Active: Lactic Acid
Description
AHA exfoliant (MW 90 Da) with humectant properties. Slightly larger than glycolic acid producing gentler exfoliation. Disrupts corneocyte cohesion and stimulates ceramide biosynthesis (L-isomer). At lower concentrations acts as a skin-identical humectant and Natural Moisturising Factor (NMF) component. Component of Jessner's solution used as a superficial-to-medium peel primer.
Function
Properties
Regulatory Status
Lactic acid is uniquely dual-function: at low concentrations and higher pH it moisturizes via NMF and ceramide activity (L-isomer); at exfoliating concentrations it rivals glycolic acid with slightly gentler kinetics. The EU limit (2.5% pH ≥5.0) effectively caps exfoliating activity. L-lactic acid is strongly preferred over D or racemic forms for barrier-repair formulations. Photosensitivity guidance required.
CIR reviewed: safe at ≤10% at pH ≥3.5 (consumer); ≤30% at pH ≥3.0 (professional). FDA references CIR guidance. Photosensitivity advisory applies. Optimal pH range 3.5–5.0 depending on target application. L-isomer clinically preferred for ceramide and barrier benefits.