I've always gotten fever blisters since I was a teenager. I mainly get them when I'm stressed or sleep deprived. Abreva has always worked for me. The minute I feel one coming on I apply it. I'm glad I finally hear of people that share the same problem as I do. No one that I know gets fever blister like I do. I went 3 years without having one and just last month I was under alot of stress and had two blisters came out back to back....big bummer!!! Good luck and I hope you find a medicine or vitamin that works for you!! If you do, share what you discovered! I'd like to know for future fever blister outbreaks for myself.