Isotope iodine 131 treatment is commonly used in the treatment of hyperthyroidism and postoperative thyroid cancer, the more common harm is that it will cause hypothyroidism, and aggravate protruding eyes, and so on. 1. Causing hypothyroidism: the principle of isotope treatment is that radioactive iodine will directly kill the thyroid tissue in the body, which may cause hypothyroidism, resulting in the need for patients to take lifelong medication. 2. Aggravation of protruding eyes: patients with combined hyperthyroidism and protruding eyes may have their protruding eyes aggravated after receiving radioactive iodine treatment. 3. Thyroid cancer: It is used to clear the thyroid after surgery and whole-body scanning to find metastases, which has little effect on tissues other than the thyroid, and does more harm than good. When corresponding symptoms appear, it is recommended to choose regular hospitals to receive standardized treatment in order to minimize the side effects of isotope therapy.