How effective is valacyclovir in preventing transmisson of hsv-2?

VALTREX (valacyclovir) FOR HSV: Valacyclovir -- the brand name is Valtrex (valacyclovir) -- is quite effective in peventing herpes simplex recurrences. Not 100%, though.

About 50%: The single research study that investigated this showed a 50% reduction in HSV-2 transmission between heterosexual partners who had unprotected vaginal sex about 2-3 times a month, when one partner had genital HSV-2. In other words, over a longstanding relationship, many partners still will be infected and other precautions remain wise, especially condoms and avoiding sex during obvious outbreaks.