Calcium Channel Blockers: What They Do and Who Needs Them

Calcium channel blockers (CCBs) are a group of prescription medicines used mainly to lower blood pressure, ease chest pain (angina), and treat certain heart rhythm problems. They relax blood vessels and, depending on the type, can slow your heart rate. If your doctor prescribes a CCB, this page helps you know what to expect and how to use them safely.

How they work and common types

CCBs fall into two main groups: dihydropyridines (DHPs) and non-dihydropyridines (non-DHPs). DHPs — like amlodipine and nifedipine — mainly relax blood vessels, which lowers blood pressure. Non-DHPs — such as verapamil and diltiazem — reduce both blood pressure and heart rate and are often used for certain arrhythmias.

Quick examples you’ll see: amlodipine (often started at 5 mg once daily), nifedipine ER (commonly 30–60 mg once daily), diltiazem ER (frequently 120–360 mg once daily), and verapamil (immediate-release or extended options exist). Your doctor will pick a drug and dose based on the condition being treated and other meds you take.

Side effects, interactions, and safety tips

Common side effects include ankle swelling, flushing, headache, dizziness, and constipation (more with verapamil). Non-DHPs can slow your heart rate and cause lightheadedness, especially if combined with beta-blockers. If you notice sudden shortness of breath, fainting, very slow heartbeat, or rapid weight gain from swelling, call your provider right away.

Watch for drug interactions. Grapefruit and grapefruit juice can raise levels of some CCBs. Verapamil and diltiazem can increase levels of certain statins and interact with other heart drugs. Tell your pharmacist about all prescriptions, supplements, and over-the-counter meds you use.

Routine blood tests aren’t usually needed just for a CCB, but monitor your blood pressure and pulse at home when you start or change dose. If you have liver disease, heart failure, or severe low blood pressure, the choice of CCB and its dose may change.

Practical tips: take your pill at the same time each day, try to sit or lie down the first few times if you feel dizzy, and avoid stopping non-DHPs abruptly without medical advice. Most CCBs require a prescription — only buy from licensed pharmacies and confirm packaging and batch numbers if ordering online.

If you’re pregnant or breastfeeding, discuss options with your doctor — some CCBs are preferred in pregnancy, but decisions are individualized. When in doubt, ask your prescriber or pharmacist for clear, medicine-specific guidance before making changes.

Need more details about a specific CCB or how it fits into your treatment? Check with your healthcare team — they can match the drug to your health needs and other meds, and help you avoid problems while getting the blood pressure or heart control you need.