Sweat itself doesn't cause breakouts, but it can mix with oils in your pores — and that can lead to acne. Friction can also aggravate acne, so wear loose-fitting clothing made of natural fabrics; synthetic fabrics such as Lycra and nylon can rub against skin, trap sweat, and clog pores. When showering after a workout, use a body wash with salicylic acid to keep pores clean.