3,644,616 24,054 Series D-3 Preferred Stock 1,498,348 1,498,348 14,789 Total 21,029,888 19,921,042 $ 97,216 Voting Rights The Legacy Allurion preferred stockholders voted as a single class together with holders of all other classes and series of stock of Legacy Allurion on all actions to be taken by the stockholders of the Company. The Legacy Allurion preferred stockholders were entitled to the number of votes equal to the number of shares of Legacy Allurion common stock into which the shares held by each holder were then convertible. The Legacy Allurion Series C Preferred Stockholders were entitled to elect two members of the Board of Directors , and the Legacy Allurion common stockholders were entitled to elect four members of the Board of Directors. Dividend Rights All Legacy Allurion preferred stock participated in dividends with Legacy Allurion common stock on an as-converted basis when declared by the Board of Directors. The Legacy Allurion preferred stockholders were entitled to receive dividends, when and if declared, on a pro rata pari passu basis according to the number of shares of Legacy Allurion common stock held by such holder. The Legacy Allurion Series D preferred stockholders were also entitled to a cumulative dividend that accrues at the rate of 6 % per annum. The dividend accrued on a daily basis from and including the issuance date of such shares, whether or not declared. Through the date of the Business Combination, no dividends had been declared. Liquidation Preference In the event of any voluntary or involuntary liquidation, dissolution, or winding-up of Legacy Allurion, before any payment were to be made to the holders of common stock, the holders of shares of Legacy Allurion preferred stock then outstanding were entitled to be paid out of the funds and assets available for distribution to Legacy Allurion’s stockholders, on a pari passu basis, an amount per share equal to (i) the Legacy Allurion Series A, Series A-1, Series B and Series C preferred stock, a per share liquidation preference equal to $ 1.092 , $ 2.850 , $ 3.563 and $ 4.935 , respectively, plus any accruing dividends accrued but unpaid, whether or not declared and (ii) the Legacy Allurion Series D-1, Series D-2, and Series D-3 preferred stock, a per share liquidation preference equal to $ 17.809 , $ 9.338 , and $ 15.137 , respectively, plus any accruing dividends accrued but unpaid, whether or not declared provided, that, if Legacy Allurion achieved a revenue milestone of $ 65.0 million in a trailing twelve month period (the “Milestone”), then in lieu of the foregoing, the holders of the Legacy Allurion Series D-1, Series D-2, and Series D-3 Preferred Stock were entitled to receive an amount per share equal to $ 11.8725 , $ 6.2256 and $ 10.0916 , respectively, plus any accruing dividends accrued but unpaid, whether or not declared (collectively, the “Preferred Stock Preference”). After payment of the Preferred Stock Preference, the funds and assets available for distribution to Legacy Allurion's stockholders, if any, would be initially distributed on a pro rata basis to the holders of common stock in Legacy Allurion in proportion to the number of shares of common stock held at an amount per share equal to 150 % of the Original Issue Price of the Legacy Allurion Series A Preferred Stock ($ 1.092 ), plus any dividends declared but unpaid thereon (the “First Catchup Amount”). Any remaining funds and assets available for distribution to Legacy Allurion stockholders, if any, after the First Catchup Amount would then be distributed on a pro rata basis to the holders of common stock and preferred stock in proportion to the number of shares of common stock or preferred stock held. Conversion Rights Each share of Legacy Allurion preferred stock was convertible at any time, at the option of the holder, into one share of Legacy Allurion common stock, based upon a per share conversion factor of each series’ applicable original issuance prices, adjustable for certain dilutive events. Conversion was mandatory upon the closing of an IPO or deSPAC transaction, or upon the election of the holders of a majority of the then-outstanding Legacy Allurion preferred stock. Redemption The holders of Legacy Allurion Series A, Series A-1, Series B, Series D-1, Series D-2, and Series D-3 preferred stock were not entitled to any redemption rights, other than those under their liquidation rights discussed above. Upon the election of the holders of a majority of shares of the Legacy Allurion Series C preferred stock, up to 50 % of the outstanding shares of Legacy Allurion Series C preferred stock were redeemable at a price equal to 1.5 times the original issuance price, plus all declared, but unpaid dividends thereon, on a pro rata basis in an equal semiannual portion, after January 17, 2022. The Legacy Allurion Series C contingent redemption upon a deemed liquidation event resulted in mezzanine equity classification (outside of permanent equity) on the Company’s consolidated balance sheet. Common Equity The Allurion certificate of incorporation authorizes the issuance of up to 1,000,000,000 shares of Allurion Common Stock. As of December 31, 2023 and 2022, 47,688,096 and 27,079,856 shares of common stock were outstanding, respectively, after retrospectively adjusting for the effect of the reverse recapitalization. The number of shares of Common Stock that have been reserved for the potential conversion or exercise, as applicable, of the Company's securities as of December 31, 2023, is as follows: Outstanding options to purchase common stock 3,886,038 Restricted Stock Units 643,635 Warrants to purchase preferred stock (as converted to warrants to purchase common stock) 138,857 Warrants to purchase common stock 264,801 Public warrants to purchase common stock 18,759,838 Earn-Out shares 9,000,000 Total 32,693,169 Warrants to Purchase Common Stock In connection with the closing of the Business Combination, all outstanding warrants to purchase Legacy Allurion preferred stock and Legacy Allurion common stock were converted into Rollover Warrants to purchase Allurion Common Stock using the Exchange Ratio. As of December 31, 2023, there were 403,658 s uch Rollover Warrants outstanding to purchase Common Stock. Upon the closing of the Business Combination, certain Legacy Allurion preferred stock and Legacy Allurion common stock warrants that were converted into Rollover Warrants were determined to be equity classified. December 31, 2023 Issuance Date Remaining Underlying Equity Instrument Balance Sheet Shares Issuable Weighted 12/1/2014 0.9 Common stock Equity 44,272 $ 2.44 3/30/2021 7.2 Common stock Liability 130,053 6.73 9/15/2022 8.7 Common stock Liability 45,238 12.14 6/4/2022 8.4 Common stock Liability 45,238 12.14 1/17/2017 3.0 Common stock Equity 73,349 0.02 8/3/2017 3.6 Common stock Equity 9,779 1.13 9/8/2017 3.7 Common stock Liability 28,764 1.05 6/19/2018 4.5 Common stock Liability 17,977 1.05 6/25/2019 5.5 Common stock Liability 8,988 1.05 403,658 December 31, 2022 Issuance Date Remaining Underlying Equity Instrument Balance Sheet Shares Issuable Weighted 4/1/2013 0.2 Series A-1 Preferred Stock Liability 16,557 $ 1.95 12/1/2014 1.9 Series B Preferred Stock Liability 60,768 2.44 3/30/2021 8.2 Series C Preferred Stock Liability 130,053 6.73 9/15/2022 9.7 Series D-1 Preferred Stock Liability 45,238 12.14 6/4/2022 9.4 Series D-1 Preferred Stock Liability 45,238 12.14 1/17/2017 4.0 Common stock Liability 73,349 0.02 8/3/2017 4.6 Common stock Liability 9,779 1.13 9/8/2017 4.7 Common stock Liability 28,764 1.05 6/19/2018 5.5 Common stock Liability 17,977 1.05 6/25/2019 6.5 Common stock Liability 8,988 1.05 436,711 In Compute Health's initial public offering, it sold units at a price of $ 10.00 per unit, which consisted of one share of Class A Common Stock, $ 0.0001 par value, of Compute Health ("Class A Common Stock") and one-half of a redeemable warrant (each a "Public Warrant") that entitled the holders the right to purchase one share of Class A Common Stock of CPUH at a price of $ 11.50 per share. On July 26, 2023, Compute Health's Public Warrant holders approved an amendment (the “Warrant Amendment”) to the warrant agreement that governed all Compute Health’s Public Warrants. Per the terms of the Warrant Amendment, upon completion of the Business Combination, each of the outstanding Compute Health Public Warrants became exercisable for 1.420455 shares of the Company’s Common Stock, par value $ 0.0001 per share, at an exercise price of $ 8.10 per share and each Compute Health Public Warrant was exchanged for 0.6125 Allurion Public Warrants in the Business Combination. The Public Warrants will expire August 1, 2030, seven years after the completion of the Business Combination, or earlier upon redemption or liquidation. The Company may redeem the outstanding Public Warrants for cash at a price of $ 0.01 per Public Warrant at any time commencing 90 days after the completion of the Business Combination, and provided that the last sales price of the Company’s Common Stock equals or exceeds $ 12.67 per share of any 20 trading days within a 30-day trading period ending on the third trading day prior to the date on which notice of redemption is given. The Company may redeem the outstanding Public Warrants for shares of our Common Stock at a price of $ 0.10 per Public Warrant at any time commencing 90 days after the completion of the Business Combination, and provided that the last sales price of the Company’s Common Stock equals or exceeds $ 7.04 per share of any 20 trading days within a 30-day trading period ending on the third trading day prior to the date on which notice of redemption is given. Holders of the Public Warrants will be able to exercise their warrants on a cashless basis prior to redemption and receive that number of shares based on the redemption date and the fair market value (the “Redemption Fair Market Value”) of the shares of the Company's Common Stock. The Redemption Fair Market Value is determined based on the volume weighted average price of the Company’s Common Stock for the ten trading days immediately following the date on which notice of redemption is sent to the holders. As of December 31, 2023, the Company has not redeemed any of the outstanding Public Warrants. As of December 31, 2023, there were 13,206,922 outstanding Public Warrants exercisable for 18,759,838 shares of Allurion Common Stock. Chardan Equity Facility On December 18, 2023, we entered into a ChEF Purchase Agreement (the "Purchase Agreement") and a Registration Rights Agreement (the "Registration Rights Agreement"), each with Chardan Capital Markets ("Chardan") related to a "ChEF," Chardan's committed equity facility (the "Chardan Equity Facility"). Pursuant to the Purchase Agreement, the Company has the right from time to time at its option to sell to Chardan up to the lesser of (i) $ 100,000,000 in aggregate gross purchase price of newly issued shares of the Company's Common Stock, and (ii) 9,482,468 shares of Common Stock, which number of shares is equal to 19.99 % of the shares of the Common Stock outstanding immediately prior to the execution of the Purchase Agreement (the "Exchange Cap"). In consideration for Chardan’s entry into the Purchase Agreement, Allurion agreed to issue to Chardan 35,511 shares of Allurion Common Stock (the "Commitment Shares"). The Company recorded $ 0.1 million to additional paid-in capital and $ 0.1 million of expense in connection with the issuance of the Commitment Shares. The Company expensed an additional $ 0.1 million related to a non-refundable structuring fee (the "Structuring Fee") immediately following commencement. As of December 31, 2023, the Company had no t sold any shares of Common Stock to Chardan in connection with the Purchase Agreement.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
Net Loss Per Share	Dec. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	13. Net Loss per Share Basic and diluted net loss per share was calculated as follows: Year Ended December 31, 2023 2022 Numerator: Net loss $ ( 80,607 ) $ ( 37,744 ) Cumulative undeclared dividends to participating securities (Legacy Series D ( 1,697 ) ( 2,907 ) Net loss attributable to common stockholders $ ( 82,304 ) $ ( 40,651 ) Denominator: Basic and diluted weighted-average common stock outstanding 35,581,656 26,918,484 Net loss per share attributable to common stockholders, basic and diluted (1) $ ( 2.31 ) $ ( 1.51 ) (1) The weighted-average common shares and thus net loss per share calculations and potentially dilutive security amounts for all periods prior to the Business Combination have been retrospectively adjusted to the equivalent number of shares outstanding immediately after the Business Combination to effect the reverse capitalization. See Note 3 for further information. The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2023 2022 Outstanding options to purchase common stock 3,886,038 4,301,960 Restricted Stock Units 643,635 1,415,104 Warrants to purchase preferred stock (as converted to warrants to purchase 138,857 297,854 Warrants to purchase common stock 264,801 138,857 Shares of Common Stock issued upon the exercise of Public Warrants 18,759,838 — Earn-Out Shares 9,000,000 — Convertible notes (as converted to common stock) — 171,256 Total 32,693,169 6,325,031

