Calcium Carbonate
Pronunciation: (tumz).
- Generic name
- calcium carbonate
- Brand names
- Rennie, Settlers, Calcium Carbonate Antacid, Calcinol, Tums, Maalox Antacid
- Drug class
- Antacid, Calcium Supplement
Availability and supply rules vary by country
Trade names by country:
Australia: · Full directory
What calcium carbonate is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how calcium carbonate works
Calcium carbonate acts as a potent antacid by directly neutralizing gastric hydrochloric acid, increasing gastric pH, and decreasing pepsin activity. This leads to rapid symptomatic relief of heartburn and indigestion. As a calcium supplement, it provides elemental calcium for bone mineralization and metabolic functions. (1) (2)
What calcium carbonate is used for
Heartburn
Heartburn (2)
Acid indigestion
Acid indigestion (2)
Sour stomach
Sour stomach (2)
Upset stomach
Upset stomach (2)
Calcium deficiency
Calcium deficiency (2)
Before taking calcium carbonate
Do not take / not appropriate for
- hypercalcemia, severe renal impairment, nephrolithiasis, and hypersensitivity to calcium carbonate. (Contraindication) (2)
Tell your clinician about
(2)How to take calcium carbonate
- General Instructions: Take Tums as needed for heartburn or as directed by your healthcare provider. Do not exceed the recommended dose.. Adult Dosing: Chew 2-4 tablets as symptoms occur. Maximum: 7,500 mg per day (usually not more than 10 tablets in 24 hours).. Pediatric Dosing: Children under 12 years: Use only under medical advice. Dosing varies by age and indication.. Administration: Chew tablets thoroughly before swallowing. Take with or without food. Drink a full glass of water after taking.. When To Stop: Seek medical attention if symptoms persist beyond 2 weeks or worsen, and let the clinician you see advise on whether to continue or stop use.. Storage: Store at room temperature, away from moisture and heat. Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you are taking Tums on a regular schedule and miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose. Do not double up.
Overdose
An overdose of calcium carbonate can cause serious symptoms such as nausea, vomiting, loss of appetite, confusion, or irregular heartbeat. Seek emergency medical help or contact a poison control center immediately. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Constipation
Incidence: Reported in the clinician-authored database; frequency not established
Bloating
Incidence: Reported in the clinician-authored database; frequency not established
Gas
Incidence: Reported in the clinician-authored database; frequency not established
Upset stomach
Incidence: Reported in the clinician-authored database; frequency not established
Kidney stones
Incidence: Reported in the clinician-authored database; frequency not established
Milk-alkali syndrome
Incidence: Reported in the clinician-authored database; frequency not established
Serious warnings
Do not use for more than 14 days unless directed by a healthcare provider — serious
Symptoms: Do not use for more than 14 days unless directed by a healthcare provider. High doses may cause hypercalcemia or kidney stones. May interfere with absorption of other medications. Use caution in patients with kidney impairment. Not recommended for children under 12 without medical supervision.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindications recorded in the clinician database — serious
Symptoms: Contraindications recorded in the clinician database: Contraindications include hypercalcemia, severe renal impairment, nephrolithiasis, and hypersensitivity to calcium carbonate. Use caution in patients with mild-to-moderate renal dysfunction, sarcoidosis, or those on digitalis glycosides due to risk of arrhythmias. Monitor for signs of milk-alkali syndrome in chronic or high-dose use.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Tums (calcium carbonate) can interact with several medications, including certain antibiotics (tetracyclines, fluoroquinolones), thyroid medications (levothyroxine), bisphosphonates, and iron supplements. These interactions may reduce the effectiveness of either medication. To minimize interactions, take Tums at least 1-2 hours apart from other medications. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Requires a primary-source research pass before this section can be completed. (2)
Breastfeeding
Requires a primary-source research pass before this section can be completed. (2)
Children
Frequency: Not applicable.. Weight Based: Not recommended for pediatric use.. Max Daily Dose: Not applicable.. Max Single Dose: Not applicable.. Age Restrictions: Safety not established in children. (2)
Renal_impairment
Requires a primary-source research pass before this section can be completed. (2)
Hepatic_impairment
Requires a primary-source research pass before this section can be completed. (2)
Monitoring
(2)Storage
Requires a primary-source research pass before this section can be completed.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Heartburn
Dose summary: Chew 2-4 tablets as needed for heartburn or indigestion.
