Beta hydroxy acid, also known by the acronym BHA, refers to the ingredient salicylic acid. A beta hydroxy acid (BHA) product with salicylic acid exfoliates skin, reduces redness, provides a mild anti-bacterial action, and stimulates collagen production. It is a multi-benefit ingredient used to improve acne, blackheads, white bumps, uneven skin tone, wrinkles, large pores, oily skin, and reddened/sensitive skin. Beta hydroxy acid can be helpful for improving redness related to the skin disorder rosacea. In order for beta hydroxy acid products to function as exfoliants, the pH of the product must be between 3 and 4 (lower pH values are effective, too, but much below pH 3 is very irritating to skin).