Leucine

An amino acid that serves as a humectant and skin-conditioning agent in cosmetics. It is an essential amino acid found in proteins and used to support moisture retention. No known sensitivities or irritation concerns exist for topical cosmetic use.

Cosmetic information for general education, not medical advice. A verdict is a reading of the published evidence, never a guarantee for your skin: any ingredient can irritate someone, so patch test new products and see a professional if you react. Concern is graded on cited evidence, never on hazard-score lists. See how we score.