Formation and Business of the Company	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Formation and Business of the Company	1.Formation and Business of the Company Menlo Therapeutics Inc. (the “Company”) is a late‑stage biopharmaceutical company focused on the development and commercialization of serlopitant for the treatment of pruritus, or itch, associated with various conditions such as prurigo nodularis, psoriasis and chronic pruritus of unknown origin. The Company believes that its product candidate, serlopitant, a highly selective once‑daily, oral small molecule inhibitor of the neurokinin 1, or NK₁receptor, has the potential to significantly alleviate pruritus. The Company was incorporated in Delaware in October 2011. Since commencing operations, the Company has devoted substantially all of its resources to developing its product candidate, serlopitant, including conducting clinical trials and providing general and administrative support for these operations. Initial Public Offering In January 2018, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 8,050,000 shares of common stock, which includes 1,050,000 shares issued pursuant to the underwriter’s option to purchase additional shares, and received net proceeds of approximately $125.4 million, after deducting underwriting discounts, commissions and offering expenses. In connection with the completion of the Company's IPO, all shares of convertible preferred stock converted into 9,629,405 shares of common stock. Liquidity and Capital Resources The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern. Since inception, the Company has incurred losses and negative cash flows from operations. For the nine months ended September 30, 2018, the Company incurred a net loss of $33.9 million and used $36.1 million of cash in operations. As of September 30, 2018, the Company had cash, cash equivalents and investments of $152.7 million and an accumulated deficit of $93.0 million. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development activities. Management plans to finance operations through equity or debt financings or other capital sources, including potential collaborations or other strategic transactions. There can be no assurances that, in the event that the Company requires additional financing, such financing will be available on terms which are favorable to the Company, or at all. If the Company is unable to raise additional funding to meet its working capital needs in the future, it will be forced to delay or reduce the scope of its research programs and/or limit or cease its operations. The Company believes that its existing cash, cash equivalents and investments as of September 30, 2018 will provide sufficient funds to enable it to meet its obligations for at least the next 12 months from the issuance of our financial statements as of and for the nine months ended September 30, 2018.

1.Formation and Business of the Company

Menlo Therapeutics Inc. (the “Company”) is a late‑stage biopharmaceutical company focused on the development and commercialization of serlopitant for the treatment of pruritus, or itch, associated with various conditions such as prurigo nodularis, psoriasis and chronic pruritus of unknown origin. The Company believes that its product candidate, serlopitant, a highly selective once‑daily, oral small molecule inhibitor of the neurokinin 1, or NK₁receptor, has the potential to significantly alleviate pruritus.

The Company was incorporated in Delaware in October 2011. Since commencing operations, the Company has devoted substantially all of its resources to developing its product candidate, serlopitant, including conducting clinical trials and providing general and administrative support for these operations.

Initial Public Offering

In January 2018, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 8,050,000 shares of common stock, which includes 1,050,000 shares issued pursuant to the underwriter’s option to purchase additional shares, and received net proceeds of approximately $125.4 million, after deducting underwriting discounts, commissions and offering expenses. In connection with the completion of the Company's IPO, all shares of convertible preferred stock converted into 9,629,405 shares of common stock.

Liquidity and Capital Resources

The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and reclassification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern. Since inception, the Company has incurred losses and negative cash flows from operations. For the nine months ended September 30, 2018, the Company incurred a net loss of $33.9 million and used $36.1 million of cash in operations. As of September 30, 2018, the Company had cash, cash equivalents and investments of $152.7 million and an accumulated deficit of $93.0 million.

Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development activities. Management plans to finance operations through equity or debt financings or other capital sources, including potential collaborations or other strategic transactions. There can be no assurances that, in the event that the Company requires additional financing, such financing will be available on terms which are favorable to the Company, or at all. If the Company is unable to raise additional funding to meet its working capital needs in the future, it will be forced to delay or reduce the scope of its research programs and/or limit or cease its operations.

The Company believes that its existing cash, cash equivalents and investments as of September 30, 2018 will provide sufficient funds to enable it to meet its obligations for at least the next 12 months from the issuance of our financial statements as of and for the nine months ended September 30, 2018.