Q. I have a question about Valtrex. I know this drug is prescribed to treat genital herpes. If someone is exposed to a partner with herpes, will taking Valtrex right away destroy any of the virus that may have been acquired before it has a chance to take hold and become dormant? In other words, can Valtrex be used as sort of a “day after” medication if taken soon enough?
A. We were intrigued by the idea that Valtrex might protect someone against genital herpes, so we asked the manufacturer, GlaxoSmithKline. We learned that GSK has never done a study to investigate this scenario. The company has only done studies in people known to be infected with herpes simplex virus. As a result, there aren’t any clinical data to support the use of Valtrex as a “day after” medication or as a prophylactic drug in uninfected individuals whose sexual partners have genital herpes.