Whenever I feel a cold sore comin' on, I immediately grab a piece of ice and press it against the side of my mouth where the sore always appears. I may ice it up to three or four times during the course of a day. And 100% of the time, that precedure has stopped the sore from developing! Well, today is one of those icing days. And, from what I see, it appears that I may have foiled the development of the sore again! Yippee!