Salicylic acid is a beta hydroxy acid that is derived from willow bark and sweet bark trees. It’s a common ingredient in most over-the-counter acne treatments as well as some anti-aging skin peels. Its job is to exfoliate the skin – removing the outermost layer and exposing newer, healthier skin underneath. It also dries out sebum from the pores and kills acne-causing bacteria.

A salicylic peel is fat-soluble, which means it can penetrate the skin easily and is tolerated by acne-prone skin, but not great for dry, sun-damaged or sensitive skin.

Salicylic acid is often combined with other acne treatments and even antibiotics in very severe cases.