Terbinafine and Rifampin Interaction
Drug interaction information between Terbinafine and Rifampin.
Terbinafine and Rifampin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Terbinafine and Rifampin. 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
Rifampin triggers the body to break down terbinafine twice as fast as usual.
What To Do
Your doctor may need to adjust your terbinafine dose to ensure the treatment remains effective.
FDA Label Information
Drug interactions have also been noted with cimetidine, fluconazole, cyclosporine, rifampin, and caffeine. Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor.
Terbinafine Also Interacts With
- Tamsulosin moderate
- Ketoconazole minor
- Fluconazole minor
- Cyclosporine minor
- Trimethoprim minor
Rifampin Also Interacts With
- Darunavir major
- Bictegravir/Emtricitabine/Tenofovir major
- Glecaprevir/Pibrentasvir major
- Nirmatrelvir/Ritonavir major
- Pitavastatin major
Frequently Asked Questions
Can I take Terbinafine and Rifampin together?
This is a minor interaction. Your doctor may need to adjust your terbinafine dose to ensure the treatment remains effective.
How serious is the interaction between Terbinafine and Rifampin?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Terbinafine and Rifampin interact?
Rifampin triggers the body to break down terbinafine twice as fast as usual.
Understanding the Terbinafine and Rifampin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Terbinafine belongs to the Allylamine Antifungal class and Rifampin belongs to the Rifamycin Antibiotic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Rifampin triggers the body to break down terbinafine twice as fast as usual. 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. Terbinafine has 17 total documented interactions on file in this dataset, and Rifampin has 137. 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 adjust your terbinafine dose to ensure the treatment remains effective. 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 Terbinafine or Rifampin 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.