v3.22.1
Document And Entity Information - USD ($)
Dec. 31, 2021
Dec. 31, 2020
Mar. 31, 2022
Jun. 30, 2021
Document Information [Line Items]        
Entity, Registrant Name ACELRX PHARMACEUTICALS, INC.      
Document, Type 10-K/A      
Document, Annual Report true      
Document, Period End Date Dec. 31, 2021      
Current Fiscal Year End Date --12-31      
Document, Fiscal Period Focus FY      
Document, Fiscal Year Focus 2021      
Document, Transition Report false      
Entity, File Number 001-35068      
Entity, Incorporation, State or Country Code DE      
Entity, Tax Identification Number 41-2193603      
Entity, Address, Address Line One 25821 Industrial Boulevard, Suite 400      
Entity, Address, City or Town Hayward      
Entity, Address, State or Province CA      
Entity, Address, Postal Zip Code 94545      
City Area Code 650      
Local Phone Number 216-3500      
Title of 12(b) Security Common Stock      
Trading Symbol ACRX      
Security Exchange Name NASDAQ      
Entity, Well-known Seasoned Issuer No      
Entity, Voluntary Filers No      
Entity, Current Reporting Status Yes      
Entity, Interactive Data, Current Yes      
Entity, Filer Category Non-accelerated Filer      
Entity, Small Business true      
Entity, Emerging Growth Company false      
ICFR Auditor Attestation Flag false      
Entity, Shell Company false      
Entity, Public Float       $ 161,163,094
Entity, Common Stock Shares, Outstanding     146,949,320  
Amendment Description On March 10, 2022, AcelRx, Inc, filed its Annual Report on Form 10-K for the year ended December 31, 2021, or the 2021 Annual Report. The 2021 Annual Report omitted Part III, Items 10 (Directors, Executive Officers and Corporate Governance), 11 (Executive Compensation), 12 (Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters), 13 (Certain Relationships and Related Transactions, and Director Independence) and 14 (Principal Accountant Fees and Services) in reliance on General Instruction G(3) to Form 10-K, which provides that such information may be either incorporated by reference from the registrant’s definitive proxy statement or included in an amendment to Form 10-K, in either case filed with the Securities and Exchange Commission, or the SEC, not later than 120 days after the end of the fiscal year.   We currently expect that our definitive proxy statement for our 2022 annual meeting of stockholders will be filed later than the 120th day after the end of the last fiscal year. Accordingly, this Amendment No. 1 to Form 10-K, or this Amendment, is being filed solely to:     ● amend Part III, Items 10, 11, 12, 13 and 14 of the 2021 Annual Report to include the information required by such items;     ● delete the reference on the cover of the 2021 Annual Report to the incorporation by reference of portions of our proxy statement into Part III of the 2021 Annual Report; and     ● file new certifications of our principal executive officer and principal financial officer as exhibits to this Amendment under Item 15 of Part IV hereof, pursuant to Rule 12b-15 under the Securities Exchange Act of 1934.   Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted. We are not including the certifications under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment.   Except as described above, this Amendment does not modify or update disclosure in, or exhibits to, the 2021 Annual Report. Furthermore, this Amendment does not change any previously reported financial results, nor does it reflect events occurring after the date of the 2021 Annual Report. Information not affected by this Amendment remains unchanged and reflects the disclosures made at the time the 2021 Annual Report was filed. Accordingly, this Amendment should be read in conjunction with the 2021 Annual Report and our other filings with the SEC.      
Auditor Name WithumSmith+Brown OUM & Co. LLP    
Auditor Firm ID 100 252    
Auditor Location San Francisco, CA San Francisco, CA    
Amendment Flag true      
Entity, Central Index Key 0001427925