Diltiazem

Sounds like 'dil-TYE-a-zem'

Easy-to-read medicine information about diltiazem – what is it, how to take diltiazem safely and possible side effects.

Type of medicine Also called
  • Antihypertensive (to lower blood pressure)
  • Used to prevent chest pain (angina)
  • Belongs to a group of medicines called calcium channel blockers
  • Apo-Diltiazem®
  • Cardizem CD®
  • Dilzem®

What is diltiazem?

Diltiazem is used to treat high blood pressure (hypertension) and to prevent chest pain (angina). It may help to increase your ability to exercise and decrease how often you get chest pain. Diltiazem may also be used to control your heart rate if you have a fast or irregular heartbeat (such as atrial fibrillation). It works by relaxing blood vessels which helps to lower blood pressure. Diltiazem belongs to a group of medicines called calcium channel blockers. In New Zealand diltiazem is available in different strengths of tablets and capsules.

  • tablets: 30 mg  and 60 mg
  • capsules: 120 mg, 180 mg, 240 mg and 360 mg.

Dose

  • The dose of diltiazem will be different for different people. Your doctor will tell you which dose is right for you.
  • Diltiazem is available in 2 forms: as immediate release tablets and slow release capsules. 
    • Tablets are usually taken 3 or 4 times a day.
    • Capsules are usually taken once a day.
  • Always take your diltiazem exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much diltiazem to take, how often to take it, and any special instructions.

How to take diltiazem

Diltiazem tablets and capsules are available in different strengths. If your tablets or capsules look different to your last supply speak with your doctor or pharmacist for advice.

Formulation How to take it
Tablets
(30mg and 60mg)
  • Tablets are usually taken 3 or 4 times daily.
  • Try to space your doses evenly throughout the day.
  • Take your tablets with a glass of water.
  • Swallow your tablets whole. If you have trouble swallowing them, they can be crushed. Ask your pharmacist for advice.

Capsules

(120 mg, 180 mg, 240 mg, 360 mg)
  • Capsules are usually taken once a day. 
  • Swallow the capsules with a glass of water. Do not chew them.
  • You can take diltiazem capsules with or without food.
  • Limit or avoid drinking alcohol while you are taking diltiazem. Alcohol may increase your chance of side-effects, such as feeling dizzy or light-headed.
  • If you forget your dose, take it as soon as you remember. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
  • Do not stop taking diltiazem suddenly; speak to your doctor or nurse before stopping.

Precautions – before taking diltiazem

  • 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 diltiazem. 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, diltiazem can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Headache
  • This is quite common when you first start taking diltiazem and usually goes away with time
  • Tell your doctor if troublesome or if it does not go away after a few days
  • Dizziness
  • Feeling light-headed
  • Feeling faint when you stand up
  • This is common when you first start taking diltiazem and usually goes away with time
  • Be careful when getting up from either lying down or sitting to avoid falls
  • Avoid drinking alcohol
  • Changes in your heartbeat (either too slow, too fast or irregular)
  • Chest tightness
  • Wheezing or trouble breathing
  • Swelling of the ankles or feet
  • Tell your doctor immediately or ring HealthLine 0800 611 116

Interactions

Diltiazem may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting diltiazem or before starting any new medicines, including those you may buy over the counter.

Learn more

The following links have more information on diltiazem.

Medsafe Consumer Information Sheet:
Cardizem CD
Dilzem

New Zealand Formulary Patient Information: Diltiazem

References

  1. Diltiazem hydrochloride New Zealand Formulary
  2. Medical management of stable angina pectoris BPAC, 2011
  3. An update on managing patients with atrial fibrillation BPAC, 2017
Credits: Sandra Ponen, Pharmacist, NZ. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 07 Nov 2018