Immunological agents, generally known as immunosuppressants, are drugs that have an inhibitory effect on the body’s immune response, inhibit the proliferation and function of cells associated with the immune response (T and B cells and macrophages), and can reduce the antibody immune response. 1. There are five main categories of commonly used immunosuppressants: (1) Glucocorticoid hormones, such as prednisone acetate, methylprednisolone and so on. (2) Microbial metabolites, such as cyclosporine and garcinia cambogia. (3) Antimetabolites, such as azathioprine and 6-mercaptopurine. (4) Polyclonal and monoclonal anti-lymphocyte antibodies, such as anti-lymphocyte globulin and OKT3. (5) Alkylating agents, such as cyclophosphamide. 2. According to the method of synthesis, immunosuppressants can be broadly categorized into: (1) Microbial fermentation products: cyclosporine CsA class, tacrolimus, rapamycin and its derivatives. (2) Completely organic synthetics: most of them are derived from antitumor substances, mainly alkylating agents and antimetabolites of two major categories. Including hormones (adrenocorticotropic hormone, glucocorticoid), azathioprine, methotrexate and so on. (3) Semi-synthetic compounds (enteric-coated tablets of sodium mescaline), etc. (4) Biological agents (rituximab), etc. If patients need to take immune preparations, they need to follow the doctor’s instructions to regulate the use of medication, and should not take medication without authorization, so as not to aggravate the condition.