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Diltiazem is a medication belonging to the class of drugs known as calcium channel blockers

Last Modified: 20 May 2024

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What is Diltiazem? 

Diltiazem is a medication belonging to the class of drugs known as calcium channel blockers. It works by relaxing the muscles of your heart and blood vessels and slow heartbeat. 

Global Name

Generic name: Diltiazem
Brand name: Cardizem, Cartia XT, Dilt-XR, Tiazac


What is Diltiazem used for? 

Diltiazem is primarily used to treat hypertension (high blood pressure), angina (chest pain), and certain heart rhythm disorders. 

How do you use Diltiazem? 

Diltiazem is available in tablet, capsule, and injectable forms. 

Dosage information: 

  • Adults: Typically, 180-240 mg once daily for extended-release forms. Dosages can vary based on the condition. 
  • Children: Use and dose must be determined by a doctor. 


  • Children: Not typically recommended. 
  • Adults: Yes, as prescribed. 
  • Elderlies: Yes, with dose adjustments. 
  • Pregnancy: Only if clearly needed or prescribed by healthcare professionals. 
  • Lactation: Caution advised, better consult with a healthcare professional.  


  • Allergies: If allergic to diltiazem or other calcium channel blockers. 
  • Certain conditions: Sick sinus syndrome, severe heart failure, low blood pressure, etc. 

Take with or without food. Avoid grapefruit and grapefruit juice as they can interfere with the body’s metabolism of diltiazem and lead to potentially dangerous effects. 

Concurrent use with beta-blockers, digoxin, or statins can increase the risk of adverse side effects. Always inform your doctor about all medications you are taking. 

Side Effects

Common side effects may include swelling, dizziness, and headaches. Serious side effects can involve heart rhythm changes, severe skin reactions, or liver problems.

Pharmacist Tips

  • Storage: Store at room temperature, protect from moisture and heat. 
  • Consistency: Take diltiazem at the same times each day to maintain an even level in your blood. 
  • Blood Pressure Monitoring: Regularly monitor your blood pressure to ensure the effectiveness of the drug. 
  • Grapefruit Interaction: Avoid grapefruit products as they can interfere in the metabolism of diltiazem, increasing the risk of adverse side effects. 


Where is Diltiazem available in Hong Kong?

Diltiazem is a prescription medication that can be prescribed by healthcare providers.


Is Diltiazem available over-the-counter?

No, a prescription is required.

How long does it take for Diltiazem to work?

It can start working within 2-3 hours, but full effects may take a few weeks.

Can I consume alcohol while taking Diltiazem?

Discuss with your doctor as alcohol may increase certain side effects of diltiazem.

Why is Diltiazem contraindicated in heart failure?

Diltiazem is a non-dihydropyridine calcium channel blocker that can have negative inotropic effects, meaning it can reduce the strength of the heart's contractions, potentially worsening heart failure in patients with systolic dysfunction. 

This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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