Sign up today to receive the latest news and updates from UpToDate. © 2026 UpToDate, Inc. and/or its affiliates. All Rights Reserved. Acyclovir works by stopping the herpes virus from making more copies of itself. It does this by entering the virus’s DNA process and stopping it from building properly. This helps reduce symptoms. What is acyclovir used for? Acyclovir is an antiviral medicine commonly used for the following conditions caused by herpes viruses. Acyclovir may also be used for other conditions as. NHS information about aciclovir, including what it's used for, who can use it, how to use it and side effects. Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus in the body. Acyclovir will not cure herpes, but it can lessen the symptoms of the infection. Acyclovir is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox. Although acyclovir will not cure shingles or genital herpes, it does help relieve the pain and discomfort and helps the sores heal faster. This medicine is available only with your doctor's prescription. This product is available in the following dosage forms: Curator reviewed · 19 structured indications. Acyclovir is a guanosine analog used to treat herpes simplex, varicella zoster, herpes zoster. View aciclovir information, including dose, uses, side-effects, renal impairment, pregnancy, breast feeding and directions for administration. Aciclovir, also known as acyclovir, [4] is an antiviral medication. [5] It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles. [6] Oral acyclovir therapy should be considered an alternative therapy to treat acute localized dermatomal herpes zoster in HIV-infected adults according to the Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents; IV acyclovir is preferred therapy with extensive cutaneous lesion or visceral.