cold sores
"I'd suffered quite a few breakouts of cold sore before discovering Valtrex so I know the pain and the lengthy healing process all too well.  This literally stops cold sore in its track the moment you take it. Whatever condition the cold sore is in when you take the medicine, it would not get worse, only better so the sooner the better.  If you take it AFTER the cold sore has become blister(s), it will stop the blister from multiplying BUT you would have to deal with the blisters bursting exposing the ulcer and then the healing of the ulcer. If you take it at the tingling/itchy stage of the cold sore BEFORE any blister is formed, you should be able to get away with the break out altogether. Goodluck!"