Ketoconazole and Sildenafil Interaction
Drug interaction information between Ketoconazole and Sildenafil.
Ketoconazole and Sildenafil have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Ketoconazole and Sildenafil. 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
Ketoconazole slows down the breakdown of sildenafil, which can lead to higher levels of the drug in your system.
FDA Label Information
7 DRUG INTERACTIONS Sildenafil can potentiate the hypotensive effects of nitrates, alpha blockers, and anti-hypertensives ( 4.1 , 5.5 , 7.1 , 7.2 , 7.3 , 12.2 ) With concomitant use of alpha blockers, initiate sildenafil at 25 mg dose ( 2.3 ) CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase sildenafil exposure ( 2.4 , 7.4 , 12.3 ) Ritonavir: Do not exceed a maximum single dose of 25 mg in a 48 hour period ( 2.4 , 5.6 ) Erythromycin or strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, saquinavir): Consider a starting dose of 25 mg ( 2.4 , 7.4...
Ketoconazole Also Interacts With
- Alfuzosin major
- Dronedarone major
- Ranolazine major
- Saxagliptin major
- Theophylline major
Sildenafil Also Interacts With
- Erythromycin major
- Itraconazole major
- Darunavir major
- Hydralazine/Isosorbide Dinitrate major
- Nirmatrelvir/Ritonavir major
Frequently Asked Questions
What SPL severity band is on file for Ketoconazole + Sildenafil?
Compiled FDA labeling labels this pair major. 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 Sildenafil's 10. In the major band specifically: Ketoconazole has 6 (also Alfuzosin, Dronedarone, Ranolazine, Saxagliptin); Sildenafil has 6 (also Erythromycin, Itraconazole, Darunavir, Hydralazine).
What mechanism field is on file for Ketoconazole and Sildenafil?
Ketoconazole slows down the breakdown of sildenafil, which can lead to higher levels of the drug in your system.
Ketoconazole's labeled portfolio outnumbers Sildenafil
SPL source-record counts only. This page's band is major · classes on file: Ketoconazole (Azole Antifungal); Sildenafil (PDE5 Inhibitor).
6 major · 22 moderate · 85 minor · 113 total
- Other major peers for Ketoconazole
- Alfuzosin
- Dronedarone
- Ranolazine
- Saxagliptin
6 major · 1 moderate · 3 minor · 10 total
- Other major peers for Sildenafil
- Erythromycin
- Itraconazole
- Darunavir
- Hydralazine
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.