Diltiazem and Simvastatin Interaction
Drug interaction information between Diltiazem and Simvastatin.
Diltiazem and Simvastatin have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Diltiazem and Simvastatin. 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
Diltiazem blocks the enzymes that break down simvastatin, causing the drug to stay in your body longer. This can lead to a higher risk of muscle pain or damage.
What To Do
Your doctor should limit your simvastatin dose to 10 mg daily while you are taking diltiazem.
FDA Label Information
Intervention: For patients taking verapamil, diltiazem, or dronedarone, do not exceed ezetimibe and simvastatin 10 mg/10 mg daily.
Diltiazem Also Interacts With
- Ezetimibe major
- Ezetimibe/Simvastatin major
- Theophylline major
- Rifampin moderate
- Digoxin moderate
Simvastatin Also Interacts With
- Verapamil major
- Cyclosporine major
- Amiodarone major
- Dronedarone major
- Ranolazine major
Frequently Asked Questions
Can I take Diltiazem and Simvastatin together?
This is a major interaction. Your doctor should limit your simvastatin dose to 10 mg daily while you are taking diltiazem.
How serious is the interaction between Diltiazem and Simvastatin?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Diltiazem and Simvastatin interact?
Diltiazem blocks the enzymes that break down simvastatin, causing the drug to stay in your body longer. This can lead to a higher risk of muscle pain or damage.
Understanding the Diltiazem and Simvastatin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Diltiazem belongs to the Calcium Channel Blocker class and Simvastatin belongs to the HMG-CoA Reductase Inhibitor (Statin) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Diltiazem blocks the enzymes that break down simvastatin, causing the drug to stay in your body longer. 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. Diltiazem has 46 total documented interactions on file in this dataset, and Simvastatin has 41. 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 limit your simvastatin dose to 10 mg daily while you are taking diltiazem. 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 Diltiazem or Simvastatin 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.