A large amount of prolonged use can cause hypercalcemia, loss of appetite, vomiting, diarrhea and even heterotopic ossification of soft tissues. If overdose, such as 100,000~200,000 units per day for adults and 20,000~30,000 units per day for children, poisoning can occur in weeks or months, with symptoms of anorexia, fatigue, weakness, nausea, vomiting, diarrhea, polyuria, profuse sweating, headache and thirst. The concentration of calcium and phosphorus in serum and urine increases, which may lead to hypertension and renal failure. Principles of treatment: 1. stop the drug immediately when poisoning occurs, limit the intake of calcium and vitamin D. 2. large amounts of fluids and maintain water and electrolyte balance. 3. in severe cases, glucocorticoids can be used to rapidly reduce blood calcium. 4. avoid sunlight exposure. 5. symptomatic treatment.