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AdizemTildiem, Zemtard

When you first start taking diltiazem you may get a headache, feel flushed, or get swollen ankles. These symptoms usually pass after a few days.

Each time you collect a new supply of diltiazem, check to make sure you have been given the same type of tablets or capsules as before.

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About diltiazem

Type of medicine

Calcium-channel blocker

Used for

High blood pressure, and angina

Also called

Adizem®; Angitil®; Dilcardia®; Retalzem®; Slozem®, Tildiem®; Viazem®; Uard®; Zemtard®

Available as

Tablets and capsules

Diltiazem is used to treat high blood pressure (hypertension) and prevent chest pain caused by angina. It works by causing some of your blood vessels to relax and widen. This lowers your blood pressure. It also reduces the force and the rate of your heartbeat, and this helps to prevent angina pain.

Before taking diltiazem

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 diltiazem it is important that your doctor knows:

  • If you are pregnant, trying for a baby or breastfeeding.

  • If you have any problems with your kidneys or liver.

  • If you have a heart condition (such as heart failure, an abnormal heart rhythm, or if you have had a heart attack recently).

  • If you have high blood sugar levels (diabetes mellitus).

  • If you have asthma or other breathing problems.

  • If you have a rare inherited blood disorder called porphyria.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to this or to any other medicine.

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How to take diltiazem

  • Before you start taking diltiazem, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about the specific brand of tablet or capsule you have been given, and a full list of side-effects which you may experience from taking it.

  • There are several different formulations of diltiazem available, so it is important that you take your tablets or capsules exactly as your doctor tells you to. 'Standard' 60 mg tablets are taken three times daily, whereas longer-acting tablets or capsules are taken once a day or twice a day. Your doctor will tell you which is right for you, and this will also be printed on the label of the pack to remind you.

  • Try to take diltiazem at the same times each day, as this will help you to remember to take your doses.

  • Swallow the tablets or capsules whole with a drink of water - do not chew, break or crush them. You can take diltiazem before or after food.

  • If you 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.

  • Your doctor will discuss with you the possibility of unwanted side-effects when you first start taking diltiazem. You may experience headaches, feeling flushed, swollen ankles and some dizziness. These effects usually only last for a few days, but if they continue or become troublesome, you should let your doctor know.

  • Different formulations and brands of diltiazem can act in a slightly different way in your body. Because of this, it is important that you continue to take the same type of tablet or capsule as you have had before. So, each time you collect a prescription, check to make sure your supply looks the same and that the brand name is the same. If you are unsure, or if have any questions about your prescription, please ask your pharmacist to check it for you.

  • If you have diabetes you may need to check your blood sugar (glucose) level more often. This is because diltiazem may raise your glucose levels. Ask your doctor or pharmacist for advice.

  • Before you buy any medicines or take any 'over-the-counter' remedies, please check with a pharmacist that they are suitable for you to take. This is because some medicines can interact with diltiazem.

  • Drinking grapefruit juice may affect the amount of diltiazem in your blood and can make you more likely to experience side-effects. Let your doctor or pharmacist know if you enjoy drinking grapefruit juice and wish to continue.

  • If you need to have an operation or any medical treatment, always tell the person carrying out the treatment which medicines you are taking. Diltiazem may interfere with the way some anaesthetics work.

  • If you drink alcohol, ask your doctor for advice. Your doctor may recommend that you do not drink alcohol while you are on this medicine as it may increase the chance that you experience side-effects, such as feeling dizzy or light-headed.

  • Suddenly stopping treatment may cause problems, so keep taking diltiazem unless your doctor tells you otherwise. If it does become necessary for you to stop treatment, your doctor will want you to reduce your dose over a few days.

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Can diltiazem cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with diltiazem. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.


diltiazem side-effects

What can I do if I experience this?

Feeling dizzy or light-headed, especially when sitting or standing up

Getting up more slowly may help. Do not drive and do not use tools or machines until you feel better


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor

Indigestion, feeling sick (nausea)

Stick to simple meals - avoid rich and spicy foods


Try to eat a well-balanced diet and drink several glasses of water each day

Red or itchy skin

Ask a pharmacist to recommend a suitable remedy. If it becomes troublesome, let your doctor know

Swollen ankles, feeling hot and flushed, being aware of your heartbeat, feeling tired

Speak with your doctor about these if any continue beyond a few days or become troublesome

Important: if you get chest pain, or if your angina pain gets worse or becomes more frequent, contact your doctor as soon as possible.

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

How to store diltiazem

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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