Stock Based Compensation

Stock Based Compensation	12 Months Ended
Stock Based Compensation	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock Based Compensation	14. Stock Based Compensation Stock Incentive Plans The Company’s 2010 Stock Option Plan (the “2010 Plan”) provided for the grant of qualified incentive stock options, nonqualified stock options, and other awards to the Company’s employees, officers, directors, advisors, and outside consultants to purchase the Company’s Common Stock. On December 11, 2020, the Company’s Board of Directors adopted the 2020 Stock Option Plan (the “2020 Plan”), which provided for the grant of qualified incentive stock options, nonqualified stock options, and other awards to the Company’s employees, officers, directors, advisors, and outside consultants to purchase the Company’s Common Stock. Each stock option from the 2010 Plan and the 2020 Plan that was outstanding immediately prior to the Business Combination, whether vested or unvested, was cancelled and exchanged for a stock option to purchase Allurion Common Stock based on the Exchange Ratio. The per share exercise price for each stock option was divided by the Exchange Ratio. In connection with the closing of the Business Combination, the Company adopted the 2023 Stock Option and Incentive Plan (the "2023 Plan"), which provides for the award of stock options (both incentive and non-qualified), stock appreciation rights, restricted stock units, restricted stock awards, cash-based awards, and dividend equivalent rights. A total of 7,822,700 shares of Allurion Common Stock were initially reserved for issuance under the 2023 Plan. The 2023 Plan provides that the number of shares reserved for issuance under the 2023 Plan will automatically increase each January 1, beginning January 1, 2024 and ending January 1, 2033, by 5 % of the number of fully diluted outstanding shares of Allurion Common Stock as of the immediately preceding December 31 or such lesser amount as determined by the Board and the Compensation Committee. As of December 31, 2023, 4,529,673 options and RSUs were issued and outstanding under the 2010 Plan, 2020 Plan, and 2023 Plan. As of December 31, 2022, 5,717,072 options and RSUs were issued and outstanding under the 2010 Plan and 2020 Plan. The stock options generally vest over a four-year period and expire 10 years from the date of grant. Stock-based compensation expense included in the consolidated statement of operations and comprehensive loss was as follows: Year Ended December 31, 2023 2022 Cost of revenue $ 32 $ — Selling, general, and administrative 8,198 400 Research and development 127 37 Total stock-based compensation expense $ 8,357 $ 437 Stock Options The following tables summarizes the option activity under the 2010 Plan, 2020 Plan, and the 2023 Plan during the year ended December 31, 2023: Number of Weighted Weighted Aggregate (per option) (in years) (in thousands) Outstanding—January 1, 2023 4,301,968 $ 2.35 7.7 $ 9,437 Granted 257,683 $ 5.41 Cancellations and forfeitures ( 375,051 ) $ 2.00 Exercised ( 298,562 ) $ 1.15 Outstanding— December 31, 2023 3,886,038 $ 2.67 6.9 $ 5,565 Exercisable at December 31, 2023 2,735,884 $ 2.23 6.2 $ 4,812 Total stock compensation expense related to stock option awards during the year ended December 31, 2023 w as $ 2.7 million. As of December 31, 2023, there was approximately $ 2.5 m illion of unrecognized compensation costs related to unvested stock options granted under the 2020 Plan, which is expected to be recognized over a weighted-average vesting term of 2.1 y ears. The weighted average grant-date fair value of the stock option awards granted during the years ended December 31, 2023 and 2022 w as $ 3.98 a nd $ 2.36 per option, respectively. The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model and the assumptions noted in the table below. Expected volatility for the Company’s Common Stock was determined based on an average of the historical volatility of a peer group of public companies which are similar to the Company. The expected term of options granted to employees was calculated using the simplified method, which represents the average of the contractual term of the option and the weighted- average vesting period of the option. The Company uses the simplified method because it does not have sufficient historical option exercise data to provide a reasonable basis upon which to estimate expected term. The expected term of options granted to non-employees is the remaining contractual term of the award. The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. The risk-free rate for periods within the expected life of the option is based upon the U.S. Treasury yield curve in effect at the time of grant. The assumptions used in the Black-Scholes option-pricing model are as follows: Year Ended December 31, 2023 2022 Expected volatility 85.8 % 63 % Risk-free interest rate 4.5 % 3.56 % Expected dividend yield — % — % Expected term (in years) 5.8 5.8 Restricted Stock Units In December 2022, the Company issued RSUs under the 2020 Plan to a member of the Board of Directors with vesting subject to both a performance-based closing condition dependent on the successful Business Combination with Compute Health and time-based vesting conditions. See Note 1, Organization and Basis of Presentation and Note 3 , Business Combination above for information about the closing of the Business Combination with Compute Health. Upon the satisfaction of the closing condition, 62.5 % of the RSUs awarded vested. Thereafter, the remaining 37.5 % of the RSUs vest monthly over a period of two years . In October 2023, the Company issued additional RSUs to Board of Director members with annual vesting over three years . All RSUs are subject to forfeiture if the grantee’s continuous service relationship as a member of the Board of Directors terminates prior to vesting. The following table summarizes the restricted stock unit activity under the 2020 Plan and 2023 Plan during the year ended December 31, 2023: Number of RSUs Weighted (per share) Outstanding—January 1, 2023 1,415,104 $ 4.51 Granted 226,175 4.32 Cancellations and forfeitures ( 79,232 ) 4.51 Vested ( 918,412 ) 4.51 Outstanding—December 31, 2023 643,635 4.45 Total stock compensation expense related to RSUs for the year ended December 31, 2023 was $ 5.7 million. As of December 31, 2023, there wer e $ 1.7 million of unrecognized compensation costs related to nonvested RSUs granted under the 2020 Plan and 2023 Plan, which is expected to be recognized over a remaining weighted-average vesting term of 2.0 years. The weighted average grant-date fair value of time-vested restricted stock units granted during the years ended December 31, 2023 and 2022 was $ 4.32 and $ 4.51 per share, respectively. Employee Stock Purchase Plan In connection with the closing of the Business Combination, the Company adopted the 2023 Employee Stock Purchase Plan (the "2023 ESPP"). Under the 2023 ESPP plan, substantially all employees may voluntarily enroll to purchase the Company's Common Stock through payroll deductions at a price equal to 85 % of the lower of the fair market values of the stock as of the beginning or end of the offering period. An employee's payroll deductions under the 2023 ESPP are limited to 15 % of the employee's compensation. A total of 1,422,309 shares of the Company's Common Stock were initially reserved and authorized for issuance under the 2023 ESPP. In addition, the number of shares of Common Stock available for issuance under the 2023 ESPP will automatically increase each January 1, beginning on January 1, 2024 and each January thereafter, by the lesser of (i) 1 % of the fully diluted outstanding shares of our Common Stock as of the immediately preceding December 31, (ii) 1,600,000 shares of our Common Stock, or (iii) such lesser number of shares determined by the administrator of the 2023 ESPP. As of December 31, 2023, no shares have been issued under the 2023 ESPP.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plan	15. Employee Benefit Plan The Company has a 401(k) retirement plan that covers eligible U.S. employees. Eligible employees may elect to contribute up to the maximum limits, as set by the Internal Revenue Service, of their eligible compensation. The Company may elect to make a discretionary contribution or match a discretionary percentage of employee contribution. During the years ended December 31, 2023 and 2022, the Company’s matching contributions to the plan were $ 0.1 million.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	16. Commitments and Contingencies Leases With respect to contracts involving the use of assets, if the Company has the right to direct the use of the asset and obtain substantially all economic benefits from the use of an asset, it accounts for the service contract as a lease. In February 2023 and August 2023, the Company executed amendments to three of its leases in Natick, Massachusetts and its Hudson, Massachusetts lease, respectively. The amendments were accounted for as a modification of the existing lease agreements, with impacts to the lease term, lease payments, and related lease liability for each of the four leases. As a result of these amendments, the leases in Natick and Hudson will now expire between June 2024 and March 2028 , and additional operating lease assets obtained in exchange for lease obligations were $ 0.9 million. As of December 31, 2023, the Company was a party to seven different leases for office, manufacturing, and laboratory space under non-cancelable office leases in three cities. These leases total approximately 51,000 square feet and will expire between June 2024 and March 2028 . The Company has a right to extend certain of these leases for periods between three and five years . The Company also holds immaterial leases related to vehicles and office equipment. Under its leases, the Company pays base rent and a proportional share of operating expenses. Such operating expenses are subject to annual adjustment and are accounted for as variable payments in the period in which they are incurred. The components of ROU assets and lease liabilities are included in the consolidated balance sheets. The short-term portion of the Company's operating lease liability is recorded as part of Accrued expenses and other current liabilities on the consolidated balance sheets. Aggregate Lease Information Other pertinent lease information is as follows (in thousands): December 31, 2023 December 31, 2022 Operating lease costs $ 1,123 $ 918 Short-term lease costs 12 14 Variable operating lease costs 187 191 Operating cash flows paid for amounts in the measurement of lease liabilities 1,084 807 Operating lease assets obtained in exchange for lease obligations 936 1,677 Future commitments under non-cancelable operating lease agreements are as follows (in thousands): 2024 $ 1,173 2025 1,114 2026 737 2027 645 2028 108 Total lease payments $ 3,777 Less: present value adjustment ( 563 ) Present value of total lease liabilities 3,214 Less: current lease liability ( 908 ) Long-term lease liabilities $ 2,306 The weighted-average remaining lease terms and discount rates related to our leases were as follows: 2023 2022 Weighted -average remaining lease term (in years) 3.5 3.9 Weighted-average discount rate 9.9 % 9.5 % Product Liability The Company has not received any material product liability claims. While product defects and adverse patient reactions associated with the Allurion Balloon have occurred, and are expected to continue to occur, the Company does not have a history of product defects or adverse patient reactions that the Company’s management believes would give rise to a material product liability claim. Furthermore, the Company has obtained insurance related to potential product liability claims. Litigation and Claims In the normal course of operations, the Company may become involved in various claims and legal proceedings related to, for example, the validity or scope of its intellectual property rights, employee-related matters, or adverse patient reactions. Additionally, during the normal course of business, the Company may be a party to legal claims that may not be covered by insurance. As of December 31, 2023 and 2022, the Company has no t recorded accruals for potential losses related to any existing or pending litigation or claims as the Company’s management has determined that there are no matters where a potential loss is probable and reasonably estimable. The Company does not believe that any existing or pending claims would have a material impact on the Company’s consolidated financial statements.

Geographic Information

Geographic Information	12 Months Ended
Geographic Information	Dec. 31, 2023
Segment Reporting [Abstract]
Geographic Information	17. Geographic Information Long-lived assets, consisting of property and equipment, net and ROU assets by geography were as follows (in thousands): December 31, 2023 2022 United States $ 5,381 $ 3,999 France 1,010 1,282 All other countries — — Long-lived assets $ 6,391 $ 5,281 Refer to Note 4, Revenue for information on revenue by geography.

