Drug interactions
Fluconazole + Foscarnet
Severity: Major
Fluconazole and Foscarnet: major interaction.
Last updated
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.
Summary
Both drugs have been associated with QT prolongation, and foscarnet causes electrolyte disturbances such as low calcium, magnesium and potassium that heighten arrhythmia risk. Foscarnet is also nephrotoxic, which may raise fluconazole levels since it is renally cleared.
What this interaction means in plain words
Fluconazole and Foscarnet can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Fluconazole belongs to Anti Fungals; Foscarnet belongs to Anti Virals.
Why it happens
Additive QT prolongation compounded by foscarnet-induced electrolyte disturbances and nephrotoxicity.
What to do
Monitor ECG, electrolytes and renal function closely, correcting deficits promptly. Adjust the fluconazole dose for renal impairment.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Fluconazole
- Dihydroergotamine intranasal + Fluconazole Contraindicated
- Dihydroergotamine + Fluconazole Contraindicated
- Dofetilide + Fluconazole Contraindicated
- Domperidone + Fluconazole Contraindicated
- Dronedarone + Fluconazole Contraindicated
- Erythromycin + Fluconazole Contraindicated
Other interactions of Foscarnet
- Cidofovir + Foscarnet Contraindicated
- Foscarnet + Pimozide Contraindicated
- Foscarnet + Thioridazine Contraindicated
- Foscarnet + Vandetanib Contraindicated
- Adagrasib + Foscarnet Major
- Adefovir + Foscarnet Major
Frequently asked questions
Can I take Fluconazole with Foscarnet?
MediHelp rates the interaction as major. Fluconazole and Foscarnet can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs have been associated with QT prolongation, and foscarnet causes electrolyte disturbances such as low calcium, magnesium and potassium that heighten arrhythmia risk. Foscarnet is also nephrotoxic, which may raise fluconazole levels since it is renally cleared.
How serious is the interaction between Fluconazole and Foscarnet?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor ECG, electrolytes and renal function closely, correcting deficits promptly. Adjust the fluconazole dose for renal impairment.
What other medicines interact with Fluconazole?
MediHelp also lists interactions of Fluconazole with, for example, Dihydroergotamine intranasal, Dihydroergotamine, Dofetilide. The full list is on the Fluconazole page.
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