Calcium Carbonate Dosing for Heartburn Management
For acute heartburn relief in adults and children ≥12 years, the recommended dose is 750-1500 mg calcium carbonate (1-2 chewable tablets) every 2-4 hours as needed, not exceeding 3750 mg (5 tablets) in 24 hours. 1
Standard Dosing Protocol
- Single dose: 750-1500 mg calcium carbonate (equivalent to 300-600 mg elemental calcium, as calcium carbonate contains 40% elemental calcium) 2, 1
- Frequency: Every 2-4 hours as symptoms occur 1
- Maximum daily dose: 3750 mg calcium carbonate (5 tablets) in any 24-hour period 1
- Duration limit: Do not use maximum dosage for more than 2 weeks without physician supervision 1
Administration Considerations
- Timing with meals: Calcium carbonate requires gastric acid for optimal absorption and should be taken with food for nutritional supplementation purposes 3. However, for heartburn relief, the antacid effect occurs regardless of meal timing 1
- Chew thoroughly: The medication must be chewed and swallowed, not swallowed whole 1
- Onset of action: Calcium carbonate provides immediate symptom relief by neutralizing esophageal acid 4
Comparative Effectiveness
Research demonstrates that calcium carbonate antacids provide rapid but relatively short-duration relief compared to acid-suppressing medications:
- Duration of relief: Standard chewable calcium carbonate antacids (1000 mg) provide symptom relief, though newer formulations like calcium carbonate gum (900 mg) have shown superior sustained relief for up to 120 minutes post-dose 4
- Mechanism: Relief correlates directly with esophageal acid neutralization and duration of esophageal antacid exposure 4, 5
Pediatric Considerations
- Age restriction: Children under 12 years require physician consultation before use 1
- Not recommended for chronic use: For children with recurrent symptoms, alternative diagnoses and treatments should be pursued rather than chronic antacid therapy
Important Warnings and Pitfalls
- Constipation: The most common adverse effect; patients should be counseled to expect this 1
- Rebound acid secretion concerns: Historical concerns about calcium carbonate causing "acid rebound" are based on flawed assumptions; gastric acid stimulation occurs with all buffers and is compensated by remaining buffer capacity 6
- Not for erosive esophagitis: Patients with frequent heartburn requiring chronic antacid use (>2 weeks at maximum dose) likely have GERD requiring acid suppression therapy rather than antacids alone 7
- Drug interactions: Calcium carbonate can interfere with absorption of certain medications when taken concurrently
When Antacids Are Insufficient
If patients require antacids more than 4 times weekly for more than 2 months, acid suppression therapy (H2-receptor antagonists or proton pump inhibitors) provides superior symptom control, esophagitis healing, and quality of life improvement compared to as-needed antacids 7, 5