UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): November 4, 2014

ACELRX PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

351 Galveston Drive

Redwood City, CA 94063

(Address of principal executive offices and zip code)

Registrant’s telephone number, including area code: (650) 216-3500

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

On November 10, 2014, AcelRx Pharmaceuticals, Inc. (the “Company”) issued a press release announcing its financial results for the quarter ended September 30, 2014. A copy of the press release is furnished as Exhibit 99.1 to this report.

The information in this Item 2.02 and in the press release furnished as Exhibit 99.1 to this current report shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information contained in this Item 2.02 and in the press release furnished as Exhibit 99.1 to this current report shall not be incorporated by reference into any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation language in such filing.

ITEM 5.02 DEPARTURE OF DIRECTORS OR CERTAIN OFFICERS; ELECTION OF DIRECTORS; APPOINTMENT OF CERTAIN OFFICERS; COMPENSATORY ARRANGEMENTS OF CERTAIN OFFICERS.

(b) On November 5, 2014, the Company announced the departure of Richard A. King, the Company’s President and Chief Executive Officer (CEO). Mr. King’s separation was not the result of any disagreement with the Company on any matter relating to the Company’s operations, policies or practices.

Mr. King will remain the Company’s CEO until the date that the Company hires a new CEO, unless the Board of Directors of the Company requests his resignation before then.

(e) On November 4, 2014, the Board of Directors of the Company adopted a supplemental Cash Bonus Plan (the “Plan”), under which the Company’s named executive officers are participants. The Plan provides that all employees as of September 1, 2014 and through March 31, 2015 are eligible to participate in the Plan. Under the Plan objectives, if the Company resubmits the NDA to the FDA on or before March 31, 2015, a bonus payment equivalent to 20% of the target annual bonus under the 2014 Cash Bonus Plan will be payable to all eligible employees, including the named executive officers.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

INDEX TO EXHIBITS