Gluconolactone (PHA)

Gluconolactone is a polyhydroxy acid (PHA) with a molecular structure far larger than AHAs, so it exfoliates only at the very surface — ideal for sensitive and rosacea-prone skin that cannot tolerate glycolic or lactic acid. Despite its gentleness, clinical studies show it improves texture and fine lines comparably to glycolic acid over time. Gluconolactone is also a powerful humectant and chelator: it binds water and metal ions, giving it antioxidant properties and helping stabilise the whole formulation. It does not increase photosensitivity meaningfully. Use 5–10% daily or alternate nights; it layers under most actives without conflict — the safest exfoliation entry point in modern skincare.