What is valacyclovir?

Valacyclovir is the generic version of the brand drug Valtrex, an antiviral medication used to treat several viruses, according to WebMD. It works by stopping the growth of particular viruses that cause infections, but the viruses still remain dormant in the body after treatment with the drug.

Doctors use valacyclovir in children to treat chickenpox. They also prescribe it for treating shingles caused by the herpes zoster virus and cold sores around the mouth that are caused by the herpes simplex virus in both children and adults. Valacyclovir is sometimes useful in treating genital herpes flares and reducing the number of future outbreaks of genital herpes, according to WebMD.