Chest and back acne usually appear in people who sweat excessively and those with extra oily skin. The bad news is, irritation can make those eruptions worse. And anything that rubs against your skin can cause irritation. But don't let those breakouts give you teenage angst, salicylic acid products are your best solutions to these unsightly blemishes. I would suggest you get the ones in liquid spray form. After shower is the best time to apply when pores are clean and open. Spritz your entire back and chest with the solution. You'll have clearer skin in as little as two weeks.