I have been getting cold sores since I can remember (age 5, maybe). They come about once evey six months or, if I'm lucky, one a year due to stress. L Lysine, the over the counter supplement, has made a huge difference in my once 6-12 day hiatus from the world due to my cold sores. My normal 2 weeks effected by cold sores was about cut in half from taking it. The recomended dosage when you have an outbreak is 3000-9000mg. It works for other strains of Herpes Simplex (the virus that causes ALL cold sores, kanker sores and Shingles) also. The pills are hard to swallow and I would recomend taking the oval shaped once as opposed to the circle shaped ones since they are easier to quickly swallow. They cost about $5 for a bottle of 50 1000mg tablets. I have found them at all drug stores, it's very common. No side effects or known drug interactions either since it's an amino acid and a supplement. If you are a sufferer I would strongly recomend this product.