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Ancobon Side Effects

Generic name: flucytosine

Medically reviewed by Last updated on Jan 6, 2021.

Note: This document contains side effect information about flucytosine. Some of the dosage forms listed on this page may not apply to the brand name Ancobon.

For the Consumer

Applies to flucytosine: oral capsule


Oral route (Capsule)

Use with extreme caution in patients with impaired renal function. Close monitoring of hematologic, renal, and hepatic status of all patients is essential.

Side effects requiring immediate medical attention

Along with its needed effects, flucytosine (the active ingredient contained in Ancobon) 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 while taking flucytosine:

More common

  • Skin rash, redness, or itching
  • sore throat and fever
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • yellow eyes or skin

Less common

  • Confusion
  • hallucinations (seeing, hearing, or feeling things that are not there)
  • increased sensitivity of skin to sunlight

Side effects not requiring immediate medical attention

Some side effects of flucytosine 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:

More common

Less common

For Healthcare Professionals

Applies to flucytosine: oral capsule


Frequency not reported: Cardiac arrest, myocardial toxicity, ventricular dysfunction, cardiac toxicity with ST elevation[Ref]


Frequency not reported: Rash, pruritus, urticaria, photosensitivity, Lyell's syndrome[Ref]


Frequency not reported: Nausea, vomiting/emesis, abdominal pain, diarrhea, dry mouth, duodenal ulcer, gastrointestinal hemorrhage/bleeding, enterocolitis, ulcerative colitis[Ref]


Frequency not reported: Crystalluria[Ref]


Frequency not reported: Anemia, agranulocytosis, aplastic anemia, eosinophilia, leukopenia, pancytopenia, thrombocytopenia, bone marrow aplasia (fatal cases), bone marrow toxicity[Ref]


Frequency not reported: Jaundice, hepatic dysfunction, elevated bilirubin, increased hepatic enzymes, acute hepatic injury, hepatic necrosis, hepatitis, alterations in liver function tests[Ref]

Acute hepatic injury including hepatic necrosis with possible fatal outcome in debilitated patients has been reported.

Alterations in liver function tests were generally dose related and reversible.[Ref]


Frequency not reported: Allergic reactions, anaphylaxis[Ref]


Frequency not reported: Anorexia, hypoglycemia, hypokalemia

Nervous system

Frequency not reported: Ataxia, hearing loss, headache, paresthesia, parkinsonism, peripheral neuropathy, vertigo, sedation, convulsions[Ref]


Frequency not reported: Pyrexia, fatigue, weakness[Ref]


Frequency not reported: Confusion, hallucinations, psychosis[Ref]


Frequency not reported: Azotemia, elevated creatinine, elevated BUN, renal failure[Ref]


Frequency not reported: Dyspnea, chest pain, respiratory arrest[Ref]


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2. "Product Information. Ancobon (flucytosine)." Roche Laboratories, Nutley, NJ.

3. Thompson GR 3rd, Cadena J, Patterson TF "Overview of antifungal agents." Clin Chest Med 30 (2009): 203-15, v

4. Stamm AM, Diasio RB, Dismukes WE, et al "Toxicity of amphotericin B plus flucytosine in 194 patients with cryptococcal meningitis." Am J Med 83 (1987): 236-42

5. Bennett JE, Dismukes WE, Duma RJ, et al "A comparison of amphotericin B alone and combined with flucytosine in the treatment of cryptococcal meningitis." N Engl J Med 301 (1979): 126-31

6. White CA, Traube J "Ulcerating enteritis associated with flucytosine therapy." Gastroenterology 83 (1982): 1127-9

7. Harder EJ, Hermans PE "Treatment of fungal infections with flucytosine." Arch Intern Med 135 (1975): 231-7

8. Kauffman CA, Frame PT "Bone marrow toxicity associated with 5-fluorocytosine therapy." Antimicrob Agents Chemother 11 (1977): 244-7

9. Wise GJ, Goldberg P, Kozinn PJ, Nawabi IU "Agranulocytosis associated with flucytosine for urinary candidiasis." Urology 8 (1976): 490-1

10. Record CO, Skinner JM, Sleight P, Speller DC "Candida endocarditis treated with 5-fluorocytosine." Br Med J 01/30/71 (1971): 262-4

11. Holdsworth SR, Atkins RC, Scott DF, Jackson R "Management of candida peritonitis by prolonged peritoneal lavage containing 5-fluorocytosine." Clin Nephrol 4 (1975): 157-9

12. Shelley WB, Sica PA Jr "Disseminate sporotrichosis of skin and bone cured with 5-fluorocytosine: photosensitivity as a complication." J Am Acad Dermatol 8 (1983): 229-35

13. Kotani S, Hirose S, Niiya K, et al "Anaphylaxis to flucytosine in a patient with AIDS." JAMA 260 (1988): 3275-6

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.