Fentanyl and Ketoconazole Interaction
Drug interaction information between Fentanyl and Ketoconazole.
Fentanyl and Ketoconazole have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Fentanyl and Ketoconazole. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
This combination can change how your body processes fentanyl, which may lower the amount of medicine in your blood. This can make the pain relief less effective or cause withdrawal symptoms.
FDA Label Information
ketoconazole), protease inhibitors (e.g., ritonavir), grapefruit juice CYP3A4 Inducers Clinical Impact: The concomitant use of Fentanyl Citrate Injection and CYP3A4 inducers can decrease the plasma concentration of fentanyl [see Clinical Pharmacology ( 12.3 )] , resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to fentanyl [see Warnings and Precautions ( 5.4 )] .
Fentanyl Also Interacts With
- Itraconazole moderate
- Tranylcypromine moderate
- Tramadol minor
- Cyclobenzaprine minor
- Diazepam minor
Ketoconazole Also Interacts With
- Alfuzosin major
- Dronedarone major
- Ranolazine major
- Saxagliptin major
- Sildenafil major
Frequently Asked Questions
What SPL severity band is on file for Fentanyl + Ketoconazole?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Ketoconazole has 113 labeled pairs on file vs Fentanyl's 28. In the minor band specifically: Fentanyl has 26 (also Tramadol, Cyclobenzaprine, Diazepam, Carbamazepine); Ketoconazole has 85 (also Abiraterone, Acetaminophen/Oxycodone, Alosetron, Amphotericin B).
What mechanism field is on file for Fentanyl and Ketoconazole?
This combination can change how your body processes fentanyl, which may lower the amount of medicine in your blood. This can make the pain relief less effective or cause withdrawal symptoms.
Ketoconazole carries more major-labeled pairs than Fentanyl
SPL source-record counts only. This page's band is minor · classes on file: Fentanyl (Opioid Analgesic); Ketoconazole (Azole Antifungal).
Ketoconazole has 6 major-labeled pairs vs Fentanyl's 0. This page itself is in the minor band, not the major band.
0 major · 2 moderate · 26 minor · 28 total
- Other minor peers for Fentanyl
- Tramadol
- Cyclobenzaprine
- Diazepam
- Carbamazepine
6 major · 22 moderate · 85 minor · 113 total
- Other minor peers for Ketoconazole
- Abiraterone
- Acetaminophen/Oxycodone
- Alosetron
- Amphotericin B
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.