Immunosuppressive drugs in the elderly mainly include glucocorticoids (e.g., methylprednisolone), cytotoxic drugs (e.g., cyclophosphamide), antimetabolites (e.g., methotrexate), microbial metabolites (e.g., cyclosporine A), and biologics (e.g., rituximab), among other drugs. Immunosuppressants are a class of drugs that can inhibit the body’s immune response, commonly used to inhibit the rejection of organ transplantation; treatment of allergic diseases, etc.; autoimmune diseases, etc.. Adverse effects of this class of drugs mainly include bone marrow transplantation; carcinogenesis, teratogenesis, sterility; infection, etc. 1. Glucocorticoids: such as methylprednisolone and prednisone acetate can reduce the number of circulating T-lymphocytes and inhibit the synthesis of interleukin-2 to achieve immunosuppression. 2. Cytotoxic drugs: such as cyclophosphamide can block DNA replication, leading to apoptosis. 3. Antimetabolites: such as methotrexate, azathioprine, etc., can change the structure of purines and pyrimidines required in DNA synthesis, specifically interfere with the replication of nucleic acids, and prevent cell division and reproduction. 4. Microbial metabolites: such as cyclosporine A, tacrolimus, etc. can inhibit signal transduction, antigen presentation and DNA synthesis in lymphocytes. 5. Biological agents: such as rituximab can play a therapeutic role by mimicking or interfering with the function of a certain cytokine in the body, blocking key inflammatory cytokines or cell surface molecules in the disease process. Different elderly people have different responses to immunosuppressants, so they need to follow the doctor’s instructions to choose the right drugs and take them according to their conditions to avoid adverse consequences.