Drug information

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Famciclovir
Other Names
Famvir
Drug Class
Antiviral (Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor)
 

What is famciclovir?What is famciclovir?

What is famciclovir?

Famciclovir is an antiviral prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of herpes simplex virus (HSV) and varicella zoster virus (VZV) infections.

In adults with normal immune systems, famciclovir is FDA-approved:

  • To treat recurrent outbreaks of cold sores (also known as herpes labialis or orolabial herpes) caused by HSV
  • To treat recurrent outbreaks of genital herpes caused by HSV and to prevent outbreaks from reoccurring
  • To treat shingles (also known as herpes zoster) caused by VZV

In adults with HIV, famciclovir is FDA-approved:

  • To treat recurrent outbreaks of orolabial or genital herpes caused by HSV

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 famciclovir used in people with HIV?How is famciclovir used in people with HIV?

How is famciclovir used in people with HIV?

The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents With HIV and/or the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children With and Exposed to HIV include recommendations on the uses of famciclovir in people with HIV to:

Treat

Prevent

  • Genital lesions caused by HSV from recurring

The recommended uses may not always be consistent with FDA-approved uses of famciclovir. See the Adult and Pediatric Opportunistic Infection Guidelines for complete information on recommended uses of famciclovir in adults and adolescents with HIV. Famciclovir may have other recommended uses not listed above. 

What should I tell my health care provider before taking famciclovir?What should I tell my health care provider before taking famciclovir?

What should I tell my health care provider before taking famciclovir?

Before taking famciclovir, tell your health care provider:

  • If you are allergic to famciclovir, penciclovir cream, or any other medicines.
  • About any medical conditions you have or have had, for example, kidney or liver problems.
  • About anything that could affect your ability to take medicines, such as difficulty swallowing or remembering to take pills.
  • If you are pregnant or plan to become pregnant. Talk to your health care provider about the risks and benefits of using famciclovir 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 famciclovir during pregnancy. Please refer to these guidelines for additional information.
  • If you are breastfeeding or plan to breastfeed. For mothers with HIV in the United States, the Guideline recommends speaking with your health care provider to discuss options for feeding your baby. Mothers with suppressed viral load have a less than 1% chance of transmitting HIV to their baby via their own milk. Although most medicines are safe to use while breastfeeding, some medicines should be avoided. Always let your health care provider know about all the medicines and supplements you are using before you start breastfeeding.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Famciclovir may affect the way other medicines or products work, and other medicines or products may affect how famciclovir works. Ask your health care provider if there are interactions between famciclovir and the other medicines you take.

How should I take famciclovir?How should I take famciclovir?

How should I take famciclovir?

Take famciclovir according to your health care provider’s instructions. Your health care provider will tell you how much famciclovir to take and when to take it. Before you start famciclovir and each time you get a refill, read any printed information that comes with your medicine.

What side effects can famciclovir cause?What side effects can famciclovir cause?

What side effects can famciclovir cause?

Famciclovir may cause side effects that can be mild or serious. To learn about possible side effects of famciclovir, see the FDA drug label or talk to your health care provider or pharmacist. Tell your health care professional if you have any side effect that bothers you or that does not go away. Your health care professional may be able to tell you about ways to prevent or reduce some side effects.

You may report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online.

How should famciclovir be stored?How should famciclovir be stored?

How should famciclovir be stored?

  • Store famciclovir at room temperature, 68°F to 77°F (20°C to 25°C).
  • Do not use famciclovir if the original seal over the container opening is broken or missing.
  • Throw away famciclovir that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
  • Keep famciclovir and all medicines out of reach of children.

Where can I find more information about famciclovir?Where can I find more information about famciclovir?

Where can I find more information about famciclovir?

 

 

Last Reviewed: April 15, 2025