> Western Medicines > Alginate

What is Alginate for?

Alginate is a substance usually used with other antacids (e.g. Calcium carbonate) for treating dyspepsia and heartburn. When it contacts the acid in your stomach, it forms a gel over the wall of your stomach which acts as a barrier to prevent acid reflux.

How to use it?

Alginate is usually combined with Sodium Bicarbonate or Potassium Bicarbonate and Calcium Carbonate. It is taken by the mouth either in chewable tablets or liquids. The usual doses for different products are listed as follows:


Gaviscon Chewable Tablet

Adults/ Child ( 12 years)
2-4 tablets after meals and before bedtime


Gaviscon Extra Strength 500 Chewable Tablet

Adults/ Child ( 12 years)
1-2 tablets after meals and before bedtime


Gaviscon Double Action Chewable Tablet

2-4 tablets after meals and before bedtime, up to 4 times daily


Gaviscon Liquid

Adults/ Child ( 12 years)
10-20 mL after meals and before bedtime


Gaviscon Advance Liquid

Adults/ Child ( 12 years)
5-10 mL after meals and before bedtime

What are the side effects of Alginate?

Common side effects of Alginate can include water retention, nausea and vomiting, and flatulence. People with high blood pressure or heart failure may need to avoid products containing Alginate as they often have a high sodium content.

Who should not take Alginate?

  • Anyone who has intestinal obstructions
  • Preterm neonates
  • Anyone who is likely to have excessive water loss (e.g. fever, diarrhoea, vomiting)

Pharmacist Tips:

  • If you have fluid retention, avoid taking preparations containing large amounts of sodium.

Common dosing schedule: 
Take the preparation after meals and at bedtime.


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


Some common medications Alginate may interact with:
Alginate does not have significant interactions with other medications.

Where to buy Alginate in Hong Kong?

In Hong Kong, Alginate is an over-the-counter medicine that 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 https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Alginate 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.

Brands in Hong Kong
Available dosage
  • 250mg/106.5mg/187.5mg / 250mg/133.5mg/80mg / 500mg/267mg/160mg (Chewable Tablets)
  • 500mg/267mg / 500mg/213mg/325mg / 1000mg/200mg (Oral Suspension)
  • 500mg/213mg/325mg / 500mg/267mg/160mg / 1000mg/200mg (Sachets)
Drug class
Acid-Reducing Drugs
Sub class
Other drugs in same class