Generic Name: flucytosine (floo-SYE-toe-seen)
Use with extreme caution in patients with impaired renal function. Close monitoring of hematologic, renal, and hepatic status of all patients is essential .
Medically reviewed by Drugs.com. Last updated on Aug 24, 2020.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Antifungal
Uses for flucytosine
Flucytosine belongs to the group of medicines called antifungals. It is used to treat certain fungus infections.
Flucytosine is available only with your doctor's prescription.
Before using flucytosine
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For flucytosine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to flucytosine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Although there is no specific information comparing use of flucytosine in children with use in other age groups, flucytosine is not expected to cause different side effects or problems in children than it does in adults.
Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of flucytosine in the elderly with use in other age groups, flucytosine is not expected to cause different side effects or problems in older people than it does in younger adults.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking flucytosine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using flucytosine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using flucytosine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of flucytosine. Make sure you tell your doctor if you have any other medical problems, especially:
- Blood disease—Flucytosine may cause blood problems
- Kidney disease—Patients with kidney disease may have an increased chance of side effects
- Liver disease—Flucytosine may cause liver side effects
Proper use of flucytosine
In some patients flucytosine may cause nausea or vomiting. If you are taking more than 1 capsule for each dose, you may space them out over a period of 15 minutes to help lessen the nausea or vomiting. If this does not help or if you have any questions, check with your doctor.
To help clear up your infection completely, keep taking flucytosine for the full time of treatment, even if you begin to feel better after a few days. Do not miss any doses.
The dose of flucytosine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of flucytosine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (capsules):
- For fungus infections:
- Adults and children—Dose is based on body weight. The usual dose is 12.5 to 37.5 milligrams (mg) per kilogram (kg) (5.7 to 17 mg per pound) of body weight every six hours.
- For fungus infections:
If you miss a dose of flucytosine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Precautions while using flucytosine
Your doctor should check your progress at regular visits to make sure that flucytosine does not cause unwanted effects.
Flucytosine may cause blood problems. These problems may result in a greater chance of infection, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work, whenever possible, should be done before you begin taking flucytosine or delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.
Flucytosine may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause skin rash, itching, redness, or other discoloration of the skin, or a severe sunburn. When you begin taking flucytosine:
- Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
- Wear protective clothing, including a hat. Also, wear sunglasses.
- Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
- Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
- Do not use a sunlamp or tanning bed or booth.
If you have a severe reaction from the sun, check with your doctor.
Flucytosine may also cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Make sure you know how you react to flucytosine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert . If these reactions are especially bothersome, check with your doctor.
Flucytosine side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Skin rash, redness, or itching
- sore throat and fever
- unusual bleeding or bruising
- unusual tiredness or weakness
- yellow eyes or skin
- hallucinations (seeing, hearing, or feeling things that are not there)
- increased sensitivity of skin to sunlight
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Abdominal pain
- loss of appetite
- nausea or vomiting
- Dizziness or lightheadedness
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
More about flucytosine
- Side Effects
- During Pregnancy
- Dosage Information
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- Drug class: miscellaneous antifungals
Other brands: Ancobon