Iodine-131 is currently used clinically to treat thyroid disorders, mainly hyperthyroidism and some thyroid cancers. Some patients may develop radioactive thyroiditis, hyperthyroid crisis and may also aggravate active thyroid-related eye disease after receiving treatment. 1. Radioactive thyroiditis: Patients may experience radioactive radiation damage to thyroid tissue when undergoing iodine-131 treatment, which usually occurs 7-10 days after surgery. 2. Hyperthyroid crisis: It mainly occurs in patients with severe uncontrolled hyperthyroidism, and patients may develop tachycardia or even atrial fibrillation; 3. Exacerbation of active thyroid-related ophthalmopathy: such patients can usually be given a period of glucocorticoid treatment before surgery. In addition, some patients may develop other non-specific systemic reactions, such as generalized weakness, loss of appetite, and skin pruritus. Patients should pay attention to regular diet and rest and drink plenty of water during treatment with iodine-131.