Alpha hydroxycarboxylic acid

An alpha hydroxy carboxylic acid or α-hydroxy carboxylic acid (AHA) is a carboxylic acid containing a hydroxy functional group separated by one carbon atoms. They are related to beta hydroxy acids, in which the two functional groups are separated by two carbon atoms. Prominent examples are glycolic acid, lactic acid, mandelic acid, and citric acid.

Alpha hydroxy acids are stronger acids than the corresponding non-alpha hydroxy carboxylic acid. Their increased acidity is attributed to internal hydrogen bonding.

α-Hydroxy acids have a variety of applications. They are used industrially as feed additives and as the basis for polymers. They are also commonly used in cosmetic products to chemically exfoliate and moisturize.