• Do not drink grapefruit juice whilst you are on verapamil.
  • The most common side-effect of verapamil is constipation.

About verapamil

Type of medicine Calcium-channel blocker
Used for Hypertension
Abnormal heart rhythms
To protect the heart after a heart attack
Also called Cordilox® MR, Half Securon SR®, Securon SR®, Univer®, Verapress MR®, Vera-Til® SR, Vertab® SR, Zolvera®
And also Tarka® (verapamil with trandolapril)
Available as Tablets, prolonged-release tablets and capsules, oral liquid, and injection

Verapamil is known as a calcium-channel blocker because it works by affecting the way calcium passes into certain muscle cells. It is used to treat various conditions such as hypertension (high blood pressure), arrhythmias (abnormal heart rhythms) and angina (chest pain).

Your heart and the walls of your arteries contain special muscle cells. These muscle cells need calcium to contract. Calcium-channel blockers reduce the amount of calcium that goes into these muscle cells. This causes the muscle cells to relax which widens your arteries and reduces the force and rate of your heartbeat. Opening up your arteries lowers your blood pressure and increases the flow of blood to your heart, which helps ease angina. Because verapamil blocks calcium going into special conducting cells in your heart and slows your heart rate, it can also be used to treat certain arrhythmias where the heart rate is abnormally fast.

Verapamil may also be used to treat certain types of headache in some circumstances. If you have been prescribed it for this reason, then you should ask your doctor if you have any questions about your treatment.

Before taking verapamil

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking verapamil it is important that your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have any other heart problems, such as heart failure (a condition where the pumping action of your heart is reduced).
  • If you have hypotension (low blood pressure).
  • If you have liver problems.
  • If you have porphyria (a rare inherited blood disorder).
  • If you are taking other medicines, including those available to buy without a prescription, herbal and complementary medicines. It is particularly important that your doctor knows if you are taking a beta-adrenoceptor blocking drug (commonly known as a beta-blocker).
  • If you have ever had an allergic reaction to this or to any other medicine.

How to take verapamil

  • Before you start this treatment, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about the specific brand of verapamil you have been given, and a full list of possible side-effects from taking it.
  • Take verapamil exactly as your doctor has told you. Your doctor or pharmacist will tell you how much to take and when to take it. Your dose will also be on the label of the pack. (You may be asked to take verapamil once, twice or three times a day depending on the preparation you are given).
  • You may take verapamil before or after food.
  • If you have been given a prolonged-release form of verapamil (these may have 'SR' or 'MR' after the brand name), it is important that you swallow the tablets or capsules whole. These tablets and capsules have been made to release verapamil slowly to give a more even effect. Do not chew, break or crush these, otherwise you could receive too much verapamil too quickly. Check the label on your pack to see if you have been given instructions to swallow your tablets or capsules whole.
  • Try to take your doses of verapamil at the same times each day. This will help you to remember to take them and to avoid missing any doses.
  • If you do forget to take a dose, take it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a forgotten dose.

Getting the most from your treatment

  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress.
  • Do not drink grapefruit juice while you are on verapamil. This is because a chemical in grapefruit juice increases the amount of verapamil in your bloodstream. This makes side-effects more likely.
  • If you drink alcohol, ask your doctor for advice about taking verapamil and alcohol. The level of alcohol in your blood may be increased by verapamil.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines. This is because some medicines such as aspirin and some herbal remedies may interfere with verapamil.

Can verapamil cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common verapamil side-effects - these affect less than 1 in 10 people who take this medicine What can I do if I experience this?
Constipation Try to eat a well-balanced diet and drink plenty of water each day. If this continues to be a problem, speak with your pharmacist or doctor for further advice
Feeling or being sick Stick to bland foods - avoid rich and spicy meals
Flushing This usually passes after a few days. It if continues or becomes a problem, speak with your doctor
Headache Ask your pharmacist to recommend a suitable painkiller
Feeling dizzy or tired If this happens, do not drive or use tools or machines
Swollen ankles Speak with your doctor if this becomes troublesome

Important: if you get either of the following, speak with your doctor or go to your local accident and emergency department straightaway as they may be signs of an allergic reaction:

  • Any wheezing or shortness of breath, or any swelling of your mouth or face.
  • A severe skin rash.

If you experience any other symptoms which you think may be due to this medicine, discuss them with your doctor or pharmacist.

How to store verapamil

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.