Beta Hydroxy Acid (Willowbark Extract)
A beta hydroxy acid (BHA) is, chemically speaking, an organic compound that contains a carboxylic acid functional group and hydroxy functional group separated by two carbon atoms. Beta hydroxy acids are closely related to alpha hydroxy acids, in which the two functional groups are separated by one carbon atom. In the same way that each alpha hydroxy acid type (glycolic, lactic, citric, etc.) has a similar but distinct way that it functions in the skin, so too do BHAs have similar but distinct methods of action in the skin.
In skincare products, the term beta hydroxy acid refers specifically to salicylic acid, as it is the only functional form for skin treatments. Salicylic acid has several natural sources, but is most often extracted from the bark of the black willow tree. Being a beta hydroxy acid, it is oil soluble, so it works perfectly alongside AHAs (which are water soluble) as it can better deep clean pores while promoting skin renewal. This has put BHAs, specifically salicylic acid, in the forefront of fighting (and preventing) acne development while helping to erase lines and wrinkles.