POWER OF ATTORNEY

        I hereby constitute and appoint each of George Tidmarsh and Ryan A. Murr
as my true and lawful attorney-in-fact to:

       (1)   execute for and on behalf of the undersigned, in the
             undersigned's capacity as an officer and/or director of La
             Jolla Pharmaceutical Company (the "Company"), Forms 3, 4 and 5
             in accordance with Section 16(a) of the Securities Exchange
             Act of 1934, as amended (the "Act"), and the rules thereunder;

       (2)   do and perform any and all acts for and on behalf of the
             undersigned which may be necessary or desirable to complete
             and execute any such Form 3, 4 or 5 and timely file such form
             with the United States Securities and Exchange Commission and
             any stock exchange or similar authority; and

       (3)   take any other action of any type whatsoever in connection
             with the foregoing which, in the opinion of such
             attorney-in-fact, may be of benefit to, in the best interest
             of, or legally required by, the undersigned, it being
             understood that the documents executed by such
             attorney-in-fact on behalf of the undersigned pursuant to this
             Power of Attorney shall be in such form and shall contain such
             terms and conditions as such attorney-in-fact may approve in
             such attorney-in-fact's discretion.

       The undersigned hereby grants to each of the attorneys-in-fact full
power and authority to do and perform any and every act and thing whatsoever
requisite, necessary or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all the acts such
attorney-in-fact shall lawfully do or cause to be done by virtue of this power
of attorney and the rights and powers herein granted. The undersigned
acknowledges that each of the foregoing attorneys-in-fact, in serving in such
capacity at the request of the undersigned, is not assuming any of the
undersigned's responsibilities to comply with Section 16 of the Act.

       This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to each
of the foregoing attorneys-in-fact.

       IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of the date set forth below.

                                      By:         /s/ Craig Johnson
                                                  -----------------------------

                                      Print Name: Craig Johnson

                                      Date:       10/17/2013
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