herpes simplex
"Abreva (docosanol) is the only over-the-counter anti-viral cold sore treatment available in the US. Most other over-the-counter brands will not have any effect on the duration and severity of the blister(s), other than treating the symptoms which include pain, itchiness etc. You should apply anti-virals once you start to feel the "tingly", warm feeling in your lip before the blister arrives. This will inhibit the virus particles to replicate and infect more cells, which would have made your sore bigger, more painful and longer lasting. That being said, this doesn't work perfectly, all the time. I swear by this, and I will NEVER waste money on anything that does not contain anti-virals. Read the content label before you purchase and google!"