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Generic name: Flucytosine [Flu-SYE toe-saen]
Brand names: Ancobon
Dosage form: oral capsule (250 mg; 500 mg)
Drug Class: Antifungal

What is Flucytosine?

Flucytosine, an antifungal drug, is used to treat infections caused by fungus. Flucytosine can be used to treat serious fungus infections in the blood, lungs, and heart. It is also effective for treating bacterial infections. Sometimes, flucytosine may be given in combination with another medication called amphotericin B. This medication guide does not list all possible uses of flucytosine.

Side effects of Flucytosine

If you experience any of the following signs of an allergic reaction: difficulty breathing, hives or swelling to lips, face, tongue or throat. Seek medical assistance immediately.

Flucytosine can cause serious side effects. If you experience:

  • Fainting; slow breathing.
  • Chest pain;
  • Confusion, hallucinations;
  • A seizure (convulsions);
  • Pale skin, easy bruising, and unusual bleeding (mouth, nose, vagina, or rectum);
  • A sudden feeling of weakness, a fever, or a sore throat or mouth;
  • Hearing problems;
  • Low sodium can result in leg cramps, constipation, an increase in thirst or urine output or an numb sensation in muscles that weaken them or even an overall limp feeling.
  • Kidney disorders: limited or no urination; painful or difficult urination; swelling in feet or ankles; feeling exhausted or short of breath are symptoms that indicate there may be issues.
  • Liver problems: nausea, upper stomach discomfort, itching and fatigue, loss of appetite. Dark urine and clay-colored stools. Jaundice.

Flucytosine can cause a variety of side effects.

  • Loss of appetite, nausea, vomiting, and diarrhea are all symptoms.
  • Headache, dizziness;
  • You may experience numbness or tingling in your feet or hands.
  • Dry mouth
  • Skin rash.

There may be other side effects.For medical advice regarding side effects, call your physician. To report side effects directly, call the FDA's Hotline at 1-800-FDA-1088.

Similar/related drugs

Fluconazole, Diflucan, Itraconazole, Voriconazole, Amphotericin B, Posaconazole, and Sporanox


Tell your doctor that you have kidney problems before you start taking flucytosine.

Before you take this drug

If you have an allergy to flucytosine, then it is best not to use this drug.

Tell your doctor about any of the following to ensure that flucytosine will not harm you:

  • Kidney disease
  • A blood cell disorder, or a bone marrow condition;
  • Weak immune system (caused either by radiation or using medicines that cause bone marrow to be suppressed);
  • An electrolyte imbalance can occur (for example, a low potassium level in the blood).

Flucytosine does not pose any threats to unborn babies and should not be taken during pregnancy or planning to become pregnant. Please inform your physician immediately if this applies to you. Flucytosine cannot be tested to see whether or not it will pass into breast milk, and could possibly pose risks to an infant who was nursing. Therefore, this medication should not be taken while breastfeeding.

How to take Flucytosine?

Do not take this medication in larger or smaller amounts or for longer than recommended, nor exceed its prescribed dosage. Always follow instructions provided to you from a healthcare provider regarding how and when to take this medicine. Flucytosine may require frequent blood tests. Each dose should be taken with 8 ounces of water. Flucytosine may cause nausea and vomiting. To minimize its side effects, take one capsule every 15 minutes if taking more than one per dose - this should help avoid potential discomfort from these side effects. Flucytosine should be taken as prescribed in order to achieve complete infection clearance and to minimize your risk for secondary fungi resistant to antifungal medication re-infections if doses are missed or missed too often. Flucytosine does not treat viral infections like flu or colds. Store away from moisture and heat at room temperature.

What happens if I miss the dose?

As soon as you remember to take it, take the missed dose immediately. If your next scheduled dosage is approaching soon after taking your missed one, do not attempt to make up the difference by increasing dosage or increasing frequency of medication use in an attempt to compensate. Doing so would only lead to additional problems and possible adverse side effects.

What happens if I overdose?

Call 1-800-222-1222 for poison help or seek immediate medical attention. Overdose symptoms include nausea, vomiting, and diarrhea. They can also cause upper stomach pain or unusual bleeding.

What should be avoided?

If your doctor prescribes any restrictions regarding food, beverage, or activity, follow their instructions.

Interaction with other drug

Make sure that your doctor knows if you plan on taking any new or different medicines. Also inform him or her if any current ones need to be discontinued.

  • Clozapine;
  • Cytosine;
  • Deferiprone.

This list is incomplete. Flucytosine may interact with other drugs, including prescription, over-the-counter, and herbal products. This medication guide does not cover all possible interactions.



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