Iodine 131 refers to iodine-131. It is not recommended to live with family members for the time being after iodine-131 treatment, and the body may have adverse reactions after iodine-131 treatment, which should be guided by a doctor. Iodine-131 treatment is one of the most important methods of treating hyperthyroidism. When hyperthyroid patients take iodine-131, it can release rays to kill thyroid cells. Having just completed iodine-131 treatment, the patient’s body will be exposed to radiation. It is recommended to isolate the patient for one week after iodine-131 treatment, sleep in a separate room for two weeks after treatment, and not to contact vulnerable groups such as pregnant women, infants and young children within one month of treatment. Iodine-131 treatment is simple, convenient and effective, and is being used more and more in clinical practice. However, the use of iodine-131 treatment also has side effects, which may easily cause hypothyroidism in patients. Iodine-131 treatment is contraindicated for pregnant and breastfeeding women, and should be used with caution in children. Iodine-131 treatment needs to be directed by a doctor, and it is recommended that patients go to a regular hospital in a timely manner.