Discontinuation of antithyroid drugs one month before iodine 131 may cause symptoms such as hand tremor, weakness, palpitations, etc. It is recommended to follow the doctor’s advice for treatment. Before iodine 131 treatment, patients are generally advised to stop taking methimazole for 2-7 days and propylthiouracil for 2-4 weeks, while special cases (e.g. severe hypermetabolic symptoms) require targeted treatment. Patients should be advised to abstain from eating seaweed, nori, deep-sea fish oil, iodine-containing multivitamins for about 2 weeks. Discontinuation of antithyroid drugs may increase the serum level of thyroid hormones, followed by palpitations, fatigue, hand tremors, increased frequency of bowel movements, weight loss, excessive sweating and other symptoms of hyperthyroidism. Patients with this condition need not be particularly worried, and can recover slowly after taking Iodine 131. It is important to note that if more serious symptoms occur after stopping the medication, it is recommended to seek immediate medical attention. Patients who need iodine 131 treatment should be under the guidance of a doctor.