I had my first cold sore outbreak on my lip about 1.5 months ago. I took Valtrex
the day I had the outbreak and it immediately provided relief and eventually the sore crusted over and healed in about 7 days but left a small scar on my lip. Two weeks later, my lip started to pulsate in the general area, not really tingle but a definite inflamed feeling. So, preemptively, I took the Valtrex.