Drug Class Guide
Calcium Channel Blockers
A first-line blood pressure option that also treats angina, with two types that act quite differently on the heart.
How Calcium Channel Blockers Work
Calcium flowing into muscle cells makes them contract. Calcium channel blockers reduce that flow in the muscle of blood vessel walls, so arteries relax and blood pressure falls. Dihydropyridines such as amlodipine act mainly on blood vessels; non-dihydropyridines (diltiazem and verapamil) also slow the heart rate.
What Calcium Channel Blockers Treat
Calcium Channel Blockers in Our Medication Guide
Common Side Effects
Amlodipine commonly causes ankle swelling, flushing and headache, and the swelling increases with the dose. Diltiazem and verapamil can slow the pulse too much, and verapamil often causes constipation.
Important Cautions
- Diltiazem and verapamil interact with many medicines, including simvastatin and some blood thinners.
- Diltiazem and verapamil are generally avoided in heart failure with a weakened heart muscle.
- Report fainting, a very slow pulse or new shortness of breath.
Common Questions About Calcium Channel Blockers
Why does amlodipine make my ankles swell?
Amlodipine widens small arteries more than veins, so pressure rises in the tiny vessels of the legs and fluid seeps into the tissue. It is not a sign of heart failure, and water pills often do not help much. A lower dose, or adding an ACE inhibitor or ARB, usually reduces it.
What is the difference between amlodipine and diltiazem?
Both lower blood pressure, but amlodipine works almost entirely on blood vessels, while diltiazem also slows the heart's rate and electrical conduction. That makes diltiazem useful for controlling heart rate in atrial fibrillation, but it also means more drug interactions and more caution in heart failure.
Are calcium channel blockers the same as calcium supplements?
No. They do not change the calcium in your bones or blood, and you can usually take calcium supplements while on them. They simply reduce how much calcium enters certain muscle cells.
This guide is general information, not a substitute for advice about your own medicines. Do not start, stop or switch a medication without talking with your doctor. Questions about a prescription? Our internal medicine team can help.
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Trusted Resources for Calcium Channel Blockers
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