Leflunomide tablets are immunosuppressive agents with antiproliferative activity used for the treatment of rheumatoid arthritis in adults. Adverse reactions such as diarrhea, pruritus, reversible elevation of liver enzymes, alopecia, rash, abdominal and back pain, hypertension, anorexia, diarrhea, dyspepsia, gastroenteritis, nausea and vomiting may occur with the use of this drug. The drug is contraindicated in patients with hypersensitivity to the drug and its metabolites, in patients with severe liver damage. When using the drug, it is necessary to pay attention to the fact that the drug is used with caution in patients with positive serological indicators of definite hepatitis B or C; before and after the use of the drug need to check the ALT on a monthly basis; the drug is used with caution in patients with immunodeficiencies, infections, active gastrointestinal disorders, renal insufficiency, as well as myelodysplasia. The drug needs to be used under the guidance of a doctor, do not use the drug without authorization.