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AIDSinfo Drug Database

AIDSinfo Drug Database

Drugs by class



Famciclovir  Audio icon

Other Names: Famvir
Drug Class: Opportunistic Infections and Coinfections
Chemical Image:
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Molecular Weight: 321.335

What is famciclovir?

Famciclovir is an antiviral prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of two types of herpes simplex virus (HSV) infection in healthy adults: cold sores (also known as herpes labialis or orolabial herpes) and genital herpes. Famciclovir is also approved to treat shingles—a varicella zoster virus (VZV) infection—and to prevent the recurrence of genital herpes in healthy adults. In HIV-infected people, famciclovir is approved to treat herpes lesions in or around the mouth, genitals, and anal area.

VZV and HSV infections are opportunistic infections. An opportunistic infection is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as those infected with HIV—than in people with healthy immune systems.

Famciclovir can also be used “off-label” to prevent and treat other opportunistic infections of HIV infection. “Off-label” use refers to use of an FDA-approved medicine in a manner different from that described on the medicine label. Good medical practice and the best interests of a patient sometimes require that a medicine be used “off-label.”

What HIV-related opportunistic infections is famciclovir used for?

The Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents, prepared by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the HIV Medicine Association of the Infectious Diseases Society of America (IDSA-HIVMA), includes recommendations on the HIV-related uses of famciclovir to:

  • Prevent:
    • Orolabial lesions (cold sores) and genital lesions caused by HSV infection from recurring (called secondary prophylaxis or maintenance therapy).
  • Treat:
    • HSV infections, including orolabial lesions and genital lesions.
    • VZV infections, including shingles (also known as herpes zoster) and chicken pox (also known as primary varicella infection). (The latter is an “off-label” use.)

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 or any other medicines.
  • About any medical conditions you have or have had, for example, diabetes 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. Whether famciclovir can harm an unborn baby is unknown.
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Ask your health care provider if there are interactions between famciclovir and the other medicines you take.

Ask your health care provider about possible side effects from famciclovir. Your health care provider will tell you what to do if you have side effects.

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.

How should famciclovir be stored?

  • Store famciclovir at room temperature, 68°F to 77°F (20°C to 25°C).
  • Safely throw away famciclovir that is no longer needed or expired (out of date).
  • Keep famciclovir and all medicines out of reach of children.

Where can I find more information about famciclovir?

More information about famciclovir is available:

The above Patient Version drug summary is based on the following FDA label(s): Tablet (film coated).

Last Reviewed: May 7, 2013

Last Updated: May 7, 2013

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