Walgreens 2% BHA Liquid Exfoliant is a unique leave-on formula with a concentration of 2% BHA (Salicylic Acid) and an optimal pH range of 3.2-3.8. BHA sheds built-up layers of skin. It's a gentle leave-on exfoliant with salicylic acid that quickly unclogs pores and exfoliates dead skin while boosting luminosity and minimizing the look of uneven skin tone.