Darifenacin and Flecainide Interaction
Drug interaction information between Darifenacin and Flecainide.
Darifenacin and Flecainide have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Darifenacin and Flecainide. 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
Darifenacin interferes with the enzyme that clears flecainide from your system. This can cause the heart medicine to reach high levels in your body that could be toxic.
What To Do
Your doctor should use caution when prescribing these together. They may need to monitor your heart rhythm or adjust your medication dose.
FDA Label Information
7 DRUG INTERACTIONS Caution should be taken when darifenacin extended-release tablets are used concomitantly with medications that are predominantly metabolized by CYP2D6 and which have a narrow therapeutic window, such as flecainide, thioridazine and tricyclic antidepressants ( 7.2 ) The concomitant use of darifenacin extended-release tablets with other anticholinergic agents may increase the frequency and/or severity of dry mouth, constipation, blurred vision and other anticholinergic pharmacological effects. 7.3 CYP2D6 Substrates Caution should be taken when darifenacin extended-release...
Darifenacin Also Interacts With
- Thioridazine moderate
- Itraconazole moderate
- Fluoxetine minor
- Duloxetine minor
- Estradiol minor
Flecainide Also Interacts With
- Nirmatrelvir/Ritonavir major
- Fluoxetine moderate
- Propranolol minor
- Diltiazem minor
- Nifedipine minor
Frequently Asked Questions
Can I take Darifenacin and Flecainide together?
This is a moderate interaction. Your doctor should use caution when prescribing these together. They may need to monitor your heart rhythm or adjust your medication dose.
How serious is the interaction between Darifenacin and Flecainide?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Darifenacin and Flecainide interact?
Darifenacin interferes with the enzyme that clears flecainide from your system. This can cause the heart medicine to reach high levels in your body that could be toxic.
Understanding the Darifenacin and Flecainide Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Darifenacin belongs to the Anticholinergic (Overactive Bladder) class and Flecainide belongs to the Class IC Antiarrhythmic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Darifenacin interferes with the enzyme that clears flecainide from your system. 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. Darifenacin has 18 total documented interactions on file in this dataset, and Flecainide has 22. 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: Your doctor should use caution when prescribing these together. 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 Darifenacin or Flecainide 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.