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Causality: well established
Causality assessment · Causality: well established
Fluconazole and QT prolongation / torsades: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Fluconazole ↔ QT prolongation / torsades
n=568 co-reports · PRR 4.8 · ROR 4.8
Fluconazole, an azole antifungal, prolongs the cardiac QT interval and carries a labelled warning, with rare reports of torsades de pointes, particularly at high doses and in patients already taking other QT-prolonging drugs. The effect is dose-related and is a genuine, mechanistically plausible cardiac toxicity rather than an idiosyncratic reaction. The 568 co-reports (PRR 4.8) reflect both the real effect and the drug's very wide use for common fungal infections.
Regulatory basis: fluconazole prescribing information (QT prolongation warning; caution with other QT-prolonging drugs).
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | QT prolongation is measured during therapy and resolves after withdrawal |
| Strength | partial | PRR 5 on a moderate co-report count |
| Consistency | met | Reproduced in ECG studies and case reports of torsades |
| Specificity | partial | A recognised azole effect, strongest for fluconazole |
| Biological gradient | partial | Dose-related and worse with other QT-prolonging drugs |
| Plausibility | met | hERG-channel blockade delays cardiac repolarisation |
| Coherence | met | Coheres with the labelled QT warning and drug-interaction cautions |
| Experiment | partial | Supported by ECG-based studies; no randomized arrhythmia RCT |
| Analogy | met | Analogous to QT risk with other azoles and QT-prolonging drugs |
This page's own qualitative read, not an automated/citation-gated assessment.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for fluconazole captured QT prolongation or torsades; the risk is characterised through ECG studies and case reports rather than a trial AE table.