Beta hydroxy acids are a group of acids whose skin treatment properties are being rediscovered. Developed long ago for acne treatment, salicylic acid, benzoic acid, butyric acid and other less well known acids have been recently reclassified as beta hydroxy acids (BHAs) or beta hydroxys.
BHAs are exfoliants, which means that they cause the top layers of the skin to exfoliate or peel. Exfoliation leaves behind fresh skin that is also smoother and softer than before. Beta hydroxys work by speeding up the turnover of skin cells. They dissolve the glue that holds dead skin cells in the top layers, allowing the fresh cells beneath to emerge. Chemical exfoliation with beta hydroxys peels away a variety of such age-related skin problems as wrinkles, acne, age spots, blemishes, and skin unevenness. Used on a regular basis at a much lower concentration as cleansers or acne treatments, BHAs refresh the skin and clear away the dirt and oils that often cause acne eruptions. In addition to cosmetic applications, these chemicals also are used as treatments for a variety of skin disorders, including psoriasis , seborrhea, dandruff , and warts .
BHAs are found in many skin care products. They are also found naturally in fresh fruit (berries, pineapple, papaya, etc.), milk and yogurt, wintergreen leaves, sweet birch, and some other plants.
Structurally, BHAs appear to be very similar to another group of chemicals used in skin care products, the alpha hydroxy acids or AHAs. These two groups of chemicals have similar activities as well; both are skin exfoliants. BHAs, however, are believed to be less irritating to the skin than AHAs. They are also more effective in preventing acne eruptions and smoothing the skin.
Many skin cleansers today contain BHAs. BHAs are effective because they help remove excess oil from the face. They can, however, remove oil only on the surface and cannot affect oil production under the skin. To help maintain healthy skin, these cleansers should be used once or twice a week to improve skin tone and texture. BHA-containing preparations should be left on the face for a short time only and rinsed off with generous amounts of water . Because the skin is more sensitive to sunlight after the use of products containing BHAs, users should apply sunscreens and avoid prolonged sun exposure.
Wrinkles and age spots
Wrinkles are signs of the normal aging process. Over the years, the skin becomes thinner, drier and less elastic as its collagen and elastin fibers gradually lose their elasticity. To improve the appearance of the skin and to correct minor blemishes and uneveness, some people have chemical peels with hydroxy acids. Chemical peels have become one of the most popular methods for removing wrinkles. This process uses concentrated preparations of BHAs, AHAs, or combinations of both to remove the top layer of skin. The chemical peel allows a newer layer of skin to replace the older layer. Some fine lines and wrinkles may also be removed.
Because of potential scarring and other severe adverse reactions, chemical peels are done by a professional, usually a board-certified dermatologist or a licensed estheticist (skin care specialist).
For best results, chemical peels are often used in combination with such other anti-wrinkle treatments as collagen or fat implants or laser surgery. For relatively young people, a chemical peel with BHA often provides satisfactory results. Those over 40 sometimes choose to have collagen or fat implants together with the peel. Some older patients may have both a chemical peel and a special kind of laser surgery called laser resurfacing. While chemical peels can remove some fine wrinkle lines, laser resurfacing is a more powerful tool. It can remove deeper wrinkles and skin imperfections.
Acne is a skin disorder caused by excessive production of oil under the uppermost layers of skin. When the oil cannot pass through the hair follicles, the pores under the skin are plugged up, trapping the oil and dead skin cells underneath the skin. These plugged pores become fertile breeding grounds for a type of bacterium called Propionibacterium acnes, sometimes called the acne bacillus, to grow inside the pore, causing irritation, inflammation, and in due time, pimples.
Because it is an effective cleanser, a 1% solution of salicylic acid, which is a BHA, can enter the pores and help to remove excess oil, dirt, and dead skin cells. It reduces skin breakouts by preventing the buildup of dead skin cells associated with acne formation. Beta hydroxy acids, including salicylic acid, are good treatments for acne because they are relatively mild. Because they are applied topically, they do not cause systemic side effects as oral antibiotics sometimes do. In addition, they are especially appropriate for the treatment of acne because they have anti-inflammatory properties. BHAs, however, do not have the antimicrobial properties of such topical medications as benzyl peroxide.
