Natural Factors L-Lysine - 500 mg - One of the most natural nutritional aids for the herpes simplex virus (HSV) is the amino acid L-Lysine. It provides cold sore relief by helping to reduce their recurrence, severity, and healing time. L-Lysine is one of nine essential amino acids that the body needs for repairing tissue, forming collagen, and producing hormones. It is considered “essential” because the body cannot manufacture it and it must be obtained through the diet. Natural Factors L-Lysine should be an essential part of everyone’s nutritional plan to prevent flare-ups of HSV, in whatever form it may take. For the most effective control of HSV, combine L-Lysine supplementation with a low-arginine diet. Taking it with vitamin C and zinc may also provide additional benefits by supporting immune system health.