Salarius Pharmaceuticals (SLRX) 10-Q 2 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 28, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Flex Pharma, Inc.
Entity Central Index Key	1,615,219
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		17,970,590

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 27,829,591	$ 66,686,695
Marketable securities	39,504,263	24,652,348
Accounts receivable	21,787	0
Inventory	230,778	0
Prepaid expenses and other current assets	1,554,270	908,574
Total current assets	69,140,689	92,247,617
Marketable securities	0	2,312,949
Property and equipment, net	619,371	382,437
Other assets	64,800	0
Restricted cash	126,595	126,835
Total assets	69,951,455	95,069,838
Current liabilities:
Accounts payable	1,256,889	875,646
Accrued expenses and other current liabilities	2,549,443	1,947,374
Deferred revenue	81,399	0
Deferred rent, current portion	25,351	24,381
Total current liabilities	3,913,082	2,847,401
Deferred rent, net of current portion	10,561	14,587
Other long term liabilities	0	15,442
Total liabilities	3,923,643	2,877,430
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at September 30, 2016 and December 31, 2015; none issued or outstanding at September 30, 2016 and December 31, 2015	0	0
Common stock, $0.0001 par value; 100,000,000 shares authorized at September 30, 2016 and December 31, 2015; 17,970,590 and 17,943,880 shares issued at September 30, 2016 and December 31, 2015, respectively, and 16,518,347 and 15,741,618 shares outstanding at September 30, 2016 and December 31, 2015, respectively	1,652	1,574
Additional paid-in capital	134,757,066	129,367,978
Accumulated other comprehensive income (loss)	14,672	(24,654)
Accumulated deficit	(68,745,578)	(37,152,490)
Total stockholders' equity	66,027,812	92,192,408
Total liabilities and stockholders' equity	$ 69,951,455	$ 95,069,838

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	17,970,590	17,943,880
Common stock, shares outstanding (in shares)	16,518,347	15,741,618

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Net product revenue	$ 586,134	$ 0	$ 698,819	$ 0
Other revenue	12,940	0	12,940	0
Total revenue	599,074	0	711,759	0
Costs and expenses:
Cost of product revenue	221,090	0	529,041	0
Research and development	5,665,357	3,445,200	16,147,357	9,440,324
Selling, general and administrative	5,447,847	4,722,281	15,937,326	11,842,896
Total costs and expenses	11,334,294	8,167,481	32,613,724	21,283,220
Loss from operations	(10,735,220)	(8,167,481)	(31,901,965)	(21,283,220)
Interest income, net	97,726	14,637	308,877	34,397
Net loss	(10,637,494)	(8,152,844)	(31,593,088)	(21,248,823)
Net loss attributable to common stockholders	$ (10,637,494)	$ (8,152,844)	$ (31,593,088)	$ (21,248,823)
Net loss per share attributable to common stockholders - basic and diluted (in usd per share)	$ (0.65)	$ (0.53)	$ (1.96)	$ (1.57)
Weighted-average number of common shares outstanding — basic and diluted (in shares)	16,361,617	15,290,435	16,104,510	13,520,438

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (10,637,494)	$ (8,152,844)	$ (31,593,088)	$ (21,248,823)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	(24,818)	(3,676)	39,326	(3,676)
Comprehensive loss	$ (10,662,312)	$ (8,156,520)	$ (31,553,762)	$ (21,252,499)

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net loss	$ (31,593,088)	$ (21,248,823)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	165,373	36,798
Stock-based compensation expense	5,367,070	4,892,998
Amortization and accretion on investments	117,236	1,192
Changes in operating assets and liabilities:
Restricted cash	240	(27)
Accounts receivable	(21,787)	0
Inventory	(109,701)	0
Prepaid expenses and other current assets	(645,696)	(715,105)
Other assets	(64,800)	(35,200)
Accounts payable	321,460	433,354
Accrued expenses and other current liabilities	647,455	1,339,165
Deferred revenue	81,399	0
Deferred rent	(3,056)	(13,161)
Other long term liabilities	(15,442)	0
Net cash used in operating activities	(25,753,337)	(15,308,809)
Investing activities
Purchases of marketable securities	(28,086,686)	(21,002,641)
Proceeds from maturities and sales of marketable securities	15,469,810	10,998,295
Purchases of property and equipment	(508,987)	(223,265)
Net cash used in investing activities	(13,125,863)	(10,227,611)
Financing activities
Proceeds from IPO, net of offering costs	0	80,435,430
Proceeds from exercise of common stock	22,096	6,372
Proceeds from early exercise of common stock	0	400,000
Net cash provided by financing activities	22,096	80,841,802
Net (decrease) increase in cash and cash equivalents	(38,857,104)	55,305,382
Cash and cash equivalents at beginning of period	66,686,695	33,854,153
Cash and cash equivalents at end of period	27,829,591	89,159,535
Supplemental cash flow information
Inventory purchases included in accounts payable and accrued expense at September 30, 2016	121,077	0
Property and equipment purchases included in accrued expense at December 31, 2015 and 2014	106,680	21,000
Property and equipment purchases included in accounts payable at September 30, 2015	0	5,070
IPO issuance costs included in accounts payable and accrued expenses at December 31, 2014	0	499,549
IPO issuance costs paid in cash through December 31, 2014	$ 0	$ 575,245

Organization and operations

Organization and operations	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and operations	Organization and operations The Company Flex Pharma, Inc. (the "Company") is a biotechnology company that is developing innovative and proprietary treatments for nocturnal leg cramps, muscle cramps and spasms associated with severe neuromuscular conditions, and exercise-associated muscle cramps. The Company's consumer product and drug product candidates are based on the potential mechanism of action described as Chemical Neuro Stimulation, which is the process by which a small molecule chemical signal, acting topically, induces a neuronal sensory signal that produces a beneficial effect. The Company's consumer product and drug product candidates activate certain receptors in primary sensory neurons, which then act via neuronal circuits to reduce the repetitive firing, or hyperexcitability, of alpha-motor neurons in the spinal cord, thereby preventing or reducing the frequency and intensity of muscle cramps and spasms. The Company intends to initially focus its drug development efforts on products to treat nocturnal leg cramps and spasms, spasticity and cramping associated with multiple sclerosis and motor neuron disease, such as amyotrophic lateral sclerosis. In the second quarter of 2016, the Company launched its consumer brand and cornerstone consumer product, HOTSHOT TM , which is intended to prevent and treat exercise-associated muscle cramps. HOTSHOT is sold directly to consumers via e-commerce on the Company's branded website and is also sold to a select number of specialty retailers and sports teams. In connection with the launch of HOTSHOT, the Company began operating as two reportable segments, Consumer Operations and Drug Development. See Note 11 for additional discussion and information on our reportable segments. The Company is subject to risks common to companies in the biotechnology and consumer products industries, including, but not limited to, risks of failure of pre-clinical studies, clinical studies and clinical trials, the need to obtain marketing approval for its drug product candidates, the need to successfully commercialize and gain market acceptance of its drug product candidates and its consumer products, dependence on key personnel, protection of proprietary technology, compliance with government regulations and development by competitors of alternative products. In February 2015, the Company sold 5,491,191 shares of common stock (inclusive of 91,191 shares of common stock sold by the Company pursuant to the exercise of an overallotment option granted to the underwriters in connection with the offering) through an underwritten initial public offering ("IPO") at a price of $16.00 per share. The aggregate net proceeds received by the Company from the offering were approximately $79,900,000 , after deducting underwriting discounts and commissions and offering expenses payable by the Company of approximately $8,000,000 (See Note 2). Liquidity The Company has incurred an accumulated deficit of $68,745,578 since inception and will require substantial additional capital to fund its research and development and commercialization and growth of its consumer brand and HOTSHOT. The Company had unrestricted cash, cash equivalents and marketable securities of $67,333,854 at September 30, 2016 . The Company believes its existing cash, cash equivalents and marketable securities will be sufficient to allow the Company to fund its current operating plan for at least the next 12 months.

