herpes simplex
"Had cold sores since I was 4 years old, when the core sore would first form it would feel tingly (NEVER ITCHY) and then as the cold sore grew it would be severely painful that if it was accidentally bumped into I would feel like going through the roof. sometimes it would grow as big as an adult males thumb nail and be about 1/2 inch thick. Initially I tried Lipactin Which I have to admit worked to make the cold sore a reasonable size.

All I can say is Thank-God for Abreva because of this medicine, I can put it on and my cold sore reduces to the size of a pea or even smaller. 
For people that haven't had results I think it matters on how you feel when the cold sore is coming on, if yours is itchy this stuff might not work."