Salicylic acid is a naturally occurring compound found in plants, such as willow bark. It is commonly used as an acne treatment and to reduce inflammation. In skin care products, salicylic acid works as a keratolytic agent, meaning it helps to break down tough skin cells. It also helps to unclog pores, reduce oiliness and exfoliate the surface of the skin. Salicylic acid can also be used to treat warts, psoriasis and other skin conditions.