Calcium supplement

Calcium supplements are salts of calcium used in a number of conditions. Supplementation is generally only required when there is not enough calcium in the diet. By mouth they are used to treat and prevent low blood calcium, osteoporosis, and rickets. By injection into a vein they are used for low blood calcium that is resulting in muscle spasms and for high blood potassium or magnesium toxicity.

Common side effects include constipation and nausea. When taken by mouth high blood calcium is uncommon. Calcium supplements, unlike calcium from dietary sources, appear to increase the risk of kidney stones. Adults generally require about a gram of calcium a day. Calcium is particularly important for bones, muscles, and nerves.

The medical use of calcium supplements began in the 19th century. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2020, it was the 204th most commonly prescribed medication in the United States, with more than 2 million prescriptions. Versions are also sold together with vitamin D. In 2020, the combination, calcium/vitamin D was the 215th most commonly prescribed medication in the United States, with more than 2 million prescriptions.