Jimb,You can have some indigestion with the calcium when you first start so it is best to start with 1/2 tablet with food 3 times a day at least 4 or 5 hours apart. You do this for 3 days then you can incresse the dose if needed. This time is needed for the body to adjust to the calcium. If you are having chest pain you may want to see your doctor or the ER.Linda