Lactobionic Acid

Lactobionic acid is an exfoliating polyhydroxy acid, or PHA, that behaves much like the AHAs, such as glycolic acid, but with a key structural difference: its molecule is larger, so it doesn't penetrate as deeply. That's what makes it less prone to causing a stinging sensation on the skin.

PHAs as a category go beyond exfoliation alone. Lactobionic acid, specifically, binds to metal ions that would otherwise fuel oxidative stress, offering antioxidant protection, and it supports a stronger, more resilient skin barrier.

In skincare formulas, it typically appears at concentrations between 0.1% and 5%. You generally need more than 3% to get a meaningful exfoliating effect. Even at lower amounts, though, it helps guard the skin's supportive structures from enzyme driven breakdown, which is part of why it's known for brightening the dull, sallow tone often seen in sun damaged skin.