The most common sequelae of Iodine 131 radiation therapy are radiation thyroiditis, thyroid crisis and hypothyroidism. 1. Radiation thyroiditis: It occurs within 7 days after treatment and can be treated with aspirin or glucocorticoids in severe cases. 2. Thyroid crisis: usually occurs in patients with uncontrolled severe hyperthyroidism, it is generally recommended that patients apply antithyroid drugs before applying iodine 131 treatment to properly control the condition. 3. Hypothyroidism: patients taking iodine 131 treatment are inevitably prone to hypothyroidism, and patients are advised to take levothyroxine tablets instead of treatment. Therefore, patients taking iodine 131 radiation therapy can have a variety of sequelae, it is recommended that patients take iodine 131 treatment in a timely manner before seeking medical treatment, under the guidance of clinicians, scientific and standardized treatment, sequelae should follow the doctor’s advice, regular monitoring of thyroid function, in order to avoid delaying the condition.