Drug interactions
Phenytoin + Rivaroxaban
Severity: Major
Phenytoin and Rivaroxaban: 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
Phenytoin is a strong inducer of CYP3A4 and P-glycoprotein and can substantially reduce rivaroxaban exposure. This may result in subtherapeutic anticoagulation and thromboembolic events.
What this interaction means in plain words
Phenytoin and Rivaroxaban 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.
Phenytoin belongs to Central Nervous System; Rivaroxaban belongs to Cardiovascular.
Why it happens
Induction of CYP3A4 and P-glycoprotein increases rivaroxaban clearance.
What to do
Avoid the combination where possible and choose a non-inducing antiepileptic or a different anticoagulant. If unavoidable, monitor closely for thrombotic events.
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 Rivaroxaban
- Defibrotide + Rivaroxaban Contraindicated
- Ketoconazole + Rivaroxaban Contraindicated
- Ketorolac + Rivaroxaban Contraindicated
- Abciximab + Rivaroxaban Major
- Acalabrutinib + Rivaroxaban Major
- Acetylsalicylic acid + Rivaroxaban Major
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Phenytoin with Rivaroxaban?
MediHelp rates the interaction as major. Phenytoin and Rivaroxaban 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. Phenytoin is a strong inducer of CYP3A4 and P-glycoprotein and can substantially reduce rivaroxaban exposure. This may result in subtherapeutic anticoagulation and thromboembolic events.
How serious is the interaction between Phenytoin and Rivaroxaban?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible and choose a non-inducing antiepileptic or a different anticoagulant. If unavoidable, monitor closely for thrombotic events.
What other medicines interact with Rivaroxaban?
MediHelp also lists interactions of Rivaroxaban with, for example, Defibrotide, Ketoconazole, Ketorolac. The full list is on the Rivaroxaban page.
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