Phenytoin and Apixaban Interaction
Drug interaction information between Phenytoin and Apixaban.
Phenytoin and Apixaban have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Phenytoin and Apixaban. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Phenytoin causes your body to get rid of apixaban much faster than it should. This means the medicine may not work well enough to stop blood clots from forming.
What To Do
Avoid using these two medicines together and ask your doctor for an alternative medication.
FDA Label Information
7.2 Combined P-gp Strong CYP3A4 Inducers Avoid concomitant use of apixaban tablets with combined P-gp and strong CYP3A4 Inducers (e.g., rifampin, carbamazepine, phenytoin, St.
Phenytoin Also Interacts With
- Nirmatrelvir/Ritonavir major
- Posaconazole major
- Ranolazine major
- Voriconazole major
- Aprepitant moderate
Apixaban Also Interacts With
- Clopidogrel moderate
- Aspirin moderate
- Warfarin moderate
- Carbamazepine moderate
- Rifampin moderate
Frequently Asked Questions
Can I take Phenytoin and Apixaban together?
This is a moderate interaction. Avoid using these two medicines together and ask your doctor for an alternative medication.
How serious is the interaction between Phenytoin and Apixaban?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Phenytoin and Apixaban interact?
Phenytoin causes your body to get rid of apixaban much faster than it should. This means the medicine may not work well enough to stop blood clots from forming.
Understanding the Phenytoin and Apixaban Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Phenytoin belongs to the Anticonvulsant (Hydantoin) class and Apixaban belongs to the Direct Oral Anticoagulant (Factor Xa Inhibitor) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Phenytoin causes your body to get rid of apixaban much faster than it should. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Phenytoin has 147 total documented interactions on file in this dataset, and Apixaban has 12. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Avoid using these two medicines together and ask your doctor for an alternative medication. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Phenytoin or Apixaban based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.