Amino acid stress fighter A highly effective immune system supporter Helps to balance high levels of the amino acid L-arginine Per GMP guidelines set forth by the FDA, most products are formulated for 24 months from the date of manufacture. Liquids and probiotics are formulated for 12 months. Stressed? When tensions run high is when you need Swanson L-lysine the most. L-lysine is classified as an essential amino acid because our bodies need it every day for regulating immune responses.