Summary of significant accounti

Summary of significant accounting policies and recent accounting pronouncements	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Summary of significant accounting policies and recent accounting pronouncements	Summary of significant accounting policies and recent accounting pronouncements The accompanying unaudited condensed consolidated financial statements reflect the application of certain significant accounting policies as described below and elsewhere in these notes to the condensed consolidated financial statements. As of September 30, 2016 , the Company’s significant accounting policies, which are detailed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2015 (the “ 2015 10-K”), have not changed, other than as noted below. Revenue Revenue is comprised of net product revenue and other revenue. Net product revenue includes sales of HOTSHOT finished goods to e-commerce customers, specialty retailers and sports teams. Other revenue consists of payments made by customers for expedited shipping and handling, which the Company began offering during the third quarter of 2016. Revenue is recognized when persuasive evidence of an arrangement exists, delivery of the product has occurred, the sales price is fixed or determinable and collectibility is reasonably assured. For sales through September 30, 2016, the Company issued refunds to e-commerce customers, upon request, within 21 days of shipment. As the Company currently does not have adequate history to accurately estimate refunds, all e-commerce sales, and their related costs, are deferred and revenue is recognized once the refund period lapses. For specialty retailers and sports teams, the Company does not offer a right of return or refund and revenue is recognized at the time products are delivered to customers. Discounts provided to customers are accounted for as a reduction of net product revenue. Net product revenue and other revenue are presented net of taxes collected from customers and remitted to governmental authorities. The Company had no customers that represented greater than 10% of total revenue during the three and nine months ended September 30, 2016. All revenue was generated from sales within the United States. Accounts receivable and allowance for doubtful accounts Accounts receivable are stated at their carrying values, net of any allowances for doubtful accounts. Accounts receivable consist primarily of amounts due from specialty retailers and sports teams, for which collectibility is reasonably assured. Receivables are evaluated for collectibility on a regular basis and an allowance for doubtful accounts is recorded, if necessary. No allowance for doubtful accounts was deemed necessary at September 30, 2016. Cost of product revenue Cost of product revenue includes the cost of raw materials utilized to produce HOTSHOT, co-packing fees, repacking fees, in-bound freight charges and warehouse and transportation costs incurred to bring HOTSHOT finished goods to salable condition. All other costs incurred after this condition is met are considered selling costs and included in selling, general and administrative expenses. Cost of product revenue also includes write-offs for inventory that has become obsolete, has a cost basis in excess of its estimated realizable value, or exceeds projected sales, as well as depreciation expense related to manufacturing equipment purchased to support production. Inventory The Company launched HOTSHOT in the second quarter of 2016 and began capitalizing inventory costs associated with HOTSHOT in the first quarter of 2016, when it was determined that the inventory costs had probable future economic benefit. Inventory is stated at the lower of cost or estimated net realizable value, on a first-in, first-out ("FIFO") basis. The Company outsources the manufacture of HOTSHOT to a co-packer. Inventory at September 30, 2016 includes raw materials available for future production runs, as well as finished goods. The Company periodically analyzes its inventory levels and writes down inventory that has become obsolete, has a cost basis in excess of its estimated realizable value, or exceeds projected sales. Estimates of excess inventory consider factors such as inventory levels, production requirements, projected sales and the estimated shelf-lives of inventory components. Inventory write-offs are recorded as a component of cost of product revenue. Advertising expense Advertising expense consists of media and production costs related to print and digital advertising. All advertising is expensed as incurred. Total advertising expenses are included in selling, general and administrative and were approximately $1,154,000 and $2,580,000 for the three and nine months ended September 30, 2016, respectively. Shipping and handling costs Shipping and handling costs related to the movement of inventory to the Company's co-packer and from the co-packer to the Company's third party warehousing partner is capitalized as inventory and expensed as a cost of product revenue when revenue is recognized. Shipping and handling costs to move finished goods from the Company's warehousing partner to the Company's third party fulfillment partner or to customer locations are included in selling, general and administrative expenses in the condensed consolidated statement of operations, and were approximately $98,000 and $126,000 for the three and nine months ended September 30, 2016 , respectively. There were no such costs in 2015 as the Company had not yet launched HOTSHOT. Unaudited interim financial information Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the 2015 10-K. The condensed consolidated financial statements as of September 30, 2016 , for the three and nine months ended September 30, 2016 and September 30, 2015 , and the related information contained within the notes to the condensed consolidated financial statements, are unaudited. The unaudited condensed consolidated financial statements have been prepared on the same basis as annual audited consolidated financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s condensed consolidated financial position as of September 30, 2016 , and the statements of operations, comprehensive loss and cash flows for the three and nine month periods ended September 30, 2016 and 2015. The results for the three and nine months ended September 30, 2016 are not necessarily indicative of results to be expected for the year ending December 31, 2016 , or any other future annual or interim periods. Initial public offering On February 3, 2015, the Company completed its IPO, whereby the Company sold 5,491,191 shares of its common stock (inclusive of 91,191 shares of common stock sold by the Company pursuant to the exercise of an overallotment option granted to the underwriters in connection with the IPO) at a price of $16.00 per share. The shares began trading on the Nasdaq Global Market on January 29, 2015. The aggregate net proceeds received by the Company from the IPO were approximately $79,900,000 , after deducting underwriting discounts and commissions and other offering expenses payable by the Company. Upon the closing of the IPO, all outstanding shares of convertible preferred stock converted into 6,971,108 shares of common stock. Additionally, the Company is now authorized to issue 100,000,000 shares of common stock. Deferred IPO issuance costs, which primarily consisted of direct incremental legal and accounting fees related to the Company's IPO, were previously capitalized at December 31, 2014. Upon the closing of the IPO in February 2015, IPO issuance costs, which totaled $1,848,737 , were offset against the IPO proceeds within additional paid-in capital. Basis of presentation and use of estimates The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP"). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company's management evaluates its estimates, which include, but are not limited to, estimates related to clinical study accruals, estimates related to inventory realizability, stock-based compensation expense and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Principles of consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries: TK Pharma, Inc., a Massachusetts Securities Corporation, and Flex Innovation Group LLC, a Delaware limited liability company, which contains the Company's consumer-related operations. All significant intercompany balances and transactions have been eliminated in consolidation. Concentration of risk The Company outsources the manufacture of HOTSHOT to a single co-packer that produces bottled finished goods. The Company also sources certain raw materials from sole suppliers. A disruption in the supply of materials or the production of finished goods could significantly impact the Company's revenues in the future as alternative sources of raw materials and co-packing may not be available at commercially reasonable rates or within a reasonably short period of time. Recent accounting pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) . The ASU provides for a single comprehensive model for use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2016 with no early adoption permitted. In July 2015, the FASB deferred the effective date of this accounting update to annual periods beginning after December 15, 2017, along with an option to permit early adoption as of the original effective date. The Company is required to adopt the amendments in the ASU using one of two acceptable methods: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), clarifying the implementation guidance on principal versus agent considerations. Specifically, an entity is required to determine whether the nature of a promise is to provide the specified good or service itself (that is, the entity is a principal) or to arrange for the good or service to be provided to the customer by the other party (that is, the entity is an agent). The determination influences the timing and amount of revenue recognition. The effective date and transition requirements for ASU 2016-08 are the same as the effective date and transition requirements for ASU 2014-09. The Company is currently evaluating the impact of the guidance related to the Company's launch of HOTSHOT, and does not expect the impact to be material. In August 2014, the FASB issued ASU No. 2014-15 Presentation of Financial Statements - Going Concern (Subtopic 205-40) . The ASU requires management of public and private companies to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Management’s evaluation should be based on relevant conditions and events that are known and reasonably knowable at the date that the financial statements are issued. If conditions or events raise substantial doubt about an entity’s ability to continue as a going concern, and substantial doubt is not alleviated after consideration of management’s plans, an entity should include a statement in the footnotes indicating that there is substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. The new standard is effective for annual periods ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The Company has concluded that if this standard had been adopted as of September 30, 2016 , no additional disclosures would be required. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330) . This ASU simplifies the measurement of inventory by requiring certain inventory to be measured at the lower of cost or net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments in this ASU are effective for fiscal years beginning after December 15, 2016 and for interim periods therein. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. The Company is currently in the process of evaluating the impact of the guidance related to the launch of HOTSHOT. In February 2016, the FASB issued ASU No. 2016-02 Leases . The ASU requires lessees to recognize the assets and liabilities on their balance sheet for the rights and obligations created by most leases and continue to recognize expenses on their income statements over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. The Company is currently evaluating the impact of ASU 2016-02 on its consolidated financial statements and disclosures. In March 2016, the FASB issued ASU No. 2016-09 Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The ASU simplifies several aspects of the accounting for employee share-based payment transactions. The amendments in the update include income tax consequences related to excess tax benefits and tax deficiencies, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The guidance is effective for annual reporting periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for all entities in any interim or annual period. The Company is currently evaluating the impact of ASU 2016-09 on its consolidated financial statements and disclosures. In August 2016, the FASB issued ASU No. 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . The update amends the guidance in ASU 230 Statement of Cash Flows , and clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows with the objective of reducing the existing diversity in practice related to eight specific cash flow issues. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect the adoption of ASU 2016-15 to have a material impact on its consolidated financial statements.

