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Beta Hydroxy Acids
Throughout the last decade, alpha hydroxy acids (AHAs) have increasingly appeared as ingredients in cosmetics intended to reduce the signs of aging in the skin. More recently, beta hydroxy acids (BHAs), or a combination of AHAs and BHAs, have appeared as ingredients in these skin care products. While both AHAs and BHAs act as exfoliants, it has been claimed that BHAs are effective in reducing the appearance of fine lines and wrinkles, and improving overall skin texture, without the occasional irritation associated with the use of AHAs.
BHA ingredients may be listed as -
- salicylic acid (or related substances, such as salicylate, sodium salicylate, and willow extract)*
- beta hydroxybutanoic acid
- tropic acid
- trethocanic acid
Currently, the BHA most commonly used in cosmetics is salicylic acid. On rare occasions, citric acid is also cited as a BHA in cosmetic formulations. More commonly, citric acid is referred to as an AHA.
The safety of salicylic acid used as a cosmetic ingredient has been evaluated by both the cosmetic industry and FDA. At a meeting in February 2000, the Cosmetic Ingredient Review (CIR) Expert Panel, the cosmetic industry's independent body for reviewing the safety of cosmetic ingredients, reached the tentative conclusion that the use of salicylic acid related substances in cosmetics is "safe as used when formulated to avoid irritation and when formulated to avoid increased sun sensitivity." CIR added that "when sun sensitivity would be expected, directions for use [should] include the daily use of sun protection."
In other words, according to CIR Director Alan Andersen, products containing salicylic acid should either contain a sunscreen or bear directions advising consumers to use other sun protection. In order to comply with the CIR recommendations, cosmetic manufacturers should test their products to determine whether or not they cause an increase in sensitivity to the harmful ultraviolet radiation in sunlight.
The long-term safety of salicylic acid in cosmetics also is being evaluated in studies initiated by FDA and sponsored by the National Toxicology Program. These government-sponsored studies are examining the long-term effects of both glycolic acid (an AHA) and salicylic acid on the skin's response to ultraviolet (UV) light. These studies have determined that applying glycolic acid to the skin can make people more susceptible to the damaging effects of the sun, including sunburn.
Until these safety assessments are completed, FDA advises that similar precautions be taken for the use of cosmetics containing AHAs and BHAs. These precautions are:
- Test any product that contains a BHA on a small area of skin before applying it to a large area. If you use cosmetics with BHAs and experience skin irritation or prolonged stinging, stop using the product and consult your physician.
- Follow the use instructions on the label. Do not exceed the recommended applications.
- Avoid using BHA-containing products on infants and children.
- Use sun protection if you use a BHA product.
*From a chemist's perspective, salicylic acid is not a true BHA. However, cosmetic companies often refer to it as a BHA and, consequently, many consumers think of it as one.