Hyperthyroidism is short for hyperthyroidism. In the instructions, methimazole is contraindicated in breastfeeding women, but studies have shown that taking low to moderate doses of propylthiouracil and methimazole is safe for breastfed children, so breastfeeding women with hyperthyroidism can be treated with methimazole as prescribed by their doctor, but it is recommended that propylthiouracil is the best choice. Breastfeeding women taking methimazole need to consider breastfeeding their infants because methimazole can be secreted through breast milk, and improper use may affect the thyroid function of the offspring. Methimazole should be taken after breastfeeding and 3 hours after taking the drug. People who are allergic to any components of methimazole need to be prohibited, in addition to abnormal liver function, granulocytopenia should be used with caution. If hyperthyroid patients need to take methimazole during breastfeeding, it is recommended to use the drug under the guidance of a professional doctor to avoid serious consequences.