Power of Attorney

    Know all by these presents that the undersigned hereby constitutes and
appoints each of John H. Tucker, Troy Ignelzi, Arthur McGivern and Courtney
Gaughan, and with full power of substitution, as the undersigned's true and
lawful attorney-in-fact to:

        (1) execute for and on behalf of the undersignedForms 3, 4, and 5 in
        accordance with Section 16(a) of the Securities Exchange Act of 1934, as
        amended, 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, complete and execute any amendment or amendments
        thereto, and timely file such form with the SEC 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 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, is not assuming, nor
is scPharmaceuticals Inc., a Delaware corporation (the "Company"), assuming, any
of the undersigned's responsibilities to comply with Section 16 of the
Securities Exchange Act of 1934, as amended.

    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.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 16 day of November, 2017.


LUNDBECKFOND INVEST A/S

By: Lundbeckfonden Ventures,
    its sole General Partner


    By: /s/ Lene Skole
        ------------------------------------------------------------------------
        Lene Skole
        Chief Executive Officer, Lundbeckfonden


    By: /s/ Mette Kirstine Agger
        ------------------------------------------------------------------------
        Mette Kirstine Agger
        Managing Partner,
        Lundbeckfonden Ventures