Canagliflozin and Phenytoin Interaction
Drug interaction information between Canagliflozin and Phenytoin.
Canagliflozin and Phenytoin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Canagliflozin and Phenytoin. 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 can cause your body to process canagliflozin more quickly, which may lower the amount of medicine in your system.
What To Do
Your doctor may need to monitor your blood sugar more closely or adjust your dose of canagliflozin.
FDA Label Information
Examples: Rifampin, phenytoin, phenobarbital, ritonavir Insulin or Insulin Secretagogues Clinical Impact: The risk of hypoglycemia is increased when INVOKANA is used concomitantly with insulin secretagogues (e.g., sulfonylurea) or insulin.
Canagliflozin Also Interacts With
- Rifampin moderate
- Phenobarbital moderate
- Lithium minor
- Digoxin minor
Phenytoin Also Interacts With
- Nirmatrelvir/Ritonavir major
- Posaconazole major
- Ranolazine major
- Voriconazole major
- Apixaban moderate
Frequently Asked Questions
Can I take Canagliflozin and Phenytoin together?
This is a moderate interaction. Your doctor may need to monitor your blood sugar more closely or adjust your dose of canagliflozin.
How serious is the interaction between Canagliflozin and Phenytoin?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Canagliflozin and Phenytoin interact?
Phenytoin can cause your body to process canagliflozin more quickly, which may lower the amount of medicine in your system.
Understanding the Canagliflozin and Phenytoin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Canagliflozin belongs to the SGLT2 Inhibitor class and Phenytoin belongs to the Anticonvulsant (Hydantoin) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Phenytoin can cause your body to process canagliflozin more quickly, which may lower the amount of medicine in your system. 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. Canagliflozin has 5 total documented interactions on file in this dataset, and Phenytoin has 147. 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: Your doctor may need to monitor your blood sugar more closely or adjust your dose of canagliflozin. 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 Canagliflozin or Phenytoin 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.