herpes simplex
"I had a really big blister when I woke up and rushed to WalMart. The only one available was Abreva. It doesn't relieve of pain or that burning/fat sensation but it did ultimately dry out my cold sore! EXCEPT NOW (Day 3) it's slowly spreading all over my lip. I was sanitary! Down to disinfecting my lip before applying Abreva. I used only Q-tips, no fingers.

In other words, it dries your first cold sore, but it doesn't stop the other cold sores for using Abreva."