The main reasons for taking iodine 131 to require bed rest include avoiding the triggering of thyroid crisis and facilitating the recovery of body functions. After iodine 131 treatment, due to the destruction of thyroid follicles, a large amount of thyroid hormones will be released into the blood, resulting in an increase in the level of thyroid hormones in the blood, which may aggravate the symptoms of hyperthyroidism in the short term. Therefore, you should rest in bed for a period of time after taking iodine 131, avoiding exertion, as well as avoiding infection, mental stimulation and other factors, otherwise it may induce thyroid crisis. Patients who need iodine 131 treatment should actively cooperate with doctors to standardize the treatment and do a good job of post-treatment care.