Fair value measurements

Fair value measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements The Company records cash equivalents and marketable securities at fair value. ASC Topic 820 Fair Value Measurements and Disclosures established a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels: Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, directly or indirectly, for substantially the full term of the asset or liability. Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date. The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 : Level 1 Level 2 Level 3 Balance as of September 30, 2016 Cash equivalents $ 20,697,042 $ — $ — $ 20,697,042 Marketable securities: Corporate debt securities — 11,418,230 — 11,418,230 U.S. government agency securities — 28,086,033 — 28,086,033 $ 20,697,042 $ 39,504,263 $ — $ 60,201,305 Level 1 Level 2 Level 3 Balance as of December 31, 2015 Cash equivalents $ 58,575,348 $ 1,410,322 $ — $ 59,985,670 Marketable securities: Corporate debt securities — 26,965,297 — 26,965,297 $ 58,575,348 $ 28,375,619 $ — $ 86,950,967 Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third-party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market based approaches and observable market inputs to determine value. The majority of the Company's cash equivalents consist of money market funds that are valued based on publicly available quoted market prices for identical securities as of September 30, 2016 . After completing its validation procedures, the Company did not adjust or override any fair value carrying amounts as of September 30, 2016 . The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1 and Level 2 during the nine months ended September 30, 2016 or the year ended December 31, 2015. The Company had no financial assets or liabilities that were classified as Level 3 at any time during the nine months ended September 30, 2016 or the year ended December 31, 2015.

Cash equivalents and marketable

Cash equivalents and marketable securities	9 Months Ended
	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Cash equivalents and marketable securities	Cash equivalents and marketable securities The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash equivalents as of September 30, 2016 and December 31, 2015 consisted of money market funds. Marketable securities as of September 30, 2016 consisted of corporate debt securities and U.S. government agency securities. Marketable securities as of December 31, 2015 consisted of corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities . Marketable securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive income (loss) in stockholders’ equity and a component of total comprehensive income (loss) in the condensed consolidated statement of comprehensive income (loss), until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were immaterial realized gains on marketable securities during the three and nine months ended September 30, 2016 and 2015. The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statement of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period. Marketable securities at September 30, 2016 and December 31, 2015 consisted of the following: Amortized Cost Unrealized Gains Unrealized Losses Fair Value As of September 30, 2016 Current (due within 1 year): Corporate debt securities $ 11,418,571 $ 334 $ (675 ) $ 11,418,230 U.S. government agency securities 28,071,020 17,937 (2,924 ) 28,086,033 Total $ 39,489,591 $ 18,271 $ (3,599 ) $ 39,504,263 Amortized Cost Unrealized Gains Unrealized Losses Fair Value As of December 31, 2015 Current (due within 1 year): Corporate debt securities $ 24,666,607 $ 1,878 $ (16,137 ) $ 24,652,348 Noncurrent (due after 1 year through 5 years): Corporate debt securities 2,323,344 — (10,395 ) 2,312,949 Total $ 26,989,951 $ 1,878 $ (26,532 ) $ 26,965,297 At September 30, 2016 , all investments held by the Company were classified as current. The Company had $24,652,348 of marketable securities classified as current and $2,312,949 of marketable securities classified as noncurrent as of December 31, 2015 . Investments classified as current have maturities of less than one year. Investments classified as noncurrent are those that (i) have a maturity greater than one year and (ii) management does not intend to liquidate within the next year, although these funds are available for use and therefore classified as available-for-sale. The Company held four and eleven debt securities that were in an unrealized loss position at September 30, 2016 and December 31, 2015 , respectively, all of which have been in a continuous loss position for less than 12 months. The aggregate fair value of debt securities in an unrealized loss position was $10,604,705 and $24,967,915 at September 30, 2016 and December 31, 2015 , respectively. There were no individual securities that were in a significant unrealized loss position as of September 30, 2016 or December 31, 2015 . The Company evaluated its securities for other-than-temporary impairment and no marketable securities were considered to be other-than-temporarily impaired as of September 30, 2016 .

Inventory

Inventory	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventory	Inventory The Company began capitalizing inventory as of March 31, 2016, when it was determined that the inventory had a probable future economic benefit. Inventory has been recorded at cost as of September 30, 2016 . Costs capitalized at September 30, 2016 relate to finished goods from the initial production run of HOTSHOT, as well as raw materials to be used in the second production run, planned for the fourth quarter of 2016. The Company held no inventory at December 31, 2015. The following table presents inventory: September 30, 2016 December 31, 2015 Raw materials $ 158,239 $ — Finished goods 72,539 — Total inventory $ 230,778 $ — In the first quarter of 2016, the Company wrote off materials purchased for the initial production run of HOTSHOT finished goods that, upon completion, were not expected to be sold based upon projected sales, estimated product shelf life, the number of units produced and production level requirements. The initial production run of HOTSHOT finished goods was completed in the second quarter of 2016, at which time the Company wrote off production costs incurred for those finished goods that were not expected to be sold. During the third quarter of 2016, the Company wrote off additional finished goods that are not expected to be sold based on shelf life requirements and the Company's next production run, which is planned to take place during the fourth quarter of 2016. Write-offs totaled $32,734 and $258,684 for the three and nine months ended September 30, 2016 , respectively, and are included in cost of product revenue in the accompanying condensed consolidated statement of operations. The cost of product revenue related to deferred revenue is capitalized and recorded as cost of product revenue at the time the revenue is recognized.

