Medicines & Supplements A to Z > Ranitidine


Last updated on 18/03/2021.

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

GENERIC NAME: Ranitidine 


BRAND NAME(S) IN HONG KONG: Ulticer, Zantac 善胃得 

DRUG CLASS: Histamine-2 receptor blocker

USED FOR: Stomach acid reflux, heartburn, stomach ulcer, duodenal ulcer, prevention of stomach ulcer in using antiplatelet medication

OTHER DRUGS IN THE SAME CLASS: Cimetidine, Famotidine

– 150mg, 300mg (tablets)
– 25mg/ml, 50mg/2ml (injections)
– 150mg (capsules)
– 150mg/10ml (syrups)

What is Ranitidine for?

Ranitidine belongs to a class of medications called histamine-2 receptor blockers. It works by suppressing the secretion of stomach acid and can be used to treat several gastrointestinal disorders, including benign gastric and duodenal ulceration, gastroesophageal reflux disease (GERD), dyspepsia (indigestion), erosive oesophagitis, and NSAID-associated ulceration.

How to use it?

Ranitidine can be taken by mouth as tablets or syrup and by injections. The oral doses for different uses and age groups are listed below (the dose shown is an adult dose unless specified): 

For benign gastric and duodenal ulceration 

150 mg twice daily for 4-8 weeks OR 300 mg once daily at night for 4-8 weeks. 

Child 1-5 months
1 mg/kg 3 times daily. The maximum dose is 3 mg/kg 3 times daily. 

Child 6 months – 2 years
2-4 mg/kg twice daily. 

Child 3 – 11 years
2-4 mg/kg twice daily. The maximum dose is 150 mg. 

Child 12-17 years
150 mg twice daily OR 300 mg once daily at night. 


150 mg twice daily OR 300 mg once daily at night for up to 8-12 weeks if necessary. For moderate to severe cases, 600 mg daily in 2-4 divided doses for up to 12 weeks. 

For dyspepsia and heartburn

For short-term dyspepsia, you should take 75 mg and may repeat up to 4 doses if necessary (a maximum of 300 mg per day).

For chronic episodic dyspepsia, you should take 150 mg twice daily for up to 6 weeks.

What are the side effects of Ranitidine? 

Common side effects of Ranitidine include diarrhoea, fatigue, and headache.

Who should not take Ranitidine?

People allergic to Ranitidine or any formulation component.

Pharmacist Tips:

Long-term use of Ranitidine (2 years or longer) may result in poor absorption of Vitamin B12. In this case, Vitamin B12 supplements may be needed. 

Common dosing schedule:
You can take Ranitidine with or without food. 

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

Some common medications Ranitidine may interact with:
– Multivitamin or mineral products, including Folic Acid and Iron 

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

Where to buy Ranitidine in Hong Kong?

In Hong Kong, Ranitidine is an over-the-counter medicine which 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 Ranitidine 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.