The duration of isolation from family members after iodine-131 treatment varies depending on the patient’s treatment dose. For Iodine 131 treatment doses of 5 mCi, 10 mCi, and 15 mCi, the duration of isolation is 1, 2, or 3 weeks, respectively. For family pregnancy, infants, and children, the isolation duration generally needs to be extended by about 1 week. The element radioactive iodine is used in iodine-131 treatment. Radioactive iodine releases rays during the decay process, so patients need to undergo isolation treatment after iodine-131 treatment in order to avoid affecting others. Iodine-131 is primarily a treatment for thyroid disease and can kill diseased or normal cells in the patient’s thyroid gland. After iodine-131 treatment, patients may experience adverse effects such as fatigue, loss of appetite and nausea. Patients are advised to use daily necessities alone, take more rest, drink more water, and avoid emotional stress and touching the thyroid gland after iodine-131 treatment. If there is any discomfort, inform the doctor promptly.