Related-party Transactions

Related-party Transactions	12 Months Ended
Related-party Transactions	Dec. 31, 2023
Related Party Transactions [Abstract]
Related-party Transactions	18. Related-party Transactions Lease Agreement with Related Party In August 2022, the Company entered into an operating lease agreement for additional office space in Paris, France with LNMP JPBC Invest. The Company’s then-Trade Marketing Director was the signor of this lease for LNMP JPBS Invest. Additionally, the Company’s Chief Commercial Officer is also a partner of LNMP JPBC Invest. The lease agreement included lease payments of approximately $ 0.1 million per year. The lease commenced August 1, 2022 and was to end on July 31, 2025 . The Company concluded that the commercial terms of the lease agreement were competitive, at the current market rate and conducted at arm’s-length. This lease was terminated in February 2024 . Consulting Agreements with KKG Enterprises, LLC and Remus Group Management, LLC In the first quarter of 2023, Allurion entered into consulting agreements with KKG Enterprises, LLC (“KKG Enterprises”) and Remus Group Management, LLC (“Remus Group Management”) to assist Allurion in building out its AI platform, augment its AI advisory board, and provide advisory services related to the Business Combination. These agreements were tied to Allurion Board-related work by Krishna Gupta, who is a director of Allurion, CEO of Remus Group Management, principal at KKG Enterprises, and affiliated with Romulus Capital, a stockholder of Allurion. The agreements included payments of $ 0.2 million to KKG Enterprises and $ 0.3 million to Remus Group Management as board compensation to Krishna Gupta. These agreements were terminated on June 20, 2023 . Convertible Note with Hunter Ventures Limited On February 15, 2023, Allurion sold $ 13 million of 2023 Convertible Notes to HVL and entered into a Side Letter with HVL, who is a limited partner of Romulus Growth Allurion L.P., which is a fund affiliated with Krishna Gupta (a director of Allurion; in addition, entities affiliated with him hold more than 5 % of our outstanding Common Stock). Refer to Note 8, Debt for additional information regarding the 2023 Convertible Notes. Consulting Agreement with Related Party In September 2023, Allurion France, a French société par actions simplifiée and wholly-owned subsidiary of Allurion, entered into a new corporate officer agreement with the Company's Chief Commercial Officer and Benoit Chardon Consulting, a French société à responsabilité limitée which is solely owned by Mr. Chardon ("BCC"), pursuant to which BCC agreed to serve as Managing Director of Allurion France. The new corporate officer agreement provided that BCC would receive base consulting fees of € 28,333.33 per month and additional variable compensation subject to the incentive plan terms issued annually by Allurion and conditional on meeting Allurion France and personal performance attainment defined each year by Allurion. This agreement was terminated on December 12, 2023 by virtue of the termination agreement described below. Termination Agreement with Related Party On December 12, 2023, Allurion France, a French société par actions simplifiée and wholly-owned subsidiary of Allurion, entered into a termination agreement with the Company's Chief Commercial Officer, Benoit Chardon and BCC. Pursuant to the termination agreement, the parties agreed to terminate the corporate officer agreement as of December 31, 2023 and BCC will resign from its duties as managing director of Allurion France effective December 31, 2023 and Allurion France will pay BCC all amounts due to it under the corporate officer agreement through December 31, 2023. In addition, Allurion France will pay BCC a lump-sum termination fee of $ 0.2 million.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP 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 consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Management considers many factors in selecting appropriate financial accounting policies and controls in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Actual results could differ from those estimates.
Reclassification of Prior Year Presentation	Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current year presentation. These reclassifications had no effect on the reported results of operations. Adjustments have been made to the consolidated statement of operations and comprehensive loss for the year ended December 31, 2022 to present the change in fair value of derivative liabilities as part of Other income (expense), net, and to present the change in fair value of warrants as its own line item. The change in fair value of derivative liabilities was a separate line item in prior years and the change in fair value of warrants was part of Other income (expense), net in prior years.
Risk of Concentration of Credit, Significant Customers and Significant Suppliers	Risk of Concentration of Credit, Significant Customers and Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash equivalents and accounts receivable, net. The Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company maintains its cash, cash equivalents and restricted cash with financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Significant customers are those which represent more than 10 % of the Company’s total revenue for the years ended December 31, 2023 and 2022 or accounts receivable, net balance as of December 31, 2023 and 2022. The following table presents customers that represent 10% or more of the Company’s total revenue and accounts receivable, net: Revenue Accounts Receivable Years Ended December 31 December 31, 2023 2022 2023 2022 Customer A 10 % N/A 16 % N/A Customer B N/A 11 % N/A N/A Customer C N/A N/A N/A 13 % Customer D N/A N/A N/A 12 % The Company relies on third parties for the supply of parts and components for its products as well as third-party logistics providers. In instances where these parties fail to perform their obligations, the Company may be unable to find alternative suppliers of parts and components to satisfactorily deliver its products to its customers on time, if at all, which could have a material adverse effect on the Company’s operating results, financial condition and cash flows and damage its customer relationships.
Leases	Leases Effective January 1, 2022, the Company adopted ASC 842, Leases (“ASC 842"). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease. A contract is or contains a lease if the contract conveys the right to control the use of an identified asset for a period of time in exchange for consideration. At the lease commencement date, when control of the underlying asset is transferred from the lessor to the Company, the Company classifies a lease as either an operating or finance lease and recognizes a right-of-use (“ROU”) asset and a current and non-current lease liability as applicable, in the consolidated balance sheets if the lease has a term greater than one year. As permitted under ASC 842, the Company has made an accounting policy election, for all classes of underlying assets, to not recognize ROU assets and lease liabilities for leases having an original term of twelve months or less. When it determines the appropriate classification and accounting for a lease arrangement, the Company typically only considers the committed lease term. Options to extend a lease are not included in the Company’s assessment unless there is reasonable certainty that the Company will either renew or not cancel the lease. At the lease commencement date, operating lease liabilities and their corresponding ROU assets are recorded at the present value of future lease payments over the expected remaining lease term using the discount rate implicit in the lease, if it is readily determinable, or the Company’s incremental borrowing rate. The Company’s incremental borrowing rate reflects the fixed rate at which the Company could borrow the amount of the lease payments in the same currency on a collateralized basis, for a similar term in a similar economic environment. Lease cost for operating leases is recognized on a straight-line basis over the lease term as an operating expense. In addition, certain adjustments to the ROU asset may be required for items such as lease prepayments, incentives received or initial direct costs. The Company enters into contracts that contain both lease and non-lease components. Non-lease components include costs that do not provide a right to use a leased asset but instead provide a service, such as maintenance costs. Variable costs associated with the lease, such as maintenance and utilities, are not included in the measurement of right-of-use assets and lease liabilities but rather are expensed when the events determining the amount of variable consideration to be paid have occurred.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash Cash consists of amounts held in bank savings and checking accounts. Cash equivalents include all highly liquid investments maturing within 90 days from the date of purchase. Cash equivalents consist of money market funds. The Company’s restricted cash consists of cash that the Company is contractually obligated to maintain and deposits of cash collateral held in accordance with the terms of various corporate credit cards. Restricted cash is included within other long-term assets on the consolidated balance sheets. A reconciliation of the amounts of cash and cash equivalents and restricted cash in the consolidated balance sheets to the amount in the consolidated statements of cash flows is as follows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 38,037 $ 7,685 Restricted cash included in other long-term assets 384 338 Cash and cash equivalents and restricted cash shown in the statement of cash flows $ 38,421 $ 8,023
Segment Reporting	Segment Reporting The Company operates in a single operating and reportable segment. Operating segments are defined as components of an enterprise for which discrete financial information is available and is regularly reviewed by the chief operating decision maker (“CODM”) in order to make decisions regarding resource allocation and performance assessment. The Company has determined that its CODM is its Chief Executive Officer. The Company’s CODM reviews financial information presented on a regular basis at the consolidated level for purposes of allocating resources and evaluating financial performance. Since the Company operates as one operating segment, all required financial segment information can be found in the consolidated financial statements. The Company’s products include the Allurion Balloon and related accessories. See Note 4, Revenue below for financial information about sales in geographic areas.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The carrying value of the Company’s financial instruments such as cash and cash equivalents, accounts payable, and accrued expenses approximate their fair values due to their short-term maturity. The carrying value of the Company’s term loan approximates its fair value as the interest rate and other terms are that which are currently available to the Company. The Company’s assets and liabilities recorded at fair value have been categorized based upon a fair value hierarchy, which is distinguished between observable and unobservable inputs in accordance with authoritative accounting guidance: Level 1 inputs: Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date Level 2 inputs: Other than quoted prices included in Level 1, inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability Level 3 inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that the observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset.
Inventories	Inventories Inventories, which include the costs of material, labor, and overhead, are stated at the lower of cost or net realizable value, with cost generally computed using the first-in, first out method. Estimated losses from obsolete and slow-moving inventories are recorded to reduce inventory values to their estimated net realizable value and are charged to cost of sales. At the point of loss recognition, a new cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in a recovery in carrying value.
Property and Equipment	Property and Equipment Property and equipment include computers, laboratory equipment, machinery, and leasehold improvements. Property and equipment are recorded at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, except for leasehold improvements, which are depreciated on a straight-line basis over the shorter of the estimated life or the lease term. Expenditures for repairs and maintenance are expensed as incurred.
Capitalized Internal-Use Software	Capitalized Internal-Use Software Software development costs consist of certain consulting costs and compensation expenses for employees who devote time to the development projects of our internal-use software, as well as certain upgrades and enhancements that are expected to result in enhanced functionality. The Company amortizes these development costs over the estimated useful life, which is determined based on our best estimate of the useful life of the internal-use software after considering factors such as continuous developments in the technology, obsolescence, and anticipated life of the service offering before significant upgrades. Management evaluates the useful lives of these assets and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. The Company determined the amount of internal software costs to be capitalized based on the amount of time spent by our developers on projects in the application stage of development. There is judgment in estimating the time allocated to a particular project in the application stage. A significant change in the time spent on each project could have a material impact on the amount capitalized and related amortization expense in subsequent periods. As of December 31, 2023 and 2022, capitalized internal-use software was immaterial.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company evaluates its long-lived assets, which consist primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds the fair value of the asset. To date, no impairments have occurred.
Debt Issuance Costs	Debt Issuance Costs The Company defers costs directly associated with acquiring third-party financing. Fees incurred to issue debt are generally deferred and amortized as a component of interest expense over the estimated term of the related debt using the effective interest rate method. Fees incurred in connection with a modification are deferred and amortized as a component of interest expense over the remaining life of the loan if due to the creditor. Third-party fees incurred in connection with a modification are expensed as incurred.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs include certain legal, accounting, consulting and other third-party fees incurred directly related to the Business Combination. The Company deferred offering costs classified as a long-term asset until the closing or termination of the transaction. At the closing of the Business Combination, these costs were recorded in stockholders’ deficit as a reduction of additional paid-in capital. Deferred offering costs are included in other long-term assets. As of December 31, 2023 and 2022, there were zero and $ 2.3 million of deferred offering costs recorded within other long-term assets on the consolidated balance sheet, respectively.
Warrants	Warrants The Company determines the accounting classification of warrants it issues, as either liability or equity classified, by first assessing whether the warrants meet liability classification in accordance with ASC 480-10, Accounting for Certain Financial Instruments with Characteristics of both Liabilities and Equity (“ASC 480-10”), then in accordance with ASC 815-40, Accounting for Derivative Financial Instruments Indexed to, and Potentially Settled in, a Company’s Own Stock (“ASC 815-40”). Under ASC 480-10, warrants are considered liability classified if the warrants are mandatorily redeemable, obligate the Company to settle the warrants or the underlying shares by paying cash or other assets, or are warrants that must or may require settlement by issuing a variable number of shares. If warrants do not meet liability classification under ASC 480-10, the Company assesses the requirements under ASC 815-40, which states that contracts that require or may require the issuer to settle the contract for cash are liabilities recorded at fair value, irrespective of the likelihood of the transaction occurring that triggers the net cash settlement feature. If the warrants do not require liability classification under ASC 815-40, and in order to conclude equity classification, the Company also assesses whether the warrants are indexed to its common stock and whether the warrants are classified as equity under ASC 815-40 or other applicable GAAP. After all relevant assessments, the Company concludes whether the warrants are classified as liability or equity. Liability classified warrants require fair value accounting at issuance and subsequent to initial issuance, with all changes in fair value after the issuance date recorded in the consolidated statements of operations. Equity classified warrants only require fair value accounting at issuance with no changes recognized subsequent to the issuance date.
Derivative Liabilities	Derivative Liabilities The Company evaluates its convertible instruments and other contracts, including warrants, to determine if those contracts or embedded components of those contracts are required to be accounted for as derivatives, either in whole or in part. If an embedded derivative is bifurcated from a debt host contract, changes in the fair value of the bifurcated derivative are recorded in the accompanying consolidated statements of operations.
2023 Convertible Notes	2023 Convertible Notes The Company accounted for the convertible notes issued between February 2023 and August 2023 (the "2023 Convertible Notes") under the fair value option (“FVO”) election of ASC Topic 825, Financial Instruments (“ASC 825”). The convertible notes accounted for under the FVO election were each debt host financial instruments containing embedded features wherein the entire financial instrument was initially measured at its issue-date estimated fair value and then subsequently remeasured at estimated fair value on a recurring basis at each reporting period date. Changes in the estimated fair value of the convertible notes were recorded as a component of Other (expense) income in the consolidated statements of operations. As a result of electing the FVO, direct costs and fees related to the 2023 Convertible Notes were expensed as incurred. The convertible notes issued in 2020, 2021 and 2022 are accounted for as disclosed in Note 8, Debt . In connection with the closing of the Business Combination on August 1, 2023, a portion of the 2023 convertible notes was repaid, with the remaining balance converted to shares of our Common Stock.
Earn-out Liabilities	Earn-Out Liabilities In connection with the Business Combination, certain holders of Legacy Allurion common stock and Legacy Allurion preferred stock and holders of vested options, warrants and restricted stock units exercisable or convertible into Legacy Allurion capital stock received the contingent right to receive up to 9,000,000 additional shares of Allurion Common Stock (the “Earn-Out Shares”) upon the achievement of certain earn-out targets. The contingent earn-out consideration contains a settlement provision that in the event of a change in control, the number of Earn-Out Shares issued may vary. This settlement provision precludes the earn-out liability from being indexed to the Company's Common Stock as a change in control event is not an input into the pricing of a fixed-for-fixed forward or option on equity shares. As such, it is classified as a liability under ASC 480, Distinguishing Liabilities from Equity ("ASC 480"). The fair value of the earn-out consideration is remeasured on a quarterly basis over the earn-out period with changes in the estimated fair value of the contingent earn-out consideration recorded in Other (expense) income in the consolidated statements of operations, and are reflected in the period in which they are identified. Changes in the estimated fair value of the contingent earn-out consideration may materially impact or cause volatility in our operating results.
Revenue Interest Financing and PIPE Conversion Option	Revenue Interest Financing and PIPE Conversion Option In connection with the Business Combination, the Company entered into a revenue interest financing agreement, dated as of February 9, 2023 (the "Revenue Interest Financing Agreement") with certain entities that have engaged RTW Investments, LP as investment manager (collectively, “RTW”), under which the Company received $ 40.0 million upfront (the "Revenue Interest Financing"). In exchange, the Company is obligated to remit to RTW certain revenue interest payments on all current and future products, digital solutions and services developed, imported, manufactured, marketed, offered for sale, promoted, sold, tested or otherwise distributed by Allurion and its subsidiaries at a rate up to 6.0 % of annual net sales prior to December 31, 2026. On or after January 1, 2027, the Company will remit revenue interest payments at a rate up to 10.0 % of annual net sales, and it will continue to make revenue interest payments to RTW until December 31, 2030. The Company accounts for the Revenue Interest Financing Agreement under the fair value option election of ASC 825. The Revenue Interest Financing Agreement accounted for under the FVO election is a debt host financial instrument that contains embedded features. The embedded features include requirements to settle the Revenue Interest Financing prior to maturity upon the occurrence of certain contingent events, a change in royalty rates upon the occurrence of certain contingent events, and the Company's ability to prepay the Revenue Interest Financing. As the Company has elected the FVO, these embedded features would not meet the criteria for bifurcation and separate accounting as the entire financial instrument is initially measured at its issue-date estimated fair value and then subsequently remeasured at estimated fair value on a recurring basis on each reporting period date. Changes in the estimated fair value of the Revenue Interest Financing Agreement are recorded as a component of Other (expense) income in the consolidated statements of operations. A portion of the estimated change in fair value must be reported in other comprehensive loss to the extent that it is attributable to instrument-specific credit risk. As a result of electing the FVO, direct costs and fees related to the Revenue Interest Financing are expensed as incurred. In connection with the Company entering in the Revenue Interest Financing, the Company and RTW entered into the RTW side letter under which RTW may elect to convert up to $ 7.5 million of its initial PIPE (as defined in Note 3, Business Combination below) subscription into an additional revenue interest financing by forfeiting a number of shares of Allurion Common Stock acquired by the PIPE subscription (the "PIPE Conversion Option"). The Company accounts for the PIPE Conversion Option as a freestanding financial instrument that qualifies for derivative liability accounting in accordance with ASC 815, Derivatives and Hedging ("ASC 815"). The PIPE Conversion Option is initially measured at its fair value within Other liabilities on the consolidated balance sheets with corresponding recognition of expense at inception as there is no right received by the Company that meets the definition of an asset and the transaction did not involve a distribution or a dividend. Subsequent changes in fair value of the derivative liability are recognized as a gain or loss as a component of Other (expense) income in the consolidated statements of operations.
Accounts Receivable	Accounts Receivable Accounts receivable are unsecured and are carried at net realizable value, including an allowance for doubtful accounts. Trade credit is generally extended on a short-term basis; trade receivables do not bear interest, although a finance charge may be applied to such receivables that are past due. The allowance for doubtful accounts is based on the Company’s assessment of the collectability of customer accounts. The Company regularly reviews the allowance by considering factors that may affect a customer’s ability to pay, such as historical expense, credit quality, the age of the account receivable balances, and current economic conditions. Amounts determined to be uncollectible are charged or written off against the allowance. The following table summarizes activity in the allowance for doubtful accounts: Year Ended December 31, 2023 2022 Balance at beginning of period $ ( 741 ) $ ( 354 ) Provision for uncollectible accounts ( 12,675 ) ( 436 ) Uncollectible accounts written off 745 49 Balance at end of period $ ( 12,671 ) $ ( 741 )
Revenue Recognition	Revenue Recognition The Company recognizes revenue under ASU No. 2014-09, Revenue from Contracts with Customers (“Topic 606” or “ASC 606”). In general, the Company’s sales contracts fall under its standard sales agreement whereby control transfers to the customer upon shipment, satisfying the performance obligations of the contract. The Company recognizes revenue when control of its products is transferred to customers at an amount that reflects the consideration it expects to receive in exchange for those products. The Company’s revenue recognition process involves identifying the contract with a customer, determining the performance obligations in the contract, determining the transaction price, allocating the transaction price to the distinct performance obligations in the contract, and recognizing revenue as performance obligations are satisfied. A performance obligation is considered distinct from other obligations in a contract when it provides a benefit to the customer either on its own or together with other resources that are readily available to the customer and is separately identified in the contract. Performance obligations are considered satisfied once the Company has transferred control of a good or service to the customer, meaning that such customer has the ability to use and obtain the benefit of the good or service. The Company has provided customers purchasing the Allurion Balloon with an implied license for access to its VCS software. This implied software license was given to customers for no additional consideration and was not negotiated as part of the customer’s contracts. Further, the customer contracts and related purchase orders do not include nor specify rights or obligations associated with the VCS software. Based on this assessment, the Company determined the implied license to be immaterial in the context of the contract with customers purchasing the Allurion Balloon, and as such did not allocate any value to the implied VCS license. The Company generates revenue from sales of its Allurion Balloon to distributors and health care providers. Customers typically purchase the Allurion Balloon, including the gastric balloon and related accessories together, although customers can purchase the gastric balloon and its accessories separately. Therefore, each component of the Allurion Balloon and accessories represents a distinct performance obligation and is separately identifiable. In arrangements with multiple performance obligations, the transaction price is allocated to each performance obligation using the relative standalone selling price. The Company determines standalone selling prices based on the price at which the performance obligation is sold separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price taking into account internally approved pricing guidelines and market conditions. Revenue is generally recognized upon shipment of the product because at that point, the customer obtains control of the product and has the ability to direct the use and obtain the benefit of the product. Components of the Allurion Balloon are typically shipped to the customer together, resulting in the performance obligations in the contract being satisfied at the same time. Components shipped separately are recognized upon shipment at their relative standalone selling price. The Company recognizes revenue at the transaction price, which reflects the consideration it believes it is entitled to receive. Transaction price includes estimates of variable consideration for promotions and prompt pay discounts, which are recorded as a reduction of transaction price in the period the related product revenue is recognized. The Company may also make payments to customers for marketing programs. Payments to customers for a distinct good or service that reasonably estimate the fair value of the distinct benefit received, such as marketing programs, are recorded as a marketing expense on the consolidated statement of operations and comprehensive loss. Shipping and logistics costs inclusive of these payments to customers and other costs included in sales and marketing expense for the years ended December 31, 2023 and 2022 were $ 3.3 million and $ 3.6 million , respectively. The Company expenses incremental costs of obtaining a contract, such as sales commissions, when incurred because the amortization period would have been one year or less. These costs are recorded within sales and marketing expenses in the Company’s consolidated statement of operations and comprehensive loss. The Company has also elected the sales tax practical expedient; therefore, sales and other taxes assessed by a governmental authority that are collected concurrently with revenue-producing activities are excluded from the transaction price. The Company has also elected the significant financing component practical expedient, which allows management to not assess whether the contract has a significant financing component in circumstances where, at contract inception, the expected contract duration is less than one year.
Product Warranty	Product Warranty The Company does not provide general rights of return of products sold to its customers. However, the Company does provide for rights of exchange to its distributors and end-use customers for products that fail to conform to the Company’s specifications for a limited time following delivery. These performance specifications include that the Allurion Balloon (i) is successfully filled upon initial placement when used according to the instructions for use provided by the Company and/or (ii) remains in the patient’s body for 90 days or more once placed. Customers may exchange product within 30 calendar days if they discover product nonconformities through a reasonable inspection and within 30 calendar days after discovery of any hidden or latent product nonconformities that could not have been discovered by a reasonable inspection. These instances of nonconformity have been immaterial, and the Company’s management expects instances of nonconformity to be extremely rare.
Research and Development Costs	Research and Development Costs The Company expenses research and development costs as incurred. Research and development expenses consist of costs associated with performing research and development activities, including salaries and benefits, stock-based compensation, product development costs, materials and supplies, clinical trial activities, depreciation of equipment, and contract and other outside services. Payments for activities that are provided by outside vendors are based upon the terms of the individual arrangements with each vendor. Costs of certain of these activities are expensed based upon an evaluation of the progress to completion of specific tasks and actual costs incurred, using information provided to the Company by its vendors. As payments for these activities may differ from the pattern of costs actually incurred, additional costs are reflected in the consolidated financial statements as prepaid or accrued research and development expenses.
Advertising and Marketing Costs	Advertising and Marketing Costs The Company expenses advertising and marketing costs as incurred. Advertising and marketing expenses are included in sales and marketing operating expenses. Advertising and marketing costs for the years ended December 31, 2023 and 2022 were $ 10.8 million and $ 16.0 million, respectively.
Intellectual Property Prosecution Costs	Intellectual Property Prosecution Costs The Company incurs registration and prosecution costs related to its intellectual property. The related costs are expensed as incurred and are classified as a component of general and administrative expenses.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the Company’s consolidated financial statements and tax returns. Deferred tax assets and liabilities are determined based upon the differences between the financial statement carrying amounts and the tax bases of existing assets and liabilities and for net operating loss and tax credit carryforwards, using enacted tax rates expected to be in effect in the year in which the differences are expected to reverse. Deferred tax assets are reduced by a valuation allowance if it is more likely than not that these assets may not be realized. The Company determines whether a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, none of the benefit attributable to the position is recognized. The tax benefit to be recognized for any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. As of December 31, 2023 and 2022, the Company has no t identified any uncertain tax positions for which reserves would be required.
Net Loss Per Share	Net Loss Per Share The Company applies the two-class method to compute basic and diluted net loss per share attributable to common stockholders, when shares meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to share in the earnings as if all income (loss) for the period had been distributed. The Company reported a net loss attributable to common stockholders for the years ended December 31, 2023 and 2022. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders less the cumulative undeclared dividend by the weighted average number of common shares outstanding for the period. Diluted net loss attributable to common stockholders is computed by adjusting net loss attributable to common stockholders to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of common stock equivalents. The holders of the Legacy Allurion Series D convertible preferred stock were contractually entitled to receive a cumulative dividend, whether or not declared, and therefore, Legacy Allurion Series D convertible preferred stocks were participating securities. The holders of all other redeemable and convertible preferred stock were not entitled to cumulative dividends. The preferred equity holders were also not contractually required to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. In periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. In connection with the Business Combination with Compute Health, the Company’s equity in previous periods has been retroactively adjusted to the earliest period presented to reflect the equivalent number of shares of Allurion Common Stock issued to the Company’s stockholders in connection with the Business Combination. As a result, net loss per share was also retrospectively adjusted for periods ended prior to the Business Combination. See Note 3, Business Combination , for details of the Business Combination.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes compensation expense for awards based on the grant-date fair value of stock-based awards on a straight-line basis over the period during which an award holder provides service in exchange for the award. The Company accounts for awards issued to nonemployees under ASU No. 2018-07, Compensation—Stock Compensation (“Topic 718”): Improvements to Nonemployee Share-Based Payment Accounting , with the measurement date for nonemployee awards being the date of grant. The fair value of stock options is calculated using the Black-Scholes option-pricing model. The fair value of Restricted Stock Units (“RSUs”) is based on the fair market value of common stock at the date of grant. The Company records forfeitures as they occur.
Comprehensive Loss	Comprehensive Loss For the year ended December 31, 2023, comprehensive loss consists of net loss and other comprehensive loss, which includes changes in the fair value attributable to instrument-specific credit risk related to the Revenue Interest Financing with RTW. There were no differences between net loss and comprehensive loss presented in the statements of operations and comprehensive loss for the year ended December 31, 2022.
Recently Adopted Accounting Pronouncements and Recently Issued Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) . The standard, including subsequently issued amendments, requires a financial asset measured at amortized cost basis, such as accounts receivable and certain other financial assets such as available for sale debt securities, to be presented at the net amount expected to be collected based on relevant information about past events, including historical experience, current conditions and reasonable and supportable forecasts that affect the collectability of the reported amount. The Company adopted ASU 2016-13 effective January 1, 2023 under the prospective transition approach. The adoption of ASU 2016-13 did not have a material impact on the Company’s consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted Debt with Conversion and Other Options and Derivatives and Hedging—Contracts in Entity’s Own Equity , which simplifies the accounting for convertible instruments. The guidance removes certain accounting models which separate the embedded conversion features from the host contract for convertible instruments. Either a modified retrospective method of transition or a fully retrospective method of transition is permissible for the adoption of this standard. Update No. 2020-06 is effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted no earlier than the fiscal year beginning after December 15, 2020. The Company does not expect the adoption of ASU 2020-06 to have a material impact on its consolidated financial statements. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, which requires disclosure of incremental segment information on an interim and annual basis. This ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal periods beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements and related disclosures. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures , which require public entities, on an annual basis, to provide disclosure of specific categories in the rate reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction. This ASU is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. The adoption of this standard is not expected to have a material impact on the Company’s consolidated financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Risk of Concentration of Credit, Significant Customers	The following table presents customers that represent 10% or more of the Company’s total revenue and accounts receivable, net: Revenue Accounts Receivable Years Ended December 31 December 31, 2023 2022 2023 2022 Customer A 10 % N/A 16 % N/A Customer B N/A 11 % N/A N/A Customer C N/A N/A N/A 13 % Customer D N/A N/A N/A 12 %
Reconciliation of Cash and Cash Equivalents and Restricted Cash	A reconciliation of the amounts of cash and cash equivalents and restricted cash in the consolidated balance sheets to the amount in the consolidated statements of cash flows is as follows (in thousands): December 31, 2023 2022 Cash and cash equivalents $ 38,037 $ 7,685 Restricted cash included in other long-term assets 384 338 Cash and cash equivalents and restricted cash shown in the statement of cash flows $ 38,421 $ 8,023
Summary of Activity in Allowance for Doubtful Accounts	The following table summarizes activity in the allowance for doubtful accounts: Year Ended December 31, 2023 2022 Balance at beginning of period $ ( 741 ) $ ( 354 ) Provision for uncollectible accounts ( 12,675 ) ( 436 ) Uncollectible accounts written off 745 49 Balance at end of period $ ( 12,671 ) $ ( 741 )

