Docosanol
herpes simplex
"I'm surprised to see any negative reviews, I guess everyone's body reacts differently and Abreva is no different.

It works for me. I've been using it for the past 6 years or more at the first sign I get, usually a tingle or tenderness on the lip. Even if a sore has already formed it seems to quickly stop it in its tracks. Definitely pricey, but the little bottle lasts me years. Love Abreva for doing what it's advertised to do!"