What it is
Lysine is one of the standard proteinogenic amino acids and, in skincare, is included as part of amino-acid blends intended to support the skin's natural moisturizing factor. It is water-soluble and is typically added at low concentrations to conditioning and hydrating formulas, including sunscreens. It contributes to a smooth skin feel and can help formulas leave skin feeling supple.
Safety & warnings
Lysine is a naturally occurring amino acid and is generally well tolerated in topical cosmetic use at the low levels typical of skincare. It is not associated with notable comedogenicity, and it is not a recognized fragrance allergen.
Origin & sourcing
Lysine for cosmetic use is generally produced by microbial fermentation of carbohydrate feedstocks, yielding the L-isomer; it can also be synthesized chemically.
Questions everyone asks
What does lysine do in a sunscreen?
It acts as a skin-conditioning and humectant ingredient, helping the formula feel hydrating and leaving skin smooth; it is not a UV filter.
Is lysine natural?
Lysine is a naturally occurring amino acid, and cosmetic-grade material is commonly made by fermentation.