Tried taking other forms of calcium but they would always bother my stomach.  Really like the Sundown Calcium in liquid filled form and do not find that there are any side effects.  Usually  can find them buy one, get one free which helps defray the cost of taking two of these daily.  One thing I would recommend that Sundown would do is put the real mg amount on the label.  To get 1200 mg you must take 2 capsules which is a little misleading if you dont read the dosage in the fine print.