Drug interactions
Fluoxetine + Warfarin
Severity: Moderate
Fluoxetine and Warfarin: moderate 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
Fluoxetine increases bleeding risk in patients on warfarin and may raise the INR. Gastrointestinal and other bleeding is more likely when other bleeding-risk drugs are also taken.
What this interaction means in plain words
Fluoxetine and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fluoxetine belongs to Central Nervous System; Warfarin belongs to Cardiovascular.
Why it happens
Fluoxetine impairs platelet serotonin-dependent aggregation and inhibits CYP2C9 and CYP3A4, which can reduce warfarin clearance.
What to do
Monitor INR more often when starting, adjusting or stopping fluoxetine, and counsel on bleeding signs. Reduce the warfarin dose if the INR rises.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin Major
Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Frequently asked questions
Can I take Fluoxetine with Warfarin?
MediHelp rates the interaction as moderate. Fluoxetine and Warfarin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fluoxetine increases bleeding risk in patients on warfarin and may raise the INR. Gastrointestinal and other bleeding is more likely when other bleeding-risk drugs are also taken.
How serious is the interaction between Fluoxetine and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor INR more often when starting, adjusting or stopping fluoxetine, and counsel on bleeding signs. Reduce the warfarin dose if the INR rises.
What other medicines interact with Warfarin?
MediHelp also lists interactions of Warfarin with, for example, Defibrotide, Ketorolac, Abciximab. The full list is on the Warfarin page.
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