I understand that valtrex (valacyclovir) is most effective at the first sign of a breakout, but is taking it after a cold sore erupts effective at all? thanks!

Herpes cold sore: Cold sores on the lips are painful and can be distressing to us. The best thing to do is prevent them from coming out by avoiding the STRESS that allows them to occur. If this fails, Valtrex (valacyclovir) is most useful when the tingling is there BEFORE the red blister. Once the infection has the upper hand, it's harder to catch up. save the Valtrex (valacyclovir) for next time- no sense in training ur virus 2B resistant 2it

Valtrex (valacyclovir): This medication works best when started at the first sign of an outbreak, as directed by your doctor. It may not work as well if you delay treatment.