What is acyclovir?
Acyclovir is an antiviral prescription medicine approved by the U.S. Food and Drug Administration (FDA) to:
- Treat and/or prevent the recurrence of certain types of herpes simplex virus (HSV) infections, including genital herpes
- Treat varicella zoster virus (VZV) infections, including chicken pox (primary varicella infection) and shingles (herpes zoster)
Acyclovir is approved in different formulations and strengths for use in specific populations, including in people who are immunocompromised.
HSV and VZV infections can be opportunistic infections (OIs) of HIV. An OI is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as people with HIV—than in people with healthy immune systems. To learn more about OIs, read the HIVinfo What is an Opportunistic Infection? fact sheet.
How is acyclovir used in people with HIV?
The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV and the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children with and Exposed to HIV include recommendations on the uses of acyclovir in people with HIV to:
- HSV infections, including:
- Oral herpes, such as cold sores (orolabial lesions) and gingivostomatitis (infection of the mouth and gums)
- Genital herpes (genital lesions)
- Central nervous system (CNS) infection or disseminated disease
- Skin infections
- Eye infections, such as keratoconjunctivitis (infection of the cornea of the eye) and acute retinal necrosis (an inflammatory condition that can damage or destroy the retina of the eye)
- VZV infections, including:
- Chicken pox
- Acute retinal necrosis and progressive outer retinal necrosis (inflammatory conditions that can damage or destroy the retina of the eye)
- Cold sores and genital lesions caused by HSV infection from recurring
- Chicken pox from occurring in certain people who come in contact with someone who has active shingles or chicken pox (also known as post-exposure prophylaxis [PEP])
The recommended uses may not always be consistent with FDA-approved uses of acyclovir. See the Adult and Pediatric Opportunistic Infection Guidelines for complete information on recommended uses of acyclovir in adults and children with HIV. Acyclovir may have other recommended uses not listed above.
What should I tell my health care provider before using acyclovir?
Before using acyclovir, tell your health care provider:
- If you are allergic to acyclovir or any other medicines.
- About any medical conditions you have or have had, such as kidney problems.
- About anything that could affect your ability to take medicines, such as difficulty swallowing pills, difficulty remembering to take pills, or any health conditions that may prevent your use of intravenous medicines.
- If you are pregnant or plan to become pregnant. Talk to your health care provider about the risks and benefits of taking acyclovir during pregnancy. The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV may include other recommendations on the use of acyclovir during pregnancy. Please refer to these guidelines for additional information.
- If you are breast/chestfeeding or plan to breast/chestfeed. For people with HIV in the United States, the Guideline recommends speaking with your health care provider to discuss options for feeding your baby. People with suppressed viral load have a less than 1% chance of transmitting HIV to their baby via their own milk.
- About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Acyclovir may affect the way other medicines or products work, and other medicines or products may affect how acyclovir works. Ask your health care provider if there are interactions between acyclovir and the other medicines you take.
Ask your health care provider about possible side effects from acyclovir. Your health care provider will tell you what to do if you have side effects.
How should I use acyclovir?
Use acyclovir according to your health care provider’s instructions. Your health care provider will tell you how much acyclovir to use and when to use it. Before you start acyclovir and each time you get a refill, read any printed information that comes with your medicine.
How should acyclovir be stored?
- Store acyclovir tablets at 59°F to 77°F (15°C to 25°C) and protect them from moisture and light.
- Store acyclovir suspension at 59°F to 77°F (15°C to 25°C) and protect it from light.
- Store acyclovir capsules at room temperature, 68°F to 77°F (20°C to 25°C), and protect them from moisture.
- Store acyclovir injection for intravenous infusion at room temperature, 68°F to 77°F (20°C to 25°C).
- Keep acyclovir in the container that it came in and keep the container tightly closed.
- Do not use acyclovir if the original seal over the container opening is broken or missing.
- Throw away acyclovir that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
- Keep acyclovir and all medicines out of reach of children.
Where can I find more information about acyclovir?
- Recommendations on the HIV-related uses of acyclovir, from the Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV and the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children with and Exposed to HIV.
- This Patient Version drug summary is based on the following FDA label(s): Capsule; Injection (solution); Suspension; Tablet.
- The American Hospital Formulary Service (AHFS) Patient Medication Information for acyclovir and acyclovir injection available from MedlinePlus.
- Acyclovir-related research studies, from ClinicalTrials.gov. (The ClinicalTrials.gov search can be modified so that you can get results that better match your interests. To learn more about the ClinicalTrials.gov search features, please see How to Search.)
Last Reviewed: June 25, 2021