Accrued expenses and other curr

Accrued expenses and other current liabilities	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Accrued expenses and other current liabilities	Accrued expenses and other current liabilities Accrued expenses and other current liabilities consisted of the following: September 30, 2016 December 31, 2015 Payroll and employee-related costs $ 1,411,663 $ 1,299,248 Research and development costs 767,327 307,666 Professional fees 211,805 129,625 Consumer product-related costs 130,679 198,887 Other 27,969 11,948 Total $ 2,549,443 $ 1,947,374

Common stock

Common stock	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Common stock	Common stock As of September 30, 2016 , the Company had authorized 100,000,000 shares of common stock, $0.0001 par value per share. Each share of common stock is entitled to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors. The Company does not intend to declare dividends for the foreseeable future. Restricted common stock to founders In March 2014, the Company sold 4,553,415 shares of restricted common stock to the founders of the Company ("recipients"), for $0.0004 per share, for total proceeds of $1,950 . In April 2014, based upon anti-dilution provisions granted to the recipients, an additional 867,314 shares of restricted common stock were sold to the same recipients, after which the anti-dilution provisions were terminated. The restricted common stock vested 25% upon issuance, and the remaining 75% vests ratably over four years , during which time the Company has the right to repurchase the unvested shares held by a recipient if the relationship between such recipient and the Company ceases. If the relationship terminates, the Company has 90 days to repurchase unvested shares at $0.0004 per share. Such shares are not accounted for as outstanding until they vest. There were 3,980,695 shares of restricted common stock outstanding as of September 30, 2016 . Unvested restricted common stock awards to non-employees are re-measured at each vest date and each financial reporting date. The following is a summary of restricted common stock activity: Number of Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2015 2,202,262 $ 0.10 Issued — — Vested (762,228 ) 0.10 Unvested at September 30, 2016 1,440,034 $ 0.10 Restricted common stock to consultants During the nine months ended September 30, 2016 , the Company issued 18,194 shares of restricted common stock to non-employee consultants and advisors. The Company has the right to repurchase any unvested shares held by a recipient if the relationship between such recipient and the Company ceases. If the relationship terminates, the Company has 90 days to repurchase unvested shares at $ 0.0001 per share. Such shares are not accounted for as outstanding until they vest. There were 5,985 shares of restricted common stock issued to consultants outstanding as of September 30, 2016 . Unvested restricted common stock awards to non-employees are re-measured at each vest date and each financial reporting date. The following is a summary of restricted common stock activity: Number of Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2015 — $ — Issued 18,194 9.51 Vested (5,985 ) 9.25 Unvested at September 30, 2016 12,209 $ 9.63

Stock-based compensation

Stock-based compensation	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-based compensation	Stock-based compensation In March 2014, the Company adopted the Flex Pharma, Inc. 2014 Equity Incentive Plan (the "2014 Plan"), under which it had the ability to grant incentive stock options ("ISOs"), non-qualified stock options, restricted stock awards, restricted stock units and stock appreciation rights to purchase up to 116,754 shares of common stock. In April 2014, the Company amended the 2014 Plan to reserve for the issuance of up to 1,451,087 shares of common stock pursuant to equity awards. In September 2014, the Company further amended the 2014 Plan to reserve for the issuance of up to 2,070,200 shares of common stock pursuant to equity awards. Terms of stock award agreements, including vesting requirements, were determined by the board of directors, subject to the provisions of the 2014 Plan. For options granted under the 2014 Plan, the exercise price equaled the fair market value of the common stock as determined by the board of directors on the date of grant. No further awards will be granted under the 2014 Plan. In January 2015, the Company's board of directors adopted, and the Company's stockholders approved, the 2015 Equity Incentive Plan (the "2015 Plan"), which became effective immediately prior to the closing of the Company's IPO. The 2015 Plan provides for the grant of ISOs, nonstatutory stock options, restricted stock awards, restricted stock units, stock appreciation rights, performance-based stock awards and other stock-based awards. Additionally, the 2015 Plan provides for the grant of performance-based cash awards. ISOs may be granted only to the Company's employees. All other awards may be granted to the Company's employees, including officers, and to non-employee directors and consultants. As of September 30, 2016 , there were 402,326 shares remaining available for the grant of stock awards under the 2015 Plan. The Company has awarded stock options to its employees, directors, advisors and consultants, pursuant to the plans described above. Stock options subsequent to the completion of the Company's IPO are granted with an exercise price equal to the closing market price of the Company's common stock on the date of grant. Stock options generally vest over one to four years and have a contractual term of ten years . Stock options are valued using the Black-Scholes option pricing model and compensation cost is recognized based on the resulting value over the service period. Unvested awards to non-employees are re-measured at each vest date and at each financial reporting date. The following table summarizes stock option activity for employees and non-employees for the nine months ended September 30, 2016 : Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Outstanding at December 31, 2015 1,824,973 $ 8.34 Granted 759,820 10.04 Exercised (8,516 ) 2.59 Cancelled or forfeited (256,030 ) 11.99 Outstanding at September 30, 2016 2,320,247 $ 8.51 8.37 $ 9,167,034 Exercisable at September 30, 2016 773,252 $ 7.31 8.05 $ 4,216,112 Vested or expected to vest at September 30, 2016 2,161,668 $ 8.69 7.99 $ 8,229,864 Total stock-based compensation expense recognized for employee and non-employee restricted common stock, and stock options granted to employees and non-employees is included in the Company's condensed consolidated statement of operations as follows: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Research and development $ 783,603 $ 617,476 $ 2,063,764 $ 2,429,769 Selling, general and administrative 1,076,985 889,203 3,303,306 2,463,229 Total $ 1,860,588 $ 1,506,679 $ 5,367,070 $ 4,892,998 As of September 30, 2016 , there was approximately $14,469,895 of total unrecognized compensation cost related to unvested equity awards. Total unrecognized compensation cost will be adjusted for the re-measurement of non-employee awards as well as future changes in employee and non-employee forfeitures, if any. The Company expects to recognize that cost over a remaining weighted-average period of 2.10 years . In November 2015, the Company granted 150,000 performance-based stock options to an employee, which would have vested upon the achievement of certain future revenue milestones. During the third quarter of 2016, these options were cancelled in conjunction with an employment termination agreement. The vesting conditions had not previously been considered probable, and no stock-based compensation expense was recorded related to this award. In May 2016, in connection with an amendment to an employment agreement, the Company recorded stock-based compensation expense for a modification to an option award that totaled approximately $227,000 . In August 2016, in connection with an employment termination agreement, the Company recorded stock-based compensation expense for a modification to an option award that totaled approximately $58,000 . Employee stock purchase plan In January 2015, the Company's board of directors adopted, and the Company's stockholders approved, the 2015 Employee Stock Purchase Plan (the "ESPP"), which became effective upon the date of execution of the underwriting agreement pursuant to which the Company's common stock was priced in connection with the IPO. As of September 30, 2016 , the Company had not yet instituted any offering periods under the ESPP and no shares of the Company's common stock have been purchased under the ESPP.

