Proper living isolation is recommended after having iodine-131 treatment. Iodine-131 that enters the bloodstream is selectively taken up by the thyroid gland and is involved in the synthesis of thyroid hormones and metabolic cycles in the body. Isolation after treatment is important because of the possibility of environmental contamination, mainly due to the fact that the drug used in iodine-131 treatment can be excreted from the body through the urinary system. As iodine-131 itself can release gamma rays, gamma rays can also cause a small amount of radiation to the surrounding population. Patients should be isolated at home, and isolation suggests a single room, with access to a separate bathroom if possible. Therefore, proper living isolation is recommended after having iodine-131 treatment. After iodine-131 treatment, patients should go to the hospital regularly for rechecking the thyroid function, blood routine, liver function, etc., in order to understand the change of the patient’s thyroid function status, and should drink more water to promote the excretion of iodine in the body.