How PHAs Differ Mechanistically
How PHAs Differ Mechanistically — polyhydroxy acids, such as gluconolactone and lactobionic acid, that exfoliate much like AHAs but carry larger molecules with multiple hydroxyl groups. Their bigger size means they penetrate the skin more slowly and superficially, which tends to make them gentler and less likely to irritate sensitive skin. The added hydroxyl groups also give them humectant and antioxidant-like qualities that AHAs largely lack.
Key points
- PHAs loosen surface cell adhesion to exfoliate, similar to AHAs but at a slower pace.
- Their larger molecular size limits penetration depth, generally reducing stinging and irritation.
- Multiple hydroxyl groups let them attract water, giving a humectant, hydrating effect.
- Some PHAs like lactobionic acid also show antioxidant and metal-chelating properties.
Frequently asked
Are PHAs better than AHAs for sensitive skin?
PHAs are often better tolerated because their larger molecules penetrate more slowly, making them a gentler option for sensitive or reactive skin.
Do PHAs cause sun sensitivity like AHAs?
PHAs are generally considered to increase photosensitivity less than AHAs, but daily sunscreen is still recommended when using any exfoliating acid.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
