Calcium Carbonate Dosage: What You Need to Know for Safe Use

When you think of calcium carbonate, a common mineral compound used to treat low calcium levels and relieve heartburn. Also known as CaCO3, it’s one of the most widely used forms of calcium in supplements and over-the-counter antacids. It’s in everything from Tums to generic calcium pills sold at pharmacies. But taking it wrong—too much, at the wrong time, or with the wrong foods—can cause problems. The calcium carbonate dosage isn’t one-size-fits-all. It changes based on why you’re taking it: for bones, for heartburn, or to balance phosphate levels if you have kidney disease.

For bone health, a key use of calcium carbonate in adults over 50, especially women after menopause, the typical daily dose is 1,000 to 1,200 mg of elemental calcium, split into two doses. Since calcium carbonate only provides about 40% elemental calcium, that means you’re likely taking 2,500 to 3,000 mg of the compound itself per day. But if you’re using it as an antacid, a fast-acting remedy for acid reflux and indigestion, the dose drops to 500–1,500 mg taken only when symptoms hit. Too much can lead to constipation, gas, or even kidney stones. And if you take it with iron or thyroid meds, it can block absorption. That’s why timing matters: take calcium carbonate with food for better absorption, but keep it at least 2 hours apart from other pills.

People with kidney issues need special care. Calcium carbonate is sometimes prescribed to bind phosphorus in the gut, helping those with chronic kidney disease avoid dangerous buildup. But that’s a medical use—doses are carefully controlled by doctors, often 1,000–2,000 mg with each meal. Self-prescribing at that level can be risky. Also, don’t assume more is better. Studies show that taking over 2,000 mg of elemental calcium daily from supplements may raise heart attack risk in some people. The goal isn’t to flood your body—it’s to support your bones and balance your system without side effects.

What you’ll find in the articles below are real comparisons and practical guides on how calcium carbonate fits into daily life—how it interacts with other meds, what alternatives exist, and how to avoid common pitfalls. No fluff. Just clear, direct info on what works, what doesn’t, and what you should ask your doctor before you swallow another pill.