Immunosuppressants are a class of drugs with immunosuppressive effects, mainly used clinically in organ transplant rejection and autoimmune reactive diseases. Most of them mainly act in the induction phase of immune response and inhibit the proliferation of lymphocytes, and some act in the effector phase of immune response, and the common classification and drugs mainly include the following: 1. The drugs may have side effects such as loss of appetite, drowsiness, tremor, abnormal sensation, gastrointestinal reactions, allergic reactions, etc.; 2. Inhibit cytokine gene expression drugs: such as prednisone, prednisolone, dexamethasone and other glucocorticoids, which can act in all periods of the immune response and have effects on the metabolic process of substances, anti-inflammatory and anti-immune. If used in large doses, adverse reactions such as infections, diabetes, peptic ulcers, etc. may occur; 3. Drugs that inhibit purine or pyrimidine synthesis: such as azathioprine, methotrexate, 6-mercaptopurine and other drugs. There may be adverse reactions such as nausea, vomiting, rash, etc.; 4. Blocking T-cell surface signaling molecules: such as monoclonal antibodies, leflunomide, motilmic acid, etc., may have chills, fever, vomiting, diarrhea, respiratory distress and neurological adverse reactions. Some drugs may have more than one effect, and their potency and indications vary. It is recommended to choose whether and which immunosuppressive drug to use under the guidance of a doctor.