Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly the herpes virus. It is effective in managing conditions such as genital herpes, cold sores, and shingles. Acyclovir works by inhibiting the replication of the virus, helping to reduce the severity and duration of outbreaks. This medication is available in various forms, including tablets, topical creams, and intravenous solutions. It is most effective when taken at the first sign of an outbreak. While Acyclovir can help manage symptoms, it does not cure the underlying viral infection, and some patients may experience side effects like nausea or headache.