Ketoconazole and Alfuzosin Interaction
Drug interaction information between Ketoconazole and Alfuzosin.
Ketoconazole and Alfuzosin have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Ketoconazole and Alfuzosin. 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 blocks the enzyme that breaks down alfuzosin, which causes the amount of alfuzosin in your blood to rise to unsafe levels.
What To Do
Do not take these two medicines together as the combination is unsafe.
FDA Label Information
7 DRUG INTERACTIONS Concomitant use of PDE5 inhibitors with alpha adrenergic antagonists, including alfuzosin hydrochloride extended-release tablets, can potentially cause symptomatic hypotension ( 5.4 , 7.4) 7.1 CYP3A4 Inhibitors Alfuzosin hydrochloride extended-release tablets are contraindicated for use with potent CYP3A4 inhibitors such as ketoconazole, itraconazole, or ritonavir, since alfuzosin blood levels are increased [see Contraindications ( 4 ), Warnings and Precautions ( 5.4) and Clinical Pharmacology ( 12.3) ].
Ketoconazole Also Interacts With
- Dronedarone major
- Ranolazine major
- Saxagliptin major
- Sildenafil major
- Theophylline major
Alfuzosin Also Interacts With
- Darunavir major
- Nirmatrelvir/Ritonavir major
- Itraconazole moderate
- Tadalafil minor
Frequently Asked Questions
Can I take Ketoconazole and Alfuzosin together?
This is a major interaction. Do not take these two medicines together as the combination is unsafe.
How serious is the interaction between Ketoconazole and Alfuzosin?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Ketoconazole and Alfuzosin interact?
Ketoconazole blocks the enzyme that breaks down alfuzosin, which causes the amount of alfuzosin in your blood to rise to unsafe levels.
Understanding the Ketoconazole and Alfuzosin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Ketoconazole belongs to the Azole Antifungal class and Alfuzosin belongs to the Alpha-1 Blocker (BPH) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Ketoconazole blocks the enzyme that breaks down alfuzosin, which causes the amount of alfuzosin in your blood to rise to unsafe levels. 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. Ketoconazole has 113 total documented interactions on file in this dataset, and Alfuzosin has 5. 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 medicines together as the combination is unsafe. 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 Ketoconazole or Alfuzosin 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.