Salicylic Acid — (See Beta Hydroxy Acid) Beta-hydroxy acids (BHAs) are keratolytic and anti-inflammatory. Salicylic acid is an effective ingredient in acne products and is widely used in acne cleansers and lotions. They work by dissolving the top layer of stratum corneum cells (reducing SC thickness), improving the look and feel of the skin. Because it is lipid soluble, BHA can more easily reduce sebaceous follicle blockage by penetrating the pores and exfoliating the dead cell accumulation. BHAs are excellent for their ability to exfoliate around the orifice of the sebaceous follicle. It is antimicrobial and anti-septic. For the treatment of aging skin, it appears to help improve skin wrinkles, roughness, and tone. Salicylic acid can be an even more effective anti-acne agent when paired with glycolic acid. In addition, it is a useful ingredient for products formulated to treat psoriasis, callouses, corns, and warts—cases where there is a buildup of dead skin cells. When applied topically, it is reported to penetrate 3 to 4 mm into the epidermis.