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AIDSinfo Drug Database

AIDSinfo Drug Database

Drugs by class



Foscarnet Sodium  Audio icon

Other Names: Foscavir
Drug Class: Opportunistic Infections and Coinfections

Chemical Image:
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foscarnet sodium
foscarnet sodium
Molecular Weight: 300.0388

What is foscarnet sodium?

Foscarnet sodium is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of cytomegalovirus (CMV) retinitis (a viral infection and inflammation of the eye’s retina) in individuals with AIDS. Foscarnet sodium is also FDA-approved for the treatment of a certain type of herpes simplex virus (HSV) infection, called mucocutaneous acyclovir-resistant HSV infection, in people with weakened immune systems.

CMV diseases—such as those affecting the eye (retinitis), esophagus (esophagitis), or colon (colitis)—and HSV diseases 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. To learn more about opportunistic infections, read the AIDSinfo What is an Opportunistic Infection? fact sheet.

Foscarnet sodium 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 foscarnet sodium 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 foscarnet sodium to:

  • Prevent:
  • Treat:
    • CMV retinitis.
    • Other types of CMV disease, including CMV pneumonitis (infection and inflammation of the lungs) and CMV neurological disease (infection and disease of the nervous system). (This is an “off-label” use.)
    • Mucocutaneous acyclovir-resistant HSV infection.
    • Certain types of varicella-zoster virus (VZV) disease, including progressive outer retinal necrosis (an infection and inflammation of the eye’s retina) and VZV infections that are resistant to treatment with the drug acyclovir. (This is an “off-label” use.)

The above list may not include all of the HIV-related uses of foscarnet sodium recommended in the Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents. Some recommended uses, such as uses in certain rare circumstances, may have been omitted.

What should I tell my health care provider before taking foscarnet sodium?

Before taking foscarnet sodium, tell your health care provider:

  • If you are allergic to foscarnet sodium 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 missing a scheduled dose or any health conditions that may prevent your use of intravenous medicines.    
  • If you are pregnant or plan to become pregnant. Whether foscarnet sodium can harm an unborn baby is unknown. Foscarnet sodium should be used during pregnancy only if clearly needed. Talk to your health care provider about possible risks with taking foscarnet sodium when pregnant.
  • 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. Foscarnet sodium may affect the way other medicines or products work, and other medicines or products may affect how foscarnet sodium works. Ask your health care provider if there are interactions between foscarnet sodium and the other medicines you take.

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

How should I take foscarnet sodium?

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

How should foscarnet sodium be stored?

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

Where can I find more information about foscarnet sodium?

More information about foscarnet sodium is available:

The above Patient Version drug summary is based on the following FDA label(s): Injection (solution).

Last Reviewed: December 9, 2016

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