Commonly found in fruit and milk sugars, alpha hydroxy acids have been used for centuries to treat wrinkles and rejuvenate skin. Some even suggest that Cleopatra bathed in sour milk, using the lactic acid to improve the appearance of her skin. If she did, apparently she had some insight others in her time did not, as alpha hydroxy acids can now be found in a number of skin care moisturizers, toners, masks, and cleansers.
Some forms are especially geared to penetrate the skin, and some have even been clinically proven to have a positive effect over others. The most common and popular types include: glycolic acid, lactic acid, malic acid, citric acid, and tartaric acid. It works largely as an exfoliant, allowing dead skin cells to fall of the skin and new skin cells to better breath and develop. It may even help the skin to produce more collagen and elastin, thereby accelerating its healing process. By using these mechanisms of action, alpha hydroxy acids may improve the appearance of wrinkles as well as roughness and discoloration. It is generally recognized to be most useful in concentrations of 5%-8%.
However, like most other powerful wrinkle fighting ingredients, alpha hydroxy acids are known to cause some side effects. Like retinol, it is known to sometimes cause irritation and higher sensitivity to sunlight. In short, while it may reduce some of the damage caused by sunlight, it may also make you more sensitive to sunlight, introducing a kind of oxymoron. Therefore, if you are going to use alpha hydroxy acids, it would be advisable to use a good sunscreen.
Because of these side effects, the FDA has mandated that alpha hydroxy acids only be used in concentrations of 10% or less. In addition, they are required to have a pH level of at least 3.5, and any product using it is required to also have a sunscreen. However, with these guidelines, you should look for products containing AHA’s with the exception of cleansers. Alpha hydroxy acids work in part by absorbing themselves into the skin. If you use a cleanser, it is washed off within minutes, not giving the elements nearly enough time to soak in. However, with a moisturizer or mask, it is allowed to sit for an extended period of time.