Alpha hydroxy acid (AHA)

Alpha hydroxy acids are a class of organic acids used for chemical exfoliation in dermatology and cosmetic products. Their main mechanism is breaking down the cohesive bonds (often via calcium chelation) between dead skin cells in the outermost layer of the epidermis (stratum corneum), leading to desquamation and increased cell turnover. The family includes glycolic acid, lactic acid, citric acid, malic acid, and tartaric acid, which occur naturally in fruit, milk, and plants. AHAs are employed to improve rough skin texture, fine lines, hyperkeratosis, and superficial pigmentation disorders. They do not act via a traditional receptor, transporter, or enzyme but through direct chemical action on epidermal structural proteins and extracellular matrix components. Notable safety concerns include skin irritation and increased sensitivity to sunlight. AHAs are not molecular targets in the classic pharmacological sense—they are chemical effectors affecting the physical properties and adhesion of cells in the stratum corneum.

Other names

Alpha-hydroxy acidAHAsAHA family

Chelation of calcium ions in the epidermis, disrupting cadherins within desmosomes and attenuating cell adhesion, leading to corneocyte desquamation. Hydrolysis/breaking of intercellular bonds (especially corneodesmosomes) between keratinocytes in the stratum corneum, promoting exfoliation. Mild stimulation of cytokine release from keratinocytes, modulation of collagen synthesis.