Gen-Tec Nutraceuticals source, blend and package 100 percent pure pharmaceutical grade L-Lysine powder. L-Lysine supplementation is ideal for individuals who are using arginine based supplements. L-Lysine is an essential amino acid commonly used for assistance with cold sore management. Clinically Lysine is commonly used to reduce the outbreak of Herpes Simplex Virus (HSV) or "cold sore" as this amino acid appears to prevent the replication of the virus, therefore reducing its ability to cause an infection (anti-viral).