[noun] Salicylic acid, the best-known BHA (beta hydroxy acid), has been used since ancient times. Though originally sourced from willow bark, whence its name, it is also present in many other plants and was traditionally used to treat pain, fever and inflammation. Today, it is one of the leading molecules used in cosmetics. Boasting recognised exfoliating, soothing and purifying properties, it is an excellent active ingredient for targeting combination or blemished skin.