Taking calcium tablets may cause constipation. Calcium is one of the most prevalent elements in the human body, with the body containing 1.5 to 2.0% of total body weight, of which bones and teeth account for about 99% and body fluids and soft tissues account for about 1%. Calcium plays an important role in the body’s metabolism, cellular function, nervous system operation, and protein kinase synthesis. The main ingredient of calcium tablets is vitamin D. It can help promote growth and development and prevent osteoporosis. Common adverse reactions are belching (burping), constipation, hypercalcemia, and renal insufficiency. Taking calcium tablets may result in calcium intake exceeding the requirement, causing a decrease in calcium absorption. When the ingested calcium is not better absorbed, it can lead to calcium aggregation in the intestinal tract, and the excess calcium will absorb a certain amount of water, leading to dry or hard stools, causing constipation, bloating and other symptoms. It should be noted that calcium tablets should be taken under the guidance of a doctor and should not be used without authorization.