Drug interactions
Carbamazepine + Warfarin
Severity: Moderate
Carbamazepine 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
Carbamazepine induces hepatic enzymes and reduces warfarin effect, lowering INR and increasing thrombotic risk. The effect develops over weeks and reverses slowly after carbamazepine is stopped.
What this interaction means in plain words
Carbamazepine 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.
Carbamazepine belongs to Central Nervous System; Warfarin belongs to Cardiovascular.
Why it happens
Induction of CYP2C9, CYP3A4 and CYP1A2 by carbamazepine accelerates warfarin clearance.
What to do
Monitor INR frequently when carbamazepine is started, changed or stopped, and raise the warfarin dose as needed. Reduce the dose again with INR monitoring if carbamazepine is withdrawn.
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 Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir Contraindicated
Frequently asked questions
Can I take Carbamazepine with Warfarin?
MediHelp rates the interaction as moderate. Carbamazepine 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. Carbamazepine induces hepatic enzymes and reduces warfarin effect, lowering INR and increasing thrombotic risk. The effect develops over weeks and reverses slowly after carbamazepine is stopped.
How serious is the interaction between Carbamazepine 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 frequently when carbamazepine is started, changed or stopped, and raise the warfarin dose as needed. Reduce the dose again with INR monitoring if carbamazepine is withdrawn.
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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