Lactobionic Acid

Lactobionic acid is a polyhydroxy acid (PHA) — the third-generation chemical exfoliants after AHAs (glycolic, lactic) and BHAs (salicylic). Built from lactose oxidation, lactobionic acid has a much larger molecular size than smaller AHAs (358 daltons vs 76 for glycolic), which means it sits on the surface and exfoliates the very top layers without penetrating deep enough to cause irritation. The same gentle profile as gluconolactone, but with an additional benefit: lactobionic acid is a strong antioxidant in its own right (it chelates iron and prevents oxidative damage) and has anti-glycation properties (prevents the AGE-formation that yellows aging skin). Approved for use in eczema-flare and rosacea protocols where AHAs would cause flare-ups. NeoStrata built their PHA line around this molecule; Exuviance and several K-beauty calming-active brands use it. Worth trying if you've reactivated to glycolic or salicylic — same exfoliation outcome at half the irritation.