What is the name of the chemical exfoliant derived from willow bark?

The chemical exfoliant derived from willow bark is salicylic acid.

Salicylic acid is an organic compound with the formula C7H6O3. Its name comes from Salix, the Latin name for the willow genus, because it was originally identified in connection with willow-derived substances. White willow bark is a natural source, although modern cosmetic products generally use purified salicylic acid made through industrial chemical processes.

In skincare, salicylic acid is valued as a chemical exfoliant because it helps loosen and remove dead cells from the outer layer of skin. It is also oil-soluble, allowing it to work inside pores and help reduce the buildup associated with acne and blackheads. These properties make it distinct from alpha hydroxy acids such as lactic acid and glycolic acid, which are generally water-soluble and work mainly on the skin’s surface.

Salicylic acid is also historically connected to aspirin: acetylsalicylic acid is produced by chemically modifying salicylic acid. A common mix-up is confusing the ingredient with willow bark extract itself. Willow bark contains salicin and other compounds; salicylic acid is the specific chemical used in many exfoliating and acne-treatment formulations.