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 strains of two types of fungi: Candida and Cryptococcus. For example, flucytosine is used to treat cryptococcosis, which is an infection caused by Cryptococcus fungi.
Cryptococcosis can be an opportunistic infection (OI) 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 flucytosine 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 use of flucytosine to treat cryptococcosis in people with HIV.
The recommended uses may not always be consistent with FDA-approved uses of flucytosine. See the Adult and Pediatric Opportunistic Infection Guidelines for complete information on recommended uses of flucytosine in adults and children with HIV. Flucytosine may have other recommended uses not listed above.
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, including
- If you are receiving radiation treatment.
- 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. Flucytosine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Talk to your health care provider about the risks and benefits of taking flucytosine during pregnancy.
- 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. 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.
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).
- Keep flucytosine in the container that it came in and keep the container tightly closed.
- 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?
- Recommendations on the HIV-related use of flucytosine, 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.
- Flucytosine-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: March 2, 2023