Medicines & Supplements A to Z > Cimetidine


Last updated on 19/03/2021.

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

GENERIC NAME: Cimetidine


BRAND NAME(S) IN HONG KONG: Cimetidine Hovid, Cimetidine-Wilson 美國基柏胃樂寧, Simaglen 胃美健, Ultipus

DRUG CLASS: Histamine-2 receptor blocker (H2RA)

USED FOR: Gastroesophageal reflux disease (GERD), heartburn, indigestion, dyspepsia

OTHER DRUGS IN THE SAME CLASS: Famotidine, Ranitidine

– 200mg, 400mg (tablets)
– 10% (injections)

What is Cimetidine for?

Cimetidine belongs to a class of medications called histamine-2 receptor blockers. It works by suppressing the secretion of stomach acid and hence can be used to treat several gastrointestinal disorders, including benign gastric and duodenal ulceration, gastroesophageal reflux disease (GERD), heartburn, and non-ulcer dyspepsia. 

How to use it?

Cimetidine can be taken orally. The adult dosages are as follows: 

For the treatment of benign gastric and duodenal ulceration, you should take 400 mg twice daily for at least 4 weeks (6 weeks for gastric ulceration) with breakfast and at night. You may also take 800 mg once daily for at least 4 weeks (6 weeks for gastric ulceration) at night. The dose can be increased up to 400 mg 4 times daily if necessary. The maintenance dose is 400 mg once daily at night or 400 mg twice daily in the morning and at night. 

For the treatment of GERD, you should take 400 mg 4 times daily or 800 mg twice daily for 4-12 weeks. 

For the treatment of heartburn or non-ulcer dyspepsia, the maximum daily dose is 800 mg in divided doses. 

For mild symptoms, you can take 200 mg of Cimetidine on an intermittent basis (as needed) 10-60 minutes before a meal that you expect to cause heartburn.

What are the side effects of Cimetidine? 

Common side effects of Cimetidine include diarrhoea, fatigue, and headache. Long-term use of Cimetidine can result in enlarged breasts in men (gynecomastia) and impotence.

Who should not take Cimetidine?

Anyone who has an allergy to Cimetidine.

Pharmacist Tips:

Elderly people and those with reduced kidney function may require lower doses of Cimetidine.

Common dosing schedule:
Take cimetidine with food. 

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

Some common medications Cimetidine may interact with:
– Some calcium channel blockers, e.g. Diltiazem, Nifedipine

Cimetidine has the potential to interact with many more medications. Please notify your doctor or pharmacist about all your current medications as dosage adjustments might be needed.

Where to buy Cimetidine in Hong Kong?

In Hong Kong, Cimetidine is an over-the-counter medicine and can be purchased without a prescription from any retail outlet in Hong Kong. This includes grocery stores, convenience stores, medicine shops, and pharmacies. 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 Cimetidine 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.