Theophylline and Metronidazole Interaction
Drug interaction information between Theophylline and Metronidazole.
Theophylline and Metronidazole have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Theophylline and Metronidazole. 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
Metronidazole may reduce the speed at which your liver clears theophylline from your blood. This can cause the drug to reach levels that are toxic to your body.
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
Metronidazole Also Interacts With
- Lithium minor
- Disulfiram minor
- Cimetidine minor
- Phenytoin minor
- Phenobarbital minor
Frequently Asked Questions
What SPL severity band is on file for Theophylline + Metronidazole?
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?
Theophylline has 86 labeled pairs on file vs Metronidazole's 10. In the major band specifically: Theophylline has 27 (also Metoprolol, Albuterol, Omeprazole, Amoxicillin); Metronidazole has 1.
What mechanism field is on file for Theophylline and Metronidazole?
Metronidazole may reduce the speed at which your liver clears theophylline from your blood. This can cause the drug to reach levels that are toxic to your body.
Theophylline carries more major-labeled pairs than Metronidazole
SPL source-record counts only. This page's band is major · classes on file: Theophylline (Methylxanthine Bronchodilator); Metronidazole (Nitroimidazole Antibiotic).
Theophylline has 27 major-labeled pairs vs Metronidazole's 1.
27 major · 5 moderate · 54 minor · 86 total
- Other major peers for Theophylline
- Metoprolol
- Albuterol
- Omeprazole
- Amoxicillin
1 major · 0 moderate · 9 minor · 10 total
Metronidazole has no other major-band peer in this dataset besides Theophylline.
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.