Hypothyroidism after iodine 131 treatment of hyperthyroidism is not scary after timely medical treatment and active treatment. Fatigue, drowsiness, weight gain, chills, convulsions, increased menstrual flow and constipation in young and middle-aged women after iodine 131 treatment suggests the possibility of hypothyroidism, which should be followed up and reviewed in a timely manner. When hypothyroidism occurs, levothyroxine sodium or thyroid tablets can be used for replacement therapy, and the dosage should be adjusted under the guidance of the physician, so that the thyroid hormone level can be adjusted to normal. During the period of replacement therapy with levothyroxine sodium or thyroid tablets, regular follow-up examinations should be conducted. After active treatment, the occurrence of hypothyroidism is not terrible. Patients need to go to the hospital regularly for review, and need to strictly follow the doctor’s instructions when using medication.