<IMG SRC="http://www.healthboards.com/ubb/round.gif"> Cold sores are caused by a virus. The virus lays in a dorment stage till your body has a lack of an amino acid called Lysine. Once you take daily doses of Lysine it will go into a dormant stage again. Stop the Lysine and it will show up again as a "cold sore" This virus will be with you all your life. Healthfood stores carry Lysine.