Income taxes

Income taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income taxes	Income taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Based upon the Company's history of operating losses and the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets. There was no significant income tax provision or benefit for the three or nine months ended September 30, 2016 or 2015.

Net loss per share

Net loss per share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Net loss per share	Net loss per share Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period, determined using the treasury stock method and the if-converted method, for convertible securities, if inclusion of these is dilutive. Because the Company has reported a net loss for the periods presented, diluted net loss per common share is the same as basic net loss per common share. The following potentially dilutive securities outstanding, prior to the use of the treasury stock method or if-converted method, have been excluded from the computation of diluted weighted-average shares outstanding for the periods indicated, because including them would have had an anti-dilutive impact: September 30, 2016 September 30, 2015 Options to purchase common stock 2,320,247 1,342,141 Unvested restricted common stock 1,452,243 2,456,338 Unvested restricted common stock issued upon early exercise of stock options — 37,064 Total 3,772,490 3,835,543

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information Effective as of the second quarter of 2016 and in connection with the launch of HOTSHOT, the Company operates as two reportable segments: • The Consumer Operations segment, which reflects the total revenue and costs and expenses related to HOTSHOT and the Company's consumer operations. • The Drug Development segment, which reflects the costs and expenses related to the Company's efforts to develop innovative and proprietary drug products to treat nocturnal leg cramps and muscle cramps and spasms associated with severe neuromuscular conditions. The Company discloses information about its reportable segments based on the way that the Company's Chief Operating Decision Maker, who the Company has identified as the Chief Executive Officer, and management, organizes segments within the Company for making operating decisions and assessing financial performance. The Company evaluates the performance of its reportable segments based on revenue and operating income or loss. The accounting policies of the segments are the same as those described herein as well as those described in Note 1 to the audited consolidated financial statements in the 2015 Form 10-K. Corporate and unallocated amounts that do not relate to a reportable segment have been allocated to "Corporate". No asset information has been provided for the Company's reportable segments as management does not measure or allocate such assets on a reportable segment basis. Information for the Company's reportable segments for the three months ended September 30, 2016 and 2015 are as follows: Three months Ended September 30, 2016 Consumer Operations Drug Development Corporate Consolidated Total revenue $ 599,074 — — $ 599,074 Interest income, net $ — — 97,726 $ 97,726 Loss from operations $ 2,690,601 5,550,853 2,493,766 $ 10,735,220 Three months Ended September 30, 2015 Consumer Operations Drug Development Corporate Consolidated Total revenue $ — — — $ — Interest income, net $ — — 14,637 $ 14,637 Loss from operations $ 2,578,891 3,258,877 2,329,713 $ 8,167,481 Information for the Company's reportable segments for the nine months ended September 30, 2016 and 2015 are as follows: Nine months Ended September 30, 2016 Consumer Operations Drug Development Corporate Consolidated Total revenue $ 711,759 — — $ 711,759 Interest income, net $ — — 308,877 $ 308,877 Loss from operations $ 8,461,803 15,517,670 7,922,492 $ 31,901,965 Nine months Ended September 30, 2015 Consumer Operations Drug Development Corporate Consolidated Total revenue $ — — — $ — Interest income, net $ — — 34,397 $ 34,397 Loss from operations $ 5,412,144 9,177,410 6,693,666 $ 21,283,220

