Leflunomide can treat rheumatoid arthritis. Leflunomide, as one of the anti-rheumatic drugs to improve the condition, mainly through the inhibition of dihydroorotic acid dehydrogenase activity affects the pyrimidine synthesis of activated lymphocytes to play an immunosuppressive role, is currently used in the treatment of rheumatoid arthritis and lupus nephritis in adults. Adverse drug reactions that often occur after taking Leflunomide include diarrhea, dizziness, headache, vomiting, etc. Patients with severe infections, patients with impaired hepatic function, patients with severely impaired bone marrow function, patients with allergies to the components of Leflunomide, and lactating, pregnant women, etc., patients with contraindications to Leflunomide should not be used to treat this drug. Leflunomide should be used under the guidance of a physician, and it is recommended that patients go to the rheumatology and immunology departments of regular hospitals and other relevant departments for detailed consultation.