Flucytosine is an antifungal medication that fights infections caused by fungus.

Flucytosine is used to treat serious fungal infections of the blood, lungs, heart, central nervous system, and urinary tract.

Flucytosine is sometimes given with another medicine called amphotericin B.

Flucytosine may also be used for purposes not listed in this medication guide.

Before you take flucytosine, tell your doctor if you have kidney disease.

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

While using flucytosine, you may need frequent blood tests.

Take each dose with a full glass (8 ounces) of water.

Flucytosine may cause nausea and vomiting. If you take more than one capsule per dose, swallow one capsule at a time over a 15-minute period to help prevent nausea and vomiting.

Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antifungal medicine. Flucytosine will not treat a viral infection such as the flu or a common cold.

Store at room temperature away from moisture and heat.

You should not use flucytosine if you are allergic to it.

To make sure flucytosine is safe for you, tell your doctor if you have:

• kidney disease;

• a blood cell disorder or bone marrow disease;

• weak immune system (caused by radiation or by using medicine that causes bone marrow suppression); or

• an electrolyte imbalance (such as low levels of potassium in your blood).

It is not known whether flucytosine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether flucytosine passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine.

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, diarrhea, upper stomach pain, or unusual bleeding or bruising.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Flucytosine may cause serious side effects. Call your doctor at once if you have:

• slow heart rate, weak pulse, fainting, slow breathing;

• chest pain;

• confusion, hallucinations;

• a seizure (convulsions);

• pale skin, easy bruising, unusual bleeding (nose, mouth, vagina, or rectum);

• sudden weakness or ill feeling, fever, chills, sore throat, mouth sores, red or swollen gums, trouble swallowing;

• problems with hearing;

• low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling;

• kidney problems--little or no urination, painful or difficult urination, swelling in your feet or ankles, feeling tired or short of breath; or

• liver problems--nausea, upper stomach pain, itching, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects of flucytosine may include:

• nausea, vomiting, loss of appetite, diarrhea;

• headache, dizziness;

• numbness, tingling, or burning pain in your hands or feet;

• dry mouth; or

• skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Tell your doctor about all your current medicines and any you start or stop using, especially:

• clozapine;

• cytosine; or

• deferiprone.

This list is not complete. Other drugs may interact with flucytosine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.