Summary of significant accoun18

Summary of significant accounting policies and recent accounting pronouncements (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Revenue	Net product revenue and other revenue are presented net of taxes collected from customers and remitted to governmental authorities. Revenue Revenue is comprised of net product revenue and other revenue. Net product revenue includes sales of HOTSHOT finished goods to e-commerce customers, specialty retailers and sports teams. Other revenue consists of payments made by customers for expedited shipping and handling, which the Company began offering during the third quarter of 2016. Revenue is recognized when persuasive evidence of an arrangement exists, delivery of the product has occurred, the sales price is fixed or determinable and collectibility is reasonably assured. For sales through September 30, 2016, the Company issued refunds to e-commerce customers, upon request, within 21 days of shipment. As the Company currently does not have adequate history to accurately estimate refunds, all e-commerce sales, and their related costs, are deferred and revenue is recognized once the refund period lapses. For specialty retailers and sports teams, the Company does not offer a right of return or refund and revenue is recognized at the time products are delivered to customers.
Revenue, Discounts and Refunds	Discounts provided to customers are accounted for as a reduction of net product revenue.
Accounts receivable	Accounts receivable are stated at their carrying values, net of any allowances for doubtful accounts. Accounts receivable consist primarily of amounts due from specialty retailers and sports teams, for which collectibility is reasonably assured.
Allowance for doubtful accounts	Receivables are evaluated for collectibility on a regular basis and an allowance for doubtful accounts is recorded, if necessary.
Inventory	Inventory The Company launched HOTSHOT in the second quarter of 2016 and began capitalizing inventory costs associated with HOTSHOT in the first quarter of 2016, when it was determined that the inventory costs had probable future economic benefit. Inventory is stated at the lower of cost or estimated net realizable value, on a first-in, first-out ("FIFO") basis. The Company outsources the manufacture of HOTSHOT to a co-packer. Inventory at September 30, 2016 includes raw materials available for future production runs, as well as finished goods. The Company periodically analyzes its inventory levels and writes down inventory that has become obsolete, has a cost basis in excess of its estimated realizable value, or exceeds projected sales. Estimates of excess inventory consider factors such as inventory levels, production requirements, projected sales and the estimated shelf-lives of inventory components. Inventory write-offs are recorded as a component of cost of product revenue.
Advertising expense	Advertising expense Advertising expense consists of media and production costs related to print and digital advertising. All advertising is expensed as incurred.
Shipping and handling costs	Shipping and handling costs Shipping and handling costs related to the movement of inventory to the Company's co-packer and from the co-packer to the Company's third party warehousing partner is capitalized as inventory and expensed as a cost of product revenue when revenue is recognized. Shipping and handling costs to move finished goods from the Company's warehousing partner to the Company's third party fulfillment partner or to customer locations are included in selling, general and administrative expenses in the condensed consolidated statement of operations
Basis of presentation	The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States ("GAAP"). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB").
Use of estimates	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company's management evaluates its estimates, which include, but are not limited to, estimates related to clinical study accruals, estimates related to inventory realizability, stock-based compensation expense and amounts of expenses during the reported period. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Principles of consolidation	Principles of consolidation The condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries: TK Pharma, Inc., a Massachusetts Securities Corporation, and Flex Innovation Group LLC, a Delaware limited liability company, which contains the Company's consumer-related operations. All significant intercompany balances and transactions have been eliminated in consolidation.
Concentration of risk	Concentration of risk The Company outsources the manufacture of HOTSHOT to a single co-packer that produces bottled finished goods. The Company also sources certain raw materials from sole suppliers. A disruption in the supply of materials or the production of finished goods could significantly impact the Company's revenues in the future as alternative sources of raw materials and co-packing may not be available at commercially reasonable rates or within a reasonably short period of time.
Recent accounting pronouncements	Recent accounting pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) . The ASU provides for a single comprehensive model for use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2016 with no early adoption permitted. In July 2015, the FASB deferred the effective date of this accounting update to annual periods beginning after December 15, 2017, along with an option to permit early adoption as of the original effective date. The Company is required to adopt the amendments in the ASU using one of two acceptable methods: retrospectively to all prior reporting periods presented, with certain practical expedients permitted; or retrospectively with the cumulative effect of initially adopting the ASU recognized at the date of initial application. In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), clarifying the implementation guidance on principal versus agent considerations. Specifically, an entity is required to determine whether the nature of a promise is to provide the specified good or service itself (that is, the entity is a principal) or to arrange for the good or service to be provided to the customer by the other party (that is, the entity is an agent). The determination influences the timing and amount of revenue recognition. The effective date and transition requirements for ASU 2016-08 are the same as the effective date and transition requirements for ASU 2014-09. The Company is currently evaluating the impact of the guidance related to the Company's launch of HOTSHOT, and does not expect the impact to be material. In August 2014, the FASB issued ASU No. 2014-15 Presentation of Financial Statements - Going Concern (Subtopic 205-40) . The ASU requires management of public and private companies to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Management’s evaluation should be based on relevant conditions and events that are known and reasonably knowable at the date that the financial statements are issued. If conditions or events raise substantial doubt about an entity’s ability to continue as a going concern, and substantial doubt is not alleviated after consideration of management’s plans, an entity should include a statement in the footnotes indicating that there is substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. The new standard is effective for annual periods ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The Company has concluded that if this standard had been adopted as of September 30, 2016 , no additional disclosures would be required. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330) . This ASU simplifies the measurement of inventory by requiring certain inventory to be measured at the lower of cost or net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The amendments in this ASU are effective for fiscal years beginning after December 15, 2016 and for interim periods therein. Subsequent measurement is unchanged for inventory measured using LIFO or the retail inventory method. The Company is currently in the process of evaluating the impact of the guidance related to the launch of HOTSHOT. In February 2016, the FASB issued ASU No. 2016-02 Leases . The ASU requires lessees to recognize the assets and liabilities on their balance sheet for the rights and obligations created by most leases and continue to recognize expenses on their income statements over the lease term. It will also require disclosures designed to give financial statement users information on the amount, timing, and uncertainty of cash flows arising from leases. The guidance is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those years. Early adoption is permitted for all entities. The Company is currently evaluating the impact of ASU 2016-02 on its consolidated financial statements and disclosures. In March 2016, the FASB issued ASU No. 2016-09 Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting . The ASU simplifies several aspects of the accounting for employee share-based payment transactions. The amendments in the update include income tax consequences related to excess tax benefits and tax deficiencies, classification of awards as either equity or liabilities, and classification on the statement of cash flows. The guidance is effective for annual reporting periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted for all entities in any interim or annual period. The Company is currently evaluating the impact of ASU 2016-09 on its consolidated financial statements and disclosures. In August 2016, the FASB issued ASU No. 2016-15 Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . The update amends the guidance in ASU 230 Statement of Cash Flows , and clarifies how entities should classify certain cash receipts and cash payments on the statement of cash flows with the objective of reducing the existing diversity in practice related to eight specific cash flow issues. The amendments in this update are effective for annual periods beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect the adoption of ASU 2016-15 to have a material impact on its consolidated financial statements.
Fair value measurements	Fair value measurements The Company records cash equivalents and marketable securities at fair value. ASC Topic 820 Fair Value Measurements and Disclosures established a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels: Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, directly or indirectly, for substantially the full term of the asset or liability. Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date.
Cash equivalents	The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents.
Marketable securities	Marketable securities as of September 30, 2016 consisted of corporate debt securities and U.S. government agency securities. Marketable securities as of December 31, 2015 consisted of corporate debt securities. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities . Marketable securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive income (loss) in stockholders’ equity and a component of total comprehensive income (loss) in the condensed consolidated statement of comprehensive income (loss), until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were immaterial realized gains on marketable securities during the three and nine months ended September 30, 2016 and 2015. The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the consolidated statement of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

Fair value measurements (Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis	The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 : Level 1 Level 2 Level 3 Balance as of September 30, 2016 Cash equivalents $ 20,697,042 $ — $ — $ 20,697,042 Marketable securities: Corporate debt securities — 11,418,230 — 11,418,230 U.S. government agency securities — 28,086,033 — 28,086,033 $ 20,697,042 $ 39,504,263 $ — $ 60,201,305 Level 1 Level 2 Level 3 Balance as of December 31, 2015 Cash equivalents $ 58,575,348 $ 1,410,322 $ — $ 59,985,670 Marketable securities: Corporate debt securities — 26,965,297 — 26,965,297 $ 58,575,348 $ 28,375,619 $ — $ 86,950,967

Cash equivalents and marketab20

Cash equivalents and marketable securities (Tables)	9 Months Ended
	Sep. 30, 2016
Cash and Cash Equivalents [Abstract]
Schedule of Marketable Securities	Marketable securities at September 30, 2016 and December 31, 2015 consisted of the following: Amortized Cost Unrealized Gains Unrealized Losses Fair Value As of September 30, 2016 Current (due within 1 year): Corporate debt securities $ 11,418,571 $ 334 $ (675 ) $ 11,418,230 U.S. government agency securities 28,071,020 17,937 (2,924 ) 28,086,033 Total $ 39,489,591 $ 18,271 $ (3,599 ) $ 39,504,263 Amortized Cost Unrealized Gains Unrealized Losses Fair Value As of December 31, 2015 Current (due within 1 year): Corporate debt securities $ 24,666,607 $ 1,878 $ (16,137 ) $ 24,652,348 Noncurrent (due after 1 year through 5 years): Corporate debt securities 2,323,344 — (10,395 ) 2,312,949 Total $ 26,989,951 $ 1,878 $ (26,532 ) $ 26,965,297

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Schedule of Inventory, Net	The following table presents inventory: September 30, 2016 December 31, 2015 Raw materials $ 158,239 $ — Finished goods 72,539 — Total inventory $ 230,778 $ —

Accrued expenses and other cu22

Accrued expenses and other current liabilities (Tables)	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses and other current liabilities consisted of the following: September 30, 2016 December 31, 2015 Payroll and employee-related costs $ 1,411,663 $ 1,299,248 Research and development costs 767,327 307,666 Professional fees 211,805 129,625 Consumer product-related costs 130,679 198,887 Other 27,969 11,948 Total $ 2,549,443 $ 1,947,374
Schedule of other current liabilities	Accrued expenses and other current liabilities consisted of the following: September 30, 2016 December 31, 2015 Payroll and employee-related costs $ 1,411,663 $ 1,299,248 Research and development costs 767,327 307,666 Professional fees 211,805 129,625 Consumer product-related costs 130,679 198,887 Other 27,969 11,948 Total $ 2,549,443 $ 1,947,374

Common stock (Tables)

Common stock (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Restricted common stock activity	The following is a summary of restricted common stock activity: Number of Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2015 2,202,262 $ 0.10 Issued — — Vested (762,228 ) 0.10 Unvested at September 30, 2016 1,440,034 $ 0.10 The following is a summary of restricted common stock activity: Number of Shares Weighted-Average Grant Date Fair Value Unvested at December 31, 2015 — $ — Issued 18,194 9.51 Vested (5,985 ) 9.25 Unvested at September 30, 2016 12,209 $ 9.63

