When taken appropriately, supplementary calcium tablets can only cause minor side effects such as gas, bloating and constipation, notes WebMD. One is advised to drink more fluids, eat high fiber foods and/or switch to another form of calcium if he experiences these side effects, according to MedlinePlus.
Calcium tablets are potentially unsafe when taken by mouth in high doses, according to WebMD. Research, although not definitive, suggests that doses over the recommended daily requirement of 1,000 to 1,300 mg daily for most adults may increase the chance of heart attack, explains WebMD. Calcium doses above the tolerable upper limits can also increase ones chances of kidney stones, prostate cancer, impaired absorption of iron and zinc, and calcium build up in your blood vessels, notes Mayo Clinic.
Calcium supplements come in two main forms: carbonate and citrate. Calcium carbonate is the cheapest and is recommended as a good first choice, states Mayo Clinic. Calcium tablets are used to treat conditions that stem from low calcium levels in the body such as osteoporosis caused by low bone density and rickets caused by softening of bones in children. Calcium is also used to treat postmenstral syndrome, leg cramps during pregnancy, hypertension during pregnancy, and also reduces the risk of colon and retinal cancer, explains WebMD.