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Heart Disease Health Center

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Calcium Channel Blockers for Fast Heart Rates


Generic Name Brand Name
diltiazem Cardizem, Cartia, Dilacor, Taztia, Tiazac
verapamil Calan, Covera, Verelan

How It Works

Certain calcium channel blockers help slow the heart rate by reducing the number of electrical impulses that pass through the atrioventricular (AV) node into the lower heart chambers (ventricles).

Why It Is Used

Diltiazem and verapamil are used to treat people with irregular or fast heartbeats.

How Well It Works

Certain calcium channel blockers (diltiazem and verapamil) can help slow a rapid heart rate.1

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

Call your doctor if you have:

Common side effects of this medicine include:

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Your doctor may ask you to take your pulse regularly to make sure your heart rate is not too slow. To learn how to take your pulse, see the topic Taking a Pulse (Heart Rate) slideshow.gif.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


  1. Drugs for cardiac arrhythmias (2007). Treatment Guidelines From The Medical Letter, 5(58): 51-58.

ByHealthwise Staff
Primary Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Specialist Medical ReviewerJohn M. Miller, MD, FACC - Cardiology, Electrophysiology

Current as ofAugust 13, 2014

WebMD Medical Reference from Healthwise

Last Updated: August 13, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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