Valaciclovir or valacyclovir is an antiviral drug used in the management of herpes simplex, herpes zoster (shingles), and herpes B. It is aprodrug, being converted in vivo to aciclovir. It is marketed by GlaxoSmithKline under the trade names Valtrex and Zelitrex. As of November 25, 2009, valacyclovir is marketed in generic form in the United States by Ranbaxy Laboratories.
Valacyclovir is used to treat infections caused by certain types of viruses. In children, it is used to treat cold sores around the mouth (caused by herpes simplex) and chickenpox (caused by varicella zoster). In adults, it is used to treat shingles (caused by herpes zoster) and cold sores around the mouth.