The questions below have been answered by renowned Dermatologist, Dr. Nelson Lee Novick, New York, NY.

What are Alpha Hydroxy Acids?

Alpha hydroxy acids or AHAs belong to a group of natural compounds called "fruit acids" found in fruits and other foods. Common AHAs include lactic acid found in sour milk, citric acid from citrus fruits and glycolic acid derived from sugar cane. Glycolic acid is the AHA most frequently used in products for improving skin appearance and function.

What can AHAs do for my skin?

On the surface they promote exfoliation, the removal of dead skin cells. AHAs are excellent moisturizers; they draw water from lower levels of the skin to promote suppleness. AHAs also function as antioxidants to protect from damaging free radicals caused by excessive sun-exposure, smoking and stress. Finally, there is growing evidence that they not only stimulate collagen production, but help plump up collagen and elastin fibers within the skin.

Why do you recommend the use of glycolic acid products over those containing other AHA's?

Glycolic acid has the smallest molecular size of all AHAs to best penetrate the topmost protective layer of the skin. Because it also possesses the smallest molecular weight, glycolic acid formulations contain more molecules than products containing other AHAs.

For what types of conditions can I use glycolic acid preparations?

Glycolic acid cleansers, creams, lotions, and toners are effective in a wide variety of troubling skin, hair, and nail conditions. These include moisturizing dry, flaking skin; treating excessive oilyness, clogged pores and acne; softening fine lines and wrinkles; lightening skin discoloration; managing shaving bumps, folliculitis, ingrown hair, and improving dry or brittle nails.

There's an array of AHA products on the market. How can I choose the best one for me?

Higher concentrations of glycolic acid tend to be more effective — choose those that contain at least a ten percent concentration. Because lower pH often leads to a greater potential for skin irritation with repeated use, look for products with an acid-base balance close to your skin's normal pH. Partially neutralized formulations with a pH of 4.0 to 4.5 are ideal for most purposes — they're effective, without being irritating.

Glycolic acid products come as cleansers, lotions and creams. How do I know which type of glycolic formulation to use?

This answer depends on the problem needing treatment. Simple guidelines: For dry skin problems known as xerosis, or flakiness of the face and neck, I recommend the use of glycolic acid facial cleanser twice daily followed by a pH-balanced, high concentration glycolic acid face cream, also used twice daily. To minimize irritation, cleanse with fingertips and apply cream sparingly. This same regimen also helps reduce fine lines and even out skin discoloration.

For less delicate skin, follow cleansing with a body lotion containing a slightly higher concentration of glycolic acid. This regimen may also help reduce inflammation of the hair follicles, a condition known as folliculitis.

For oily and acne prone skin, use of a glycolic acid toner during the day helps reduce facial shine and unclog pores. It may also soften inflamed, ingrown hairs which can result from shaving.

Flaky scalps can often benefit from glycolic acid shampoo used two to three times weekly, left on for at least three minutes before rinsing.

Dry or brittle nails can be alleviated by applying a high concentration of glycolic body lotion directly to the nails after soaking them nightly in warm water for five minutes.

These are merely general guidelines for dealing with certain common conditions. For any specific questions and problems, please consult a skin specialist.

Can I use AHAs along with my regular cosmetics or sunscreens?

Absolutely. Often the softness and smoothness that results from AHAs will make cosmetic application more smooth and even. Sunscreens may also be applied easily after AHAs. There is some research to suggest that AHAs may actually help suppress sun-induced redness following ultraviolet exposure. In general, it is best to wait a few minutes after applying AHA products before applying makeup or sunscreens.

At what age is it safe to use AHAs?

There are no age restrictions for using AHAs. I have found them safe for all age groups, including young children and seniors.