The possible harms to the body after iodine 131 treatment may include radiation thyroiditis, gastrointestinal adverse reactions, hematologic adverse reactions, salivary gland damage, abnormal taste, radiation pneumonitis and pulmonary fibrosis. The main symptoms of radiation thyroiditis are neck pain and swelling. Gastrointestinal adverse reactions are caused by hypothyroidism after iodine 131 treatment, which causes a decrease in basal metabolic rate and a slowing of gastrointestinal motility. Hematologic adverse reactions are dominated by a decrease in white blood cells, mostly mild. The main symptoms of lacrimal gland injury are tear spillage, photophobia and ocular dryness, which are often mild and mostly resolved on their own. It is recommended that patients who need iodine 131 treatment strictly follow medical advice, and carry out treatment and isolation protection under the guidance of a doctor, so as not to cause adverse consequences.