L-lysine, is an essential amino acid, meaning it is necessary for human health, but the body cannot make it. L-Lysine is a precursor to many proteins. It contains an α-amino group, an α-carboxylic acid group, and a side chain lysyl, classifying it as a basic, charged, aliphatic amino acid. L-Lysine has many benefits that range from preventing cold sores to reducing anxiety and promoting wound healing.