Terbinafine and Fluconazole Interaction
Drug interaction information between Terbinafine and Fluconazole.
Terbinafine and Fluconazole have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Terbinafine and Fluconazole. 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
Fluconazole interferes with the way the body processes terbinafine, leading to higher amounts of terbinafine in the bloodstream.
What To Do
Your doctor may need to watch for increased side effects or adjust your terbinafine dose.
FDA Label Information
Drug interactions have also been noted with cimetidine, fluconazole, cyclosporine, rifampin, and caffeine. The influence of terbinafine on the pharmacokinetics of fluconazole, cotrimoxazole (trimethoprim and sulfamethoxazole), zidovudine or theophylline was not considered to be clinically significant. Coadministration of a single dose of fluconazole (100 mg) with a single dose of terbinafine resulted in a 52% and 69% increase in terbinafine C max and AUC, respectively.
Terbinafine Also Interacts With
- Tamsulosin moderate
- Ketoconazole minor
- Cyclosporine minor
- Trimethoprim minor
- Rifampin minor
Fluconazole Also Interacts With
- Pimozide major
- Clarithromycin major
- Eplerenone major
- Atorvastatin moderate
- Simvastatin moderate
Frequently Asked Questions
Can I take Terbinafine and Fluconazole together?
This is a minor interaction. Your doctor may need to watch for increased side effects or adjust your terbinafine dose.
How serious is the interaction between Terbinafine and Fluconazole?
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 Fluconazole interact?
Fluconazole interferes with the way the body processes terbinafine, leading to higher amounts of terbinafine in the bloodstream.
Understanding the Terbinafine and Fluconazole 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 Fluconazole belongs to the Azole Antifungal class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Fluconazole interferes with the way the body processes terbinafine, leading to higher amounts of terbinafine in the bloodstream. 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 Fluconazole has 67. 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 watch for increased side effects or adjust your terbinafine dose. 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 Fluconazole 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.