Vitamin D is not toxic when taken under medical advice and in the doses required by the instructions; it is the long-term, excessive use of the drug that can cause toxicity. The early stages of poisoning may include bone and joint pain and swelling, itchy skin or dry lips, sometimes fever and headache, and symptoms of vomiting, constipation, diarrhea and nausea in the digestive system. If symptoms of overdose occur, you must seek medical attention in a timely manner. During the period of taking the drug, you should adopt a low-calcium diet and drink a lot of water to promote the excretion of calcium, and at the same time, you should pay attention to avoid exposure to sunlight, which will also increase the absorption of vitamin D and aggravate the symptoms caused by overdose.