Diltiazem

Diltiazem relaxes blood vessels and slows the heart. It is used for angina and high blood pressure, and as an ointment for anal fissures.

Type of medicine

Calcium channel blocker

Also known as

Tildiem, Adizem, Slozem, Zemtard, Anoheal

Comes as

tablets, modified-release tablets and capsules, ointment

How you get it

Prescription only

What it is used for

Preventing angina
High blood pressure (some long-acting forms)
Anal fissure (ointment)

Read our guides:

Off-label uses

Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.

Controlling heart rate in atrial fibrillation
Raynaud's phenomenon

How it works

Diltiazem blocks calcium from entering muscle cells in the heart and blood vessel walls. This widens the blood vessels and slows the heart, lowering blood pressure and the heart's need for oxygen.

Side effects

Like all medicines, Diltiazem can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.

Common side effects

swollen ankles
headache
flushing
feeling dizzy or tired
a slow heartbeat
constipation

Tell your doctor or pharmacist if these bother you or do not go away.

Serious side effects

These are rare. Call 111 or contact your doctor straight away if you get:

a very slow heartbeat, fainting or feeling faint
breathlessness or swollen ankles that get worse
a skin rash with blisters or peeling

Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.

You can report any side effect to the Yellow Card scheme, run by the medicines regulator.

Stopping and withdrawal

Important safety information

Different brands of long-acting diltiazem release the medicine differently. Stay on the same brand.
It interacts with many medicines, including some statins and beta blockers.
Avoid grapefruit juice.

Questions about your medicine?

A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.