Theophylline and Felodipine Interaction
Drug interaction information between Theophylline and Felodipine.
Theophylline and Felodipine have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Theophylline and Felodipine. 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
This blood pressure drug does not change the amount of theophylline that stays in your blood or how the liver handles it.
What To Do
No dosage adjustment is typically required, but you should still report any unusual symptoms to your healthcare provider.
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
Felodipine Also Interacts With
- Itraconazole major
- Nirmatrelvir/Ritonavir moderate
- Metoprolol minor
- Spironolactone minor
- Ketoconazole minor
Frequently Asked Questions
Can I take Theophylline and Felodipine together?
This is a major interaction. No dosage adjustment is typically required, but you should still report any unusual symptoms to your healthcare provider.
How serious is the interaction between Theophylline and Felodipine?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Theophylline and Felodipine interact?
This blood pressure drug does not change the amount of theophylline that stays in your blood or how the liver handles it.
Understanding the Theophylline and Felodipine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Theophylline belongs to the Methylxanthine Bronchodilator class and Felodipine belongs to the Calcium Channel Blocker class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: This blood pressure drug does not change the amount of theophylline that stays in your blood or how the liver handles it. 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. Theophylline has 86 total documented interactions on file in this dataset, and Felodipine has 18. 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: No dosage adjustment is typically required, but you should still report any unusual symptoms to your healthcare provider. 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 Theophylline or Felodipine 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.