Alpha hydroxy acids, or AHAs, are a category of organic compounds consisting of a fatty acid substituted with an alkali on the next carbon with an amino group attached at the two or three carbons. They can be naturally occurring or artificial. AHAs have been used for decades to remove surface stains and brown spots from the skin. They have recently gained popularity as an alternative to chemical peels and dermabrasion. The peel method is also known as abrasive chemical exfoliation. Glycolic acid is one of the most commonly used AHAs and is found in many creams, facial cleansers, and soaps.
Common complaints from those using AHAs include redness, burning, stinging, dryness, itching, irritation, and “coarse” hair and skin texture. AHAs work by peeling the top layer of skin (the one with the topmost dead cells) and exposing healthier skin beneath it. The peeling action causes the top layer of dead cells to break off and flake off. The new skin underneath is more sensitive and can produce more allergic or inflammatory reactions than the surrounding skin. Because of this, it’s important to use an alpha hydroxy acid skin care product with a sufficient concentration to not only get rid of the unwanted layer but to also refresh and hydrate the skin.
Among the types of AHAs available, three in particular have become very popular in recent years. They include alpha hydroxy acids derived from citrus fruits, milk, and wine; glycolic acid derived from milk and wine; and lactic acid derived from milk and honey. AHAs in these form tend to be less potent than their gel counterparts and are therefore less likely to cause serious allergic reactions, although there may be some people who are allergic to some of the ingredients used in AHAs. Before using any type of AHA as part of your skin care routine, it’s a good idea to consult with your physician and cosmetic dermatologist.
Of the three AHAs mentioned, the most well-known and frequently prescribed AHAs for use on patients with moderate to severe acne problems are glycolic and lactic acid. According to many skin care experts and dermatologists, both of these acids are best used in conjunction with another type of AHA. That other type of AHA is the beta hydroxy acid. According to says nussbaum, who also serves as a dermatologist and science writer for Consumer Reports, the majority of people with acne do not respond well to the use of alpha hydroxy acid. In addition, he says, the acidic nature of the beta hydroxy acid can cause redness, irritation, and burning in some people.
That said, says nussba, who also writes for the Los Angeles Times, “glycolic acid is a terrific skin treatment. It is gentle, fast acting, and inexpensive. Glycolic acid also fades scars and blemishes, and can be applied at home.” As far as other types of AHAs, he continues, “glycolic acid is just about the most popular. There are other types, including the traditional salicylic acid, but it is the easiest to use, cheapest, and most effective.”
According to a March 2020 issue of Dermatology, the only time that AHAs should be used by themselves is under special circumstances. One of those circumstances is when a patient has a very low blood count, in which case a very high concentration of AHAs could potentially cause a serious adverse reaction. Another is when a patient is allergic to one or more of the ingredients used to formulate the AHAs. In those cases, he says, the cosmetic manufacturer should use a sunscreen that contains an alpha hydroxy acid. The sunscreen might also need to be formulated with a copper peptides concentration that’s lower than 2.5%, in order to prevent a reaction. The cosmetic manufacturer might also want to use a copper-zinc combination instead of a copper peptides concentration, and use a sunscreen containing at least 10% zinc to protect the skin from the sun when it’s exposed to sunlight for long periods of time.