Renal context: The independent MedlinePlus (NIH/NLM) guidance reviewed for this page gives no numeric renal dose-adjustment table for calcium carbonate antacid, but flags kidney disease as history the prescriber should be told about. A real, well-documented clinical risk exists that this page did not previously cover: calcium-alkali (milk-alkali) syndrome — hypercalcemia, metabolic alkalosis, and reduced kidney function — has been reported with excessive or prolonged calcium carbonate intake (historically at doses of roughly 4-5 g/day or more), and people with reduced kidney function are more susceptible. MedlinePlus advises not using calcium carbonate as an antacid for more than 2 weeks unless a doctor says otherwise, which is especially important for anyone with kidney disease. (1) (2)
Hepatic guidance
The independent MedlinePlus (NIH/NLM) guidance reviewed for this page gives no specific dosing or safety information for liver disease or hepatic impairment for calcium carbonate. No numeric hepatic dose-adjustment table exists for this OTC antacid/calcium supplement; general precautions (do not exceed the labeled duration, tell your doctor about other conditions) apply.
Frequently asked questions
How quickly does Tums work?
Tums usually starts to relieve heartburn and indigestion within minutes of chewing the tablet.
Can I take Tums every day?
Tums is safe for occasional use. Do not use daily for more than 2 weeks unless directed by your doctor.
Is Tums safe during pregnancy?
Tums is generally considered safe for short-term use during pregnancy, but always consult your healthcare provider before use.
Can children take Tums?
Tums should not be given to children under 12 years unless prescribed by a healthcare professional.
What should I do if I take too many Tums?
Seek medical attention immediately if you suspect an overdose. Symptoms may include nausea, vomiting, confusion, or irregular heartbeat.
Can I take Tums with other medications?
Tums can interact with several medications. Take it at least 1-2 hours apart from other drugs and consult your doctor or pharmacist.
Does Tums provide calcium for bone health?
Yes, Tums contains calcium carbonate and can be used as a calcium supplement, but consult your doctor for appropriate dosing.
What happens if I take too much Tums (calcium carbonate)?
Taking too much Tums can lead to symptoms like nausea, vomiting, constipation, abdominal pain, and muscle weakness. In severe cases, it can cause hypercalcemia, which may affect kidney function and heart rhythm. If you suspect an overdose or experience severe symptoms, seek immediate emergency medical attention.
Can I drink alcohol while taking Tums (calcium carbonate)?
While there isn't a direct dangerous interaction between Tums and alcohol, alcohol can irritate the stomach lining and worsen the symptoms Tums is meant to treat, such as heartburn. Therefore, it's generally advisable to limit alcohol consumption when experiencing digestive discomfort to allow the medication to be most effective.
Is Tums (calcium carbonate) safe during pregnancy?
Tums (calcium carbonate) is generally considered safe for use during pregnancy for heartburn relief and as a calcium supplement, often falling into Pregnancy Category B. However, it is crucial to consult your healthcare provider before taking any medication, including Tums, while pregnant to ensure appropriate dosage and rule out any potential risks specific to your individual health.
What is the mechanism of action of calcium carbonate?
Calcium carbonate acts as a potent antacid by directly neutralizing gastric hydrochloric acid, increasing gastric pH, and decreasing pepsin activity. This leads to rapid symptomatic relief of heartburn and indigestion. As a calcium supplement, it provides elemental calcium for bone mineralization and metabolic functions. (1) (2)
What is the generic name of Calcium Carbonate?
The generic name is calcium carbonate. It is sold under brand names including Rennie, Settlers, Calcium Carbonate Antacid, Calcinol, Tums, Maalox Antacid.
What class of drug is calcium carbonate?
Calcium Carbonate is classed as: Antacid, Calcium Supplement.
References
- Clinician-authored medicine record for Tums (calcium carbonate) (MedGuideGlobal medicines database) · · accessed 2026-08-07 · source 1
- Calcium Carbonate — MedlinePlus Drug Information (NIH/NLM) · · accessed 2026-08-07 · source 2
- WINCO FOODS ANTACID ULTRA STRENGTH (CALCIUM CARBONATE) TABLET, CHEWABLE [WINCO FOODS, LLC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- ANTACID — FDA approval record (Drugs@FDA part331)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- calcium carbonate — RxNorm normalized drug concept (RXCUI 1897)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient calcium carbonate names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.