1. Organization and Description of Business	9 Months Ended
Sep. 30, 2019
Accounting Policies [Abstract]
Organization and Description of Business Operations	1. Organization and Description of Business Seelos Therapeutics, Inc. and its subsidiaries (the "Company") plan on developing its clinical and regulatory strategy with its internal research and development team with a view toward prioritizing market introduction as quickly as possible. The Company's lead programs are SLS-002 for the potential treatment of suicidality in post-traumatic stress disorder, and in major depressive disorder, SLS-005 for Sanfilippo syndrome and SLS-006 for the potential treatment of Parkinson's Disease ("PD"). Additionally, the Company is developing several preclinical programs, most of which have well-defined mechanisms of action, including: SLS-004 and SLS-007 for the potential treatment of PD, SLS-008 targeted at chronic inflammation in asthma and orphan indications such as pediatric esophagitis, SLS-010, in narcolepsy and related disorders and SLS-012, an injectable therapy for post-operative pain management. Merger with Apricus Biosciences, Inc. On January 24, 2019, Apricus Biosciences, Inc., a Nevada corporation ("Apricus"), completed a business combination with Seelos Therapeutics, Inc., a Delaware corporation ("Seelos"), in accordance with the terms of the Agreement and Plan of Merger Reorganization (the "Merger Agreement") entered into on July 30, 2018. Pursuant to the Merger Agreement, (i) a subsidiary of Apricus merged with and into Seelos, with Seelos (renamed as "Seelos Corporation") continuing as a wholly owned subsidiary of Apricus and the surviving corporation of the merger and (ii) Apricus was renamed as "Seelos Therapeutics, Inc." (the "Merger"). The Merger was accounted for as a reverse recapitalization under United States generally accepted accounting principles ("U.S. GAAP") because the primary assets of Apricus were nominal following the close of the Merger. Seelos was determined to be the accounting acquirer based upon the terms of the Merger and other factors, including: (i) Seelos' stockholders and other persons holding securities convertible, exercisable or exchangeable directly or indirectly for Seelos common stock owned the majority of Apricus immediately following the effective time of the Merger, (ii) Seelos holds the majority (four of five) of board seats of the combined company and (iii) Seelos' management holds all key positions in the management of the combined company. Accordingly, the historical financial statements of Seelos Therapeutics, Inc. became the Company's historical financial statements, including the comparative prior periods. All references in the unaudited condensed consolidated financial statements to the number of shares and per-share amounts of common stock have been retroactively restated to reflect the exchange rate.
Liquidity	Liquidity The Company had no revenues, incurred operating losses since inception, and expects to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of September 30, 2019, the Company had $15.3 million in cash and an accumulated deficit of $45.4 million. The Company has historically funded its operations through the issuance of convertible notes (the "Notes") (see Note 6), the sale of common stock (see Note 3) and the sale of warrants (see Note 7). On August 23, 2019, the Company entered into a Securities Purchase Agreement with certain institutional investors (the "Securities Purchase Agreement"), pursuant to which the Company agreed to issue and sell an aggregate of 4,475,000 shares of common stock in a registered direct offering, resulting in total gross proceeds of approximately $6.7 million, before deducting the placement agents' fees and other estimated offering expenses (see Note 3). On June 17, 2019, the Company entered into an Equity Distribution Agreement (the "Equity Distribution Agreement") with Piper Jaffray & Co., as sales agent ("Piper Jaffray"), pursuant to which the Company may offer and sell, from time to time, through Piper Jaffray up to $50,000,000 in shares of its common stock. During the three and nine months ended September 30, 2019, the Company sold 1,197,676 shares for net proceeds of approximately $2.6 million pursuant to the Equity Distribution Agreement (see Note 3). As of September 30, 2019, the Company had approximately $87.0 million available under its Form S-3 shelf registration statement. Under current regulations of the Securities and Exchange Commission (the "SEC"), in the event the aggregate market value of the Company's common stock held by non-affiliates ("public float"), is less than $75.0 million, the amount it can raise through primary public offerings of securities, including sales under the Securities Purchase Agreement and the Equity Distribution Agreement, in any twelve-month period using shelf registration statements is limited to an aggregate of one-third of the Company's public float. SEC regulations permit the Company to use the highest closing sales price of the Company's common stock (or the average of the last bid and last ask prices of the Company's common stock) on any day within 60 days of sales under the shelf registration statement. As of September 30, 2019, the Company's public float was approximately $39.1 million based on 26.9 million shares of the Company's common stock outstanding at a price of $1.78 per share, which was the closing sale price of the Company's common stock on August 22, 2019. As the Company's public float was less than $75.0 million as of September 30, 2019, the Company's usage of its S-3 shelf registration statement is limited. The Company still maintains the ability to raise funds through other means, such as through the filing of a registration statement on Form S-1 or in private placements. The rules and regulations of the SEC or any other regulatory agencies may restrict the Company's ability to conduct certain types of financing activities, or may affect the timing of and amounts it can raise by undertaking such activities. The Company evaluated whether there are any conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year beyond the filing of this Quarterly Report on Form 10-Q. Based on such evaluation and the Company's current plans, which are subject to change, management believes that the Company's existing cash and cash equivalents as of September 30, 2019 are sufficient to satisfy its operating cash needs for at least one year after the filing of this Quarterly Report on Form 10-Q. The accompanying unaudited condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from uncertainty related to its ability to continue as a going concern. The Company's future liquidity and capital funding requirements will depend on numerous factors, including: its ability to raise additional funds to finance its operations; its ability to maintain compliance with the listing requirements of The Nasdaq Capital Market ("Nasdaq"); the outcome, costs and timing of clinical trial results for the Company's current or future product candidates; the extent and amount of any indemnification claims, including any made by Ferring International Center S.A. ("Ferring") under the asset purchase agreement with Ferring, entered into on March 8, 2017, pursuant to which the Company sold to Ferring its ex-U.S. assets and rights related to products in development, intended for the topical treatment of erectile dysfunction, which are known as Vitaros in certain countries outside of the United States; potential litigation expenses; the emergence and effect of competing or complementary products or product candidates; its ability to maintain, expand and defend the scope of its intellectual property portfolio, including the amount and timing of any payments the Company may be required to make, or that it may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights; its ability to retain its current employees and the need and ability to hire additional management and scientific and medical personnel; the terms and timing of any collaborative, licensing or other arrangements that it has or may establish; the trading price of its common stock; its ability to secure a development partner for the CVR Product Candidate (as defined below) in order to overcome deficiencies raised in the 2018 complete response letter issued by the U.S. Food and Drug Administration (the "FDA") related to the CVR Product Candidate; and its ability to increase the number of authorized shares outstanding to facilitate future financing events. The Company will need to raise substantial additional funds through one or more of the following: issuance of additional debt or equity and/or the completion of a licensing or other commercial transaction for one or more of the Company's product candidates. If the Company is unable to maintain sufficient financial resources, its business, financial condition and results of operations will be materially and adversely affected. This could affect future development and business activities and potential future clinical studies and/or other future ventures. Failure to obtain additional equity or debt financing will have a material, adverse impact on the Company's business operations. There can be no assurance that the Company will be able to obtain the needed financing on acceptable terms or at all. Additionally, equity or convertible debt financings will likely have a dilutive effect on the holdings of the Company's existing stockholders.

