Drug interactions
Itraconazole + Warfarin
Severity: Major
Itraconazole and Warfarin: major interaction.
Last updated Sources: US FDA label
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
Itraconazole can enhance warfarin's anticoagulant effect, raising INR and bleeding risk. Cases of marked INR elevation have been reported.
What this interaction means in plain words
Itraconazole and Warfarin 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.
Itraconazole belongs to Anti Fungals; Warfarin belongs to Cardiovascular.
Why it happens
Inhibition of CYP3A4 metabolism of the R-enantiomer of warfarin.
What to do
Check INR within a few days of starting or stopping itraconazole and adjust the warfarin dose accordingly. Counsel the patient on bleeding signs.
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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References
Other interactions of Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Frequently asked questions
Can I take Itraconazole with Warfarin?
MediHelp rates the interaction as major. Itraconazole and Warfarin 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. Itraconazole can enhance warfarin's anticoagulant effect, raising INR and bleeding risk. Cases of marked INR elevation have been reported.
How serious is the interaction between Itraconazole and Warfarin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR within a few days of starting or stopping itraconazole and adjust the warfarin dose accordingly. Counsel the patient on bleeding signs.
What other medicines interact with Itraconazole?
MediHelp also lists interactions of Itraconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Itraconazole page.
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