What it is
Lysine HCl is a water-soluble amino acid salt that helps attract and bind moisture at the skin surface, supporting a soft, conditioned feel. In sunscreens and other leave-on formulas it is typically included as part of an amino acid blend that contributes to the natural moisturizing factor profile of the skin. It dissolves readily in the water phase and is generally used at low concentrations.
Safety & warnings
Lysine HCl is an amino acid salt that is generally well tolerated in topical use and is not associated with significant irritation or sensitization at cosmetic levels. It is water-soluble and noncomedogenic. It is not a recognized fragrance allergen.
Origin & sourcing
Lysine is produced commercially by bacterial fermentation of carbohydrate feedstocks, then converted to its hydrochloride salt; the material used in cosmetics is typically synthetic-grade and biotechnology-derived rather than extracted from plant or animal tissue.
Questions everyone asks
What does lysine HCl do in a sunscreen?
It acts as a humectant and skin-conditioning amino acid, helping the formula feel moisturizing and supporting the skin's surface hydration.
Is lysine HCl the same as plain lysine?
It is the hydrochloride salt form of lysine, which is more stable and water-soluble; functionally it serves the same conditioning role in formulas.