Common side effects of low-dose methotrexate include: liver function impairment, bone marrow suppression, oral ulcers, gastrointestinal reactions, urticaria, hair loss, headache, dizziness, etc. Therefore, during the period of taking methotrexate, we recommend: 1. to review the routine blood test once every week; if abnormal (commonly, white blood cells are lower than normal), give “recombinant human granulocyte stimulating factor injection” for symptomatic treatment; 2. to take liver-protective drugs for a long time during the treatment period; and to review the liver function once every week; if abnormal (commonly, liver function is abnormal, bi-directional transaminase is elevated), give “recombinant human granulocyte stimulating factor injection” for symptomatic treatment. 3.Mouth ulcers that occur after medication: calcium folinic acid 3mg + 250ml sodium chloride (0.9%) with gargle; 4.Diet: light, high protein, high fiber and fresh vegetables and fruits. Most of these adverse reactions are mild in degree and can improve with symptomatic treatment; if they cannot be relieved after treatment, you may need to stop the drug or reduce the dose, please contact your primary care physician in time. In addition, some rare but serious side effects may occur with long-term low-dose methotrexate therapy, such as interstitial lung injury, renal damage, and central nervous system damage. If you experience cough, fever, shortness of breath, swelling, headache, dizziness, hand tremor, etc., for no apparent reason during the treatment period (especially after 3 or 4 months), you should take it seriously and discontinue the drug immediately and visit a specialist hospital.