You can drink water immediately after taking iodine 131, but in moderation. Iodine 131 treatment is commonly used clinically for the treatment of hyperthyroidism and as adjuvant therapy after surgery for thyroid malignant tumors. Fast for at least 2 hours before taking iodine 131 orally. Fast for 2 hours after taking Iodine 131, but you can drink moderate amount of water. Within 2 days after Iodine 131 treatment, patients are advised to increase drinking water moderately to promote the excretion of iodine in the body. After Iodine 131, patients should maintain a good attitude, strengthen nutrition and avoid overwork. Try not to consume high iodine food, such as seaweed, nori and seafood, so as not to affect the effect of taking iodine. Patients are advised to have regular thyroid function tests to observe the treatment effect and patient’s recovery. Patients who are not satisfied with the effect of iodine 131 treatment can receive a second treatment under the guidance of the doctor.