Alpha–hydroxy is a chemical compound derived from fruit and milk sugars. Alpha–hydroxy acids (AHAs) are used in topical skin care products to exfoliate, or slough away, dead skin cells and promote collagen growth.
AHAs work by removing dead cells at the surface of the skin. In higher concentrations, alpha hydroxy promotes collagen production, which may reduce the appearance of fine lines and wrinkles in the skin. The acids penetrate deep into the skin, where they actually begin to damage skin cells. This skin damage triggers the production of collagen, a fibrous protein and a building block of tissue and skin, as the body attempts to repair the cell damage.
AHAs are available in a number of different synthetic and natural formulations. Lactic AHA is derived from milk products, while glycolic AHA is derived from sugarcane. Other AHA compounds include citric acid derived from citrus fruit, malic acid derived from apples, and tartaric acid derived from grapes
AHA may be an ingredient in over–the–counter products such as creams, lotions, and moisturizers that are marketed for their supposed anti–aging properties. They may be useful in promoting smoother, more even–toned skin and may reduce the appearance of wrinkles and fine lines in some individuals. Products containing AHA may be used to treat acne, age spots, and other irregular skin pigmentations. Products containing AHA are used to smooth fine lines and surface wrinkles, unblock or open pores, and improve overall skin appearance and conditions, including acne and oily skin.
Over–the counter products generally have an AHA concentration of 10% or less. AHA may also be used in chemical peels used to treat skin conditions such as wrinkles, acne, scarring, and oily skin. The concentration of AHA products used by trained cosmetologists may run between 20% and 30%, while those used by doctors may range from 50% to 70%.
AHA preparations are available in over–the–counter and prescription products, including gel, lotion, toner, and cream formulations. The United States Food and Drug Administration (FDA) regulates these products as cosmetics, so the products do not undergo the rigorous testing for safety and effectiveness that is required for pharmaceutical drugs. However, the FDA does become involved when it appears that cosmetics may contain ingredients that are harmful to humans.
A report linking AHA usage to increased sensitivity to the sun’s ultraviolet (UV) rays was sponsored by the Cosmetic, Toiletry, and Fragrance Association. In December 1996, the Association’s cosmetic ingredient review panel reported on AHA studies that had started in 1994. The panel stated that over–the–counter products containing AHAs were safe when the alpha–hydroxy concentration was 10% or less. However, the safety depended on the product having a formulation of pH of 3.5 or greater. A lower pH number designates more acidity, which could increase the skin’s sensitivity to the sun. On products with a lower pH, the product directions should include use of sun protection every day. Furthermore, the report stated that salon products were safe if the AHA concentrations were less than or equal to 30%. Safety was based on a pH level of 3.0 or higher.
Moreover, the FDA’s Office of Women’s Health sponsored two studies in 2000 that affirmed the connection between AHA and increased sensitivity to the sun. However, that sensitivity diminished soon after a person stopped using products with AHA. In 2002, the FDA required that manufacturers label products containing AHAs with a warning that the acids may
increase the risk of sunburn.
Between 1992 and 2004, the FDA received a total of 114 reports of people experiencing adverse results from using skin care products containing AHA. The most common complaint was burning, followed by dermatitis or rash, swelling, pigmentary changes, blisters or welts, skin peeling, itching, chemical burns, and increased susceptibility to sunburn. In 2005, the FDA
issued the report, Guidance for Industry: Labeling of Cosmetics Containing Alpha Hydroxy Acids as Ingredients. This report recommended that products containing AHA should be labeled with a sunburn alert to warn consumers about the increased sensitivity to sun that the product may cause.
Selecting AHA products
The manufacturer is not required to list the strength of AHA on the package labeling. However, product ingredients must be listed sequentially in the order of highest concentration, so products that list AHA compounds second or third are usually more beneficial than those who list them in the middle and toward the end of the ingredient list.
Depending on their skin type, certain individuals may find some carrier formulas (i.e., cream, gel, lotion, toner) more effective than others. Those with dry skin may find moisturizing AHA creams and lotions more effective, while individuals with oily skin may prefer a less oily toner or gel.
Individuals who are considering using AHA products for the first time may want to start with a low AHA concentration. It is important to perform a skin–patch test to check for skin sensitivity to the substance. A small, dime–sized drop of the AHA product should be applied to a patch of skin inside
the elbow or wrist. The skin patch should be monitored for 24 hours to ensure no excessive or unusual redness, swelling, blistering, or rash occurs. If a reaction does occur, the test may be repeated with an AHA product with a lower alpha–hydroxy acid concentration. Individuals who experience a severe reaction to a skin patch test of AHA are advised not to use the product. A dermatologist or other healthcare professional may be able to recommend a suitable alternative.
Individuals who are prescribed AHA formulations by a healthcare professional should follow their doctor’s directions for use of the product.
People should carefully read the labels of products containing AHA products that conform to the Cosmetic Ingredient Review guidelines of 10% or less AHA and with a pH of 3.5 or higher.
AHA products increase sun sensitivity. Individuals using AHA products should use a sunscreen with an SPF (sun protection factor) of at least 15 to protect against burning. Sunscreen should be applied no less than 15 minutes after the AHA formula is applied to prevent neutralizing the acids. Shading the face with a wide–brimmed hat may also be useful.
Exfoliative products should be used with care, as over–exfoliation could cause damage to the skin. AHA products should not be combined with other exfoliative products such as facial scrubs, buff pads, or loofahs. In addition, individuals should only use one AHA product at a time.
Higher concentration prescription AHA products have a great likelihood of producing side effects, so individuals taking them should contact their healthcare provider immediately if they experience burning, redness, or any other negative reaction to the product.
Individuals who experience adverse reactions to AHA treatments should report them to both the manufacturer of the product and to the FDA’s Office of Consumer Affairs. A patient’s dermatologist or healthcare provider may also make this report anonymously for the patient. Although these products do not require FDA approval for market release, the FDA is responsible for monitoring their safety and may initiate a product recall or removal of a specific brand or formulation if enough adverse effects occur to make these steps necessary.
AHA chemical peels and other high concentration AHA treatments should only be administered by a licensed cosmetologist, licensed dermatologist, or
other qualified healthcare professional.
The major side effect of using products containing alpha–hydroxy acids is increased sensitivity to the sun’s UV rays. This heightened sensitivity may increase the risk of sunburn. People may also experience mild skin irritation. In some cases, products with AHA may cause burning, a rash, or redness. Because of these reactions, it is very important for people to read the directions and warnings on the package before using a product. Individuals should do a skin–patch test and then use the product sparingly until they know whether or not it causes side effects.
As of April 2013, there were no known interactions between alpha–hydroxy acid products and other medications and substances when these were administered in recommended strengths. However, because over–the–counter AHA products are considered cosmetics and not pharmaceuticals, existing research on possible interactions has thus far been minimal. Furthermore, alpha–hydroxy products may enhance the effects of other products or medications with similar therapeutic properties.