Psoriasis is a chronic skin condition requiring lifelong treatment with topical lotions and creams, phototherapy (using radiation or ultraviolet light), or medications taken by mouth. Salicylic acid can be used to treat psoriasis. Salicylic acid facilitates the removal of scaly skin. In so doing, it helps moisturizers and other topical medications for psoriasis work more effectively.
Salicylic acid is also an effective and mild treatment for warts and plantar warts. Patients should wash and dry the area around the wart thoroughly before applying the product. Then they should apply a thin film of salicylic acid over each wart and allow it to dry. The product should be applied once or twice a day. Salicylic acid acts slowly and may take as long as 12 weeks before one can see results.
The anti-inflammatory properties of BHAs are useful in treating such other skin conditions as dandruff or seborrheic dermatitis .
Salicylic acid is often found in many over-thecounter skin care products such as soaps, cleansers, acne medications, and anti-wrinkle creams. These products, however, contain only 2% of salicylic acid. This concentration is strong enough for exfoliation but not for chemical peel treatment.
Chemical peel preparations contain very high concentrations (up to 30%) of beta hydroxy acids in combination with alpha hydroxy acids. Because of the potential for scarring and other severe adverse reactions, these prescription-strength products are not sold to the general public. They are available only to licensed dermatologists or estheticians.
BHAs can also be found in certain fruits and vegetables. For example, thin layers of papaya can be applied on the face and allowed to remain for a while. Papaya pulp helps soften the skin and decrease its unevenness. It is most beneficial to dry, sun-damaged skin, although it may also cause allergic reactions in some sensitive people. Pineapple is another natural product that contains beta hydroxy acid. Pineapple can be put into a blender or juicer to obtain fresh juice. The juice can be applied to the skin; again, however, it may cause allergic reactions.
People who use skin care products containing BHAs should be aware of the following considerations and side effects:
- Increased sensitivity to sunlight. Exfoliated skin is very tender and sensitive to sunlight. Studies have shown that skin treated with these exfoliants has twice the sun damage compared to untreated skin. Therefore, it is important to use suncreen and avoid direct exposure to the sun when using products containing BHAs.
- Sensitization to other products. The use of salicylic acid sometimes sensitizes the skin to other cosmetics and causes redness and irritation. In other to avoid skin sensitization, it is best to use only mild cleansers and wait at least 10–30 minutes before using another cosmetic or skin care product. Another way to avoid skin sensitization is to use the BHA product every other day instead of daily.
- Stinging. Salicylic acid can produce a stinging sensation when first applied. That is because it is a mild skin irritant. Products containing salicylic acid should not be applied on raw or abraded skin, as they may cause redness and intense itching.
- Allergic reactions. Some salicylic acid products can provoke hypersensitivity reactions. Any products that cause skin to burn, sting, redden, or break out should be discontinued immediately.
- Blotchy skin. Sometimes BHA chemical peels cause scarring and discoloration of some parts of the skin. This occurs most often with the more concentrated BHA products. Scarring and blotchy skin also tend to occur more frequently in people with darker skin.
- Dry skin. A person with dry skin should not use BHA cleansers too frequently (more than once a week) because they tend to dry the skin even further.
- Eye irritation. Skin care products containing salicylic acid tend to cause the eyes to redden and water. Avoid applying these cleansers, cream or lotion too close to the eyes.
Patients should stop using the product and contact their doctors or pharmacists for advice if the following adverse effects occur:
- dry skin
- eye irritation
- allergic reactions
- skin irritation
Because salicylic acid tends to sensitize the skin, allow at least 10–30 minutes to elapse between the use of products containing salicylic acid and applying cosmetics or other skin care products.
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American Academy of Dermatology. P.O. Box 4014. Schaumburg, IL 60168-4014. (888) 462-DERM. Fax: (847) 330-8907. <http://www.aad.org>.
Samuel Uretsky, Pharm.D.