I, too, agree that Lysine is the magic vitamin and preventor/and healer of Canker Sores. My son suffered with them all his young life and my health food store recommended them. He takes one (I think 500 or 1,000) mg. a day) for maintainance. Then, IF he gets a sore, which hardly ever does, he takes 3 a day and that heals it up in a few days.It is a wonderful discovery for us. Stress seems to bring them on in his younger years. He now is 23 and rarely gets one because of the maintaince dose he takes everyday.