Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not enough. Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve heartburn, acid indigestion, and upset stomach. It is available with or without a prescription.

• This medication is used to treat symptoms caused by too much stomach acid such as heartburn, upset stomach, or indigestion.
• It is an antacid that works by lowering the amount of acid in the stomach.

• Constipation, gas, and burping may occur.​​​​​
• Many people using this medication do not have serious side effects.
• Tell your doctor right away if any of these unlikely but serious side effects occur: loss of appetite, nausea/vomiting, unusual weight loss, bone/muscle pain, mental/mood changes (e.g., confusion), headache, increased thirst/urination, unusual weakness/tiredness.

• Before taking calcium carbonate, tell your doctor or pharmacist if you are allergic to it. This product may contain inactive ingredients (such as milk or dairy products found in some brands), which can cause allergic reactions or other problems.
• If you have any of the following health problems, consult      your doctor or pharmacist before using this medication: highypercalcemia, intestinal blockage, kidney disease (such as kidney stones).
• Some products may contain aspartame. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame (or phenylalanine), consult your doctor or pharmacist about using this drug safely.
• Tell your doctor if you are pregnant before using this medication.
• This medication passes into breast milk. Consult your doctor before breast-feeding.