What are calcium channel blockers?

Calcium channel blockers (CCB) are a group of medicines used to help treat several different medical conditions including angina (chest pain), hypertension (high blood pressure) and some arrhythmias (abnormal heart rhythm).

How do calcium channel blockers work?

Calcium channel blockers work by stopping calcium from entering the cells of the heart and arteries.

Normally, calcium causes blood vessels and the muscles of the heart to contract (squeeze). Calcium is also important in controlling the electrical pathways and pacemaker cells in the heart.

By blocking calcium, these medicines allow blood vessels to relax and open up, helping to reduce blood pressure. The non-dihydropyridines class can also lower the rate and force of the hearts contractions.

The 2 different classes of CCBs, dihydropyridines and non-dihydropyridines, work in slightly different ways. This is because they work on different cells in the body.

Dihydropyridines

The dihydropyridines include medicines that end with ‘depine’ including nifedipine, amlodipine and felodipine.

Dihydropyridines work by relaxing the muscle within the walls of blood vessels — lowering blood pressure.

Non-dihydropyridines

Non-dihydropyridines include the medicines verapamil and diltiazem.

These medicines work by relaxing the muscle within the walls of blood vessels and can also lower the rate and force of the heart's contractions.

Verapamil can be used to treat angina and hypertension. It can also be used to treat heart arrhythmias, including conditions called supraventricular tachycardia and atrial fibrillation (known as AF).

Diltiazem has less effect on the heart’s ability to contract compared to verapamil and is mainly used for treating angina.

What types of calcium channel blockers might I be prescribed?

There are 2 different types of CCBs: the dihydropyridines and non-dihydropyridines. These are only available with a doctor’s prescription.

Common dihydropyridines used in Australia include amlodipine, felodipine, lercanidipine and nifedipine.

Non-dihydropyridines commonly used include verapamil and diltiazem.

The specific type and dose of CCB your doctor prescribes is based on your individual circumstances, including the condition being treated as well as any other health problems you may have. Your doctor may start you on a low dose first, and then slowly increase it over time.

If the medicine you have been prescribed doesn’t fully control your health condition, your doctor might prescribe a CCB with another medicine. For example, your doctor may prescribe you a CCB combined with another type of medicine called an ACE inhibitor to help control your high blood pressure. Sometimes these medicines are in the same tablet so you don’t have to take too many pills.

What are the risks of using calcium channel blocker medicines?

Like all medicines, calcium channel blockers may cause side effects.

Common side effects include:

• dizziness
• headaches
• nausea
• flushed skin
• ankle swelling
• constipation

Serious side effects can include:

• angina (chest pain)
• palpitations (abnormal heart beats)
• symptoms of a heart attack

You can help prevent dizziness by getting up slowly from a lying or sitting position. If you do feel dizzy, sit back down and wait for the feeling to pass before you try again to get up slowly and with support. Tell your doctor if you continue to feel dizzy after the first few weeks on the medicine.

It is important to take your CCB exactly as your doctor recommended. Most CCBs are taken once a day. Ask your doctor or pharmacist if you need to take it with food or on an empty stomach.

Avoid eating grapefruit or drinking grapefruit juice while taking CCBs since grapefruit can affect the way your body processes some of these medicines.

When should I see my doctor?

If you have severe side effects including palpitations or shortness of breath, see a doctor immediately.

If dizziness continues beyond the first few weeks of treatment, see your doctor.

Speak to your pharmacist or doctor about any other side effects that may be troubling you. Never stop your prescribed medicines without talking to your doctor first.

Let your doctor know about any other prescription or non-prescription medicines that you are taking before you start taking a CCB.

Are there any alternatives to this medicine?

There are other classes of medicines that your doctor might prescribe to treat your health condition.

For example, medicines known as ACE-inhibitors and ARBs can be used to treat high blood pressure and medicines known as nitrates can be used to treat angina. Discuss your different medication options with your doctor.

Lifestyle changes can also help lower your blood pressure. A healthy diet, reducing your salt and alcohol intake, regular physical activity and achieving a healthy body weight are all effective in lowering blood pressure. Quitting smoking also helps to reduce your risk of heart problems.

Resources and support

For more information on calcium channel blockers see this information page by Monash heart.

For more information about hypertension and how to manage it, see the Heart foundation website.

Call healthdirect on 1800 022 222 at any time to speak to a registered nurse (known as NURSE-ON-CALL in Victoria) for more information and advice.