Acyclovir is an antiviral drug prescribed to treat infections such as chickenpox, genital herpes, shingles and cold sores, which are caused by herpes viruses. It decreases the growth and spread of herpes virus in the body and helps faster healing of sores. Acyclovir eye ointment is used to treat viral eye infections caused by herpes simplex viruses. Acyclovir is available as tablet, topical cream and eye ointment forms. This medicine may also be used to treat other conditions as determined by your doctor.