Medicines & Supplements A to Z > Diltiazem


Last updated on 22/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Diltiazem 


BRAND NAME(S) IN HONG KONG: Cartil, Herbesser, Messer, Wontizem 

DRUG CLASS: Calcium channel blocker; Antianginal; Antihypertensive  

USED FOR: Angina, high blood pressure 

OTHER DRUGS IN THE SAME CLASS: Amlodipine, Felodipine, Nifedipine, Verapamil

– 30mg, 60mg, 90mg (tablets)
– 90mg, 100mg, 180mg, 200mg (capsules)
– 10mg, 50mg (injections)

What is Diltiazem for?

Diltiazem belongs to a class of medications called calcium channel blockers. It is used to treat and prevent angina, control abnormal heart rhythms (e.g. atrial fibrillation), and treat high blood pressure. It is also occasionally used for anal fissures.

How to use it?

Diltiazem can be taken by mouth as tablets or capsules, or given in hospital by injection. Usual oral starting doses of immediate release Diltiazem are 30 to 60 mg four times per day. The maximum daily dose is often 480 mg per day (120 mg four times per day). Long-acting (sustained release) products have less frequent dosing and should not be crushed. Examples of long-acting Diltiazem products are Herbesser R (or equivalent) and Herbesser SR (or equivalent), and they are taken on a daily basis.

What are the side effects of Diltiazem?

Common side effects of Diltiazem include dizziness, low heart rate, low blood pressure, flushing, headache, nausea and vomiting, palpitations, lower leg swelling, cardiac conduction disorders, and constipation.

Who should not take Diltiazem?

– People who are allergic to Diltiazem or any ingredient of the formulation
– Patients with heart failure or a slow heartbeat
– Patients with acute porphyria (a blood disorder)

Pharmacist Tips:

One of the most common side effects of Diltiazem is lower limb swelling, which usually occurs within 2-3 weeks after starting Diltiazem. Because of how calcium channel blockers dilate blood vessels, fluid can accumulate in the lower limbs. If you experience swelling, see your doctor so they can make changes to your blood pressure medicine.

Common dosing schedule:
Diltiazem can be taken with or without food. Evening or bedtime dosing may be the best time to take most of the high blood pressure medicines.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Diltiazem may interact with:
Antiepileptics, e.g. Carbamazepine, Phenytoin
Antifungal agents, e.g. Itraconazole, Ketoconazole
Macrolide antibiotics, e.g. Clarithromycin, Erythromycin

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Diltiazem in Hong Kong?

In Hong Kong, Diltiazem is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Diltiazem in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.