What it is
This is the cyclic lactone form of gluconic acid and is classified as a polyhydroxy acid. It is multifunctional in formulas, acting as a humectant that helps bind water, contributing to pH control as it slowly hydrolyzes to gluconic acid, and helping chelate metal ions. As a PHA it is often described as gentler than smaller alpha hydroxy acids because of its larger molecular size.
Safety & warnings
Gluconolactone is generally well tolerated and is regarded as a milder exfoliating acid than smaller alpha hydroxy acids, in part because its larger molecule penetrates more slowly. As with any hydroxy acid, very sensitive skin may still experience mild tingling, and acid use can increase the skin's sensitivity to sunlight. It is not a recognized fragrance allergen and is not associated with comedogenicity.
Origin & sourcing
Typically produced by the oxidation or fermentation of glucose; it is the cyclic ester (lactone) of gluconic acid.
Questions everyone asks
What kind of acid is gluconolactone?
It is a polyhydroxy acid (PHA), the lactone form of gluconic acid, and is generally considered gentler than smaller alpha hydroxy acids.
What does gluconolactone do besides exfoliate?
It also acts as a humectant that binds water, helps buffer the formula's pH, and can chelate metal ions.