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
Business Combination (Tables)	Dec. 31, 2023
Business Combinations [Abstract]
Reconciles of Business Combination to Condensed Consolidated Statement	The following table reconciles the elements of the Business Combination to the consolidated statement of cash flows and the consolidated statement of changes in equity: December 31, 2023 Cash – CPUH trust (net of redemptions) $ 38,395 Cash – PIPE Investors 37,922 Gross Proceeds 76,317 Less: transaction costs paid ( 14,665 ) Net proceeds from the Business Combination (1) 61,652 Less: warrant liabilities assumed (2) ( 13,762 ) Less: repayment of note assumed in the Business Combination (1) ( 2,500 ) Less: accrued transaction costs at December 31, 2023 (1) ( 580 ) Business Combination, net of transaction costs $ 44,810 (1) The Net proceeds from the Business Combination, less the repayment of note assumed in the Business Combination, less the accrued transaction costs at December 31, 2023 are presented net in the consolidated statements of stockholders deficit within line "Reverse recapitalization, net of transaction costs (Note 3)". (2) The warrant liabilities assumed are presented separately from the "Reverse recapitalization, net of transaction costs (Note 3)" line within the consolidated statements of stockholders deficit.
Number of Shares of Allurion Common Stock Outstanding	The number of shares of Allurion Common Stock outstanding immediately following the consummation of the Business Combination was as follows: Common Stock Legacy Allurion Equityholders (1) 27,897,387 CPUH Stockholders (2) 5,165,698 Shares Issued to PIPE Investors (2) 5,386,695 Shares issued to RTW and Fortress (3) 1,900,000 Shares issued to convertible note holders 3,301,222 CPUH Sponsor Shares (2) 3,262,711 Side Letter Termination Shares (3) 387,696 Total shares of Common Stock immediately after Business Combination 47,301,409 (1) Consists of Legacy Allurion common stock and Legacy Allurion preferred stockholders, plus the issuance of common stock in connection with the vesting of RSUs at closing, less the Gaur Contributed Shares (as defined below). (2) The CPUH Stockholders shares, PIPE shares, and CPUH Sponsor shares are presented combined within the consolidated statements of redeemable convertible preferred stock and stockholders deficit on the "Reverse recapitalization, net of transaction costs" line, which is less the Gaur Contributed Shares (as defined below). (3) The shares issued to RTW and Fortress and the Side Letter Termination shares are presented combined within the consolidated statements of redeemable convertible preferred stock and stockholders deficit on the "Derecognition of liabilities associated with the Backstop Shares, Hunter shares, and additional RTW and Fortress shares and issuance of related shares" line.

Revenue (Tables)

Revenue (Tables)	12 Months Ended
Revenue (Tables)	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Revenues by Geographic Region	Revenue by geographic region is based on the country in which our customer is domiciled and is summarized by geographic area as follows (in thousands): Year Ended December 31, 2023 2022 France $ 5,569 $ 6,032 Turkey 5,494 4,079 Spain 4,618 6,852 Chile 2,708 5,008 All other countries 35,078 42,240 Total Revenues $ 53,467 $ 64,211

Inventory (Tables)

Inventory (Tables)	12 Months Ended
Inventory (Tables)	Dec. 31, 2023
Table Text Block [Abstract]
Schedule of Inventory	Inventory consists of the following (in thousands): December 31, 2023 2022 Finished goods $ 3,427 $ 2,096 Work in progress 967 213 Raw materials 1,777 1,556 Total Inventory $ 6,171 $ 3,865

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
Property and Equipment, net (Tables)	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consist of the following (in thousands): December 31, Estimates Useful Life (in Years) 2023 2022 Computers and purchased software 3 $ 618 $ 575 Leasehold improvements Shorter of useful life 1,943 1,822 Furniture and fixtures 5 291 251 Machinery and equipment 3 - 5 2,893 2,002 Property and equipment—at cost 5,745 4,650 Less accumulated depreciation and amortization ( 3,559 ) ( 2,851 ) Construction in progress 1,195 583 Property and equipment—net $ 3,381 $ 2,382
Schedule of Depreciation Expense	Depreciation expense was $ 0.7 million and $ 0.9 million for the years ended December 31, 2023 and 2022, respectively, recorded as follows (in thousands): Year Ended December 31, 2023 2022 Cost of revenue $ 367 $ 568 Research and development 179 90 General and administrative 138 160 Sales and marketing 62 57 Total depreciation and amortization expense $ 746 $ 875

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
Accrued Expenses and Other Current Liabilities (Tables)	Dec. 31, 2023
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): December 31, 2023 2022 Distributor fees and marketing reimbursements $ 2,834 $ 6,348 Accrued compensation 1,687 3,453 Accrued clinical trials and R&D 3,694 228 Accrued selling and marketing 1,110 481 Accrued professional fees 1,505 2,105 Accrued interest — 489 Accrued warranty 44 48 Accrued restructuring 655 — Other accrued expenses 3,966 2,641 Total accrued expenses and other current liabilities $ 15,495 $ 15,793 In connection with strategic initiatives implemented during the period ended December 31, 2023, the Company's management approved and initiated plans to reduce its cost structure. The Company recorded $ 1.0 million of restructuring charges during the year ended December 31, 2023, of which $ 0.4 million has been paid as of December 31, 2023. The restructuring charges are included in operating expenses in the statement of operations. Substantially all of this charge represents the severance cost of terminated employees.

Debt (Tables)

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2023
Debt Disclosure [Abstract]
Summary of Components of Third-Party Debt	The components of the Company’s third-party debt consisted of the following (in thousands): December 31, 2023 2022 Fortress Term Loan $ 43,100 $ — 2021 Term Loan — 55,000 Convertible Notes — 3,103 Total principal amounts of debt 43,100 58,103 Plus: Accretion 148 213 Less: current portion of long-term debt, net of discounts ( 38,643 ) ( 53,360 ) Less: unamortized deferred financing costs and debt discounts ( 4,605 ) ( 1,853 ) Long-term debt, net of current portion and discounts $ — $ 3,103
Schedule of Future Maturities of the Term Loan Facility	Scheduled future maturities of the Fortress Term Loan for years subsequent to December 31, 2023 are as follows (in thousands): December 31, 2024 — December 31, 2025 — December 31, 2026 8,979 December 31, 2027 34,121 $ 43,100

Revenue Interest Financing, S_2

Revenue Interest Financing, Side Letter, and PIPE Conversion Option (Tables)	12 Months Ended
	Dec. 31, 2023
Contract with Customer, Liability [Abstract]
Summary of Components of Revenue Interest Financing	The components of the Company’s Revenue Interest Financing consist of the following (in thousands): December 31, 2023 Revenue Interest Financing liability $ 40,000 Total principal amounts of debt 40,000 Less: Royalty payments ( 1,092 ) Less: Change in fair value of debt ( 2,708 ) Long-term Revenue Interest Financing liability $ 36,200

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value at Issuance Date and on Recurring Basis	The following tables present the fair value hierarchy for assets and liabilities that are measured at fair value at issuance date and on a recurring basis and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value (in thousands): Fair Value Measurement as of December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Cash equivalents Money market funds $ 30,582 $ 30,582 $ — $ — Total assets $ 30,582 $ 30,582 $ — $ — Liabilities: Legacy Allurion Common Stock Warrant Liabilities $ 821 $ — $ — $ 821 Public Warrants 5,943 5,943 — — Revenue Interest Financing 36,200 — — 36,200 PIPE Conversion Option 5,600 — — 5,600 Earn-out Liability 23,990 — — 23,990 Term Loan Derivative Liability 1,895 — — 1,895 Success Fee Derivative Liability 14 — — 14 Total Liabilities $ 74,463 $ 5,943 $ — $ 68,520 Fair Value Measurement as of December 31, 2022 Total Level 1 Level 2 Level 3 Assets: Cash equivalents Money market funds $ 4,925 $ 4,925 $ — $ — Total assets $ 4,925 $ 4,925 $ — $ — Liabilities: Legacy Allurion Series C Common Stock Warrant Liability $ 340 $ — $ — $ 340 Legacy Allurion Series B Preferred Stock Warrant Liability 303 — — 303 Legacy Allurion Series A-1 Preferred Stock Warrant Liability 82 — — 82 Other Common Stock Warrant Liabilities 255 — — 255 Legacy Allurion Series C Preferred Stock Warrant Liability 684 — — 684 Derivative Liability—Success Fee 180 — — 180 Legacy Allurion Series D-1 Preferred Stock Warrant Liability 707 — — 707 Total Liabilities $ 2,551 $ — $ — $ 2,551
Schedule of Assumptions used in Pricing Model	The Company has classified the warrants within Level 3 of the hierarchy as the fair value is derived using the Black-Scholes option pricing model, which uses a combination of observable (Level 2) and unobservable (level 3) inputs. See table below for the assumptions used in the pricing model: Measurement Date Interest Exercise Estimated Fair Expected Expected Legacy Allurion Series C Preferred Stock warrants (as converted to Common) December 31, 2023 3.88 % 6.73 3.74 100 % 7.25 Other Common Stock December 31, 2023 3.95 % 1.05 3.74 100 % 3.69 Legacy Allurion Series D-1 Preferred Stock warrants (as converted to Common) December 31, 2023 3.88 % 12.14 3.74 100 % 7.25 - 8.71 Measurement Date Interest Exercise Estimated Fair Expected Expected Legacy Allurion Series A-1 Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 4.42 % $ 1.90 $ 6.75 69 % 0.25 Legacy Allurion Series B Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 4.41 % 2.38 6.91 65 % 2.00 Legacy Allurion Series C Common Stock warrants (as converted to Rollover warrants) December 31, 2022 4.11 % 0.01 4.54 63 % 4.00 Legacy Allurion Series C Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 3.92 % 6.58 7.24 63 % 8.20 Other Common Stock Warrants December 31, 2022 3.99 % 1.02 - 1.10 4.54 63 % 4.6 - 4.7 Legacy Allurion Series D-1 Preferred Stock warrants (as converted to Rollover warrants) December 31, 2022 3.88 - 3.92 % 11.87 11.31 63 % 8.2 - 9.7
Schedule of Changes in Fair Values	The following table reconciles the changes in fair value for the years ended December 31, 2023 and 2022 of the warrant liabilities valued using Level 3 inputs: Preferred Stock Warrants (as converted to Common) Common Stock Warrants Total Balance – January 1, 2022 $ 510 $ 231 $ 741 Fair value upon issuance 834 — 834 Change in fair value 456 365 821 Exercise of warrants ( 23 ) — ( 23 ) Balance – December 31, 2022 $ 1,777 $ 596 $ 2,373 Change in fair value ( 720 ) 172 ( 548 ) Exercise of warrants ( 75 ) — ( 75 ) Derecognition of liability to equity ( 340 ) ( 589 ) ( 929 ) Balance – December 31, 2023 $ 642 $ 179 $ 821
Schedule of Estimated Fair Value was Measured Using a Monte Carlo Simulation Method	The assumptions used in the Black-Scholes option-pricing model are as follows: Year Ended December 31, 2023 2022 Expected volatility 85.8 % 63 % Risk-free interest rate 4.5 % 3.56 % Expected dividend yield — % — % Expected term (in years) 5.8 5.8
Public Warrants
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Schedule of Changes in Fair Values	The changes in the fair values of the Success Fee derivative liability, 2023 Convertible Notes, PubCo Additional Shares liability, Base PubCo Shares and Backstop Shares liability, Revenue Interest Financing, PIPE Conversion Option, Earn-out liability, and Term Loan Derivative Liability categorized with Level 3 inputs for the years ended December 31, 2023 and 2022 were as follows: Success Fee 2023 PubCo Base Revenue PIPE Earn-Out Term Loan Derivative Liability Total Balance – January 1, 2022 $ 159 $ — $ — $ — $ — $ — $ — $ — $ 159 Fair value upon issuance — — — — — — — — — Change in fair value 19 — — — — — — — 19 Exercise of warrants — — — — — — — — — Balance – December 31, 2022 $ 178 $ — $ — $ — $ — $ — $ — $ — $ 178 Fair value upon issuance — $ 28,700 3,370 3,264 40,000 3,340 53,040 1,895 133,609 Change in fair value ( 164 ) 3,751 ( 642 ) 10,106 ( 3,408 ) 2,260 ( 29,050 ) — ( 17,147 ) Change in fair value - OCI — — — — 700 — — — 700 Payments — ( 10,750 ) — — ( 1,092 ) — — — ( 11,842 ) Derecognition of liability to — ( 21,701 ) ( 2,728 ) ( 13,370 ) — — — — ( 37,799 ) Balance – December 31, 2023 $ 14 $ — $ — $ — $ 36,200 $ 5,600 $ 23,990 $ 1,895 $ 67,699
Earn-Out Liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Schedule of Estimated Fair Value was Measured Using a Monte Carlo Simulation Method	The estimated fair value of the earn-out shares was determined using a Monte Carlo Simulation Method using the following assumptions at the valuation date: December 31, 2023 Stock Price 3.74 Risk-free interest rate 3.9 % Expected term (in years) 4.6 Expected volatility 87.0 %
Revenue Interest Financing and PIPE Conversion Option
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Schedule of Estimated Fair Value was Measured Using a Monte Carlo Simulation Method	The fair value of the PIPE Conversion Option was accounted for as a derivative under ASC 815. The instrument is measured using a Monte Carlo Simulation Method using the number of shares convertible of 1,065,341 and the following assumptions: December 31, 2023 Stock Price 3.74 Risk-free interest rate 4.46 % Expected term (in years) 1.6 Expected volatility 82.5 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Domestic and Foreign Components of Net Loss Before Income Taxes	The components of net loss before income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 U.S. $ ( 81,259 ) $ ( 38,267 ) Foreign 916 666 Loss before income taxes $ ( 80,343 ) $ ( 37,601 )
Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate	The reconciliation between the effective tax rate and the statutory federal income tax rate for the years ended December 31, 2023 and 2022 is as follows: Year Ended December 31, 2023 2022 U.S. statutory federal income tax rate 21.0 % 21.0 % State income taxes, net of federal income tax benefit 7.1 % 6.9 % Change in fair value of financial instruments 3.0 % 0.0 % Tax credits 0.4 % 1.0 % Valuation allowance ( 30.5 )% ( 29.0 )% Non-deductible expenses ( 0.9 )% 0.0 % Other ( 0.4 )% ( 0.2 )% Effective tax rate ( 0.3 )% ( 0.3 )%
Schedule of Deferred Tax Assets	Significant components of the Company’s deferred tax assets are as follows (in thousands): December 31, 2023 2022 U.S. federal and state net operating loss carryforwards $ 36,092 $ 25,051 Capitalized start-up and research and development expenses 10,868 5,377 Research and development tax credits 2,275 1,780 Interest expense 3,918 — Lease liability 659 838 Depreciation 203 236 Bad debt reserve 3,461 — Other temporary differences 2,145 994 Total deferred tax assets 59,621 34,276 Valuation allowance ( 57,985 ) ( 33,484 ) Net deferred tax assets 1,636 792 Right of use asset ( 623 ) ( 792 ) Other deferred tax liability ( 1,013 ) — Total deferred tax liabilities ( 1,636 ) ( 792 ) Net deferred tax asset $ — $ —
Summary of Valuation Allowance	Changes to the Com pany’s valuation allowance are as follows (in thousands): Year Ended December 31, 2023 2022 Beginning balances $ 33,484 $ 22,579 Additions charged to net loss 24,501 10,905 Ending balances $ 57,985 $ 33,484

