Alpha hydroxy acid

α-hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid substituted with a hydroxy group on the adjacent carbon. They may be either naturally occurring or synthetic. AHAs are well-known for their use in the cosmetics industry. They are often found in products claiming to reduce wrinkles or the signs of aging, and improve the overall look and feel of the skin. They are also used as chemical peels available in a dermatologist's office, beauty and health spas and home kits, which usually contain a lower concentration. Their effectiveness is documented.

Several common AHAs include:


 * Glycolic acid is the most widely used of out of the group and is usually manufactured from sugar cane. It is fairly well known and considered the most effective of the AHAs.
 * Lactic acid, derived primarily from milk is considered to be milder and less irritating than glycolic acid, and is therefore considered ideal for those with sensitive skin. Its origins can be traced back to Cleopatra, who purportedly used sour milk on her skin.
 * Citric acid from citrus fruits, malic acid from apples and pears and tartaric acid from grapes are not as common and their effectiveness is still not clear.

Safety
AHAs are generally safe when used on the skin as a cosmetic agent using the recommended dosage. The most common side-effects are mild skin irritations, redness and flaking. The severity usually depends on the pH and the concentration of the acid used. Chemical peels tend to have more severe side-effects including blistering, burning and skin discoloration, although they are usually mild and go away a day or two after treatment.

The FDA has also warned consumers that care should be taken when using AHAs after an industry-sponsored study found that they can increase photosensitivity to the sun.