Maximum Recommended Dosage of Calcium Carbonate for Adults
The maximum recommended dosage of calcium carbonate for adults is 5 tablets in a 24-hour period, which should not be used for more than 2 weeks without medical supervision. 1
Dosage Guidelines
The FDA-approved labeling for calcium carbonate provides clear guidance:
- Adults and children 12 years and older: Chew and swallow 1-2 tablets every 2-4 hours as needed
- Maximum daily dosage: Do not exceed 5 tablets in 24 hours
- Duration limitation: Do not use the maximum dosage for more than 2 weeks without physician supervision 1
Calcium Intake Recommendations
When considering calcium supplementation for specific health conditions:
- For general supplementation in adults over 50 years: 1200-1500 mg/day 2
- For premenopausal adults (19-50 years): 1000 mg/day 2
- For postmenopausal women: 1200 mg/day 2
- For men over 70 years: 1200 mg/day 2
Safety Considerations
Upper Limits
- Safe upper limit for total calcium intake: 2500 mg/day 2
- Total calcium intake (diet plus supplements) should not exceed:
- 2000 mg/day for adults over 50
- 1200 mg/day for other populations 2
Absorption Optimization
- Maximum absorption occurs with doses of 500 mg elemental calcium at one time 3
- Calcium carbonate should be taken with meals to ensure optimal absorption 3
- Splitting the total daily dose into multiple smaller doses improves absorption 3
Potential Adverse Effects
- Common side effects include constipation, bloating, and gas 2
- Risk of kidney stones increases with calcium supplements (but not with dietary calcium) 2
- Excessive intake (>1500 mg/day) has been associated with increased risk of advanced prostate cancer 3
- Severe hypercalcemia can occur with excessive intake, as documented in a case where a patient consumed 6.6-7.9g of calcium carbonate daily for 2 years 4
Special Populations
For patients with specific medical conditions:
- Patients with achlorhydria or those taking acid-reducing medications should consider calcium citrate instead of calcium carbonate 3
- Patients with 22q11.2 Deletion Syndrome may require calcium supplementation due to high prevalence (80%) of hypocalcemia 2
- For patients with renal failure on dialysis, calcium carbonate may be used as a phosphate binder, though dosing should be determined by a nephrologist 5
Monitoring Recommendations
- Assess calcium intake at least annually 2
- For long-term supplementation, consider measuring serum calcium levels periodically
- Be alert for symptoms of hypercalcemia (constipation, nausea, vomiting, confusion)
Remember that calcium carbonate contains approximately 40% elemental calcium, so a 1250 mg calcium carbonate tablet provides about 500 mg of elemental calcium. This is important when calculating total daily calcium intake.