Stock-based compensation (Table

Stock-based compensation (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of stock option activity	The following table summarizes stock option activity for employees and non-employees for the nine months ended September 30, 2016 : Shares Weighted-Average Exercise Price Weighted-Average Remaining Contractual Term (in years) Aggregate Outstanding at December 31, 2015 1,824,973 $ 8.34 Granted 759,820 10.04 Exercised (8,516 ) 2.59 Cancelled or forfeited (256,030 ) 11.99 Outstanding at September 30, 2016 2,320,247 $ 8.51 8.37 $ 9,167,034 Exercisable at September 30, 2016 773,252 $ 7.31 8.05 $ 4,216,112 Vested or expected to vest at September 30, 2016 2,161,668 $ 8.69 7.99 $ 8,229,864
Summary of stock-based compensation expense	Total stock-based compensation expense recognized for employee and non-employee restricted common stock, and stock options granted to employees and non-employees is included in the Company's condensed consolidated statement of operations as follows: Three Months Ended September 30, 2016 Three Months Ended September 30, 2015 Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Research and development $ 783,603 $ 617,476 $ 2,063,764 $ 2,429,769 Selling, general and administrative 1,076,985 889,203 3,303,306 2,463,229 Total $ 1,860,588 $ 1,506,679 $ 5,367,070 $ 4,892,998

Net loss per share (Tables)

Net loss per share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of antidilutive securities excluded from computation of earnings per share	The following potentially dilutive securities outstanding, prior to the use of the treasury stock method or if-converted method, have been excluded from the computation of diluted weighted-average shares outstanding for the periods indicated, because including them would have had an anti-dilutive impact: September 30, 2016 September 30, 2015 Options to purchase common stock 2,320,247 1,342,141 Unvested restricted common stock 1,452,243 2,456,338 Unvested restricted common stock issued upon early exercise of stock options — 37,064 Total 3,772,490 3,835,543

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Schedule of Information for the Company's Operating Segments	Information for the Company's reportable segments for the three months ended September 30, 2016 and 2015 are as follows: Three months Ended September 30, 2016 Consumer Operations Drug Development Corporate Consolidated Total revenue $ 599,074 — — $ 599,074 Interest income, net $ — — 97,726 $ 97,726 Loss from operations $ 2,690,601 5,550,853 2,493,766 $ 10,735,220 Three months Ended September 30, 2015 Consumer Operations Drug Development Corporate Consolidated Total revenue $ — — — $ — Interest income, net $ — — 14,637 $ 14,637 Loss from operations $ 2,578,891 3,258,877 2,329,713 $ 8,167,481 Information for the Company's reportable segments for the nine months ended September 30, 2016 and 2015 are as follows: Nine months Ended September 30, 2016 Consumer Operations Drug Development Corporate Consolidated Total revenue $ 711,759 — — $ 711,759 Interest income, net $ — — 308,877 $ 308,877 Loss from operations $ 8,461,803 15,517,670 7,922,492 $ 31,901,965 Nine months Ended September 30, 2015 Consumer Operations Drug Development Corporate Consolidated Total revenue $ — — — $ — Interest income, net $ — — 34,397 $ 34,397 Loss from operations $ 5,412,144 9,177,410 6,693,666 $ 21,283,220

Organization and operations (De

Organization and operations (Details)	Feb. 03, 2015USD ($)$ / sharesshares	Feb. 28, 2015USD ($)$ / sharesshares	Sep. 30, 2016USD ($)segment	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)
Subsidiary, Sale of Stock [Line Items]
Number of reportable segments | segment			2
Proceeds from IPO, net of offering costs	$ 79,900,000	$ 79,900,000	$ 0	$ 80,435,430
Underwriting discounts, commissions, and offering expenses		$ 8,000,000
Retained earnings (accumulated deficit)			(68,745,578)		$ (37,152,490)
Cash, cash equivalents, and marketable securities			$ 67,333,854
IPO
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued | shares	5,491,191	5,491,191
Common stock, price per share (in usd per share) | $ / shares	$ 16	$ 16
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued | shares	91,191	91,191

Summary of significant accoun28

Summary of significant accounting policies and recent accounting pronouncements - Narrative (Details) - USD ($)	Feb. 03, 2015	Feb. 28, 2015	Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Subsidiary, Sale of Stock [Line Items]
Refund period from day of shipment (in days)					21 days
Advertising expense			$ 1,154,000		$ 2,580,000
Shipping and handling costs			$ 98,000	$ 98,000	126,000		$ 0
Proceeds from IPO, net of offering costs	$ 79,900,000	$ 79,900,000			$ 0	$ 80,435,430
Common stock, number of shares issued from conversion of preferred stock (in shares)	6,971,108
Common stock, shares authorized (in shares)			100,000,000		100,000,000		100,000,000
IPO issuance cost	$ 1,848,737
IPO
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued	5,491,191	5,491,191
Common stock, price per share (in usd per share)	$ 16	$ 16
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Common stock, shares issued	91,191	91,191

Fair value measurements (Detail

Fair value measurements (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Marketable securities:
Fair Value	$ 39,504,263	$ 26,965,297
Corporate debt securities
Marketable securities:
Fair Value	11,418,230
U.S. government agency securities
Marketable securities:
Fair Value	28,086,033
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,697,042	59,985,670
Marketable securities:
Total assets	60,201,305	86,950,967
Fair Value, Measurements, Recurring | Corporate debt securities
Marketable securities:
Fair Value	11,418,230	26,965,297
Fair Value, Measurements, Recurring | U.S. government agency securities
Marketable securities:
Fair Value	28,086,033
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20,697,042	58,575,348
Marketable securities:
Total assets	20,697,042	58,575,348
Fair Value, Measurements, Recurring | Level 1 | Corporate debt securities
Marketable securities:
Fair Value	0	0
Fair Value, Measurements, Recurring | Level 1 | U.S. government agency securities
Marketable securities:
Fair Value	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	1,410,322
Marketable securities:
Total assets	39,504,263	28,375,619
Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities
Marketable securities:
Fair Value	11,418,230	26,965,297
Fair Value, Measurements, Recurring | Level 2 | U.S. government agency securities
Marketable securities:
Fair Value	28,086,033
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities:
Total assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities
Marketable securities:
Fair Value	0	$ 0
Fair Value, Measurements, Recurring | Level 3 | U.S. government agency securities
Marketable securities:
Fair Value	$ 0

Cash equivalents and marketab30

Cash equivalents and marketable securities (Details)	Sep. 30, 2016USD ($)security	Dec. 31, 2015USD ($)security
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 39,489,591	$ 26,989,951
Unrealized Gains	18,271	1,878
Unrealized Losses	(3,599)	(26,532)
Fair Value	39,504,263	26,965,297
Marketable securities, current	39,504,263	24,652,348
Marketable securities, noncurrent	$ 0	$ 2,312,949
Number of debt securities held | security	4	11
Aggregate fair value of debt securities in an unrealized loss position	$ 10,604,705	$ 24,967,915
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,418,571
Unrealized Gains	334
Unrealized Losses	(675)
Fair Value	11,418,230
Corporate debt securities | Current Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		24,666,607
Unrealized Gains		1,878
Unrealized Losses		(16,137)
Fair Value		24,652,348
Corporate debt securities | Noncurrent Assets
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,323,344
Unrealized Gains		0
Unrealized Losses		(10,395)
Fair Value		$ 2,312,949
U.S. government agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,071,020
Unrealized Gains	17,937
Unrealized Losses	(2,924)
Fair Value	$ 28,086,033

