Alpha Hydroxyacids

Alpha Hydroxyacids (AHA) are weak organic acids found in fruits, plants and milk sugars. Most researched forms, and commonly, widely used AHAs are primarily in the form of lactic acid and glycolic acid because they have a molecular size that allows effective penetration into the top layers of skin. For centuries, alpha hydroxyacids have been one of the most commonly utilized peeling agents used to treat dry skin, acne, actinic damage and to improve skin color/texture. At low concentrations AHAs promotes exfoliation by decreasing corneocyte cohesion and stimulating new growth in the basal layer, while at higher concentrations AHAs promote epidermolysis and dispersed basal layer melanin. Lactic acid and glycolic acid are AHAs derived from sour milk and sugarcane juice, respectively. Alpha-hydroxy acids have been shown to lighten melasma, solar lentigines, and postinflammatory hyperpigmentation. Glycolic acid which acts as exfoliant is used as an ingredient in skin-lightening products in low concentrations. It may also be used as a peeling agent in concentrations of 30-70% to increase the efficacy of other lightening agents such as hydroquinone by removal of the epidermis, thus enhancing the penetration of hydroquinone. Repeated peels every 2-3 weeks are necessary to attain significant lightening. In an Indian study of 40 patients with skin types III-IV with moderate-to-severe melasma, glycolic acid peels were used in addition to a modified Kligman hydroquinone formula in a 21-week open pilot study. Eighty percent of patients in the peel group noted excellent improvement, while only 60% of the control group had the same improvement.