Ranolazine and Phenobarbital Interaction
Drug interaction information between Ranolazine and Phenobarbital.
Ranolazine and Phenobarbital have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Ranolazine and Phenobarbital. 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
Phenobarbital triggers your liver to process ranolazine too quickly, meaning there won't be enough medicine in your blood.
What To Do
Do not take these two drugs together.
FDA Label Information
CYP3A Inducers Do not use ranolazine with CYP3A inducers such as rifampin, rifabutin, rifapentine, phenobarbital, phenytoin, carbamazepine, and St.
Ranolazine Also Interacts With
- Ketoconazole major
- Carbamazepine major
- Clarithromycin major
- Rifampin major
- Phenytoin major
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
- Clarithromycin moderate
Frequently Asked Questions
Can I take Ranolazine and Phenobarbital together?
This is a major interaction. Do not take these two drugs together.
How serious is the interaction between Ranolazine and Phenobarbital?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Ranolazine and Phenobarbital interact?
Phenobarbital triggers your liver to process ranolazine too quickly, meaning there won't be enough medicine in your blood.
Understanding the Ranolazine and Phenobarbital Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Ranolazine belongs to the Late Sodium Current Inhibitor (Antianginal) class and Phenobarbital belongs to the Anticonvulsant (Barbiturate) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Phenobarbital triggers your liver to process ranolazine too quickly, meaning there won't be enough medicine in your blood. 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. Ranolazine has 31 total documented interactions on file in this dataset, and Phenobarbital has 59. 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: Do not take these two drugs together. 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 Ranolazine or Phenobarbital 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.