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Flucytosine Side Effects

The most commonly reported side effects of flucytosine include off label use, immune reconstitution inflammatory syndrome, and acute kidney injury, based on 1,353 FDA adverse event reports from 2004 to 2025. 30.2% of reports found the drug to be ineffective.

Flucytosine side effects

Percentages show how often each reaction appears relative to total reports for flucytosine.

1
Drug Ineffective30.2%408
2
Off Label Use9.1%123
3
Immune Reconstitution Inflammatory Syndrome7.7%104
4
Acute Kidney Injury6.4%87
5
Meningitis Cryptococcal6.1%83
6
Renal Impairment4.9%66
7
Condition Aggravated4.6%62
8
Disseminated Cryptococcosis4.1%55
9
Renal Failure4.0%54
10
Cryptococcosis3.9%53
11
Drug Interaction3.6%49
12
Pyrexia3.5%47
13
Headache3.2%43
14
Neutropenia3.1%42
15
Drug Ineffective For Unapproved Indication3.1%42

These are voluntary reports and do not establish that flucytosine caused these reactions.

Report severity

95.7%Serious1,295 reports
44.1%Hospitalizations596 reports
33.9%Fatal458 reports

Seriousness is determined by the reporter, not by OpenClaim.

Flucytosine drug interactions

Other drugs that appear in adverse event reports alongside flucytosine. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Amphotericin-b53.3%721
2
Fluconazole26.8%363
3
Tacrolimus11.1%150
4
Voriconazole8.8%119
5
Mycophenolate8.1%109
6
Prednisone7.8%105
7
Dexamethasone5.5%75
8
Prednisolone4.8%65
9
Caspofungin-acetate4.4%59
10
Miltefosine4.4%59
11
Micafungin-sodium4.1%55
12
Posaconazole4.0%54
13
Azithromycin4.0%54
14
Vancomycin3.8%51
15
Methylprednisolone3.8%51

Taken alongside

1
Amphotericin-b24.5%331
2
Fluconazole16.0%217
3
Voriconazole7.0%95
4
Prednisone7.0%95
5
Dexamethasone6.5%88
6
Vancomycin4.3%58
7
Azithromycin4.2%57
8
Sulfamethoxazole3.3%45
9
Ceftriaxone-sodium3.3%45
10
Tacrolimus3.3%44
11
Meropenem3.2%43
12
Prednisolone3.1%42
13
Amoxicillin2.9%39
14
Caspofungin-acetate2.7%36
15
Micafungin-sodium2.6%35

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports flucytosine side effects

34.1% of flucytosine adverse event reports involve female patients and 59.1% involve male patients. The largest age group is adult at 66%. These figures reflect who reports side effects, not underlying risk.

Sex

Female34.1%
Male59.1%
Unknown6.9%

Age group

< 21.1%
2–114.3%
12–173.0%
18–6465.7%
65+26.0%

What is flucytosine used for

Conditions and purposes for which patients were taking flucytosine when the adverse event was reported.

Acanthamoeba InfectionAcquired Immunodeficiency SyndromeAcute LeukaemiaAcute Lymphocytic LeukaemiaAcute Myeloid LeukaemiaAmoebic Brain AbscessAntibiotic TherapyAntifungal TreatmentAspergillosisAspergillus InfectionAcanthamoeba InfectionAcanthamoeba KeratitisAcinetobacter InfectionAcute Lymphocytic Leukaemia RecurrentAcute Myeloid Leukaemia Recurrent

Showing 15 of 176 indications

Flucytosine brand names and reporting trend

Flucytosine is sold under the brand name Ancobon.

Brand names

Ancobon1,583

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking flucytosine with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.