X0508 4 2023-12-21 0001267565 COLLEGIUM PHARMACEUTICAL, INC COLL 0001443841 Ciaffoni Joseph C/O COLLEGIUM PHARMACEUTICAL, INC. 100 TECHNOLOGY CENTER DRIVE STOUGHTON MA 02072 1 1 0 0 President and CEO 1 Common Stock 2023-12-21 4 M 0 4357 21.34 A 279357 D Common Stock 2023-12-21 4 S 0 4357 30.3825 D 275000 D Stock Option (Right to Purchase) 21.34 2023-12-21 4 M 0 4357 0 D 2030-02-05 Common Stock 4357 16875 D The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 27, 2023. The price reported in column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $30.13 to $30.64, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. Twenty-five percent (25%) of the option vests and becomes exercisable on February 10, 2021, and the balance vests in equal quarterly installments (rounded up to the nearest whole share of common stock) over the following three-year period, subject to the Reporting Person's continued service with the Issuer. /s/ Colleen Tupper as Attorney-In-Fact For Joseph Ciaffoni 2023-12-22