Iodine-131 is radioactive iodine, which will release rays during decay. Its physical half-life is 8.05 days and effective half-life is 7.6 days. Generally, the human body can metabolize the radioactive iodine completely after 5 half-lives, and it is usually considered that the radiation is strongest within 2 weeks after iodine 131 treatment. The following aspects should be noted after iodine 131 treatment: 1. Iodine-131 treatment is radioactive, patients should pay attention to isolation after taking iodine-131, it is not recommended to contact minors, they should not breastfeed, and communication with adults should be separated by more than 1 meter to prevent radiation from causing certain damage to family members’ bodies, usually in 35-40 days it can be completely metabolized, and they can resume normal life; 2. Patients’ excrement should be cleaned up in time to avoid causing pollution to 3. 1 month after iodine-131 treatment, thyroid function should be rechecked to facilitate timely adjustment of treatment by the doctor. In addition, 1-2 weeks after iodine-131 treatment, patients should pay attention to rest, avoid staying up late and straining, mental stimulation and strenuous exercise, prevent colds, and avoid taking iodine-containing foods or drugs, such as anti-thyroid drugs, kelp, nori, etc., to avoid affecting the therapeutic effect.