Strike a match and blow it out. Run it quickly under water and then press the end of the match against the cold sore. I do this when I feel that tingle and perhaps see a small red bump beginning to form. I hold the match on for 30 sec. then I strike another.
I burn 3 matches all together and I do this 2-3 times a day for 1-2 days. When I do this I never get the cold sore. It dries out before forming and just goes away. It has been the only sure "fire" way to keep from getting the monster sore! Try it! It has always worked for me.