Inventory (Details)

Inventory (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 158,239	$ 158,239	$ 0
Finished goods	72,539	72,539	0
Total inventory	230,778	230,778	$ 0
Write-off of inventory	$ 32,734	$ 258,684

Accrued expenses and other cu32

Accrued expenses and other current liabilities (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Payroll and employee-related costs	$ 1,411,663	$ 1,299,248
Research and development costs	767,327	307,666
Professional fees	211,805	129,625
Consumer product-related costs	130,679	198,887
Other	27,969	11,948
Total	$ 2,549,443	$ 1,947,374

Common stock - Narrative (Detai

Common stock - Narrative (Details) - USD ($)	1 Months Ended		9 Months Ended
	Apr. 30, 2014	Mar. 31, 2014	Sep. 30, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)			100,000,000	100,000,000
Common stock, par value (in usd per share)			$ 0.0001	$ 0.0001
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock, shares sold	867,314	4,553,415
Restricted common stock, price per share (in usd per share)		$ 0.0004
Proceeds from sale of restricted common stock to founders		$ 1,950
Restricted common stock, repurchase period (in days)			90 days
Restricted common stock, repurchase price (in usd per share)			$ 0.0004
Restricted common stock, shares outstanding			3,980,695
Restricted stock | Non-employee Consultants and Advisers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock, shares sold			18,194
Restricted common stock, repurchase period (in days)			90 days
Restricted common stock, repurchase price (in usd per share)			$ 0.0001
Restricted common stock, shares outstanding			5,985
Restricted stock | Vests upon issuance
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock, percent vested			25.00%
Restricted stock | Vests ratably over four years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted common stock, percent vested			75.00%
Restricted common stock, vesting period (in years)			4 years

Common stock - Restricted commo

Common stock - Restricted common stock activity (Details) - Restricted stock	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance, unvested, number of shares | shares	2,202,262
Issued, number of shares | shares	0
Vested, number of shares | shares	(762,228)
Ending balance, unvested, number of shares | shares	1,440,034
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, weighted average grant date fair value (in usd per share) | $ / shares	$ 0.10
Issued, weighted average grant date fair value (in usd per share) | $ / shares	0
Vested, weighted average grant date fair value (in usd per share) | $ / shares	0.10
Ending balance, weighted average grant date fair value (in usd per share) | $ / shares	$ 0.10
Non-employee Consultants and Advisers
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance, unvested, number of shares | shares	0
Issued, number of shares | shares	18,194
Vested, number of shares | shares	(5,985)
Ending balance, unvested, number of shares | shares	12,209
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Beginning balance, weighted average grant date fair value (in usd per share) | $ / shares	$ 0
Issued, weighted average grant date fair value (in usd per share) | $ / shares	9.51
Vested, weighted average grant date fair value (in usd per share) | $ / shares	9.25
Ending balance, weighted average grant date fair value (in usd per share) | $ / shares	$ 9.63

Stock-based compensation - Narr

Stock-based compensation - Narrative (Details) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended
	Aug. 31, 2016	May 31, 2016	Nov. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Apr. 30, 2014	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost				$ 14,469,895		$ 14,469,895
Unrecognized compensation cost, recognition period (in years)						2 years 1 month 6 days
Shares granted						759,820
Stock-based compensation expense				$ 1,860,588	$ 1,506,679	$ 5,367,070	$ 4,892,998
Employee stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, contractual term						10 years
Stock-based compensation expense	$ 58,000	$ 227,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			150,000
Minimum | Employee stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)						1 year
Maximum | Employee stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, vesting period (in years)						4 years
Flex Pharma, Inc. 2014 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized								2,070,200	1,451,087	116,754
2015 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares remaining available for grant of stock awards				402,326		402,326

Stock-based compensation - Summ

Stock-based compensation - Summary of stock option activity (Details)	9 Months Ended
	Sep. 30, 2016USD ($)$ / sharesshares
Shares
Shares outstanding, Beginning Balance | shares	1,824,973
Shares granted | shares	759,820
Shares exercised | shares	(8,516)
Shares canceled or forfeited | shares	(256,030)
Shares outstanding, Ending Balance | shares	2,320,247
Shares exercisable | shares	773,252
Shares vested or expected to vest | shares	2,161,668
Weighted-Average Exercise Price
Shares outstanding, weighted-average exercise price, Beginning Balance (in usd per share) | $ / shares	$ 8.34
Shares granted, weighted-average exercise price (in usd per share) | $ / shares	10.04
Shares exercised, weighted-average exercise price (in usd per share) | $ / shares	2.59
Shares canceled or forfeited, weighted-average exercise price (in usd per share) | $ / shares	11.99
Shares outstanding, weighted-average exercise price, Ending Balance (in usd per share) | $ / shares	8.51
Shares exercisable, weighted-average exercise price (in usd per share) | $ / shares	7.31
Shares vested or expected to vest, weighted-average exercise price (in usd per share) | $ / shares	$ 8.69
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, weighted-average remaining contractual term (in years)	8 years 4 months 13 days
Exercisable, weighted-average remaining contractual term (in years)	8 years 18 days
Vested or expected to vest, weighted-average remaining contractual term (in years)	7 years 11 months 27 days
Outstanding, aggregate intrinsic value | $	$ 9,167,034
Exercisable, aggregate intrinsic value | $	4,216,112
Vested or expected to vest, aggregate intrinsic value | $	$ 8,229,864

Stock-based compensation - Su37

Stock-based compensation - Summary of stock-based compensation expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,860,588	$ 1,506,679	$ 5,367,070	$ 4,892,998
Research and development
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	783,603	617,476	2,063,764	2,429,769
Selling, general and administrative
Employee Service Share-Based Compensation Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,076,985	$ 889,203	$ 3,303,306	$ 2,463,229

Income taxes (Details)

Income taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income tax provision (benefit)	$ 0	$ 0	$ 0	$ 0

Net loss per share (Details)

Net loss per share (Details) - shares	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,772,490	3,835,543
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 (in shares)	2,320,247	1,342,141
Unvested restricted common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,452,243	2,456,338
Unvested restricted common stock issued upon early exercise of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	37,064

Segment Information (Details)

Segment Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)segment	Sep. 30, 2015USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Total revenue	$ 599,074	$ 0	$ 711,759	$ 0
Interest income, net	97,726	14,637	308,877	34,397
Loss from operations	10,735,220	8,167,481	31,901,965	21,283,220
Operating Segments | Consumer Operations
Segment Reporting Information [Line Items]
Total revenue	599,074	0	711,759	0
Interest income, net	0	0	0	0
Loss from operations	2,690,601	2,578,891	8,461,803	5,412,144
Operating Segments | Drug Development
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Interest income, net	0	0	0	0
Loss from operations	5,550,853	3,258,877	15,517,670	9,177,410
Corporate
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Interest income, net	97,726	14,637	308,877	34,397
Loss from operations	$ 2,493,766	$ 2,329,713	$ 7,922,492	$ 6,693,666