Ahas

AHAs, or alpha hydroxy acids, are a class of water-soluble organic acids used primarily in skincare and cosmetics for chemical exfoliation. They occur naturally in some foods and fruit-derived ingredients and include glycolic acid (from sugar cane), lactic acid (from milk), mandelic acid (from almonds), and, less commonly, citric, malic, and tartaric acids. As exfoliants, they help loosen the links between dead cells in the stratum corneum, promoting desquamation and accelerated skin turnover.

Glycolic acid has the smallest molecule and penetrates most deeply; lactic acid is often more moisturizing; mandelic acid is gentler due to a larger molecular size; citric, malic, and tartaric acids can be more irritating in higher concentrations but contribute antioxidant effects and additional exfoliation.

In cosmetics, AHAs are used to treat signs of aging, hyperpigmentation, rough texture, and certain forms of acne. They are often formulated in products at 5-20% with pH around 3-4 for at-home use; professional or medical-grade peels use higher concentrations and lower pH with clinician supervision.

Safety and use: AHAs increase photosensitivity, so daily sunscreen is essential. Start with lower concentrations and shorter exposure, and gradually increase if tolerated. Do not apply on broken skin or open wounds; be cautious when using with other actives such as retinoids or benzoyl peroxide; those with sensitive skin or certain skin conditions should consult a dermatologist prior to use. Mild redness and tingling are common; more severe reactions may indicate irritation or allergy.

AHAs are distinct from other exfoliants such as beta hydroxy acids (BHAs). They are widely used in moisturizers, toners, serums, and chemical peels, and consumer guidance emphasizes using products appropriate for one's skin type and sensitivity.