herpes simplex
"I've always suspected that when I use abreva, while it may shorten the life of one cold sore, another often developed right after it. It happened this time, so now I'm convinced. I had 3 different spots that took 9 days to heal and now that those are gone, I have another popping up!  I'm thinking you just have to let them run their course- maybe use a lysine product to reduce pain."