Alpha hydroxy is a familiar name to those seeking youthful skin; it is one in a long line of wonder ingredients in cosmetics and skin care products. It is an entire family of acids that can be derived from fruit, milk or sugar. The most widely used in skin care is glycolic acid (made from sugar) and lactic acid (made from milk). They are also called fruit or citric acids; women have been using lemon juice for "bleaching" freckles for centuries. Surprisingly, to those hardened by years of over-hyped product claims, alpha hydroxy acid (AHA) does do what it claims it will.
The way alpha hydroxy works is by exfoliating the skin; that is, causing the surface skin cells to slough off, revealing newer, less damaged skin cells beneath. This can be done in a dermatologist's office, using a high concentration of acid, in which case it is known as a chemical peel. Lower concentrations applied over a longer period of time have a similar effect, but can take weeks or longer for the effects to appear.
Since alpha hydroxy is an acid, it may irritate the skin, leaving it red, itchy or painful. In commercial, over-the-counter preparations, this acid should be in concentrations of less than 10%. Its long-term use also appears to leave the user more sensitive to UV light and therefore more prone to sunburn. The US Food and Drug Administration warns that users should be sure to wear wide brimmed hats or strong sunscreen when outdoors to prevent them from re-damaging the skin they have gone to such lengths to repair.
A recent competitor to AHA is its close kin, beta hydroxy acid (BHA). Unlike alpha hydroxy, there is only one beta hydroxy acid, salicylic acid. Derived from the same acid as aspirin (acetylsalicylic acid), beta hydroxy shares some of its anti-inflammatory properties, is less irritating to most skin types, and can work at much lower concentrations. Unfortunately, it too makes the user more susceptible to sun-damage.
When shopping for skincare products, consumers should look for AHA, BHA, glycolic acid, lactic acid, or salicylic acid in the listed ingredients. They should be in products that stay on the skin, since they must be absorbed to be effective. Users should always remember to wear sunscreen.