Skin Reaction to Alpha Hydroxy

The use of alpha hydroxy acids (AHAs) for skin rejuvenation and anti-aging purposes can be traced as far back as ancient Egypt, when Cleopatra soaked in milk baths to keep her skin soft and smooth. Once exclusively available through dermatologists, AHAs are now used as the major active ingredient in many anti-aging skin-care products. The mass marketing of such products expanded in the mid-1990s, after cosmetics companies were authorized to use low concentrations of the chemical product to correct and combat signs of aging in the skin.

Function

AHAs work to rejuvenate and restore the skin by expediting its natural exfoliation process. The old, dead cells of the skin's outermost layer are loosened and shed, revealing a new, more evenly toned layer of skin. AHAs also work to correct the signs of aging skin by diminishing hyper-pigmentation, commonly in the form of age spots and liver spots caused by sun exposure. The regeneration of new skin cells and stimulation of collagen also helps reduce fine lines and wrinkles.

Types of AHAs

Glycolic acid and lactic acid are the most common AHAs used in anti-aging skin-care products. Glycolic acid, extracted from sugar cane, is the stronger of the two. Used as the major ingredient in chemical peels, glycolic acid is able to penetrate the skin and produce rapid effects on the skin's texture and overall appearance. While dermatologists are authorized to use concentrations of 20 to 70 percent, glycolic-acid concentrations in retail products are usually no more than 10 percent. Potency is determined by both the concentration and pH level (acidity).

Found in milk, lactic acid also functions as an anti-aging exfoliating agent for the skin, shedding old skin cells and promoting cell rejuvenation. This form of AHA is gentler than glycolic acid, and therefore more ideal for sensitive skin. Lactic acid also acts as a humectant, softening and hydrating the skin. Citric acid, malic acid and tartaric acid (each found in fruits) are other examples of AHAs. "Bleaching" freckles, moles and age spots with citrus fruits is a centuries-old home remedy.

Effects on the Skin

Your skin condition, the concentration and pH level of the chemical you use, and the frequency of application are all factors that determine how your skin responds to AHAs. Chemical peels produce dramatic effects, as high AHA concentrations are used by dermatologists, diminishing the appearance of age spots, fine lines and wrinkles, scars or stretch marks more rapidly than retail products. At-home skin care products have lower levels of AHA concentration, requiring continual and consistent application in order to produce visible effects beyond just improved complexion and skin tone. With regard to the pH levels of AHAs, the ideal level for home use is a pH of 3.5 or higher; the lower the pH number, the higher the acidity.

Warnings

Remember the chemical power of AHAs. They are acids, and acids have the power to irritate the skin. Always test products on a small patch of skin first, as adverse reactions to AHAs are not infrequent. Stinging, itchiness and redness are undesirable skin reactions, and sometimes occur after chemical peels. Although chemical peels are now sold for home use, be extremely cautious and consult with a dermatologist before using them. Also keep in mind that the visible, more youthful results achieved by the use of AHAs leaves the skin significantly more sensitive to UV rays, so it is more crucial than ever to protect yourself with a product with SPF 30 or higher.

Expert Insight

AHAs, BHA (beta hydroxy acid, salicylic acid) and retinoids are the most sought-after skin-care ingredients. However, they should not be used together. According to Dr. Leslie Baumann, chief of the cosmetic-dermatology department at the University of Miami's School of Medicine, retinoids mixed with AHAs and BHA result in ineffective retinoids. Dr. Baumann recommends using retinoids at night, and using AHA and/or BHA skin-care products only in the morning, as part of a skin-care regimen that ends with applying a strong SPF cream or lotion.

References

• SkinTypeSolutions.com - About Dr. Baumann
• "Alpha Hydroxy Skin Care: Smooth Sailing or Rough Seas?" US FDA; 1999