Alpha-hydroxy acids are chemicals derived from various types of sugar. Skin care product manufacturers include these ingredients for the purpose of desquamation, more commonly known as exfoliation. Many skin rejuvenation and acne treatment products contain alpha hydroxy acids. The extent of desquamation depends on the amount of alpha hydroxy acid included.
Function
Alpha hydroxy acids slough away dead skin cells that accumulate on the skin surface. These cells usually flake off every month or so, but excessively oily skin can prevent this, and so can aging skin. A build-up of dead skin cells can clog pores and cause them to be enlarged. The cells also make fine lines more noticeable and lead to rougher skin texture. Removal of dead skin cells allows smooth new cells to surface and stimulates healthy new skin growth, as explained by the University of Maryland Medical Center (UMMC). It stimulates production of collagen and elastin, and smooths skin texture.
Types
The most widely used alpha hydroxy acids in skin care are glycolic acid, derived from sugarcane, and lactic acid from milk, according to the U.S. Food and Drug Administration (FDA). They are included in various products, and people also may use glycolic acid peels in differing strengths. Other alpha hydroxy acids include citric acid, hydroxycaprylic acid and hydroxycapric acid.
Expert Insight
Treatment with alpha hydroxy acids has significant benefits, as explained by a pilot study of alpha hydroxy acids published in the February 1996 Journal of the American Academy of Dermatology. These acids significantly reverse photoaging, or damage caused by exposure to ultraviolet light over many years. Study participants experienced increased skin thickness, improved elasticity and increased collagen density.
Strengths
Some alpha hydroxy acid products contain relatively high concentrations of the substance. They are marketed as "skin peelers" because they remove the upper layers of the skin. Glycolic acid peels also remove the upper layers of the skin. Lower-strength glycolic acid peels are available for home use, while higher-strength "chemical peels" are typically performed in a dermatologist's office. Products containing lower amounts of alpha hydroxy acids also help slough away dead skin cells, but effects can be more subtle and take longer to appear.
Considerations
Higher-strength alpha hydroxy acid products can cause severe skin irritation, including rash, swelling, blistering, burning sensations and itching. The more serious reactions appear to be most likely with products that cause the greatest amount of desquamation, according to the FDA. Over-the-counter products usually have 10 percent strength or less alpha hydroxy acid. Long-term use appears to make the user more sensitive to ultraviolet light and more prone to sunburn.
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