Capital Stock and Stockholder_2

Capital Stock and Stockholders' Deficit (Tables)	12 Months Ended
Capital Stock and Stockholders' Deficit (Tables)	Dec. 31, 2023
Equity [Abstract]
Schedule of Preferred Stock and Common Stock	The following table summarizes details of Legacy Allurion Preferred Stock authorized, issued, and outstanding immediately prior to the Business Combination (in thousands, except share amounts): Preferred Stock (1) Preferred Stock Issued Carrying Value Series A Preferred Stock 2,276,786 2,276,786 $ 1,542 Series A-1 Preferred Stock 1,513,028 1,486,048 2,842 Series B Preferred Stock 2,298,929 2,245,515 5,253 Series C Preferred Stock 8,113,616 7,927,446 39,122 Series D-1 Preferred Stock 1,684,565 842,283 9,614 Series D-2 Preferred Stock 3,644,616 3,644,616 24,054 Series D-3 Preferred Stock 1,498,348 1,498,348 14,789 Total 21,029,888 19,921,042 $ 97,216 The number of shares of Common Stock that have been reserved for the potential conversion or exercise, as applicable, of the Company's securities as of December 31, 2023, is as follows: Outstanding options to purchase common stock 3,886,038 Restricted Stock Units 643,635 Warrants to purchase preferred stock (as converted to warrants to purchase common stock) 138,857 Warrants to purchase common stock 264,801 Public warrants to purchase common stock 18,759,838 Earn-Out shares 9,000,000 Total 32,693,169
Summary of Warrants to Purchase the Classes of Preferred Stock and Common Stock Outstanding	As of December 31, 2023, there were 403,658 s uch Rollover Warrants outstanding to purchase Common Stock. Upon the closing of the Business Combination, certain Legacy Allurion preferred stock and Legacy Allurion common stock warrants that were converted into Rollover Warrants were determined to be equity classified. December 31, 2023 Issuance Date Remaining Underlying Equity Instrument Balance Sheet Shares Issuable Weighted 12/1/2014 0.9 Common stock Equity 44,272 $ 2.44 3/30/2021 7.2 Common stock Liability 130,053 6.73 9/15/2022 8.7 Common stock Liability 45,238 12.14 6/4/2022 8.4 Common stock Liability 45,238 12.14 1/17/2017 3.0 Common stock Equity 73,349 0.02 8/3/2017 3.6 Common stock Equity 9,779 1.13 9/8/2017 3.7 Common stock Liability 28,764 1.05 6/19/2018 4.5 Common stock Liability 17,977 1.05 6/25/2019 5.5 Common stock Liability 8,988 1.05 403,658 December 31, 2022 Issuance Date Remaining Underlying Equity Instrument Balance Sheet Shares Issuable Weighted 4/1/2013 0.2 Series A-1 Preferred Stock Liability 16,557 $ 1.95 12/1/2014 1.9 Series B Preferred Stock Liability 60,768 2.44 3/30/2021 8.2 Series C Preferred Stock Liability 130,053 6.73 9/15/2022 9.7 Series D-1 Preferred Stock Liability 45,238 12.14 6/4/2022 9.4 Series D-1 Preferred Stock Liability 45,238 12.14 1/17/2017 4.0 Common stock Liability 73,349 0.02 8/3/2017 4.6 Common stock Liability 9,779 1.13 9/8/2017 4.7 Common stock Liability 28,764 1.05 6/19/2018 5.5 Common stock Liability 17,977 1.05 6/25/2019 6.5 Common stock Liability 8,988 1.05 436,711

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
Stock Based Compensation (Tables)	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Stock-based Compensation Expense	Stock-based compensation expense included in the consolidated statement of operations and comprehensive loss was as follows: Year Ended December 31, 2023 2022 Cost of revenue $ 32 $ — Selling, general, and administrative 8,198 400 Research and development 127 37 Total stock-based compensation expense $ 8,357 $ 437
Summary of Option Activity Under the Plan	The following tables summarizes the option activity under the 2010 Plan, 2020 Plan, and the 2023 Plan during the year ended December 31, 2023: Number of Weighted Weighted Aggregate (per option) (in years) (in thousands) Outstanding—January 1, 2023 4,301,968 $ 2.35 7.7 $ 9,437 Granted 257,683 $ 5.41 Cancellations and forfeitures ( 375,051 ) $ 2.00 Exercised ( 298,562 ) $ 1.15 Outstanding— December 31, 2023 3,886,038 $ 2.67 6.9 $ 5,565 Exercisable at December 31, 2023 2,735,884 $ 2.23 6.2 $ 4,812
Schedule of Assumptions Used in Black-Scholes Option Pricing Model	The assumptions used in the Black-Scholes option-pricing model are as follows: Year Ended December 31, 2023 2022 Expected volatility 85.8 % 63 % Risk-free interest rate 4.5 % 3.56 % Expected dividend yield — % — % Expected term (in years) 5.8 5.8
Summary of Restricted Stock Unit Activity Under the Plan	The following table summarizes the restricted stock unit activity under the 2020 Plan and 2023 Plan during the year ended December 31, 2023: Number of RSUs Weighted (per share) Outstanding—January 1, 2023 1,415,104 $ 4.51 Granted 226,175 4.32 Cancellations and forfeitures ( 79,232 ) 4.51 Vested ( 918,412 ) 4.51 Outstanding—December 31, 2023 643,635 4.45

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Other Pertinent Lease Information	Other pertinent lease information is as follows (in thousands): December 31, 2023 December 31, 2022 Operating lease costs $ 1,123 $ 918 Short-term lease costs 12 14 Variable operating lease costs 187 191 Operating cash flows paid for amounts in the measurement of lease liabilities 1,084 807 Operating lease assets obtained in exchange for lease obligations 936 1,677
Schedule of Future Commitments Under Non-cancelable Operating Lease Agreements	Future commitments under non-cancelable operating lease agreements are as follows (in thousands): 2024 $ 1,173 2025 1,114 2026 737 2027 645 2028 108 Total lease payments $ 3,777 Less: present value adjustment ( 563 ) Present value of total lease liabilities 3,214 Less: current lease liability ( 908 ) Long-term lease liabilities $ 2,306
Schedule of Weighted-Average Remaining Lease Terms and Discount Rates Related Leases	The weighted-average remaining lease terms and discount rates related to our leases were as follows: 2023 2022 Weighted -average remaining lease term (in years) 3.5 3.9 Weighted-average discount rate 9.9 % 9.5 %

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
Geographic Information (Tables)	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of Long-lived Assets by Geography	Long-lived assets, consisting of property and equipment, net and ROU assets by geography were as follows (in thousands): December 31, 2023 2022 United States $ 5,381 $ 3,999 France 1,010 1,282 All other countries — — Long-lived assets $ 6,391 $ 5,281

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
Net Loss Per Share (Tables)	Dec. 31, 2023
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share was calculated as follows: Year Ended December 31, 2023 2022 Numerator: Net loss $ ( 80,607 ) $ ( 37,744 ) Cumulative undeclared dividends to participating securities (Legacy Series D ( 1,697 ) ( 2,907 ) Net loss attributable to common stockholders $ ( 82,304 ) $ ( 40,651 ) Denominator: Basic and diluted weighted-average common stock outstanding 35,581,656 26,918,484 Net loss per share attributable to common stockholders, basic and diluted (1) $ ( 2.31 ) $ ( 1.51 ) (1) The weighted-average common shares and thus net loss per share calculations and potentially dilutive security amounts for all periods prior to the Business Combination have been retrospectively adjusted to the equivalent number of shares outstanding immediately after the Business Combination to effect the reverse capitalization. See Note 3 for further information.
Summary of Dilutive Securities Excluded from Computation of Basic and Diluted Net Loss Per Common Share	The Company’s potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2023 2022 Outstanding options to purchase common stock 3,886,038 4,301,960 Restricted Stock Units 643,635 1,415,104 Warrants to purchase preferred stock (as converted to warrants to purchase 138,857 297,854 Warrants to purchase common stock 264,801 138,857 Shares of Common Stock issued upon the exercise of Public Warrants 18,759,838 — Earn-Out Shares 9,000,000 — Convertible notes (as converted to common stock) — 171,256 Total 32,693,169 6,325,031

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Aug. 01, 2023	Dec. 31, 2023 USD ($) Country $ / shares	Dec. 31, 2022 USD ($) $ / shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of countries, currently markets the program \| Country		50
Common stock, par value \| $ / shares		$ 0.0001	$ 0.0001
Gains (losses) from foreign currency translation adjustment		$ 100	$ (700)
Net losses		80,607	37,744
Cash outflows from operating activities		63,982	46,981
Accumulated deficit		$ 212,799	$ 132,192
Common Stock \| Business Combination Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Exchange ratio	0.978
Common stock, par value \| $ / shares		$ 0.0001

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)			12 Months Ended
	Aug. 01, 2023	Feb. 09, 2023	Dec. 31, 2023	Dec. 31, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales and marketing			$ 46,857,000	$ 50,405,000
Advertising and marketing costs			10,800,000	16,000,000
Uncertain tax positions for which reserves would be required			$ 0	$ 0
Common stock, par value			$ 0.0001	$ 0.0001
Proceeds from revenue interest financing			$ 40,000,000
Right-of-use asset			3,010,000	$ 2,899,000
Revenue Interest Financing Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from revenue interest financing	$ 40,000,000
Shipping and Logistics
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales and marketing			3,300,000	3,600,000
Other Long-Term Assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred offering costs			$ 0	$ 2,300,000
New Allurion \| Revenue Interest Financing Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from revenue interest financing	$ 40,000,000
ASU 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting principle accounting standards update adopted			true
Change in accounting principle accounting standards update adoption date			Jan. 01, 2023
Change in accounting principle accounting standards update immaterial effect			true
Total Revenue \| Customer Concentration Risk \| Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk, percentage			10%	10%
Accounts Receivable \| Customer Concentration Risk \| Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk, percentage			10%	10%
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Earn-out shares receivable	9,000,000
Maximum \| Revenue Interest Financing Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of annual net sales		6%
Remittance of revenue interest payments percentage		10%
Additional revenue interest		$ 7,500,000
Maximum \| New Allurion \| Revenue Interest Financing Agreement
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percentage of annual net sales		6%
Remittance of revenue interest payments percentage		10%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Risk of Concentration of Credit, Significant Customers (Details) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Total Revenue \| Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	10%
Total Revenue \| Customer B
Concentration Risk [Line Items]
Concentration risk, percentage		11%
Accounts Receivable \| Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	16%
Accounts Receivable \| Customer C
Concentration Risk [Line Items]
Concentration risk, percentage		13%
Accounts Receivable \| Customer D
Concentration Risk [Line Items]
Concentration risk, percentage		12%

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Cash and cash equivalents	$ 38,037	$ 7,685
Restricted cash included in other long-term assets	$ 384	$ 338
Restricted Cash and Cash Equivalents, Statement of Financial Position [Extensible Enumeration]	Other Assets, Noncurrent	Other Assets, Noncurrent
Cash and cash equivalents and restricted cash shown in the statement of cash flows	$ 38,421	$ 8,023

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Activity in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Balance at beginning of period	$ (741)	$ (354)
Provision for uncollectible accounts	(12,675)	(436)
Uncollectible accounts written off	745	49
Balance at end of period	$ (12,671)	$ (741)

Business Combination - Addition

Business Combination - Additional Information (Details)		12 Months Ended
Business Combination - Additional Information (Details)	Aug. 01, 2023 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) shares	Feb. 09, 2023 USD ($)	Dec. 31, 2022 USD ($) shares
Business Acquisition [Line Items]
Proceeds from revenue interest financing \| $		$ 40,000,000
Warrants outstanding \| shares		403,658
Warrants converted into warrants exercisable \| shares		403,658		436,711
Outstanding public warrants to purchase \| shares	18,759,838
Transaction costs \| $	$ 22,700,000
Additional paid-in capital \| $	15,200,000	$ 143,007,000		$ 99,875,000
Business combination expense \| $	5,000,000
Business combination one-time insurance payment \| $	3,600,000
Public warrant liabilities \| $		5,943,000
Earn-out liabilities \| $	53,000,000	23,990,000
General and Administrative
Business Acquisition [Line Items]
Business combination expense \| $	5,000,000
Fortress Term Loan
Business Acquisition [Line Items]
Issuance costs \| $	$ 2,500,000
Public Warrants
Business Acquisition [Line Items]
Warrants outstanding \| shares	13,206,922
Public warrant liabilities \| $	$ 13,800,000
Business Combination Agreement
Business Acquisition [Line Items]
Sponsor loan excess amount \| $	3,700,000
Revenue Interest Financing Agreement
Business Acquisition [Line Items]
Proceeds from revenue interest financing \| $	40,000,000
Direct costs and fees \| $	1,200,000
Issuance costs \| $	1,200,000
Revenue Interest Financing Agreement \| Maximum
Business Acquisition [Line Items]
Percentage of annual net sales			6%
Remittance of revenue interest payments percentage			10%
Conversion of PIPE subscription to revenue interest finance \| $		$ 7,500,000	$ 7,500,000
Revenue Interest Financing Agreement \| New Allurion
Business Acquisition [Line Items]
Proceeds from revenue interest financing \| $	$ 40,000,000
Revenue Interest Financing Agreement \| New Allurion \| Maximum
Business Acquisition [Line Items]
Percentage of annual net sales			6%
Remittance of revenue interest payments percentage			10%
Fortress Credit Agreement
Business Acquisition [Line Items]
Shares issued \| shares	950,000
Fortress Credit Agreement \| Term Loan Facility
Business Acquisition [Line Items]
Term loan borrowed \| $	$ 60,000,000
Backstop Agreement
Business Acquisition [Line Items]
Aggregate principal amount \| $	$ 2,000,000
Shares issued upon conversion of convertible notes \| shares	700,000
RSU Forfeiture Agreement
Business Acquisition [Line Items]
Number of shares forfeited \| shares	79,232
PIPE Subscription Agreements
Business Acquisition [Line Items]
Aggregate purchase of shares \| shares	5,386,695
Purchase price per share \| $ / shares	$ 7.04
Aggregate purchase price \| $	$ 37,900,000
Common Stock \| Convertible Notes
Business Acquisition [Line Items]
Accured interest \| $	$ 21,800,000
Shares issued upon conversion of convertible notes \| shares	3,301,222
Aggregate recognition APIC amount \| $	$ 25,600,000
Common Stock \| Business Combination Agreement
Business Acquisition [Line Items]
Exchange ratio	0.978
Conversion of shares \| shares	525,568
Sale of stock \| $ / shares	$ 8.1
Common Stock \| Business Combination Agreement \| Warrant Amendment
Business Acquisition [Line Items]
Sale of stock \| $ / shares	$ 8.1
Common Stock \| RTW Side Letter
Business Acquisition [Line Items]
Shares issued \| shares	250,000
Common Stock \| Backstop Agreement
Business Acquisition [Line Items]
Shares issued \| shares	700,000
Common Stock \| HVL Termination Agreement
Business Acquisition [Line Items]
Shares issued \| shares	387,696
Common Stock \| Gaur Contribution Agreement
Business Acquisition [Line Items]
Contribution of capital \| shares	79,232
Class A Common Stock \| Business Combination Agreement
Business Acquisition [Line Items]
Conversion of shares \| shares	1.420455
Class A Common Stock \| Sponsor Contribution Agreement
Business Acquisition [Line Items]
Contribution of capital \| shares	161,379
Class A Common Stock \| Sponsor Support Agreement \| CPUH Stockholders
Business Acquisition [Line Items]
Warrants outstanding \| shares	12,833,333
Warrants converted into warrants exercisable \| shares	2,088,327
Shares issued upon conversion \| shares	21,120
Class B Common Stock \| Sponsor Support Agreement \| CPUH Stockholders
Business Acquisition [Line Items]
Recapitalization of common stock \| shares	21,442,500
Recapitalization of additional shares \| shares	30,000

