A polyhydroxy acid: a large, gentle exfoliant that also holds water. Suits skin that can't tolerate glycolic acid; the evidence base is small.
Gluconolactone is a polyhydroxy acid (PHA) derived from glucose. Its larger molecule enters skin slowly, so it exfoliates more gently than glycolic acid, and its many hydroxyl groups make it a humectant. It is also an antioxidant.
PHAs are pitched for sensitive or rosacea-prone skin and for pairing with retinoids. The rationale is sound; the supporting studies are few and small.
A double-blind trial in 150 people found 14% gluconolactone lotion and 5% benzoyl peroxide both reduced acne lesions versus vehicle, with fewer side effects from gluconolactone. Other reports describe smoothing and anti-aging benefits and good tolerance on sensitive skin, but independent replication is limited.
In a double-blind trial of 150 people with mild to moderate acne, 14% gluconolactone and 5% benzoyl peroxide both reduced inflamed and non-inflamed lesions versus vehicle; gluconolactone caused fewer side effects.
Reviews polyhydroxy acids such as gluconolactone, reporting AHA-like smoothing and anti-aging effects with less stinging, added humectant properties, and compatibility with sensitive skin, rosacea and use after procedures.