Mexiletine and Cimetidine Interaction
Drug interaction information between Mexiletine and Cimetidine.
Mexiletine and Cimetidine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Mexiletine and Cimetidine. 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
Cimetidine can change how your liver handles mexiletine, which might cause mexiletine levels to rise or fall.
What To Do
You should be monitored closely by your healthcare provider while taking these drugs together. Report any new symptoms or changes in how you feel to your doctor.
FDA Label Information
Concurrent administration of cimetidine and mexiletine has been reported to increase, decrease, or leave unchanged mexiletine plasma levels; therefore patients should be followed carefully during concurrent therapy.
Mexiletine Also Interacts With
- Lidocaine Topical moderate
- Propranolol minor
- Digoxin minor
- Propafenone minor
- Theophylline minor
Cimetidine Also Interacts With
- Levofloxacin major
- Posaconazole major
- Risperidone major
- Valproate major
- Empagliflozin moderate
Frequently Asked Questions
Can I take Mexiletine and Cimetidine together?
This is a minor interaction. You should be monitored closely by your healthcare provider while taking these drugs together. Report any new symptoms or changes in how you feel to your doctor.
How serious is the interaction between Mexiletine and Cimetidine?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Mexiletine and Cimetidine interact?
Cimetidine can change how your liver handles mexiletine, which might cause mexiletine levels to rise or fall.
Understanding the Mexiletine and Cimetidine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Mexiletine belongs to the Class IB Antiarrhythmic class and Cimetidine belongs to the H2 Receptor Antagonist class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Cimetidine can change how your liver handles mexiletine, which might cause mexiletine levels to rise or fall. 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. Mexiletine has 14 total documented interactions on file in this dataset, and Cimetidine has 77. 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: You should be monitored closely by your healthcare provider while taking these drugs 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 Mexiletine or Cimetidine 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.