Business Combination - Reconcil

Business Combination - Reconciles of Business Combination to Condensed Consolidated Statement (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Business Acquisition [Line Items]
Gross Proceeds	$ 76,317
Less: transaction costs paid	(14,665)
Net proceeds from the Business Combination	61,652
Less: warrant liabilities assumed	(13,762)
Less: repayment of note assumed in the Business Combination	(2,500)
Less: accrued transaction costs at December 31, 2023	(580)
Reverse merger, net of transaction costs	44,810
Cash - CPUH trust
Business Acquisition [Line Items]
Gross Proceeds	38,395
Cash - PIPE Investors
Business Acquisition [Line Items]
Gross Proceeds	$ 37,922

Business Combination - Number o

Business Combination - Number of Shares of Allurion Common Stock Outstanding (Details) - shares	Dec. 31, 2023	Aug. 01, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination	47,688,096	47,301,409	27,079,856
Legacy Allurion Equityholders
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		27,897,387
CPUH Stockholders
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		5,165,698
Shares Issued to PIPE Investors
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		5,386,695
Shares issued to RTW and Fortress
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		1,900,000
Shares Issued to Convertible Note Holders
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		3,301,222
CPUH Sponsor Shares
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		3,262,711
Side Letter Termination Shares
Business Acquisition [Line Items]
Total shares of Common Stock immediately after Business Combination		387,696

Revenue - Schedule of Revenues

Revenue - Schedule of Revenues by Geographic Region (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 53,467	$ 64,211
France
Disaggregation of Revenue [Line Items]
Revenue	5,569	6,032
Turkey
Disaggregation of Revenue [Line Items]
Revenue	5,494	4,079
Spain
Disaggregation of Revenue [Line Items]
Revenue	4,618	6,852
Chile
Disaggregation of Revenue [Line Items]
Revenue	2,708	5,008
All Other Countries
Disaggregation of Revenue [Line Items]
Revenue	$ 35,078	$ 42,240

Revenue - Additional Informatio

Revenue - Additional Information (Details) $ in Thousands	12 Months Ended
Revenue - Additional Information (Details) $ in Thousands	Dec. 31, 2023 USD ($) Country	Dec. 31, 2022 USD ($) Country
Disaggregation of Revenue [Line Items]
Revenue \| $	$ 13,300	$ 16,000
Number of countries generate revenue \| Country	4	4
United States
Disaggregation of Revenue [Line Items]
Revenue \| $	$ 0
Each Country \| Revenue from Contract with Customer Benchmark \| Geographic Concentration Risk \| Minimum
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	5%	6%
Each Country \| Revenue from Contract with Customer Benchmark \| Geographic Concentration Risk \| Maximum
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	9%	7%
All Other Countries
Disaggregation of Revenue [Line Items]
Number of countries generate revenue by sales \| Country	55	50
Four Countries Included Within All Other Countries \| Revenue from Contract with Customer Benchmark \| Geographic Concentration Risk
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	25%	25%

Inventory - Schedule of Invento

Inventory - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory, Gross [Abstract]
Finished goods	$ 3,427	$ 2,096
Work in progress	967	213
Raw materials	1,777	1,556
Total Inventory	$ 6,171	$ 3,865

Inventory - Additional Informat

Inventory - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Inventory [Line Items]
Provision for excess and obsolete inventory		$ 0
Maximum
Inventory [Line Items]
Provision for excess and obsolete inventory	$ 0.1

Property and Equipment, net - S

Property and Equipment, net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 5,745	$ 4,650
Less: accumulated depreciation and amortization	(3,559)	(2,851)
Property and equipment net	$ 3,381	2,382
Computers and purchased software
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Property and equipment at cost	$ 618	575
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 1,943	1,822
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Property and equipment at cost	$ 291	251
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 2,893	2,002
Machinery and equipment \| Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Machinery and equipment \| Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment at cost	$ 1,195	$ 583

Property and Equipment, net - A

Property and Equipment, net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 746	$ 875

Property and Equipment, net -_2

Property and Equipment, net - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 746	$ 875
Cost of Revenue
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	367	568
Research and Development
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	179	90
General and Administrative
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	138	160
Sales and Marketing
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 62	$ 57

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
Distributor fees and marketing reimbursements	$ 2,834	$ 6,348
Accrued compensation	1,687	3,453
Accrued clinical trials and R&D	3,694	228
Accrued selling and marketing	1,110	481
Accrued professional fees	1,505	2,105
Accrued interest		489
Accrued warranty	44	48
Accrued restructuring	655
Other accrued expenses	3,966	2,641
Total accrued expenses and other current liabilities	$ 15,495	$ 15,793

Accrued Expenses and Other Cu_4

Accrued Expenses and Other Current Liabilities - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Debt Disclosure [Abstract]
Restructuring charges	$ 1
Payments for restructuring	$ 0.4

Debt - Summary of Components of

Debt - Summary of Components of Third-Party Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total principal amount of debt	$ 43,100	$ 58,103
Plus: Accretion	148	213
Less: current portion of long-term debt, net of discounts	(38,643)	(53,360)
Less: unamortized deferred financing costs and debt discounts	(4,605)	(1,853)
Long-term debt, net of current portion and discounts		3,103
Convertible Notes
Debt Instrument [Line Items]
Total principal amount of debt		3,103
2021 Term Loan
Debt Instrument [Line Items]
Total principal amount of debt		$ 55,000
Fortress Term Loan
Debt Instrument [Line Items]
Total principal amount of debt	$ 43,100

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)

1 Months Ended

4 Months Ended

5 Months Ended

7 Months Ended

12 Months Ended

Aug. 01, 2023

May 02, 2023

Aug. 31, 2023

Sep. 30, 2022

Jan. 31, 2022

Dec. 31, 2021

Mar. 31, 2021

Sep. 30, 2022

Dec. 31, 2023

Aug. 31, 2023

Dec. 31, 2023

Dec. 31, 2022

Dec. 29, 2023

Debt Instrument [Line Items]

Principal balance

$ 43,100,000

$ 58,103,000

Loss on extinguishment of debt

$ 3,929,000

Warrants converted into warrants exercisable

403,658

436,711

Proceeds from issuance of convertible notes

$ 28,700,000

$ 1,103,000

Repayment of convertible debt

$ 10,750,000

Backstop Agreement

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

$ 2,000,000

Shares issued upon conversion of outstanding notes

700,000

Fortress Credit Agreement

Debt Instrument [Line Items]

Interest, frequency of payment

The Fortress Term Loan has a maturity date of June 30, 2027 and accrues interest per annum at a rate of 6.44% plus the greater of (i) the Wall Street Journal Prime Rate and (ii) 3.0%, which interest is payable in arrears on a monthly basis. An exit payment equal to 3.0% of the Fortress Term Loan (the "Exit Fee") is due upon prepayment or the maturity date of the Fortress Term Loan, in addition to any early prepayment fee.

2021 Convertible Notes

Debt Instrument [Line Items]

Interest expense

$ 100,000

100,000

Proceeds from issuance of convertible notes

$ 2,000,000

Interest rate

Debt instrument, term

36 months

Unamortized debt issuance costs

$ 0

Conversion divided by capped conversion price

600,000,000

2021 Convertible Notes | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of outstanding notes

133,617

Aggregate recognition APIC amount

$ 2,200,000

2022 Convertible Notes

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

$ 1,100,000

Interest rate

Debt instrument, term

36 months

2022 Convertible Notes | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of outstanding notes

83,216

Aggregate recognition APIC amount

$ 1,200,000

2022 Convertible Notes | Maximum

Debt Instrument [Line Items]

Interest expense

100,000

200,000

2023 Convertible Notes

Debt Instrument [Line Items]

Interest expense

500,000

Proceeds from issuance of convertible notes

$ 28,700,000

Repayment of principal

500,000

Interest rate

Debt instrument maturity date

Dec. 31, 2026

Conversion divided by discounted capped conversion price

$ 217,300,000

Capped price

$ 260,000,000

Percentage of conversion discounted price is calculated of cash price

85%

Repayment of convertible debt

2,000,000

Debt prepayment penalty

$ 1,500,000

2023 Convertible Notes | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of outstanding notes

3,084,389

Aggregate recognition APIC amount

$ 22,200,000

Side Letter Holder Bridge Note

Debt Instrument [Line Items]

Principal balance

6,300,000

Proceeds from issuance of convertible notes

$ 2,700,000

Shares issued upon conversion of outstanding notes

387,696

Aggregate recognition APIC amount

$ 2,700,000

Repayment of convertible debt

6,300,000

Debt instrument, convertible price for calculating equity securities

$ 5

Deferred liability for issuance of additional shares

$ 3,400,000

Side Letter Holder Bridge Note | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of outstanding notes

300,000

Side Letter Holder Bridge Note | Minimum

Debt Instrument [Line Items]

Repayment of convertible debt

$ 6,000,000

Side Letter Holder Bridge Note | Backstop Agreement

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

2,000,000

Deferred liability for issuance of additional shares

3,300,000

Side Letter Holder Bridge Note | Backstop Agreement | Maximum

Debt Instrument [Line Items]

Proceeds from issuance of convertible notes

$ 2,000,000

2021 Term Loan

Debt Instrument [Line Items]

Interest expense

5,000,000

4,300,000

Contractual interest

4,700,000

3,800,000

Amortization of the debt discount

100,000

200,000

Accretion

100,000

200,000

Principal balance

55,000,000

Amortization of the warrant

100,000

2021 Term Loan | 2021 Term Loan Agreement | Runway

Debt Instrument [Line Items]

Initial cash proceeds

$ 15,000,000

Available capacity based upon the achievement of certain revenue thresholds

5,000,000

Loss on extinguishment of debt

3,900,000

Total payoff amount

58,000,000

Repayment of principal

55,000,000

Prepayment fee

1,100,000

Final payment fee

$ 1,600,000

Prepayment fee percentage

Original final payment

$ 100,000

Final payment fee percentage

2021 Term Loan | 2021 Term Loan Agreement | Runway | Maximum

Debt Instrument [Line Items]

Additional borrowings

$ 10,000,000

Term C Loan | Amended 2021 Term Loan Agreement | Runway

Debt Instrument [Line Items]

Additional borrowings

$ 15,000,000

20,000,000

$ 15,000,000

Available capacity based upon the achievement of certain revenue thresholds

$ 15,000,000

Maturity Date

Dec. 30, 2025

Equal monthly principal payments commencing date

Dec. 30, 2024

Revenue thresholds achieved date

Jun. 30, 2022

Issuance costs

$ 300,000

$ 700,000

$ 300,000

Fair value of the warrants

$ 300,000

300,000

Warrant liability

400,000

Term C Loan | Amended 2021 Term Loan Agreement | Runway | Legacy Allurion Series C Preferred Stock

Debt Instrument [Line Items]

Warrants exercisable

132,979

Term C Loan | Amended 2021 Term Loan Agreement | Runway | Common Stock

Debt Instrument [Line Items]

Warrants converted into warrants exercisable

130,053

Term C Loan | Amended 2021 Term Loan Agreement | Runway | Series D-1 Preferred Stock

Debt Instrument [Line Items]

Warrants exercisable

44,220

Term D Loan | Amended 2021 Term Loan Agreement | Runway

Debt Instrument [Line Items]

Additional borrowings

15,000,000

Maturity Date

Dec. 30, 2026

Interest rate

3.25%

Basis spread on variable rate

6.44186%

Fair value of the warrants

400,000

$ 400,000

Description of interest rate variable

change the interest rate to the higher of the prime rate or 3.25% plus the applicable margin of 6.44186%,

Term D Loan | Amended 2021 Term Loan Agreement | Runway | Common Stock

Debt Instrument [Line Items]

Warrants converted into warrants exercisable

90,476

Term D Loan | Amended 2021 Term Loan Agreement | Runway | Series D-1 Preferred Stock

Debt Instrument [Line Items]

Warrants exercisable

44,220

Warrants converted into warrants exercisable

88,440

Term D Loan | Amended 2021 Term Loan Agreement | Runway | Maximum

Debt Instrument [Line Items]

Additional borrowings

$ 15,000,000

Fortress Term Loan

Debt Instrument [Line Items]

Principal balance

43,100,000

$ 43,100,000

Issuance costs

$ 2,500,000

Fortress Term Loan | Fortress Credit Agreement

Debt Instrument [Line Items]

Initial cash proceeds

$ 60,000,000

Interest expense

4,100,000

Contractual interest

3,800,000

Amortization of the debt discount

200,000

Accretion

$ 100,000

Interest rate

6.44%

14.94%

Basis spread on variable rate

Debt instrument exit payment percentage

Issuance costs

$ 2,500,000

Debt instrument maturity date

Jun. 30, 2027

Minimum Liquidity Amount

$ 12,500,000

Increase in interest rate

Default interest rate

Fair value of term loan derivative liability

$ 1,900,000

Fortress Term Loan | Fortress Amendment

Debt Instrument [Line Items]

Unamortized debt issuance costs

800,000

Principal amount

20,000,000

Debt fee amount incurred

3,100,000

Fortress Term Loan | Fortress Amendment | Until March 31, 2024

Debt Instrument [Line Items]

Minimum Liquidity Amount

33,500,000

Fortress Term Loan | Fortress Amendment | From April 1, 2024 to June 30, 2024

Debt Instrument [Line Items]

Minimum Liquidity Amount

23,500,000

Fortress Term Loan | Fortress Amendment | From July 1, 2024 to September 30, 2024

Debt Instrument [Line Items]

Minimum Liquidity Amount

16,900,000

Fortress Term Loan | Fortress Amendment | On October 1, 2024 and Thereafter

Debt Instrument [Line Items]

Minimum Liquidity Amount

12,500,000

Fortress Term Loan | Fortress Amendment | Maximum | Common Stock

Debt Instrument [Line Items]

Principal balance

$ 20,000,000

Fortress Term Loan | Side Letter Holder Bridge Note | Backstop Agreement | Common Stock

Debt Instrument [Line Items]

Shares issued upon conversion of outstanding notes

950,000

Aggregate recognition APIC amount

$ 13,400,000

Debt - Schedule of Future Matur

Debt - Schedule of Future Maturities of the Term Loan Facility (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total principal amount of debt	$ 43,100	$ 58,103
Fortress Term Loan
Debt Instrument [Line Items]
December 31, 2026	8,979
December 31, 2027	34,121
Total principal amount of debt	$ 43,100
2021 Term Loan
Debt Instrument [Line Items]
Total principal amount of debt		$ 55,000

Revenue Interest Financing, S_3

Revenue Interest Financing, Side Letter, and PIPE Conversion Option - Additional Information (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 09, 2023 USD ($) Days $ / shares	Dec. 31, 2023 USD ($)	Aug. 01, 2023 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Change in fair value of revenue interest financing		$ (700)
Revenue Interest Financing Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues Interest Financing Liability		40,000	$ 40,000
Pre payments percentage	165%
Gain in fair value of revenue interest financing		3,400
Change in fair value of revenue interest financing		(700)
Royalty Payments		1,092
Issuance costs			1,200
Stock price \| $ / shares	$ 10
Revenue Interest Financing Agreement \| December 31, 2027
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash payments percentage	100%
Revenue Interest Financing Agreement \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of annual net sales	6%
Remittance of revenue interest payments percentage	10%
Revenue interest payments percentage	260%
Volume weighted average price per share \| $ / shares	$ 7.04
Conversion of PIPE subscription to revenue interest finance	$ 7,500	$ 7,500
Trading days \| Days	30
Revenue Interest Financing Agreement \| Maximum \| December 31, 2030
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash payments percentage	240%
Revenue Interest Financing Agreement \| Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payments percentage	100%
Trading days \| Days	20
Revenue Interest Financing Agreement \| Minimum \| December 31, 2030
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue interest payments percentage	240%
Revenue Interest Financing Agreement \| PIPE Conversion Option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issue-date estimated fair value			$ 3,300

