Valacyclovir Tablets USP, 1000 mg are oral antiviral medications used to treat infections caused by herpes viruses, including shingles (herpes zoster), genital herpes, and cold sores (herpes labialis). The active ingredient, valacyclovir hydrochloride, is a prodrug that is quickly converted into acyclovir in the body. Acyclovir works by stopping the replication of viral DNA, helping to control outbreaks and reduce symptoms.