The main side effects of methotrexate are: i. Gastrointestinal reactions, mainly stomatitis, mouth and lip ulcers, pharyngitis, nausea, vomiting, gastritis, as well as diarrhea. Second, bone marrow suppression, mainly manifested as a decline in white blood cells, also has a certain effect on platelets, and in severe cases, there can be a decline in whole blood, skin or visceral bleeding. Third, a large number of one-time application, can lead to elevated serum ALT and drug hepatitis; small amount of persistent application, can lead to hepatic cirrhosis. Kidney damage, common in high doses, hematuria, proteinuria, oliguria, uremia and so on. Alopecia, dermatitis, hyperpigmentation and drug pneumonitis. Sixth, the use of early pregnancy, can cause teratogenesis. A few patients have delayed menstruation and hypogonadism.