1. Organization and Description of Business

9 Months Ended

Sep. 30, 2019

Organization and Description of Business Operations

1. Organization and Description of Business

Seelos Therapeutics, Inc. and its subsidiaries (the "Company") plan on developing its clinical and regulatory strategy with its internal research and development team with a view toward prioritizing market introduction as quickly as possible. The Company's lead programs are SLS-002 for the potential treatment of suicidality in post-traumatic stress disorder, and in major depressive disorder, SLS-005 for Sanfilippo syndrome and SLS-006 for the potential treatment of Parkinson's Disease ("PD"). Additionally, the Company is developing several preclinical programs, most of which have well-defined mechanisms of action, including: SLS-004 and SLS-007 for the potential treatment of PD, SLS-008 targeted at chronic inflammation in asthma and orphan indications such as pediatric esophagitis, SLS-010, in narcolepsy and related disorders and SLS-012, an injectable therapy for post-operative pain management.

Merger with Apricus Biosciences, Inc.

On January 24, 2019, Apricus Biosciences, Inc., a Nevada corporation ("Apricus"), completed a business combination with Seelos Therapeutics, Inc., a Delaware corporation ("Seelos"), in accordance with the terms of the Agreement and Plan of Merger Reorganization (the "Merger Agreement") entered into on July 30, 2018. Pursuant to the Merger Agreement, (i) a subsidiary of Apricus merged with and into Seelos, with Seelos (renamed as "Seelos Corporation") continuing as a wholly owned subsidiary of Apricus and the surviving corporation of the merger and (ii) Apricus was renamed as "Seelos Therapeutics, Inc." (the "Merger").

The Merger was accounted for as a reverse recapitalization under United States generally accepted accounting principles ("U.S. GAAP") because the primary assets of Apricus were nominal following the close of the Merger. Seelos was determined to be the accounting acquirer based upon the terms of the Merger and other factors, including: (i) Seelos' stockholders and other persons holding securities convertible, exercisable or exchangeable directly or indirectly for Seelos common stock owned the majority of Apricus immediately following the effective time of the Merger, (ii) Seelos holds the majority (four of five) of board seats of the combined company and (iii) Seelos' management holds all key positions in the management of the combined company. Accordingly, the historical financial statements of Seelos Therapeutics, Inc. became the Company's historical financial statements, including the comparative prior periods. All references in the unaudited condensed consolidated financial statements to the number of shares and per-share amounts of common stock have been retroactively restated to reflect the exchange rate.

