Medicines & Supplements A to Z > Calcium Carbonate

Calcium Carbonate

Last updated on 19/03/2021.

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

GENERIC NAME: Calcium Carbonate


BRAND NAME(S) IN HONG KONG: Gaviscon 嘉胃斯康 (contains Calcium Carbonate, Sodium Alginate, Sodium Bicarbonate), Megagel (contains Calcium Carbonate and Simethicone

DRUG CLASS: Antacid, dietary supplement, phosphate binder

USED FOR: Indigestion and heartburn, increasing calcium levels, reducing blood phosphate levels in chronic kidney disease

OTHER DRUGS IN THE SAME CLASS: Aluminium Hydroxide, Magnesium Carbonate

– 1000mg (chewable tablets)
– 1200mg/15ml, 8% (oral suspension)

What is Calcium Carbonate for?

Calcium Carbonate is commonly used as a dietary supplement for people with low calcium levels and in calcium deficiency states. Calcium is important for the development of healthy bones. Calcium is sometimes combined with Vitamin D. Calcium Carbonate can also be used to treat indigestion and heartburn. It can neutralize stomach acid due to its alkaline property.

How to use it?

Calcium Carbonate can be taken by mouth in many forms, like tablets, suspensions, and sachets. 

If you are using it for low calcium levels or calcium deficiency states, you should take 0.5-4 g daily in 1-3 divided doses. 

If you are using it for indigestion or heartburn, you should take 0.5-3 g as soon as symptoms appear. 

The maximum daily dose is 7.5 g for up to 2 weeks. The doses vary between different products so you are advised to check with your doctor, pharmacist, or the product label. 

What are the side effects of Calcium Carbonate?

Common side effects of Calcium Carbonate include constipation, flatulence and burping.

Who should not take Calcium carbonate?

Anyone with hypercalcemia. 

Pharmacist Tips:

– Calcium absorption might not be efficient if Calcium Carbonate is administered without food.
– Do more outdoor activities daily to ensure you absorb enough Vitamin D from sunlight. Vitamin D deficiency may cause a reduction in Calcium absorption. 

Common dosing schedule:
Calcium Carbonate is usually taken with meals.

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

Some common medications Calcium Carbonate may interact with:
– Atazanavir
– Quinolone antibiotics, e.g. Ciprofloxacin, Moxifloxacin, Levofloxacin
– Tetracycline antibiotics, e.g. Tetracycline, Doxycycline, Minocycline

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

Where to buy Calcium Carbonate in Hong Kong?

In Hong Kong, Calcium Carbonate 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 Calcium Carbonate 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.