LANTHEUS HOLDINGS, INC.

                                   POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes and appoints
each of the President, Treasurer, each Assistant Treasurer, Secretary and each
Assistant Secretary of Lantheus Holdings, Inc. (the "Company"), acting singly or
together and with full power of substitution, as the undersigned's true and
lawful attorney-in-fact with full power and authority to act in the name of and
for and on behalf of the undersigned to:

        (1)    prepare, execute in the undersigned's name and on the
               undersigned's behalf, and submit to the U.S. Securities and
               Exchange Commission (the "SEC") a Form ID, including amendments
               thereto, and any other documents necessary or appropriate to
               obtain codes and passwords enabling the undersigned to make
               electronic filings with the SEC of reports required by Section
               16(a) of the Securities Exchange Act of 1934 or any rule or
               regulation of the SEC;

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

        (3)    do and perform any and all acts for and on behalf of the
               undersigned which may be necessary or desirable to obtain and
               maintain the undersigned's filings codes, complete and execute
               any such Form 3, 4 or 5, complete and execute any amendment or
               amendments thereto, and timely file such form with the SEC and
               any stock exchange or similar authority; and

        (4)    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
               or of, 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 such attorney-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 that such attorney-in-fact, or such
attorney-in-fact's substitute or substitutes, 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 the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.

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 the foregoing attorneys-in-fact.

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

                                        /s/ James H. Thrall
                                        -------------------------
                                        Signature

                                        James H. Thrall
                                        -------------------------
                                        Print Name

                                        2/26/2018
                                        -------------------------
                                        Date