Drug interactions
fluconazole + ketoconazole
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 QT-prolongation risk and increased ketoconazole exposure from CYP3A4 inhibition by fluconazole; higher risk of torsades and hepatotoxicity.
Mechanism of action
Fluconazole inhibits CYP3A4 → ↑ ketoconazole levels; both agents can prolong QT and are hepatotoxic.
Clinical management
Avoid combined systemic use. If unavoidable, assess QT risk, correct electrolytes, consider baseline/periodic ECGs, and monitor LFTs closely; use lowest effective doses and consider alternative single-agent therapy.
Drug reference
Frequently asked questions
Can I take fluconazole with ketoconazole?
The interaction is rated: Major. Additive QT-prolongation risk and increased ketoconazole exposure from CYP3A4 inhibition by fluconazole; higher risk of torsades and hepatotoxicity.
How serious is the interaction between fluconazole and ketoconazole?
The interaction is rated: Major. Evidence level: Moderate.
How is the interaction between fluconazole and ketoconazole managed?
Avoid combined systemic use. If unavoidable, assess QT risk, correct electrolytes, consider baseline/periodic ECGs, and monitor LFTs closely; use lowest effective doses and consider alternative single-agent therapy.
Why do fluconazole and ketoconazole interact?
Fluconazole inhibits CYP3A4 → ↑ ketoconazole levels; both agents can prolong QT and are hepatotoxic.
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