Diazepam and Ketoconazole Interaction
Drug interaction information between Diazepam and Ketoconazole.
Diazepam and Ketoconazole have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Diazepam and Ketoconazole. 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
Ketoconazole stops the body from breaking down diazepam normally. This can cause diazepam to build up in your system.
What To Do
Tell your doctor if you feel overly tired, as they may need to lower your diazepam dose.
FDA Label Information
At present, this reaction is known to occur with cimetidine, ketoconazole, fluvoxamine, fluoxetine, and omeprazole.
Diazepam Also Interacts With
- Clonazepam moderate
- Fluoxetine moderate
- Mirtazapine moderate
- Raloxifene moderate
- Omeprazole minor
Ketoconazole Also Interacts With
- Alfuzosin major
- Dronedarone major
- Ranolazine major
- Saxagliptin major
- Sildenafil major
Frequently Asked Questions
Can I take Diazepam and Ketoconazole together?
This is a minor interaction. Tell your doctor if you feel overly tired, as they may need to lower your diazepam dose.
How serious is the interaction between Diazepam and Ketoconazole?
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 Diazepam and Ketoconazole interact?
Ketoconazole stops the body from breaking down diazepam normally. This can cause diazepam to build up in your system.
Understanding the Diazepam and Ketoconazole Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Diazepam belongs to the Benzodiazepine class and Ketoconazole belongs to the Azole Antifungal class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Ketoconazole stops the body from breaking down diazepam normally. 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. Diazepam has 26 total documented interactions on file in this dataset, and Ketoconazole has 113. 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: Tell your doctor if you feel overly tired, as they may need to lower your diazepam 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 Diazepam or Ketoconazole 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.