Lysine is possibly effective for cold sores (herpes simplex labialis) treatment. Lysine is available under the following different brand names: L-lysine and Lysine Monohydrochloride.
Lysine (symbol Lys or K)[2] is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH3+ form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO− form under biological conditions),