Valacyclovir is an antiviral medication primarily used to treat infections caused by certain viruses, including herpes simplex and varicella zoster. It works by inhibiting the replication of viral DNA, which helps to reduce the severity and duration of outbreaks. This medication is often prescribed for conditions such as genital herpes, cold sores, and shingles. Valacyclovir is usually taken orally in tablet form and is most effective when started at the first sign of an outbreak. It is important to follow the prescribed dosage to achieve the best results.