NOW L-Cysteine is a non-essential amino acid that is an important component of hair, nails and the keratin of the skin. L-Cysteine stabilizes protein structure and aids in the formation of collagen, thereby promoting healthy skin, hair and nail texture and elasticity.Ingredients L-Cysteine (from L-Cysteine Hydrochloride), vitamin C and B-6 Free From Contains no sugar, salt, starch, yeast, wheat, gluten, soy, milk, egg, shellfish or preservatives.