Drug interactions
Fluconazole + Moxifloxacin
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Overview
Additive QTc prolongation with risk of torsades de pointes; pharmacodynamic interaction. Pharmacokinetic interaction is unlikely.
Mechanism of action
Additive QTc prolongation via IKr (hERG) blockade; both agents have known risk for QT prolongation. Moxifloxacin is not a significant CYP substrate, so PK interaction with fluconazole’s CYP inhibition is minimal.
Clinical management
Avoid combination when possible. If necessary, obtain baseline and follow-up ECGs; correct and maintain electrolytes (e.g., K >4 mEq/L, Mg >2 mg/dL); avoid additional QT-prolonging drugs; monitor for syncope/palpitations. Discontinue/modify therapy if QTc ≥500 ms or increases >60 ms from baseline.
Drug reference
References
- Fluconazole (Diflucan) Prescribing Information — FDA Label
- Avelox (moxifloxacin) Prescribing Information — FDA Label
- QTDrugs Lists: Fluconazole; Moxifloxacin (Known Risk of Torsades de Pointes) — CredibleMeds
- Fluconazole and Moxifloxacin: Drug Interactions Monograph — Lexicomp
Frequently asked questions
Can I take Fluconazole with Moxifloxacin?
The interaction is rated: Major. Additive QTc prolongation with risk of torsades de pointes; pharmacodynamic interaction. Pharmacokinetic interaction is unlikely.
How serious is the interaction between Fluconazole and Moxifloxacin?
The interaction is rated: Major. Evidence level: Moderate.
How is the interaction between Fluconazole and Moxifloxacin managed?
Avoid combination when possible. If necessary, obtain baseline and follow-up ECGs; correct and maintain electrolytes (e.g., K >4 mEq/L, Mg >2 mg/dL); avoid additional QT-prolonging drugs; monitor for syncope/palpitations. Discontinue/modify therapy if QTc ≥500 ms or increases >60 ms from baseline.
Why do Fluconazole and Moxifloxacin interact?
Additive QTc prolongation via IKr (hERG) blockade; both agents have known risk for QT prolongation. Moxifloxacin is not a significant CYP substrate, so PK interaction with fluconazole’s CYP inhibition is minimal.
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