Abstract: Objective: To compare the adverse effects following long-term (above 12 weeks) use of conventional immunosuppressive agents. Methods: The data of the patients with prolonged (more than 12 weeks) use of methotrexate (MTX), cyclophosphamide (CTX), cyclosporine (CsA), mycophenolate mofetil (MMF) and thalidomide (THD) with complete laboratory examination from January 2019 to October 2023, and their routine blood, liver function and renal function laboratory tests were retrospectively analyzed. Results: A total of 1507 patients using conventional immunosuppressants were analyzed, including 1142 using MTX, 135 using cyclophosphamide CTX, 67 using cyclosporine CsA, 66 using mycophenolate mofetil MMF, 97 using thalidomide THD, and the incidence of the adverse effects were 38.18%, 56.30%, 44.30%, 27.27%, 22.39%, The most common adverse reactions were liver function injury (24.22%), renal function injury (12.61%) and myelosuppression (9.69%). And there was a correlation between the duration of patient use and the incidence of adverse events with traditional immunosuppressive agents. Conclusion: Prolonged use of conventional immunosuppressive agents can lead to the development of adverse reactions, most commonly with the drug CTX, and therefore patients on long-term CTX should be monitored regularly. 

Key words: traditional immunosuppressive agents, adverse effects, hematopoietic suppression, renal function impairment, hepatic function impairment