Medicines & Supplements A to Z > Cimetidine


Last updated on July 2, 2019.

Overview   |   Dosage   |   Side Effects   |   Where To Buy  

GENERIC NAME: Cimetidine 


COMMON BRANDS IN HONG KONG: Simaglen 胃美健, Ultipus, Cimetidine Hovid, Cimetidine-Wilson 美國基柏胃樂寧

What is Cimetidine for?

Cimetidine belongs to a class of medications called histamine-2 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.

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

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.