Calcium carbonate
Also sold as: Tums
Usual adult dose
Usual adult dose as a calcium supplement: 500 mg to 1 g of calcium a day, split into doses and taken with meals. As an antacid: chew 1 to 2 tablets when needed. Take at least 2 hours apart from iron tablets.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- constipation
- gas
- bloating
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- signs of high calcium (constant thirst
- confusion
- vomiting)
- kidney stone pain
Do not take it, or take care, if
- High calcium in the blood
- Kidney stones or serious kidney disease (use with caution)
- Do not use as an antacid for more than 2 weeks without seeing a doctor
Interactions
Medicines that can react with this one.
Moderate5 medicinesTake together only with care. Ask your doctor or pharmacist.
- Alendronic acid
Calcium blocks absorption of alendronic acid; take alendronic acid first and wait at least 30 minutes.
- Ciprofloxacin
Calcium reduces absorption of ciprofloxacin; take the antibiotic 2 hours before or 6 hours after calcium.
- Doxycycline
Calcium binds doxycycline in the gut; take them at least 2 to 3 hours apart.
- Levothyroxine
Calcium reduces absorption of levothyroxine; take them at least 4 hours apart.
- Tetracycline
Calcium blocks absorption; leave 2 to 3 hours between them.
Minor2 medicinesUsually not a problem, but tell your doctor.
- Ferrous sulfate
Calcium reduces iron absorption; take them at least 2 hours apart.
- Ferrous sulfate + Folic acid
Calcium reduces iron absorption; take them at least 2 hours apart.