If there is vitamin A and vitamin D deficiency, men can take cod liver oil to play a supplementary role; if there is no deficiency and long-term use of cod liver oil may lead to chronic poisoning. The main active ingredients of cod liver oil are vitamin A and vitamin D, which are essential substances for human growth and development, and can be supplemented by cod liver oil if they are deficient. If there is no deficiency of the above two substances and still take cod liver oil for a long time, it may cause chronic poisoning. Because both are fat-soluble vitamins, easy to accumulate in the body. The main manifestations of chronic poisoning are bone and joint pain and swelling, itchy skin, dry and cracked lips, weakness, fever, headache, vomiting, constipation, diarrhea and so on. Therefore, it is not recommended to take cod liver oil on your own, you need to complete the relevant examinations in the hospital, clear the existence of vitamin A or D deficiency, and then by the doctor according to the patient’s condition to formulate the cod liver oil supplement program.