Alpha Hydroxy Acids

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Alpha hydroxy acids


Alpha hydroxy acids (AHAs) are also referred to as fruit acids because they are compounds most often found in fruits. They are used cosmetically to improve the appearance of skin and to reduce age-related skin problems.

Description Alpha hydroxy acids are a groups of acids found in fruits and milk that share a certain chemical composition. AHAs are found in citrus fruits and in apples, grapes, strawberries, and sugar cane. Common examples of alpha hydroxy acids from fruits are malic acid, citric acid, and glycolic acid. An AHA found in milk is lactic acid. These names included on cosmetic labels indicate AHAs are present in the product.

These organic acids act by penetrating and disrupting the upper layer of skin and are used to encourage the shedding of the outer layer of dead skin cells from the surface of the skin. This process is also known as exfoliating. This process results in a more regular skin surface or reduction of fine lines and surface wrinkles . AHA are used to counteract the signs of aging on the skin.

AHAs became popular in the early 1990s and in the 2000s are found in an increasing number of cosmetic products, including lotions, sun blocks, peels, masks, and toners. Consumers should note both of their presence and their concentration in products they use. Used routinely at low concentrations, these products claim to improve the appearance of skin and can help to moisturize the skin. In higher concentrations, they are used as chemical peels that by dermatologists. Marketing claims for AHAs include their being able to improve acne, remove or decrease wrinkles, diminish excess pigmentation spots, moisturize, tighten the skin, repair sun damage, improve the underlying collagen and elastic tissues of the skin, and even remove viral warts and calluses. Scientific evidence proving these benefits, though, are inconclusive. Often anecdotal testamonials are employed, which may be exaggerated in advertizing. However, AHAs are known to act as mild to extreme exfoliants depending upon the dose.

AHAs are similar but not identical to beta hydroxy acids also used in cosmetics for reducing wrinkles. The main beta hydroxy acid used is salicylic acid. One big difference is that AHAs are water soluble and, therefore, must be delivered in a water soluble base, whereas beta hydroxy acids are oil soluble and are delivered in an oil base. Enzymes such as papain from papaya and bromelain from pineapple are also used in a similar manner for skin exfoliation.

Recommended dosage

Products containing AHAs fall into three dosage ranges. The lowest concentration products, which are typically marketed to consumers, contain less than 10 percent AHAs and have a pH of 3.5 or higher. They are used primarily as mild exfoliants and as moisturizers. concentration products have an AHA concentration from 20–30% and are used for a light peel. Products in this range are often used in salons by cosmetologists or aestheticians trained in their use. At this concentration, these products should not be used daily; however, weekly or biweekly use is considered safe. Products with concentrations of 30% and higher are intended only for use by trained dermatologists. This type is used as a chemical peel, and the likeliness of skin irritation is increased. Chemical peels may use products with concentrations as high as 70%. Consumers should remember that AHAs are considered cosmetics and not drugs. This category receives minimal safety oversight by the Food and Drug Administration (FDA) regarding marketing and proper dosing.


AHAs act by penetrating the skin and partially removing the outer layer of cells. This treatment decreases the normal protective function of the skin and can result in redness, swelling, burning, blistering, and even bleeding, rash, itching, and discoloration. The risk of side effects increases with increased concentrations of AHAs and increased frequency of their use. Therefore, higher concentration products should be used at no more than at 2 week intervals. Consumers should read the label or ask a dermatologist about how frequently a given product should be used. AHA products should never be used around the eyes due to possible inflammation. Increased sensitivity to the sun can occur following AHA, so consumers ought to use a good sunscreen and a wide-brimmed hat after a treatment. The Cosmetic, Toiletry, and Fragrance Association concluded that AHAs are safe in cosmetic products at concentrations equal to or less than 10% of the final product. It also stated that AHAs are safe for use by a trained professional at a concentration equal to or less than 30% when used for a brief time. AHAs are not recommended for children or infants. Individuals with rosacea ought not to use AHAs. All product labels should be read so consumers know if AHAs are included and if so at what strength.

Side effects

Documented side effects of AHA use includes skin irritation, stinging, blistering, and burning on the skin. Before using AHAs on the entire face, consumers should first try the product on a small area of skin to test for possible side effects. If adverse reactions occur, product use should be stopped immediately. One of the most alarming side effects of AHA use is increased sensitivity to the sun, which can lead to sunburn. Sunburn can actually increase the signs of skin aging, defeating the purpose of the product. A good sunscreen or sunblock should be used following AHA treatment. Higher concentrations of AHAs are more likely to cause side effects than lower concentrations. Because AHAs are not considered drugs, the FDA does not review them for safety before they are put on the market. Adverse reaction can, however, be reported to the FDA Office of Consumer Affairs.


Alpha hydroxy acids (AHAs) —Acids present in fruit and milk.

Beta hydroxy acids —Oil soluble acids, such as salicylic acid, used in cosmetics.

Papain —An enzyme derived from papaya used for skin exfoliation.


As of 2008, no known interactions between AHAs and other medications had been verified. People using exfoliating products such as Retin-A should not use AHAs simultaneously, and some physicians recommend that anyone who has used Accutane within the previous six months should not use AHAs. Consumers ought to consult their physician before using AHA peels.

Caregiver concerns Caregivers should look for signs of sensitivity after using an AHA containing product. These include redness, rash, or blistering of the skin. If any of these side effects occur, a physician should be consulted. Sun exposure should be avoided after AHA treatment. If this is not possible, sunscreen and a wide-brimmed hat should be worn outdoors following AHA treatment.



Gilchrest, Barbara A., and Jean Krutmann. Skin Aging. New York: Springer Berlin Heidelberg, 2006.

Goldberg, David J., and Eva M. Herriott. Secrets of Great Skin: The Definitive Guide to Anti-Aging Skin Care. New York: Innova, 2005.


Bruce, Suzanne. “Cosmeceuticals for the attenuation of extrinsic and intrinsic dermal aging (Drug overview).” Journal of Drugs in Dermatology 7, no. 2 (February 2008): 17(6).

Uitto, Jouni. “The role of elastin and collagen in cutaneous aging: intrinsic aging versus photoexposure (Disease/Disorder overview).

” Journal of Drugs in Dermatology 7, no. 2 (February 2008): 12(5).


American Academy of Dermatology, PO Box 4014, Schaumburg, IL, 60618-4014, 866-503-SKIN (7546), 847-240-1859, [email protected],

Dermatology Foundation, 1560 Sherman Ave., Suite 870, Evanston, IL, 60201-4808, (847) 328-2256, (847) 328-0509,

U.S. Department of Health & Human Services, 200 Independence Ave. SW, Washington, DC, 20201, (877) 696-6775,

Cindy L.A. Jones Ph.D.