Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
little or no urinating;
swelling, rapid weight gain; or
high levels of calcium in your blood--nausea, vomiting, constipation, increased thirst or urination, muscle weakness, bone pain, confusion, lack of energy, or feeling tired.
Common side effects may include:
upset stomach, gas; or
constipation.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Calcium carbonate side effects (more detail)
What other drugs can affect calcium carbonate?
Calcium can make it harder for your body to absorb certain medicines. If you take other medications, take them at least 2 hours before or 4 or 6 hours after you take calcium carbonate.
Other drugs may interact with calcium carbonate, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.
