Salicylic acid, the other most common over-the-counter (OTC) acne-fighting ingredient, is a beta hydroxy acid (aka BHA). This chemical exfoliant works by breaking down dirt or oil in your pores. "This is helpful as a spot treatment, wash, or lotion for reducing whiteheads and blackheads, which are caused by plugs of skin cells in a pore," Dr. Roa explained. She also noted that salicylic acid can be used in higher concentrations as a chemical peel in your dermatologist's office.