Revenue Interest Financing, S_4

Revenue Interest Financing, Side Letter, and PIPE Conversion Option - Summary of Components of Revenue Interest Financing (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Aug. 01, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Long-term Revenue Interest Financing liability	$ 36,200
Revenue Interest Financing Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues Interest Financing Liability	40,000	$ 40,000
Total principal amounts of debt	40,000
Less: Royalty payments	(1,092)
Less: Change in fair value of debt	(2,708)
Long-term Revenue Interest Financing liability	$ 36,200

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value at Issuance Date and on Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 30,582	$ 4,925
Total Liabilities	5,943
Level 1 \| Public Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	5,943
Level 1 \| Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	30,582	4,925
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	68,520	2,551
Level 3 \| Legacy Allurion Common Stock Warrant Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	821
Level 3 \| Revenue Interest Financing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	36,200
Level 3 \| PIPE Conversion Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	5,600
Level 3 \| Earn-out Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	23,990
Level 3 \| Term Loan Derivative Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	1,895
Level 3 \| Legacy Allurion Series C Common Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		340
Level 3 \| Legacy Allurion Series B Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		303
Level 3 \| Legacy Allurion Series A-1 Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		82
Level 3 \| Other Common Stock Warrant Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		255
Level 3 \| Legacy Allurion Series C Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		684
Level 3 \| Derivative Liability-Success Fee
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	14	180
Level 3 \| Legacy Allurion Series D-1 Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		707
Total Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	30,582	4,925
Total Liabilities	74,463	2,551
Total Carrying Value \| Legacy Allurion Common Stock Warrant Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	821
Total Carrying Value \| Public Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	5,943
Total Carrying Value \| Revenue Interest Financing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	36,200
Total Carrying Value \| PIPE Conversion Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	5,600
Total Carrying Value \| Earn-out Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	23,990
Total Carrying Value \| Term Loan Derivative Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	1,895
Total Carrying Value \| Legacy Allurion Series C Common Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		340
Total Carrying Value \| Legacy Allurion Series B Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		303
Total Carrying Value \| Legacy Allurion Series A-1 Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		82
Total Carrying Value \| Other Common Stock Warrant Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		255
Total Carrying Value \| Legacy Allurion Series C Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		684
Total Carrying Value \| Derivative Liability-Success Fee
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities	14	180
Total Carrying Value \| Legacy Allurion Series D-1 Preferred Stock Warrant Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Liabilities		707
Total Carrying Value \| Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Assets	$ 30,582	$ 4,925

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Assumptions used in Pricing Model (Details) - Black-Scholes Option Pricing Model - Level 3	Dec. 31, 2023	Dec. 31, 2022
Interest Rate \| Other Common Stock
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	0.0395
Interest Rate \| Other Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0399
Interest Rate \| Legacy Allurion Series A 1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0442
Interest Rate \| Legacy Allurion Series B Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0441
Interest Rate \| Legacy Allurion Series C Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0411
Interest Rate \| Legacy Allurion Series C Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	0.0388	0.0392
Interest Rate \| Legacy Allurion Series D-1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	0.0388
Interest Rate \| Legacy Allurion Series D-1 Preferred Stock Warrants \| Minimum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0388
Interest Rate \| Legacy Allurion Series D-1 Preferred Stock Warrants \| Maximum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.0392
Exercise Price \| Other Common Stock
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	1.05
Exercise Price \| Other Common Stock Warrants \| Minimum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		1.02
Exercise Price \| Other Common Stock Warrants \| Maximum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		1.1
Exercise Price \| Legacy Allurion Series A 1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		1.9
Exercise Price \| Legacy Allurion Series B Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		2.38
Exercise Price \| Legacy Allurion Series C Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.01
Exercise Price \| Legacy Allurion Series C Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	6.73	6.58
Exercise Price \| Legacy Allurion Series D-1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	12.14	11.87
Estimated Fair Value of Underlying Share Price \| Other Common Stock
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	3.74
Estimated Fair Value of Underlying Share Price \| Other Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		4.54
Estimated Fair Value of Underlying Share Price \| Legacy Allurion Series A 1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		6.75
Estimated Fair Value of Underlying Share Price \| Legacy Allurion Series B Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		6.91
Estimated Fair Value of Underlying Share Price \| Legacy Allurion Series C Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		4.54
Estimated Fair Value of Underlying Share Price \| Legacy Allurion Series C Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	3.74	7.24
Estimated Fair Value of Underlying Share Price \| Legacy Allurion Series D-1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	3.74	11.31
Expected Volatility \| Other Common Stock
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	1
Expected Volatility \| Other Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.63
Expected Volatility \| Legacy Allurion Series A 1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.69
Expected Volatility \| Legacy Allurion Series B Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.65
Expected Volatility \| Legacy Allurion Series C Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input		0.63
Expected Volatility \| Legacy Allurion Series C Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	1	0.63
Expected Volatility \| Legacy Allurion Series D-1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants measurement input	1	0.63
Expected Life (Years) \| Other Common Stock
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term	3 years 8 months 8 days
Expected Life (Years) \| Other Common Stock Warrants \| Minimum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term		4 years 7 months 6 days
Expected Life (Years) \| Other Common Stock Warrants \| Maximum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term		4 years 8 months 12 days
Expected Life (Years) \| Legacy Allurion Series A 1 Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term		3 months
Expected Life (Years) \| Legacy Allurion Series B Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term		2 years
Expected Life (Years) \| Legacy Allurion Series C Common Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term		4 years
Expected Life (Years) \| Legacy Allurion Series C Preferred Stock Warrants
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term	7 years 3 months	8 years 2 months 12 days
Expected Life (Years) \| Legacy Allurion Series D-1 Preferred Stock Warrants \| Minimum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term	7 years 3 months	8 years 2 months 12 days
Expected Life (Years) \| Legacy Allurion Series D-1 Preferred Stock Warrants \| Maximum
Fair Value, Assets Measured on Recurring Basis, Observable and Unobservable Input Reconciliation [Line Items]
Warrants term	8 years 8 months 15 days	9 years 8 months 12 days

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Aug. 01, 2023 $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022
Fortress Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan \| $		$ 43.2
Public Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock price		$ 0.45
Expected Dividend Yield \| Level 3 \| Black-Scholes Option Pricing Model
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants measurement input		0	0
PubCo Additional Shares Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of estimated number of shares \| shares	387,696
Fair value of estimated price of shares	$ 7.04
Base PubCo Shares and Backstop Shares Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of estimated number of shares \| shares	950,000
Fair value of estimated price of shares	$ 7.04
Term Loan Derivative Liability \| Estimated Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, measurement input		24.4
2019 Term Loan and Success Fee
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assumptions of liquidity event term		4 years
2023 Convertible Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated share price at conversion	$ 7.04
Revenue Interest Financing and PIPE Conversion Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of estimated number of shares \| shares		1,065,341
Stock price		$ 3.74
Revenue Interest Financing and PIPE Conversion Option \| Estimated Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, measurement input		24.4

Fair Value Measurements - Sch_3

Fair Value Measurements - Schedule of Changes in Fair Values (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 2,373	$ 741
Fair value upon issuance		834
Change in fair value	$ (548)	$ 821
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Fair Value Adjustment of Warrants	Fair Value Adjustment of Warrants
Exercise of warrants	$ (75)	$ (23)
Derecognition of liability to equity	(929)
Ending Balance	821	2,373
Preferred Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,777	510
Fair value upon issuance		834
Change in fair value	(720)	456
Exercise of warrants	(75)	(23)
Derecognition of liability to equity	(340)
Ending Balance	642	1,777
Common Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	596	231
Change in fair value	172	365
Derecognition of liability to equity	(589)
Ending Balance	179	596
Public Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	178	159
Fair value upon issuance	133,609
Change in fair value	(17,147)	19
Change in fair value - OCI	700
Payments	(11,842)
Derecognition of liability to equity	(37,799)
Ending Balance	67,699	178
Public Warrants \| Success Fee Derivative Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	178	159
Change in fair value	(164)	19
Ending Balance	14	$ 178
Public Warrants \| 2023 Convertible Notes
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	28,700
Change in fair value	3,751
Payments	(10,750)
Derecognition of liability to equity	(21,701)
Public Warrants \| PubCo Share Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	3,370
Change in fair value	(642)
Derecognition of liability to equity	(2,728)
Public Warrants \| Base PubCo and Backstop Share Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	3,264
Change in fair value	10,106
Derecognition of liability to equity	(13,370)
Public Warrants \| Term Loan Derivative Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	1,895
Ending Balance	1,895
Public Warrants \| Revenue Interest Financing
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	40,000
Change in fair value	(3,408)
Change in fair value - OCI	700
Payments	(1,092)
Ending Balance	36,200
Public Warrants \| PIPE Conversion Derivative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	3,340
Change in fair value	2,260
Ending Balance	5,600
Public Warrants \| Earn-Out Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value upon issuance	53,040
Change in fair value	(29,050)
Ending Balance	$ 23,990

Fair Value Measurements - Sch_4

Fair Value Measurements - Schedule of Estimated Fair Value was Measured Using a Monte Carlo Simulation Method (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Risk-free interest rate	4.50%	3.56%
Expected term (in years)	5 years 9 months 18 days	5 years 9 months 18 days
Expected volatility	85.80%	63%
Revenue Interest Financing and PIPE Conversion Option
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock price	$ 3.74
Risk-free interest rate	4.46%
Expected term (in years)	1 year 7 months 6 days
Expected volatility	82.50%
Earn-Out Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock price	$ 3.74
Risk-free interest rate	3.90%
Expected term (in years)	4 years 7 months 6 days
Expected volatility	87%

Income Taxes - Domestic and For

Income Taxes - Domestic and Foreign Components of Net Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
U.S.	$ (81,259)	$ (38,267)
Foreign	916	666
Loss before income taxes	$ (80,343)	$ (37,601)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Tax Rate and Statutory Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. statutory federal income tax rate	21%	21%
State income taxes, net of federal income tax benefit	7.10%	6.90%
Change in fair value of financial instruments	3%	0%
Tax credits	0.40%	1%
Valuation allowance	(30.50%)	(29.00%)
Non-deductible expenses	(0.90%)	0%
Other	(0.40%)	(0.20%)
Effective tax rate	(0.30%)	(0.30%)

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of Deferred Tax Assets and Liabilities [Abstract]
U.S. federal and state net operating loss carryforwards	$ 36,092	$ 25,051
Capitalized start-up and research and development expenses	10,868	5,377
Research and development tax credits	2,275	1,780
Interest expense	3,918
Lease liability	659	838
Depreciation	203	236
Bad debt reserve	3,461
Other temporary differences	2,145	994
Total deferred tax assets	59,621	34,276
Valuation allowance	(57,985)	(33,484)	$ (22,579)
Net deferred tax assets	1,636	792
Right of use asset	(623)	(792)
Other deferred tax liability	(1,013)
Total deferred tax liabilities	$ (1,636)	$ (792)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
Income Taxes - Additional Information (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 264,000	$ 143,000
Valuation allowance increased	24,501,000	10,905,000
Net operating loss carryforwards	$ 36,092,000	$ 25,051,000
Effective tax rates	(0.30%)	(0.30%)
Uncertain tax positions	$ 0	$ 0
Accrued interest and penalties	0	$ 0
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	131,700,000
Tax credit carry forwards research and development	$ 900,000
Tax credits research and development expiration year	2028
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 132,200,000
Tax credit carry forwards research and development	$ 1,500,000
Tax credits research and development expiration year	2031
Earliest Tax Year \| State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration period	2030
Earliest Tax Year \| Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration period	2030
Latest Tax Year \| Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration period	2037
Latest Tax Year \| State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards expiration period	2042
Expire between 2030 and 2037 \| Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 12,800,000
Do not expire \| Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 119,500,000

Income Taxes - Summary of Valua

Income Taxes - Summary of Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Valuation Allowance [Abstract]
Beginning balances	$ 33,484	$ 22,579
Additions charged to net loss	24,501	10,905
Ending balances	$ 57,985	$ 33,484

Capital Stock and Stockholder_3

Capital Stock and Stockholders' Deficit - Schedule of Preferred Stock Details Prior to Business Combination (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Preferred Stock Authorized	100,000,000	100,000,000
Preferred Stock Issued	0	0
Preferred Stock Outstanding	0	0
Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	21,029,888
Preferred Stock Issued	19,921,042
Preferred Stock Outstanding	19,921,042
Carrying Value	$ 97,216
Series A Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	2,276,786
Preferred Stock Issued	2,276,786
Preferred Stock Outstanding	2,276,786
Carrying Value	$ 1,542
Series A-1 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	1,513,028
Preferred Stock Issued	1,486,048
Preferred Stock Outstanding	1,486,048
Carrying Value	$ 2,842
Series B Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	2,298,929
Preferred Stock Issued	2,245,515
Preferred Stock Outstanding	2,245,515
Carrying Value	$ 5,253
Series C Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	8,113,616
Preferred Stock Issued	7,927,446
Preferred Stock Outstanding	7,927,446
Carrying Value	$ 39,122
Series D-1 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	1,684,565
Preferred Stock Issued	842,283
Preferred Stock Outstanding	842,283
Carrying Value	$ 9,614
Series D-2 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	3,644,616
Preferred Stock Issued	3,644,616
Preferred Stock Outstanding	3,644,616
Carrying Value	$ 24,054
Series D-3 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred Stock Authorized	1,498,348
Preferred Stock Issued	1,498,348
Preferred Stock Outstanding	1,498,348
Carrying Value	$ 14,789

