Diltiazem

Blood pressure

Also known as Cardizem, Cartia XT

Diltiazem is a calcium channel blocker. It relaxes the muscle in your blood vessel walls and slows the electrical signals in your heart — which lowers blood pressure, prevents chest pain, and can steady certain fast heart rhythms. Most people take a long-acting capsule once or twice a day.

How to take it

When

Same time every day. Extended-release versions are taken once or twice daily.

Food

Go easy on grapefruit and grapefruit juice — it can raise diltiazem levels in your body.

Avoid

Never crush or chew extended-release capsules — you'd get a whole day's medicine at once. Swallow them whole.

Good to know

Swollen ankles and constipation are common. Mention them to your doctor — there are often easy fixes.

Missed a dose?

Take it as soon as you remember, unless it's close to your next dose — then skip the missed one. Never double up.

Common side effects

Swollen ankles or feet
Constipation
Headache
Dizziness
Tiredness

Call a doctor if

A very slow heartbeat or fainting — get help now
New or worsening chest pain — get help now
Trouble breathing or sudden swelling and weight gain
A spreading rash or blistering skin — call your doctor right away

Educational only. This summary is drawn from public FDA labeling and MedlinePlus and simplified for readability. Your prescription label and your pharmacist always come first — doses and instructions vary from person to person.