Calcium channel blockers: What to know

Calcium channel blockers are a type of medication that people take to increase the flow of blood and oxygen to the heart. Doctors may prescribe a calcium channel blocker to treat high blood pressure or a variety of heart conditions.

Calcium channel blockers are common medications that have a low risk of complications. In this article, we discuss how these drugs work, as well as their uses and possible side effects.

What is a calcium channel blocker?

A man pouring Calcium channel blockers from a pill container into his hands.
A doctor may prescribe calcium channel blockers to treat high blood pressure.

Calcium is necessary for muscle contractions to occur throughout the body. This mineral enters muscle cells through ion channels, which are tiny pores on the surface of the cell. This process is essential for normal bodily functioning.

Calcium channel blockers reduce the amount of calcium that can enter muscle cells in the heart and blood vessel walls via these channels.

In doing this, they lower the pressure in the blood vessels and on the heart.


Doctors commonly use calcium channel blockers to treat high blood pressure. These drugs also have a range of other possible uses, such as for:

Scientists are currently exploring other potential uses for calcium channel blockers. For example, by reducing high blood pressure, they believe that calcium channel blockers may be able to lower the risk of Alzheimer’s disease.

Several other types of medication have an effect similar to that of calcium channel blockers.


Beta-blockers slow heart activity by limiting the effects of stress hormones, such as epinephrine and norepinephrine. These medications are effective in lowering blood pressure. Examples of beta-blockers include atenolol (Tenormin) and metoprolol (Lopressor).

Researchers have found that both beta-blockers and calcium channel blockers are effective in lowering blood pressure, making them useful treatments for a variety of conditions that affect the heart, including angina and arrhythmia.

However, the American Heart Association recommend calcium channel blockers as a first-line pharmacological treatment for high blood pressure in most people and advise that beta-blockers should be a second-choice option.

ACE inhibitors

a woman speaking to a male pharmacist
ACE inhibitors can help manage a variety of heart conditions.

Angiotensin converting enzyme (ACE) inhibitors are another type of medication for high blood pressure and a variety of heart conditions. They relax blood vessels and make it easier for the heart to pump blood around the body.

ACE inhibitors work by blocking the enzymes that narrow blood vessels, which allows blood to flow through the vessels without putting as much pressure on them.

Examples of ACE inhibitors include lisinopril (Prinivil, Zestril), enalapril (Vasotec), and benazepril (Lotensin). They can cause some common side effects, such as a cough or skin irritation.

A doctor may sometimes prescribe an ACE inhibitor with a calcium channel blocker.

Types and examples

There are two different types of calcium channel blocker, which are called dihydropyridines and nondihydropyridines.


Dihydropyridines target a specific type of calcium channel in the body. They cause the blood vessels to widen, lowering blood pressure.

Examples of dihydropyridines include:

  • amlodipine (Norvasc)
  • felodipine (Plendil)
  • nicardipine (Cardene)
  • nifedipine (Adalat, Procardia)
  • nimodipine (Nimotop)

It is sometimes possible for these medications to widen the blood vessels too much, which can result in swelling in the feet and legs. Doctors are careful to prescribe a dosage that reduces the risk of this happening.

Doctors may also minimize this risk by prescribing extended release calcium channel blockers. The body absorbs this form of the drug over a longer period, which prevents the blood vessels from widening too much.


Nondihydropyridines widen blood vessels in the same way as dihydropyridines. However, they have additional effects on the heart that can help control a rapid heart rate.

Currently, there are only two nondihydropyridine medications: verapamil (Calan, Isoptin) and diltiazem (Cardizem).

Verapamil specifically targets heart muscle cells, or the myocardium. Doctors use this drug to reduce chest pain as it relaxes blood vessels and reduces the amount of oxygen that the heart requires.

Verapamil is also useful for slowing abnormally rapid and potentially dangerous heart rhythms, such as supraventricular tachycardia.

Diltiazem is a medication for controlling heart dysrhythmias (rapid or irregular heart rhythms) and lowering blood pressure. In comparison with verapamil, it has a less significant effect on the heart rate.

Side effects and risks

a man at work yawning at his desk
Fatigue is a possible side effect of calcium channel blockers.

Common side effects of calcium channel blockers include:

Less commonly, these medications can cause:

The rarest side effects that occur with calcium channel blockers include:

If a person experiences any of these side effects from taking calcium channel blockers, they should see a doctor. If the side effects are causing serious problems, a doctor may change the prescription or reduce the dosage.


Calcium channel blockers are effective and widely used medications for the treatment of high blood pressure and several heart conditions. They work by relaxing blood vessels and reducing pressure on the heart.

A range of alternative medications, such as ACE inhibitors and beta-blockers, are available for high blood pressure and heart conditions. They have a similar effect on the body, and doctors may prescribe a combination of these medicines.

Calcium channel blockers can cause several side effects, such as fatigue and swelling in the abdomen, feet, and legs. Anyone who experiences worsening side effects should talk to a doctor about changing medications or reducing the dosage.

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