Hyperthyroidism is a condition in which the thyroid gland synthesizes and releases too much thyroid hormone, causing hyper-metabolism and sympathetic excitation, resulting in palpitations, sweating, increased eating and bowel movements, and weight loss. Most patients also often have proptosis, eyelid edema, and loss of vision. Studies over the past 20 years have shown that anti-thyroid medication is safe in lactating patients with hyperthyroidism, and the use of propylthiouracil 150 mg/day or methimazole 10 mg/day has no effect on infant brain development, but the infant’s thyroid function should be monitored; no complications such as granulocytopenia or liver function impairment have been found in the offspring of mothers treated with anti-thyroid medication for hyperthyroidism during lactation. However, special attention should be paid to the following points in the treatment of hyperthyroidism during breastfeeding: 1. Mothers should take antithyroid drugs after finishing breastfeeding, and then the next breastfeeding should be performed 3-4 hours later; 2. Since the milk excretion of methimazole is 7 times higher than that of propylthiouracil, as in pregnancy, propylthiouracil should be preferred in the treatment of hyperthyroidism during breastfeeding; 3. Iodine-131 is prohibited for the treatment of hyperthyroidism in women during breastfeeding and pregnancy.