Valacyclovir
"This stuff makes a huge difference in the duration and pain of cold sores.  My dentist prescribes it for me because without it, I get a cold sore every darn time I go to the dentist.  For those who have problems with frequent outbreaks, do some research on things you shouldn't eat.  Nuts and seeds are huge cold sore triggers because of the arginine in them.  Other things that will trigger and outbreak for me:  too much direct sun on my face and too much exposure to extreme cold on my face.  If I'm really careful about avoiding the things that cause me problems, I can prevent them but it's nice to have the valacyclovir for those times when I don't get it right."