Glycolic acid (hydroacetic acid or hydroxyacetic acid); chemical formula C2H4O3 (also written as HOCH2CO2H), is the smallest α-hydroxy acid (AHA). This colorless, odorless, and hygroscopic crystalline solid is highly soluble in water. It is used in various skin-care products. It is found in some sugar-crops. A glycolate or glycollate is a salt or ester of glycolic acid.

Applications

Glycolic acid is used in the textile industry as a dying and tanning agent, in food processing as a flavoring agent and as a preservative, and in the pharmaceutical industry as a skin care agent. It is also used in adhesives and plastics. It is often included into emulsion polymers, solvents and additives for ink and paints in order to improve flow properties and impart gloss. It is used in surface treatment products that increase the coefficient of friction on tile flooring.

Skin care

Due to its excellent capability to penetrate the skin, it finds applications in skin care products, most often as a chemical peel performed by a dermatologist in concentrations of 20 to 70% or at-home kits in lower concentrations between 10 and 20%. In addition to concentration, pH also plays a large part in determining the potency of glycolic acid in solution.

Physician-strength peels can have a pH as low as 0.6 (strong enough to completely keratolyze the epidermis), while acidities for home peels can be as high as 2.5.

It is used to improve the skin's appearance and texture. It may reduce wrinkles, acne scarring, hyperpigmentation and improve many other skin conditions, including actinic keratosis, hyperkeratosis, and seborrheic keratosis. Once applied, glycolic acid reacts with the upper layer of the epidermis, weakening the binding properties of the lipids that hold the dead skin cells together. This allows the stratum corneum to be exfoliated, exposing live skin cells. Highly purified grades of glycolic acid are commercially available for personal care applications.