Leflunomide can be taken for a long time, but the liver and kidney function should be rechecked regularly as prescribed by the doctor during the medication. Leflunomide is a kind of immunosuppressant, commonly used in the treatment of autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, etc. Its common adverse effects are liver function damage, bone marrow suppression, long metabolic cycle in the body, and so on, and immune system disorders need to be treated with the drug for a long time. Therefore, in the case of long-term use of Leflunomide, it is necessary to regularly review the blood routine, liver and kidney function, white blood cells and so on, if there is any abnormality, it is necessary to deal with it under the guidance of the doctor in a timely manner. If the patient has a plan to prepare for pregnancy during the period of taking the drug, it is necessary to inform the attending physician in advance, and stop using Leflunomide in advance. Common adverse reactions mainly include diarrhea, itching, reversible liver enzyme elevation, alopecia, rash and so on. This drug is contraindicated in patients with severe liver damage. Note that this drug should be used with caution in patients with renal insufficiency, active gastrointestinal disease, and bone marrow dysplasia. It is recommended that patients who need to use Leflunomide promptly go to the hospital, consult the doctor for specific medication, and follow the doctor’s instructions for medication.