Gluconolactone & PHAs

Polyhydroxy acids, or PHAs, are exfoliating acids with multiple hydroxyl groups. Gluconolactone is the best-known example and gradually converts to gluconic acid in water-based formulas; lactobionic acid is another PHA. Their larger, highly water-binding structures often produce a slower, gentler-feeling exfoliation than glycolic acid, although pH, concentration, and the complete formula still determine activity.

Gluconolactone and related PHAs are used in toners, serums, creams, cleansers, masks, and professional peels to soften surface buildup and support hydration. Small human studies have reported improvements in hydration, transepidermal water loss, and skin pH after specific gluconolactone treatments. Those findings should not be stretched into a promise that every PHA formula is irritation-free.

They may appeal to dry, sensitive-feeling, or first-time acid users who want smoother texture with a more cushioned feel. Experienced exfoliant users may also enjoy PHAs between stronger treatment nights.

PHAs pair well with glycerin, hyaluronic acid, panthenol, ceramides, niacinamide, and soothing emollients. They can share a broader routine with retinoids or other acids, but alternating use is often more comfortable than layering several exfoliants at once.