Calcium is essential for healthy bones and teeth and for proper function of the heart, nervous system and muscles. Because many people consume less than half the amount of calcium needed for effective bone maintenance, according to the University of Maryland Medical Center, or UMMC, they can benefit from calcium supplements. These can be in the form of calcium carbonate or calcium citrate. Some calcium citrate supplements contain vitamin D because this vitamin is necessary for calcium absorption. However, such supplements may come with side effects.
Calcium citrate plus D supplements can cause mild constipation, according to Harvard Health Publications. They usually do not cause serious constipation unless the person is taking another supplement or medication that causes constipation as well.
High Calcium Levels
Hypercalcemia is very high levels of calcium in the blood, which can be caused by consuming too much calcium citrate plus D. Very high doses of calcium citrate plus D can cause dry mouth, increased thirst, increased urination, headaches, depression, fatigue, loss of appetite, nausea, vomiting, kidney toxicity, confusion and irregular heart rhythm. Total calcium intake, from both diet and supplements, should not exceed 2500 milligrams per day, according to the UMMC. People with overactive parathyroid glands, kidney disease, sarcoidosis or cancer should not take calcium supplements because these people may be at risk for elevated calcium levels.
Taking supplements of 1000 milligrams calcium and 400 international units of vitamin D per day was linked to a 17 percent increase in the risk of kidney stones in postmenopausal women, in a study published in the 2006 "New England Journal of Medicine." People with a history of kidney stones should talk to a doctor before taking calcium citrate plus D.
Higher intake of calcium, whether from supplements or dairy products, is associated with an increased risk of prostate cancer, according to the UMMC. The exact mechanism of how calcium affects prostate cancer remains unclear, but the 2013 issue of the "Journal of Nutrition" reports that intake of low-fat or skim milk increases the risk of developing non-agressive prostate cancer, while whole milk increases the risk of fatal prostate cancer. On the other hand, a study in the 2012 issue of "Preventing Chronic Disease" reports that calcium intake from food, as opposed to supplements, is associated with a lower risk of prostate cancer. Men should talk with a doctor before taking calcium citrate plus D supplements.
Although unlikely, some people may experience an allergic reaction to calcium citrate plus D, as noted by Drugs.com. Signs include rash or hives, itching, difficulty breathing, chest tightness and facial or mouth swelling.