Back acne is different from face acne because the skin on your back is thicker and has larger pores, but the mechanism is similar: oil, sweat, and dead skin cells clogging follicles. The gym sweat is 100% a trigger. Sweat mixed with bacteria and tight synthetic fabrics creates a perfect storm. Here is the protocol: Shower immediately after working out (within 15 minutes). Use a body wash with benzoyl peroxide (not salicylic acid – benzoyl peroxide kills the bacteria better for bodies). Leave it on for 2-3 minutes before rinsing. Wear loose, cotton shirts. Change your bedsheets weekly. If that fails, a dermatologist can prescribe a topical clindamycin solution or even a short course of oral antibiotics. For existing spots, avoid scrubbing – it spreads the bacteria. Use a soft cloth.