Docosanol
"This is amazing. Never had sores until in my 20's and the first outbreak and several after that were horrifying...entire top and bottom lip covered in enormous sores at least ten on top and ten on bottom. I couldn't eat or drink unless from a straw it was that bad.I couldn't leave the house or people stared like I was a monster. Got an rx for valtrex and if I feel the tingle I take 2 pills then another 2 pills 8/12 hrs later I forget which it is, and I immediately dab abreva on (always with tissue I never directly touch the sore) and continue to apply it every few hrs as it states on package. Usually they may look like a tiny pimple and thats as big as they get then they just disappear. Valtrex alone doesn't help me I need abreva too. Great stuff!"