Beta Hydroxy Acid (aka. BHA or salicylic acid) is a chemical exfoliant that works by essentially dissolving the glue that holds dead skin cells together. BHA is oil soluble, meaning that it can get past the sebum in clogged pores to remove build up and clean pores out. For this reason, BHA is commonly found in acne treatments, but may also improve the appearance of large pores, fine lines, and uneven skin tone. BHA works best at a pH of between 3 and 4.
Because BHAs work to expose new skin, users will be more sensitive to the damaging effects of the sun. Use of a daily sunscreen is an imperative part of any routine that includes BHAs.