Theophylline and Ketoconazole Interaction
Drug interaction information between Theophylline and Ketoconazole.
Theophylline and Ketoconazole have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Theophylline 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
Ketoconazole can slow down the liver's ability to process theophylline. This can cause the medicine to build up in your body to unsafe levels.
FDA Label Information
albuterol, systemic and inhaled mebendazole amoxicillin medroxyprogesterone ampicillin, with or without sulbactam methylprednisolone atenolol metronidazole azithromycin metoprolol caffeine, dietary ingestion nadolol cefaclor nifedipine co-trimoxazole (trimethoprim and sulfamethoxazole) nizatidine diltiazem norfloxacin dirithromycin ofloxacin enflurane omeprazole famotidine prednisone, prednisolone felodipine ranitidine finasteride rifabutin hydrocortisone roxithromycin isoflurane Sorbitol (purgative doses do not inhibit theophylline absorption) isoniazid sucralfate isradipine terbutaline,...
Theophylline Also Interacts With
- Metoprolol major
- Albuterol major
- Omeprazole major
- Amoxicillin major
- Famotidine major
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 Theophylline + Ketoconazole?
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 Theophylline's 86. In the major band specifically: Theophylline has 27 (also Metoprolol, Albuterol, Omeprazole, Amoxicillin); Ketoconazole has 6 (also Alfuzosin, Dronedarone, Ranolazine, Saxagliptin).
What mechanism field is on file for Theophylline and Ketoconazole?
Ketoconazole can slow down the liver's ability to process theophylline. This can cause the medicine to build up in your body to unsafe levels.
Theophylline carries more major-labeled pairs than Ketoconazole
SPL source-record counts only. This page's band is major · classes on file: Theophylline (Methylxanthine Bronchodilator); Ketoconazole (Azole Antifungal).
Theophylline has 27 major-labeled pairs vs Ketoconazole's 6.
27 major · 5 moderate · 54 minor · 86 total
- Other major peers for Theophylline
- Metoprolol
- Albuterol
- Omeprazole
- Amoxicillin
6 major · 22 moderate · 85 minor · 113 total
- Other major peers for Ketoconazole
- Alfuzosin
- Dronedarone
- Ranolazine
- Saxagliptin
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.