Liquidity

Liquidity

The Company had no revenues, incurred operating losses since inception, and expects to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of September 30, 2019, the Company had $15.3 million in cash and an accumulated deficit of $45.4 million. The Company has historically funded its operations through the issuance of convertible notes (the "Notes") (see Note 6), the sale of common stock (see Note 3) and the sale of warrants (see Note 7).

On August 23, 2019, the Company entered into a Securities Purchase Agreement with certain institutional investors (the "Securities Purchase Agreement"), pursuant to which the Company agreed to issue and sell an aggregate of 4,475,000 shares of common stock in a registered direct offering, resulting in total gross proceeds of approximately $6.7 million, before deducting the placement agents' fees and other estimated offering expenses (see Note 3).

On June 17, 2019, the Company entered into an Equity Distribution Agreement (the "Equity Distribution Agreement") with Piper Jaffray & Co., as sales agent ("Piper Jaffray"), pursuant to which the Company may offer and sell, from time to time, through Piper Jaffray up to $50,000,000 in shares of its common stock. During the three and nine months ended September 30, 2019, the Company sold 1,197,676 shares for net proceeds of approximately $2.6 million pursuant to the Equity Distribution Agreement (see Note 3).

As of September 30, 2019, the Company had approximately $87.0 million available under its Form S-3 shelf registration statement. Under current regulations of the Securities and Exchange Commission (the "SEC"), in the event the aggregate market value of the Company's common stock held by non-affiliates ("public float"), is less than $75.0 million, the amount it can raise through primary public offerings of securities, including sales under the Securities Purchase Agreement and the Equity Distribution Agreement, in any twelve-month period using shelf registration statements is limited to an aggregate of one-third of the Company's public float. SEC regulations permit the Company to use the highest closing sales price of the Company's common stock (or the average of the last bid and last ask prices of the Company's common stock) on any day within 60 days of sales under the shelf registration statement. As of September 30, 2019, the Company's public float was approximately $39.1 million based on 26.9 million shares of the Company's common stock outstanding at a price of $1.78 per share, which was the closing sale price of the Company's common stock on August 22, 2019. As the Company's public float was less than $75.0 million as of September 30, 2019, the Company's usage of its S-3 shelf registration statement is limited. The Company still maintains the ability to raise funds through other means, such as through the filing of a registration statement on Form S-1 or in private placements. The rules and regulations of the SEC or any other regulatory agencies may restrict the Company's ability to conduct certain types of financing activities, or may affect the timing of and amounts it can raise by undertaking such activities.

The Company evaluated whether there are any conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year beyond the filing of this Quarterly Report on Form 10-Q. Based on such evaluation and the Company's current plans, which are subject to change, management believes that the Company's existing cash and cash equivalents as of September 30, 2019 are sufficient to satisfy its operating cash needs for at least one year after the filing of this Quarterly Report on Form 10-Q.

The accompanying unaudited condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from uncertainty related to its ability to continue as a going concern.

The Company's future liquidity and capital funding requirements will depend on numerous factors, including:

its ability to raise additional funds to finance its operations;
its ability to maintain compliance with the listing requirements of The Nasdaq Capital Market ("Nasdaq");
the outcome, costs and timing of clinical trial results for the Company's current or future product candidates;
the extent and amount of any indemnification claims, including any made by Ferring International Center S.A. ("Ferring") under the asset purchase agreement with Ferring, entered into on March 8, 2017, pursuant to which the Company sold to Ferring its ex-U.S. assets and rights related to products in development, intended for the topical treatment of erectile dysfunction, which are known as Vitaros in certain countries outside of the United States;
potential litigation expenses;
the emergence and effect of competing or complementary products or product candidates;
its ability to maintain, expand and defend the scope of its intellectual property portfolio, including the amount and timing of any payments the Company may be required to make, or that it may receive, in connection with the licensing, filing, prosecution, defense and enforcement of any patents or other intellectual property rights;
its ability to retain its current employees and the need and ability to hire additional management and scientific and medical personnel;
the terms and timing of any collaborative, licensing or other arrangements that it has or may establish;
the trading price of its common stock;
its ability to secure a development partner for the CVR Product Candidate (as defined below) in order to overcome deficiencies raised in the 2018 complete response letter issued by the U.S. Food and Drug Administration (the "FDA") related to the CVR Product Candidate; and
its ability to increase the number of authorized shares outstanding to facilitate future financing events.

The Company will need to raise substantial additional funds through one or more of the following: issuance of additional debt or equity and/or the completion of a licensing or other commercial transaction for one or more of the Company's product candidates. If the Company is unable to maintain sufficient financial resources, its business, financial condition and results of operations will be materially and adversely affected. This could affect future development and business activities and potential future clinical studies and/or other future ventures. Failure to obtain additional equity or debt financing will have a material, adverse impact on the Company's business operations. There can be no assurance that the Company will be able to obtain the needed financing on acceptable terms or at all. Additionally, equity or convertible debt financings will likely have a dilutive effect on the holdings of the Company's existing stockholders.