Methimazole tablets and propylthiouracil tablets are both antithyroid drugs, and there is no clinical comparison of the magnitude of side effects. Both methimazole tablets and propylthiouracil tablets can inhibit the synthesis of thyroid hormones, and propylthiouracil tablets have the effect of inhibiting the conversion of T4 to T3, and work more rapidly than methimazole tablets. However, liver toxicity is greater than methimazole tablets, so methimazole tablets are generally preferred. Propylthiouracil tablets are safer during pregnancy and are preferred during preparation for and during pregnancy. The side effects of methimazole tablets and propylthiouracil tablets are similar in that both may lead to leukocyte and neutrophil deficiencies, hepatic impairment, and can cause allergic skin reactions such as rash, itching, and hives. For severe liver function damage, granulocyte deficiency, allergy to drugs should be prohibited, pregnant women should be used with caution. Methimazole tablets and propylthiouracil tablets need to be taken under the guidance of a doctor, according to the specific situation of the patient, do not blindly use the drug. At the same time in the process of medication should be closely monitored for side effects caused by the drug.