Iodine 131 has a certain radiation hazard, but the range of radiation is very small, so keep a certain distance from the people around you, the general harm is not great. Iodine 131 is a radioactive element, mainly using iodine 131 decay radiation to kill diseased cells, its effective range is only 0.5 ~ 2 mm, can selectively destroy the thyroid gland follicular epithelium without affecting the neighboring tissues. Because of its short effective range, keep a certain distance (more than 1 meter) from the people around you, the general harm is not great. However, it should be kept away from infants, young children and pregnant women to avoid affecting the development of infants and young children as well as causing fetal malformation. It is recommended that patients who have had iodine 131 should keep themselves away from other people, and preferably stay alone in a room, so that other people do not come close to them. Patients are also advised to drink plenty of water to promote the body’s metabolism. Iodine 131 itself will continue to decay, so the patient alone for a period of time is basically no radiation hazard. Patients should follow the doctor’s advice and actively treat, consult the doctor if there is any problem and deal with it accordingly!