The dangers of too much calcium supplementation include affecting the nervous, cardiovascular, digestive and urinary systems, drowsiness, arrhythmia, anorexia, polyuria and other symptoms. 1. Neurological system: mostly manifested as drowsiness, inattention, depression, rigidity, ataxia and other symptoms. 2. Cardiovascular system: arrhythmia, bradycardia, elevated blood pressure and other manifestations can be seen. 3. Digestive system: anorexia, nausea, vomiting, constipation and other discomforts are easily seen. 4. Urinary system: often manifested as polyuria, kidney stones, decreased glomerular filtration rate and so on. 5. Others: some people may also have muscle weakness, dehydration and other manifestations. Under normal circumstances, the reference value of blood calcium for adults is about 2.15~2.6mmol/L. If the calcium supplementation is too much, more than 2.6mmol/L, it is defined as hypercalcemia. All in all, when the body is deficient in calcium, it is necessary to go to the hospital and take calcium supplements under the guidance of the doctor, so as to avoid further affecting the health of the body.