Vidarabine Monohydrate is primarily used as an antiviral medication, particularly effective against herpes simplex virus and varicella-zoster virus. It is applied in the treatment of herpes simplex encephalitis, a severe infection of the brain caused by the herpes simplex virus. Additionally, it is used to manage herpes zoster (shingles) in immunocompromised patients, helping to reduce the severity and duration of the infection. In ophthalmology, Vidarabine Monohydrate is formulated into eye ointments to treat herpes simplex keratitis, an infection of the eye caused by the herpes simplex virus, aiding in the prevention of corneal damage and vision loss. Its mechanism involves inhibiting viral DNA synthesis, thereby controlling the spread of the virus within the host.