Methotrexate is a drug that will be used in many departments. Although methotrexate may be used in hematology for leukemia or tumor treatment a little more, it can also be used in nephrology, including rheumatology. Its main side effects are: 1, gastrointestinal symptoms, some people eat after the symptoms will be very obvious, such as nausea, vomiting, diarrhea and other gastrointestinal symptoms; 2, liver damage, liver function abnormalities, jaundice, increased transaminases, increased alkaline phosphatase, and even serious will lead to fatty liver, cirrhosis and other more serious complications; 3, kidney function damage, kidney function damage may be due to its metabolites, resulting in kidney crystallization, hyperuricemia, crystallization leading to proteinuria, hematuria, and even causing renal function damage; 4. Some other patients may cause bone marrow suppression, leading to leukopenia and increased infection; 5. Some other patients may have allergic reactions, skin manifestations, etc. In conclusion, methotrexate has a therapeutic effect, but it can also cause liver and kidney damage. Therefore, when using this drug, it is generally recommended that patients should preferably check their liver and kidney functions and urinary routine once a month so that patients do not experience side effects without knowing them. If side effects occur, the dosage can be reduced or some kidney and liver protecting drugs can be added to reduce its toxic effects on people.