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AIDSinfo Drug Database

AIDSinfo Drug Database

Drugs by class



Flucytosine  Audio icon

Other Names: 5-flucytosine, Ancobon
Drug Class: Opportunistic Infections and Coinfections

Chemical Image:
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Molecular Weight: 129.094

What is flucytosine?

Flucytosine is an antifungal prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of serious infections caused by certain types of two different fungi: Candida and Cryptococcus.

Cryptococcosis, which is an infection caused by Cryptococcus fungi, is an opportunistic infection. 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.

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 use of flucytosine to treat cryptococcosis.

The above may not include all of the HIV-related uses of flucytosine 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 flucytosine?

Before taking flucytosine, tell your health care provider:

  • If you are allergic to flucytosine 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 flucytosine can harm an unborn baby is unknown. Talk to your health care provider about possible risks with taking flucytosine 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. Flucytosine may affect the way other medicines or products work, and other medicines or products may affect how flucytosine works. Ask your health care provider if there are interactions between flucytosine and the other medicines you take.

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

How should I take flucytosine?

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

How should flucytosine be stored?

  • Store flucytosine capsules at 77°F (25°C). Flucytosine may be stored temporarily at 59°F to 86°F (15°C to 30°C).
  • Do not use flucytosine if the original seal over the container opening is broken or missing.
  • Throw away flucytosine that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
  • Keep flucytosine and all medicines out of reach of children.

Where can I find more information about flucytosine?

More information about flucytosine is available:

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

Last Reviewed: January 17, 2017

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