UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K/A

(Amendment No. 1)

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): December 16, 2014

SALIX PHARMACEUTICALS, LTD.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (919) 862-1000

Not Applicable

(Former name or former address, if changed since last report)

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:

EXPLANATORY NOTE

This Amendment No. 1 on Form 8-K (this “Amendment”) amends the Current Report on Form 8-K (the “Original Filing”) of Salix Pharmaceuticals, Ltd. (“Salix” or the “Company”) furnished to the Securities and Exchange Commission on December 16, 2014. The Company is filing this Amendment to provide that the information disclosed in the Original Filing shall be incorporated by reference in the Company’s registration statements under the Securities Act of 1933, as amended (the “Securities Act”). The Original Filing is not modified in any other respect.

Item 7.01. Regulation FD Disclosure.

On December 16, 2014, the Company issued a press release announcing: (i) its plan to accelerate the reduction of wholesaler inventory levels of XIFAXAN^® 550, APRISO^® and UCERIS^® to Salix’s target of approximately three months by the end of 2015; (ii) the Food and Drug Administration’s extension of the Prescription Drug User Fee Act Action Date for XIFAXAN^® 550 for the treatment of irritable bowel syndrome with diarrhea to May 27, 2015; and (iii) the Company’s preliminary guidance for full years 2015 and 2016. A copy of the press release is attached hereto as Exhibit 99.1 (the “Exhibit”).

The information in this Current Report, including the Exhibit, is being filed pursuant to Item 7.01 of Form 8-K and General Instruction B.2 thereunder. The information in this Current Report shall be deemed to be “filed” for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and shall be incorporated by reference in the Company’s registration statements under the Securities Act. This information will not be deemed an admission as to the materiality of such information that is being disclosed solely pursuant to Regulation FD.

Item 9.01. Financial Statements and 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.

Exhibit Index