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 14, 2011

Cadence Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

12481 High Bluff Drive, Suite 200

San Diego, California 92130

(Address of principal executive offices, including zip code)

(858) 436-1400

(Registrant’s telephone number, including area code)

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):

Item 8.01. Other Events.

On November 14, 2011, Cadence Pharmaceuticals, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Deutsche Bank Securities Inc., as representative of the several underwriters named therein (the “Underwriters”), relating to the issuance and sale of 19,000,000 shares of the Company’s common stock, par value $0.0001 per share (“Common Stock”). The price to the public in the offering is $3.75 per share, and the Underwriters have agreed to purchase the shares from the Company pursuant to the Underwriting Agreement at a price of $3.5625 per share. The net proceeds to the Company from the offering are expected to be approximately $67.4 million, after deducting the underwriting discounts and commissions and estimated offering expenses payable by the Company. Under the terms of the Underwriting Agreement, the Company also granted the Underwriters an option, exercisable for 30 days, to purchase up to an additional 2,800,000 shares of Common Stock to cover over-allotments, if any. The offering is expected to close on or about November 18, 2011, subject to customary closing conditions.

The offering is being made pursuant to the Company’s effective shelf registration statement on Form S-3 (Registration Statement No. 333-173295) previously filed with and declared effective by the Securities and Exchange Commission (the “SEC”) and a final prospectus supplement filed with the SEC.

The Underwriting Agreement contains customary representations, warranties and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement, and may be subject to limitations agreed upon by the contracting parties.

A copy of the Underwriting Agreement is attached as Exhibit 1.1 to this report and is incorporated by reference herein, and the foregoing description of the terms of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to such exhibit. A copy of the opinion of Latham & Watkins LLP relating to the legality of the issuance and sale of the Common Stock in the offering is attached as Exhibit 5.1 to this report.

The Company issued press releases on November 14, 2011 and November 15, 2011 announcing the commencement of the offering and the pricing of the offering, respectively, which press releases are attached as Exhibits 99.1 and 99.2, respectively, to this report and are incorporated by reference herein.

Forward-Looking Statements

The Company cautions readers that statements included in this report that are not a description of historical facts are forward-looking statements. For example, statements regarding the Company’s expectations regarding the completion of the public offering and the expected net proceeds therefrom are forward-looking statements. The inclusion of forward-looking statements should not be regarded as a representation by the Company that any of its plans will be achieved. Actual results may differ materially from those set forth in this report due to the risks and uncertainties, including, without limitation, those associated with market conditions and the satisfaction of customary closing conditions related to the public offering, as well as those inherent in the Company’s business and finances in general, including the risks detailed in the Company’s press releases as well as in the Company’s periodic and other public filings with the SEC.

Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, and the Company undertakes no obligation to revise or update this report to reflect events or circumstances after the date hereof. This caution is made under the safe harbor provisions of Section 21E of the Securities Exchange Act of 1934, as amended.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

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.

Date: November 16, 2011

EXHIBIT INDEX