Calcium Channel Blockers

Frequently Asked Questions

What are calcium channel blockers?

Calcium channel blockers are medicines that help relax the pressure in blood vessel walls. Examples are diltiazem, verapamil, nifedipine, and amlodipine. Which one is best for you depends on your condition and health.

How do calcium channel blockers work?

Calcium channel blockers slow the movement of calcium from the blood into the muscle cells of the heart. This relaxes the vessels and blood flows more easily through them. This helps lower blood pressure. Muscle cells need calcium to be able to squeeze (contract). Muscle cells in other parts of the body store their own calcium and don’t depend on getting calcium from the blood.

When are calcium channel blockers used?

The major use of these drugs is to treat high blood pressure (hypertension). By partly blocking the transfer of calcium to the blood vessel muscle cells, the blood vessels relax and open up. This lowers blood pressure.

Calcium channel blockers are also used to treat angina (chest pain caused by blockage of an artery in the heart), and some abnormal heart rhythms. They may be prescribed to treat Raynaud’s phenomenon (a blood vessel problem) or to prevent migraine headaches.

When should I call my healthcare provider?

Some calcium channel blockers may make angina worse or cause the heart to beat too slowly. Talk with your healthcare provider about this.

For most people, calcium channel blockers’ good effect of lowering blood pressure outweighs its bad effect of slightly reducing the heart’s pumping ability. In other people, however, the reduced pumping of the heart causes heart failure. Heart failure is a condition in which the heart does not pump well enough to prevent the fluid buildup in body tissues. If you are taking calcium blockers and notice increasing shortness of breath or swelling in your legs or ankles, call your healthcare provider right away. Other side effects to report to your healthcare provider include constipation, headache, rash, drowsiness, flushing, fast heartbeat, and nausea.

Do not eat grapefruit or drink grapefruit juice while taking a calcium channel blocker. Grapefruit affects the way this medicine works and may increase the risk of side effects.