[ Scientific name —Salicylic acid ]
Salicylic acid is a beta hydroxy acid (BHA) derived from the bark of the willow tree.
Salicylic acid is an oil-soluble ingredient and that means it can penetrate more deeply into the layers of the skin than other exfoliants, through the lipid layers between the skin cells. Salicylic acid unclog pores and dissolves skin debris and (at a lower concentration) slough off seborrheic dermatitis.
For this reason, it is a common ingredient in formulas that target acne, especially whiteheads and blackheads.