Antithyroid drug therapy, which acts to inhibit thyroid gland synthesis of thyroid hormone, is the basic treatment for hyperthyroidism. The commonly used antithyroid drugs are divided into two categories: thioureas and imidazoles. Thioureas include propylthiouracil and methiocarbital. The imidazole class includes methimazole (tabazol) and carbimazole. Methimazole and prothiouracil are commonly used in China. Propylthiouracil is chosen in case of hyperthyroidism and thyroid crisis in T₁ period (1~3 months) of pregnancy. In other cases because the side effects of propylthiouracil are greater than methimazole, and methimazole has a long half-life and can be taken as a single dose every day, so it tends to be preferred to methimazole. Indications for antithyroid drug therapy: mild to moderate disease; mild to moderate enlargement of the thyroid gland; pregnant women, elderly people or those who are not suitable for surgery due to other serious diseases; preparation before surgery and 131I treatment; recurrence after surgery and those who are not suitable for 131I treatment. Antithyroid drugs have certain side effects, the common ones are: 1. granulocyte deficiency, so patients receiving antithyroid drugs need to have their peripheral blood white blood cell count checked regularly and monitored for clinical symptoms such as fever and sore throat. 2, rash, mild rash can be given antihistamines, or switch to another anti-thyroid drug; those who have severe rash reactions need to discontinue the drug without switching to other anti-thyroid drugs. 3. Toxic liver disease, fulminant hepatic necrosis caused by propylthiouracil, has a rapid onset, progresses rapidly, and is unpredictable. The hepatotoxic effect of methimazole is mainly cholestasis, which occurs mainly in high-dose and elderly patients. 4. Vasculitis and propylthiouracil can induce small vessel vasculitis, and the incidence increases with prolonged dosing time. Both propylthiouracil and methimazole can cause arthropathy and lupus syndrome. Therefore, antithyroid drug therapy mainly includes the above two categories and has certain side effects, so patients must be under the guidance of doctors to regulate the use of drugs. In addition, the cure rate of simple anti-thyroid medication is only 50%, and the relapse rate is as high as 50%. Therefore, it is important to choose the appropriate treatment according to your condition, and not to rely on medication alone.