What it is used for
- High blood pressure (hypertension)
- Chest pain from angina
- Controlling the heart rate in some irregular rhythms such as atrial fibrillation
How it works
Diltiazem relaxes blood vessels and also slows electrical signals in the heart, which lowers blood pressure, eases the heart's workload, and helps control a fast or irregular heartbeat.
How it is taken
Available as immediate-release and extended-release tablets or capsules, and as an injection given by a healthcare professional. Extended-release forms are usually taken once or twice a day and should be swallowed whole. Take it exactly as your doctor or pharmacist directs and follow the label, and do not stop suddenly without advice.
No doses here on purpose. The right strength and schedule depend on you — only a doctor or pharmacist should set them. Always follow your prescription and the label.
Common side effects
- Ankle or leg swelling
- Dizziness
- Headache
- Slow heartbeat
- Constipation
- Flushing
Serious effects — get help
- Very slow heartbeat, fainting, or severe dizziness
- Worsening breathlessness or new ankle swelling (possible heart strain)
- Signs of liver problems such as yellowing of the skin or eyes
- Signs of a serious skin or allergic reaction
If a reaction is severe — for example trouble breathing, swelling of the face or throat, or collapse — go to the nearest emergency room now or call your local emergency number. Do not wait for an online consultation.
Interactions to watch
- Beta blockers such as atenolol or bisoprolol (added slowing of the heart)
- Some statins such as simvastatin (dose limits may apply)
- Digoxin (levels may rise)
- Other blood pressure medicines
- Grapefruit and grapefruit juice
- Certain medicines that affect liver enzymes
Who should take care
- Tell your clinician about heart rhythm or conduction problems and heart failure
- Do not combine with rate-slowing medicines without advice
- Swallow extended-release forms whole unless told otherwise
- Discuss liver problems and pregnancy or breastfeeding with your doctor
- Do not stop suddenly without medical advice