POWER OF ATTORNEY



 Know all by these presents, that the undersigned hereby constitutes

and appoints each of Paul Brannelly and Michael T. Heffernan, with full power

to act singly, as the undersigned's true and lawful attorney-in-fact with full

power of substitution to:



 (1)  execute for and on behalf of the undersigned, in the

undersigned's capacity as an officer and/or director and/or beneficial owner

of Collegium Pharmaceutical Inc.  (the "Company"), Form ID Application,

Forms 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 ID Application, Forms 3, 4 or 5, complete and execute any

amendment or amendments thereto and timely file such forms 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 the 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.



 This power of attorney shall remain in full force and effect until

revoked by the undersigned in a signed writing delivered to the attorney-in-fact.



 IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney

to be executed as of the 24th day of April, 2015.







     /s/Alison B. Fleming, Ph.D.

     Name: Alison B. Fleming, Ph.D.

                                        Title: VP, Product Development