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What does it do?

Diltiazem is used to treat irregular heartbeats, high blood pressure, angina, and sometimes other conditions. It keeps your heartbeat regular and steady by controlling the electrical signals in your heart. It also relaxes blood vessels, which lowers blood pressure and makes it easier for your heart to pump blood around your body.

Before you start

  • Tell your doctor if you have heart failure.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take diltiazem regularly as directed with a glass of water. You can take it with or without food.
Slow-release capsule: Swallow whole - do not crush or chew.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with diltiazem including:

  • anti-inflammatories, such as diclofenac (e.g. Voltaren®), ibuprofen (e.g. Nurofen®), or aspirin (e.g. Disprin®, in doses used for pain relief). These can also be found in some cold and flu medicines (e.g. Nurofen Cold and Flu®).

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products (e.g. St John's wort) or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Symptoms of a slow or irregular heartbeat including: feeling your heart skips a beat, dizziness or fainting

Tell your doctor immediately

Swollen feet or legs, short of breath

Tell your doctor

Flushing

Headache

Tell your doctor if troublesome

Symptoms of low blood pressure such as dizziness or fainting

Stand up slowly. If it continues, or is severe, tell your doctor

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Do not stop taking diltiazem without talking to your doctor first.

This leaflet contains important, but not all, information about this medicine.

Prepared by the MyMedicines Committee at Christchurch Hospital, Te Whatu Ora - Waitaha, New Zealand. March 2023

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at Te Whatu Ora – Waitaha. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed