Calcium channel blockers

Calcium channel blockers are a group of medicines that are used to treat a variety of conditions related to your heart.

What are calcium channel blockers?

Calcium channel blockers (CCBs) are a group of medicines commonly prescribed to treat conditions of the heart and blood vessels, such as high blood pressure (hypertension), chest pain (angina), and some abnormal heart rhythms. They may also be used to treat Raynaud’s syndrome, a condition that causes painful and cold fingers and toes due to narrowing of the blood vessels in your hands and feet. Calcium-channel blockers affect the way calcium passes into certain muscle cells causing these muscle cells to relax. 

Examples of calcium channel blockers

There are several calcium channel blockers and some are a bit different. Your doctor will advise which one is best for you.

Precautions – before taking calcium channel blockers

  • Do you have problems with your kidneys, lungs or liver?
  • Do you have heart problems such as heart failure, a slow heart rate, low blood pressure or have you had a heart attack recently?
  • Do you have diabetes?
  • Are you pregnant, trying for a baby or breastfeeding?
  • Are you taking any other medicines? This includes any medicines you buy without a prescription, such as herbal and complementary medicines.

If so, it’s important that you tell your doctor or pharmacist before you start calcium channel blockers. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Possible side effects

Like all medicines, calcium channel blockers can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine. For most people who take calcium channel blockers, serious side effects are rare.

The most common side effects are dizziness, ankle swelling, flushing, headache and palpitations. These things may get better as your body gets used to the medicine. Verapamil can also cause constipation and may slow your heart rate. If you get any symptoms, talk to your doctor as soon as possible. Don’t stop taking your calcium channel blocker suddenly, as this can make you feel unwell and can cause chest pain. 


  1. Calcium-channel blockers New Zealand Formulary
Credits: Sandra Ponen, pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 18 Dec 2018