A generic brand name of its active ingredient, Valacyclovir. This is an anti-viral prescription medicine used to treat infections caused by certain types of viruses. In children, it is used to treat cold sores (herpes simplex) and chickenpox (varicella zoster). In adults, it is used to treat shingles (herpes zoster). Valacyclovir is also used to treat outbreaks of genital herpes and used to prevent cytomegalovirus following kidney transplant in high risk cases. In people with frequent outbreaks, this medication is used to reduce the number of future episodes.