Calcium Channel Blockers

Calcium channel blockers are used to control high blood pressure (hypertension), chest pain (angina), and irregular heartbeats (arrhythmia).

Why do I need to take a calcium channel blocker?

Calcium channel blockers are used to control high blood pressure (hypertension), chest pain (angina), and irregular heartbeats (arrhythmia).

How do calcium channel blockers work?

Calcium channel blockers slow the rate at which calcium passes into the heart muscle and into the vessel walls. This relaxes the vessels. The relaxed vessels let blood flow more easily through them, thereby lowering blood pressure.

How much do I take?

There are many different kinds of calcium channel blockers. The amount of medicine you need to take may vary. Talk to your doctor or pharmacist for more information about how and when to take this medicine.

If you are taking an “extended-release” calcium channel blocker (any that end in XL, XR, XT), do not chew or crush the pills.

What if I am taking other medicines?

Other medicines that you may be taking can increase or decrease the effect of calcium channel blockers. These effects are called an interaction. Be sure to tell your doctor about every medicine and vitamin or herbal supplement that you are taking, so he or she can make you aware of any interactions.

The following are categories of medicines that can increase or decrease the effects of calcium channel blockers. Because there are so many kinds of medicines within each category, not every type of medicine is listed by name. Tell your doctor about every medicine that you are taking, even if it is not listed below.

  • Other medicines used to treat high blood pressure, especially beta-blockers and ACE inhibitors.
  • Medicines to treat an irregular heartbeat (antiarrhythmics).
  • Diuretics.
  • Digitalis.
  • Certain medicines for your eyes.
  • Corticosteroids or any cortisone-like medicines.
  • Large doses of calcium or Vitamin D supplements.

While on calcium channel blockers, you should also avoid smoking. Smoking while you are on calcium channel blockers may cause a rapid heartbeat (tachycardia). Also, some studies have shown that grapefruit juice interferes with your body’s absorption of this medicine. If you are going to drink grapefruit juice, you should wait at least 4 hours after having taken your medicine.

What else should I tell my doctor?

Talk to your doctor about your medical history before you start taking calcium channel blockers. The risks of taking the medicine need to be weighed against its benefits. Here are some things to consider if you and your doctor are deciding whether you should take a calcium channel blocker.

  • You have allergies to foods or dyes.
  • You are thinking of becoming pregnant, you are pregnant, or you are breast-feeding your baby.
  • You are over 60. Younger people tend to have fewer problems while taking calcium channel blockers.
  • You have very low blood pressure.
  • You have heart failure or other heart or blood vessel conditions.
  • You have a history of heart rhythm problems.
  • You have kidney or liver disease.
  • You have low blood sugar. This medicine can lower your blood sugar if your daily dose is more than 60 mg.
  • You have Parkinson’s disease.
  • You have a history of depression.

What are the side effects?

Sometimes a medicine causes unwanted effects. These are called side effects. Not all of the side effects for calcium channel blockers are listed here. If you feel these or any other effects, you should check with your doctor.

Common side effects:

  • Feeling tired
  • Flushing
  • Swelling of the abdomen, ankles, or feet
  • Heartburn

Less common side effects:

  • Very fast or very slow heartbeat
  • Wheezing, coughing, or shortness of breath
  • Trouble swallowing
  • Dizziness
  • Numbness or tingling in the hands or feet
  • Upset stomach
  • Constipation

Rare side effects:

  • Headache
  • Fainting
  • Chest pain
  • Yellowing of the skin or eyes (jaundice)
  • Fever
  • Rash
  • Bleeding, swollen, or tender gums
  • Vivid dreams

Again, tell your doctor right away if you have any of these side effects. Do not stop taking your medicine unless your doctor tells you to. If you stop taking your medicine without checking with your doctor, it can make your condition worse.


The information in this Medicines for Cardiovascular Disease section has been taken from a number of sources. It is meant to give you information about certain medicines, but it does not cover all of the possible uses, warnings, side effects, or interactions with other medicines and vitamin or herbal supplements. This information should not be used as medical advice for individual problems. Please talk to your doctor and/or your pharmacist for prescription instructions.