Lactic Acid
Definition
Lactic acid is an alpha hydroxy acid (AHA) derived from milk that serves as a gentle chemical exfoliant. It has a larger molecular size than glycolic acid, which means it penetrates the skin more slowly and evenly, making it better tolerated by sensitive skin types. Lactic acid works by dissolving the bonds between dead skin cells, promoting their removal to reveal brighter, smoother skin. Beyond exfoliation, lactic acid is also a humectant — it attracts and retains moisture in the skin, providing hydrating benefits that set it apart from other AHAs. It can help improve skin texture, reduce the appearance of fine lines, fade mild hyperpigmentation, and support a more even skin tone. Common concentrations in at-home products range from 5% to 10%. Like all AHAs, lactic acid increases sun sensitivity, so sunscreen use is essential.
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