I used to have canker sores ALL the time. I was so miserable! Then a friend told me about L-Lysine. Now whenever I feel a canker sore coming on, I take two L-Lysine tablets and poof! No more canker sore! They say there are no miracle pills for chronic health problems but that pill sure as heck cures at least one chronic health problem for me. NOTE: My nutrition/health manual states that amino acids are NOT to be taken every day for the rest of one's life. Therefore, I only take L-lysine when I feel a canker sore coming on.