Organization and operations	6 Months Ended
Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and operations	Organization and operations The Company Flex Pharma Inc., or the Company, is a biotechnology company that was previously focused on developing innovative and proprietary treatments for muscle cramps, spasms and spasticity associated with severe neurological conditions. In June 2018, the Company announced that it was ending its ongoing Phase 2 clinical trials of its lead drug product candidate, FLX-787, in patients with motor neuron disease, or MND, primarily with amyotrophic lateral sclerosis, or ALS, and in patients with Charcot-Marie-Tooth disease, or CMT, due to oral tolerability concerns observed in both studies. The wind-down of the activities associated with these studies was completed in the third quarter of 2018. In 2016, the Company launched its consumer product, HOTSHOT®, to prevent and treat exercise-associated muscle cramps, or EAMCs. The Company continues to market and sell HOTSHOT to endurance athletes who drink it before, during and after exercise to prevent and treat EAMCs. In June 2018, the Company initiated a process to explore a range of strategic alternatives for enhancing stockholder value, including the potential sale or merger of the Company. Following an extensive process of evaluating strategic alternatives for the Company, on January 3, 2019, the Company entered into an Agreement and Plan of Merger, or the Merger Agreement, with Salarius Pharmaceuticals, LLC, or Salarius, under which the privately held Salarius will merge with a wholly owned subsidiary of the Company. At a special meeting on July 12, 2019, the merger was approved by the Company's stockholders and the merger is expected to close on or about July 19, 2019. Upon completion of the merger, the business of Salarius will continue as the business of the combined company. The Company operates as two reportable segments, Consumer Operations and Drug Development. See Note 12 for additional discussion and information on the reportable segments. Liquidity The Company incurred a loss of $1,384,777 for the three months ended June 30, 2019, a loss of $3,615,207 for the six months ended June 30, 2019 and had an accumulated deficit of $136,576,482 as of June 30, 2019. The Company had unrestricted cash and cash equivalents of $6,514,215 at June 30, 2019. The Company's operating plan assumes limited research and development activities and that the Consumer Operations segment will continue to sell HOTSHOT. In the event the merger with Salarius is not completed, the Company will reconsider its strategic alternatives, including to (i) pursue a dissolution and liquidation of the Company, (ii) pursue another strategic transaction or (iii) continue to market HOTSHOT and operate its consumer business. If the Company dissolves and liquidates, the Company's common stockholders may lose their entire investment. The amount of assets available for distribution to the Company's stockholders would depend heavily on the timing of such liquidation as well as the amount of cash that would be needed for commitments and contingent liabilities. Based on the Company's current operating plan, the Company believes that its existing cash and cash equivalents will be sufficient to allow the Company to fund its current operating plan for at least 12 months from the date the financial statements are issued. The Company cannot predict the outcome of the merger or whether and to what extent it will resume drug development activities and to what extent it will promote and sell HOTSHOT or other consumer products in the future. Accordingly, it is difficult to predict future cash needs. Management does expect the Company to continue to incur losses for the foreseeable future. The Company's ability to achieve profitability in the future is dependent upon achieving a level of revenues adequate to support the Company's cost structure. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital. If the Company raises funds through the sale of equity or convertible debt securities, the issuance of those securities could result in substantial dilution of the stockholders' ownership in the Company. There can be no assurances, however, that additional funding will be available on terms acceptable to the Company, or at all.

Organization and operations

The Company

Flex Pharma Inc., or the Company, is a biotechnology company that was previously focused on developing innovative and proprietary treatments for muscle cramps, spasms and spasticity associated with severe neurological conditions. In June 2018, the Company announced that it was ending its ongoing Phase 2 clinical trials of its lead drug product candidate, FLX-787, in patients with motor neuron disease, or MND, primarily with amyotrophic lateral sclerosis, or ALS, and in patients with Charcot-Marie-Tooth disease, or CMT, due to oral tolerability concerns observed in both studies. The wind-down of the activities associated with these studies was completed in the third quarter of 2018.

In 2016, the Company launched its consumer product, HOTSHOT®, to prevent and treat exercise-associated muscle cramps, or EAMCs. The Company continues to market and sell HOTSHOT to endurance athletes who drink it before, during and after exercise to prevent and treat EAMCs.

In June 2018, the Company initiated a process to explore a range of strategic alternatives for enhancing stockholder value, including the potential sale or merger of the Company. Following an extensive process of evaluating strategic alternatives for the Company, on January 3, 2019, the Company entered into an Agreement and Plan of Merger, or the Merger Agreement, with Salarius Pharmaceuticals, LLC, or Salarius, under which the privately held Salarius will merge with a wholly owned subsidiary of the Company. At a special meeting on July 12, 2019, the merger was approved by the Company's stockholders and the merger is expected to close on or about July 19, 2019. Upon completion of the merger, the business of Salarius will continue as the business of the combined company.

The Company operates as two reportable segments, Consumer Operations and Drug Development. See Note 12 for additional discussion and information on the reportable segments.

Liquidity

The Company incurred a loss of $1,384,777 for the three months ended June 30, 2019, a loss of $3,615,207 for the six months ended June 30, 2019 and had an accumulated deficit of $136,576,482 as of June 30, 2019. The Company had unrestricted cash and cash equivalents of $6,514,215 at June 30, 2019. The Company's operating plan assumes limited research and development activities and that the Consumer Operations segment will continue to sell HOTSHOT.

In the event the merger with Salarius is not completed, the Company will reconsider its strategic alternatives, including to (i) pursue a dissolution and liquidation of the Company, (ii) pursue another strategic transaction or (iii) continue to market HOTSHOT and operate its consumer business. If the Company dissolves and liquidates, the Company's common stockholders may lose their entire investment. The amount of assets available for distribution to the Company's stockholders would depend heavily on the timing of such liquidation as well as the amount of cash that would be needed for commitments and contingent liabilities.

Based on the Company's current operating plan, the Company believes that its existing cash and cash equivalents will be sufficient to allow the Company to fund its current operating plan for at least 12 months from the date the financial statements are issued.

The Company cannot predict the outcome of the merger or whether and to what extent it will resume drug development activities and to what extent it will promote and sell HOTSHOT or other consumer products in the future. Accordingly, it is difficult to predict future cash needs. Management does expect the Company to continue to incur losses for the foreseeable future. The Company's ability to achieve profitability in the future is dependent upon achieving a level of revenues adequate to support the Company's cost structure. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital. If the Company raises funds through the sale of equity or convertible debt securities, the issuance of those securities could result in substantial dilution of the stockholders' ownership in the Company. There can be no assurances, however, that additional funding will be available on terms acceptable to the Company, or at all.