Capital Stock and Stockholder_4

Capital Stock and Stockholders' Deficit - Additional Information (Details) - USD ($)			12 Months Ended
	Dec. 18, 2023	Aug. 01, 2023	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Preferred stock, shares authorized			100,000,000	100,000,000
Preferred stock, shares outstanding			0	0
Dividends declared			$ 0
Preferred stock, par value			$ 0.0001	$ 0.0001
Number of shares authorized			1,000,000,000	1,000,000,000
Number of shares outstanding		47,301,409	47,688,096	27,079,856
Warrants outstanding			403,658
Common stock, par value			$ 0.0001	$ 0.0001
Warrants exercisable price			$ 8.1
Public warrant liabilities			$ 5,943,000
Issuance of convertible preferred stock for the exercise of warrant (in shares)		18,759,838
Additional paid-in capital		$ 15,200,000	$ 143,007,000	$ 99,875,000
ChEF Purchase Agreement \| Chardan Equity Facility
Class of Stock [Line Items]
Number of shares sold per unit			0
Stock issued during period value	$ 100,000,000
Expense of issuance of commitment shares	100,000
Additional paid-in capital	100,000
Structuring fee payable	$ 100,000
Common Stock \| ChEF Purchase Agreement \| Chardan Equity Facility
Class of Stock [Line Items]
Number of shares outstanding	9,482,468
Percentage of common stock, shares, outstanding	19.99%
Commitment Shares \| ChEF Purchase Agreement \| Chardan Equity Facility
Class of Stock [Line Items]
Stock issued during period value	$ 35,511
Public Warrant
Class of Stock [Line Items]
Public warrant liabilities			$ 13,206,922
Issuance of convertible preferred stock for the exercise of warrant (in shares)			18,759,838
Public Warrant \| Scenario Plan Three
Class of Stock [Line Items]
Warrants redumption price per share			$ 0.01
Stock price			12.67
Public Warrant \| Scenario Plan Four
Class of Stock [Line Items]
Warrants redumption price per share			0.1
Stock price			7.04
Compute Health
Class of Stock [Line Items]
Sale of stock			$ 10
Compute Health \| IPO
Class of Stock [Line Items]
Number of shares sold per unit			1
Class of Warrant Exchanged			0.6125
Compute Health \| Public Warrant
Class of Stock [Line Items]
Number of shares sold per unit			0.5
Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			21,029,888
Preferred stock, shares outstanding			19,921,042
Preferred stock voting rights			The Legacy Allurion preferred stockholders voted as a single class together with holders of all other classes and series of stock of Legacy Allurion on all actions to be taken by the stockholders of the Company. The Legacy Allurion preferred stockholders were entitled to the number of votes equal to the number of shares of Legacy Allurion common stock into which the shares held by each holder were then convertible. The Legacy Allurion Series C Preferred Stockholders were entitled to elect two members of the Board of Directors
Common stock voting rights			common stockholders were entitled to elect four members of the Board of Directors.
Revenue milestone			$ 65,000,000
Percentage of shares of common stock held			150%
Preferred stock conversion rights			Each share of Legacy Allurion preferred stock was convertible at any time, at the option of the holder, into one share of Legacy Allurion common stock, based upon a per share conversion factor of each series’ applicable original issuance prices, adjustable for certain dilutive events. Conversion was mandatory upon the closing of an IPO or deSPAC transaction, or upon the election of the holders of a majority of the then-outstanding Legacy Allurion preferred stock.
Series A Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			2,276,786
Preferred stock, shares outstanding			2,276,786
Preferred stock liquidation preference per share			$ 1.092
Original issue price			$ 1.092
Series A-1 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			1,513,028
Preferred stock, shares outstanding			1,486,048
Preferred stock liquidation preference per share			$ 2.85
Series B Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			2,298,929
Preferred stock, shares outstanding			2,245,515
Preferred stock liquidation preference per share			$ 3.563
Series C Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			8,113,616
Preferred stock, shares outstanding			7,927,446
Preferred stock liquidation preference per share			$ 4.935
Preferred Stock redemption value to price			1.5
Series C Preferred Stock \| Legacy Allurion \| Maximum
Class of Stock [Line Items]
Percentage of outstanding shares of redeemable			50%
Series D Preferred Stock
Class of Stock [Line Items]
Percentage of preferred stock dividend			6%
Series D-1 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			1,684,565
Preferred stock, shares outstanding			842,283
Preferred stock liquidation preference per share			$ 17.809
Preferred stock, par value			$ 11.8725
Series D-2 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			3,644,616
Preferred stock, shares outstanding			3,644,616
Preferred stock liquidation preference per share			$ 9.338
Preferred stock, par value			$ 6.2256
Series D-3 Preferred Stock \| Legacy Allurion
Class of Stock [Line Items]
Preferred stock, shares authorized			1,498,348
Preferred stock, shares outstanding			1,498,348
Preferred stock liquidation preference per share			$ 15.137
Preferred stock, par value			$ 10.0916
Class A Common Stock
Class of Stock [Line Items]
Number of shares sold per unit			1
Common stock, par value			$ 0.0001
Class A Common Stock \| Compute Health \| IPO
Class of Stock [Line Items]
Sale of stock			$ 11.5
Shares issuable for each outstanding warrants exercised			1.420455

Capital Stock and Stockholder_5

Capital Stock and Stockholders' Deficit - Summary of Reserved for Issuance Upon the Potential Conversion or Exercise (Details)	Dec. 31, 2023 shares
Class of Stock [Line Items]
Common stock shares reserved for future issuance	32,693,169
Restricted Stock Units
Class of Stock [Line Items]
Common stock shares reserved for future issuance	643,635
Outstanding Options to Purchase Common Stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance	3,886,038
Warrants to Purchase Preferred Stock (as converted to warrants to purchase common stock)
Class of Stock [Line Items]
Common stock shares reserved for future issuance	138,857
Warrants to Purchase Common Stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance	264,801
Public Warrants to Purchase Common Stock
Class of Stock [Line Items]
Common stock shares reserved for future issuance	18,759,838
Earn-Out Shares
Class of Stock [Line Items]
Common stock shares reserved for future issuance	9,000,000

Capital Stock and Stockholder_6

Capital Stock and Stockholders' Deficit - Summary of Warrants to Purchase Classes of Preferred Stock and Common Stock Outstanding (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Class of Warrant or Right [Line Items]
Shares Issuable Upon Exercise of Warrant	403,658	436,711
Weighted Average Exercise Price	$ 8.1
April 1, 2013 \| Series A-1 Preferred Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)		2 months 12 days
Shares Issuable Upon Exercise of Warrant		16,557
Weighted Average Exercise Price		$ 1.95
December 1, 2014 \| Series B Preferred Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)		1 year 10 months 24 days
Shares Issuable Upon Exercise of Warrant		60,768
Weighted Average Exercise Price		$ 2.44
December 1, 2014 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	10 months 24 days
Shares Issuable Upon Exercise of Warrant	44,272
Weighted Average Exercise Price	$ 2.44
March 30, 2021 \| Series C Preferred Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)		8 years 2 months 12 days
Shares Issuable Upon Exercise of Warrant		130,053
Weighted Average Exercise Price		$ 6.73
March 30, 2021 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	7 years 2 months 12 days
Shares Issuable Upon Exercise of Warrant	130,053
Weighted Average Exercise Price	$ 6.73
September 15, 2022 \| Series D-1 Preferred Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)		9 years 8 months 12 days
Shares Issuable Upon Exercise of Warrant		45,238
Weighted Average Exercise Price		$ 12.14
September 15, 2022 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	8 years 8 months 12 days
Shares Issuable Upon Exercise of Warrant	45,238
Weighted Average Exercise Price	$ 12.14
June 4, 2022 \| Series D-1 Preferred Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)		9 years 4 months 24 days
Shares Issuable Upon Exercise of Warrant		45,238
Weighted Average Exercise Price		$ 12.14
June 4, 2022 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	8 years 4 months 24 days
Shares Issuable Upon Exercise of Warrant	45,238
Weighted Average Exercise Price	$ 12.14
January 17, 2017 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	3 years	4 years
Shares Issuable Upon Exercise of Warrant	73,349	73,349
Weighted Average Exercise Price	$ 0.02	$ 0.02
August 3, 2017 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	3 years 7 months 6 days	4 years 7 months 6 days
Shares Issuable Upon Exercise of Warrant	9,779	9,779
Weighted Average Exercise Price	$ 1.13	$ 1.13
September 8, 2017 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	3 years 8 months 12 days	4 years 8 months 12 days
Shares Issuable Upon Exercise of Warrant	28,764	28,764
Weighted Average Exercise Price	$ 1.05	$ 1.05
June 19, 2018 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	4 years 6 months	5 years 6 months
Shares Issuable Upon Exercise of Warrant	17,977	17,977
Weighted Average Exercise Price	$ 1.05	$ 1.05
June 25, 2019 \| Common Stock
Class of Warrant or Right [Line Items]
Remaining Contractual Term (in years)	5 years 6 months	6 years 6 months
Shares Issuable Upon Exercise of Warrant	8,988	8,988
Weighted Average Exercise Price	$ 1.05	$ 1.05

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Numerator:
Net loss		$ (80,607)	$ (37,744)
Cumulative undeclared dividends to participating securities (Legacy Series D convertible preferred stock)		(1,697)	(2,907)
Net loss attributable to common stockholders		$ (82,304)	$ (40,651)
Denominator:
Basic weighted-average common stock outstanding		35,581,656	26,918,484
Diluted weighted-average common stock outstanding		35,581,656	26,918,484
Net loss per share attributable to common stockholders, basic	[1]	$ (2.31)	$ (1.51)
Net loss per share attributable to common stockholders, diluted	[1]	$ (2.31)	$ (1.51)

[1] The weighted-average common shares and thus net loss per share calculations and potentially dilutive security amounts for all periods prior to the Business Combination have been retrospectively adjusted to the equivalent number of shares outstanding immediately after the Business Combination to effect the reverse capitalization. See Note 3 for further information.

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Dilutive Securities Excluded from Computation of Basic and Diluted Net Loss Per Common Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	32,693,169	6,325,031
Outstanding Options to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,886,038	4,301,960
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	643,635	1,415,104
Warrants to Purchase Preferred Stock (as converted to warrants to purchase Common Stock)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	138,857	297,854
Warrants to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	264,801	138,857
Shares of Common Stock Issued Upon the Exercise of Public Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	18,759,838
Earn-Out Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	9,000,000
Convertible Note
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		171,256

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock shares reserved for future issuance		32,693,169
Unrecognized compensation costs		$ 1,700
Remaining weighted-average period		2 years
Stock compensation expense		$ 8,357	$ 437
Common stock, shares issued		47,688,096	27,079,856
Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting percentage		62.50%
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period	3 years	2 years
Stock compensation expense		$ 5,700
Restricted Stock Units \| Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Remaining vesting percentage		37.50%
Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average grant-date fair value of the stock option awards granted		$ 3.98	$ 2.36
Remaining weighted-average period		2 years 1 month 6 days
Stock compensation expense		$ 2,700
Time-Vested Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average grant-date fair value of time-vested restricted stock units granted		$ 4.32	$ 4.51
2010 Plan and 2020 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options and RSUs issued and exercisable under the plan			5,717,072
2010 Plan, 2020 Plan, and 2023 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options and RSUs issued and exercisable under the plan		4,529,673
Vesting period		4 years
Expiration period		10 years
2020 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation costs		$ 2,500
2023 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock shares reserved for future issuance		7,822,700
Increase (decrease) in percentage of number of shares reserved for future issuance		5%
2023 ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock shares reserved for future issuance		1,422,309
Percentage of price lower of fair value market value		85%
Percentage of employees compensation to payroll deductions		15%
Percentage of diluted shares outstanding		1%
Common stock, shares issued		0
2023 ESPP \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, shares issued		1,600,000

Stock Based Compensation - Sche

Stock Based Compensation - Schedule of Stock Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 8,357	$ 437
Cost of Revenue
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	32
Selling, General and Administrative
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	8,198	400
Research and Development
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 127	$ 37

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Stock Option Activity Under the Plan (Details) - 2010 Plan, 2020 Plan, 2023 Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Options, Beginning balance	4,301,968
Number of Options, Granted	257,683
Number of Options, Cancellations and forfeitures	(375,051)
Number of Options, Exercised	(298,562)
Number of Options, Ending balance	3,886,038	4,301,968
Number of Options, Exercisable	2,735,884
Weighted-Average Exercise Price, Beginning balance	$ 2.35
Weighted-Average Exercise Price, Granted	5.41
Weighted-Average Exercise Price, Cancellations and forfeitures	2
Weighted-Average Exercise Price, Exercised	1.15
Weighted-Average Exercise Price, Ending balance	2.67	$ 2.35
Weighted-Average Exercise Price, Exercisable	$ 2.23
Weighted-Average Remaining Contractual Term	6 years 10 months 24 days	7 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable	6 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 5,565	$ 9,437
Aggregate Intrinsic Value, Exercisable	$ 4,812

Stock Based Compensation - Sc_2

Stock Based Compensation - Schedule of Assumptions used in Black-Scholes Option-Pricing Model (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Expected volatility	85.80%	63%
Risk-free interest rate	4.50%	3.56%
Expected term (in years)	5 years 9 months 18 days	5 years 9 months 18 days

Stock Based Compensation - Su_2

Stock Based Compensation - Summary of Restricted Stock Unit Activity Under the Plan (Details) - Restricted Stock Units - 2020 Plan and 2023 Plan	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of RSUs, Beginning balance \| shares	1,415,104
Number of RSUs, Granted \| shares	226,175
Number of RSUs, Cancellations and forfeitures \| shares	(79,232)
Number of RSUs, Vested \| shares	(918,412)
Number of RSUs, Ending balance \| shares	643,635
Weighted Average Grant Date Fair Value, Beginning balance \| $ / shares	$ 4.51
Weighted Average Grant Date Fair Value, Granted \| $ / shares	4.32
Weighted Average Grant Date Fair Value, Cancellations and forfeitures \| $ / shares	4.51
Weighted Average Grant Date Fair Value, Vested \| $ / shares	4.51
Weighted Average Grant Date Fair Value, Ending balance \| $ / shares	$ 4.45

Employee Benefit Plan - Additio

Employee Benefit Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan matching contributions	$ 0.1	$ 0.1

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	1 Months Ended		12 Months Ended
	Aug. 31, 2023	Feb. 28, 2023	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Lease description			In February 2023 and August 2023, the Company executed amendments to three of its leases in Natick, Massachusetts and its Hudson, Massachusetts lease, respectively. The amendments were accounted for as a modification of the existing lease agreements, with impacts to the lease term, lease payments, and related lease liability for each of the four leases.
Operating lease assets obtained in exchange for lease obligations			$ 936,000	$ 1,677,000
Lease total area of land \| ft²			51,000
Lessee, operating lease, right to extend			The Company has a right to extend certain of these leases for periods between three and five years.
Lessee, operating lease, right to extend [true false]			true
Operating lease, weighted average remaining lease term			3 years 6 months	3 years 10 months 24 days
Operating lease liability, weighted average discount rate, percent			9.90%	9.50%
Loss contingency accruals for probable losses			$ 0	$ 0
Natick and Hudson
Loss Contingencies [Line Items]
Operating lease assets obtained in exchange for lease obligations			$ 900,000
Maximum
Loss Contingencies [Line Items]
Lessee, operating lease, remaining lease term			5 years
Maximum \| Natick and Hudson
Loss Contingencies [Line Items]
Lessee operating lease expiration period	2028-03	2028-03
Minimum
Loss Contingencies [Line Items]
Lessee, operating lease, remaining lease term			3 years
Minimum \| Natick and Hudson
Loss Contingencies [Line Items]
Lessee operating lease expiration period	2024-06	2024-06

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	$ 71,712	$ 51,370
Total liabilities	142,199	83,684
Total Equity	$ (70,487)	$ (32,314)	$ 4,837

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Other Pertinent Lease Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating lease costs	$ 1,123	$ 918
Finance lease costs
Short-term lease costs	12	14
Variable operating lease costs	187	191
Operating cash flows paid for amounts in the measurement of finance lease liabilities	1,084	807
Operating lease assets obtained in exchange for lease obligations	$ 936	$ 1,677

Commitments and Contingencies_4

Commitments and Contingencies - Schedule Leases are Included In On Our Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Operating leases
Total operating lease assets	$ 3,010	$ 2,899
Current portion of lease liabilities	908	905
Lease liabilities, net of current portion	$ 2,306	$ 2,163

Commitments and Contingencies_5

Commitments and Contingencies - Schedule of Future Commitments Under Non-cancelable Operating Lease Agreements (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Operating leases
Less: current lease liability	$ (908)	$ (905)
Long-term operating lease liabilities	2,306	$ 2,163
Total
2024	1,173
2025	1,114
2026	737
2027	645
2028	108
Total lease payments	3,777
Less: present value adjustment	(563)
Present value of total lease liabilities	3,214
Less: current lease liability	(908)
Long-term lease liabilities	$ 2,306

Commitments and Contingencies_6

Commitments and Contingencies - Schedule of Weighted-Average Remaining Lease Terms and Discount Rates Related Leases (Details)	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating leases, weighted -average remaining lease term (in years)	3 years 6 months	3 years 10 months 24 days
Operating leases, weighted-average discount rate	9.90%	9.50%

Geographic Information - Schedu

Geographic Information - Schedule of Long-lived Assets by Geography (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 6,391	$ 5,281
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	5,381	3,999
France
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,010	$ 1,282

Related-party Transactions - Ad

Related-party Transactions - Additional Information (Details) $ in Millions			1 Months Ended		3 Months Ended
	Dec. 12, 2023 USD ($)	Feb. 15, 2023 USD ($)	Sep. 30, 2023 EUR (€)	Aug. 31, 2022 USD ($)	Mar. 31, 2023 USD ($)
Related Party Transaction [Line Items]
Percentage of outstanding capital stock		5%
2023 Convertible Notes \| Hunter Ventures Limited [Member]
Related Party Transaction [Line Items]
Debt instrument issued		$ 13
Consulting Agreements
Related Party Transaction [Line Items]
Agreements termination date					Jun. 20, 2023
LNMP JPBC Invest
Related Party Transaction [Line Items]
Operating lease, payments				$ 0.1
Operating lease commencement date				Aug. 01, 2022
Operating lease end date				Jul. 31, 2025
Lease terminated date				2024-02
KKG Enterprises \| Consulting Agreements
Related Party Transaction [Line Items]
Payments of advisory services related to business combination					$ 0.2
Remus Group Management \| Consulting Agreements
Related Party Transaction [Line Items]
Payments of advisory services related to business combination					$ 0.3
Benoit Chardon Consulting \| Consulting Agreements
Related Party Transaction [Line Items]
Agreements termination date			Dec. 12, 2023
Consulting fees \| €			€ 28,333.33
Benoit Chardon Consulting \| Termination Agreement
Related Party Transaction [Line Items]
Termination fees	$ 0.2