Skip to main content
PlainMeds

What the label lists and what reports show

Flucytosine side effects

Flucytosine's FDA label lists its adverse reactions in its own words. FAERS holds 1,369 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is immune reconstitution inflammatory syndrome (103 reports).

  • Generic listed
  • Boxed warning

Check it at the source: the flucytosine FDA label on DailyMed (effective February 2, 2022, Bausch Health US LLC); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

The adverse reactions which have occurred during treatment with ANCOBON are grouped according to organ system affected. Cardiovascular: Cardiac arrest, myocardial toxicity, ventricular dysfunction. Respiratory: Respiratory arrest, chest pain, dyspnea. Dermatologic: Rash, pruritus, urticaria, photosensitivity. Gastrointestinal: Nausea, emesis, abdominal pain, diarrhea, anorexia, dry mouth, duodenal ulcer, gastrointestinal hemorrhage, acute hepatic injury including hepatic necrosis with possible fatal outcome in debilitated patients, hepatic dysfunction, jaundice, ulcerative colitis, enterocolitis, bilirubin elevation, increased hepatic enzymes. Genitourinary: Azotemia, creatinine and BUN elevation, crystalluria, renal failure. Hematologic: Anemia, agranulocytosis, aplastic anemia, eosinophilia, leukopenia, pancytopenia, thrombocytopenia, and fatal cases of bone marrow aplasia. …

Source: FDA drug label, Bausch Health US LLC, effective February 2, 2022 (SPL set aea0df00-a88c-4a16-abcf-750f3ff2004e), via openFDA; the full label on DailyMed

What do FAERS reports show?

1,369 reports list flucytosine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 486 are coded as a death and 628 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 18 reactions below, 7 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

Reports received each year

The 25 most reported reactions

  • Drug Ineffective (a use or a product term, not a reaction)452
  • Off Label Use (a use or a product term, not a reaction)133
  • Immune Reconstitution Inflammatory Syndrome103
  • Meningitis Cryptococcal92
  • Acute Kidney Injury87
  • Renal Impairment (named in the label)77
  • Condition Aggravated (a use or a product term, not a reaction)73
  • Cryptococcosis (a use or a product term, not a reaction)61
  • Disseminated Cryptococcosis61
  • Pyrexia (named in the label)58
  • Headache (named in the label)57
  • Renal Failure (named in the label)57
  • Drug Interaction (a use or a product term, not a reaction)49
  • Drug Ineffective For Unapproved Indication (a use or a product term, not a reaction)47
  • Neutropenia46
  • Drug Resistance41
  • Vomiting41
  • Pancytopenia (named in the label)38
  • Nausea (named in the label)37
  • Toxicity To Various Agents37
  • Respiratory Failure36
  • Treatment Failure (a use or a product term, not a reaction)33
  • Ischaemic Stroke31
  • Cerebral Infarction29
  • Hypokalaemia (named in the label)29

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Flucytosine: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions