calcium carbonate at a glance
Medicine class
Antacid
Usual role
Short-term relief of heartburn, indigestion and other acid-related stomach symptoms
Available forms
Selected products include chewable tablets and medicated chewing gum
Persistent symptoms
Frequent, worsening or persistent symptoms need assessment by a pharmacist or clinician
What is calcium carbonate used for?
Selected UK products are licensed for relief of acid-related digestive symptoms.
Heartburn and acid indigestion
Indigestion, dyspepsia and hyperacidity
Upset stomach associated with overindulgence in food or drink
Acid-related symptoms during pregnancy
Associated flatulence or stomach discomfort
How does calcium carbonate work?
Calcium carbonate reacts with hydrochloric acid in the stomach to form water, carbon dioxide and calcium salts. This raises stomach pH and reduces acid-related discomfort. Some calcium may be absorbed; the remainder becomes insoluble salts and passes in the stool.
calcium carbonate preparations and strengths
Chewable tablet
Route: Oral
Strengths: 500 mg, 1500 mg
Medicated chewing gum
Route: Oromucosal
Strengths: 750 mg
How to take calcium carbonate
Follow the instructions for your exact product because administration differs between formulations.
Chewable tablets may be chewed or sucked before swallowing.
Chew medicated gum thoroughly, then discard the remaining gum rather than swallowing it.
Avoid excessive quantities of milk or dairy foods.
Ask a pharmacist about separating calcium carbonate from other medicines.
calcium carbonate side effects
Common or expected effects
- Nausea, vomiting or stomach discomfort; frequency is not known.
- Constipation or diarrhoea; frequency is not known.
Get urgent medical advice
- Difficulty breathing, facial or throat swelling, widespread rash or other signs of a severe allergic reaction.
- Persistent vomiting, pronounced weakness, headache, altered taste or kidney symptoms that could indicate excess calcium or milk-alkali syndrome, particularly with prolonged excessive use or renal impairment.
calcium carbonate in pregnancy
Selected products are licensed for acid-related indigestion during pregnancy and may be used as directed. Ask a pharmacist or prescriber which antacid is suitable, avoid excessive combined calcium intake from milk or dairy products, and seek advice if symptoms persist.
calcium carbonate while breastfeeding
Calcium carbonate antacids can be used as directed while breastfeeding. Calcium is naturally present in breast milk, systemic absorption is limited, and specific monitoring of a healthy full-term infant is not usually required.
calcium carbonate interactions
Calcium carbonate can alter stomach acidity or bind other medicines, reducing their absorption. Ask a pharmacist about suitable separation.
Tetracycline and quinolone antibiotics
Calcium can form complexes with these antibiotics and reduce their absorption.
Levothyroxine
Calcium carbonate can reduce its absorption, so the products should be taken separately.
Common questions about calcium carbonate
Answers are fully visible for fast scanning and source review.
What does calcium carbonate do for heartburn?
It neutralises stomach acid, increasing stomach pH and easing acid-related burning or discomfort. It does not correct the underlying cause of recurrent heartburn.
Can calcium carbonate help acid reflux?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.