Poly Hydroxy Acids (PHAs)

Poly hydroxy acids (PHAs) are a group of gentle exfoliating acids often described as a milder relative of AHAs. The best known examples are gluconolactone and lactobionic acid.

Like AHAs, PHAs help loosen dead cells at the skin surface to promote smoother, brighter-looking skin. Their molecules are larger than those of typical AHAs such as glycolic acid, so they penetrate more slowly and tend to be less irritating. Many PHAs also have humectant properties, meaning they can help attract and hold water in the skin, and some are described as having antioxidant activity.

These features make PHAs a common choice for sensitive, reactive, or dry skin, and for anyone who finds stronger acids too harsh. They are frequently used in leave-on and rinse-off products designed for gentle, gradual exfoliation.

PHAs are generally well tolerated, but as with any exfoliating acid they can still cause irritation if overused or combined with too many other actives. Daily sunscreen remains advisable while using any exfoliant.