Leflunomide (Arava)

Leflunomide is a disease-modifying antirheumatic drug (DMARD) used to treat adults with moderate to severe inflammatory arthritis, such as rheumatoid arthritis. It works by suppressing the immune system and decreasing inflammation, which helps reduce joint pain, swelling, and prevents further joint damage. Leflunomide blocks the formation of DNA needed for rapidly dividing cells, including immune cells involved in inflammation.

How To Take It

Leflunomide is usually taken as a 20 mg tablet once daily, although some patients may take 10 mg daily if they experience side effects with the higher dose. The medication can be taken with food. Improvement in symptoms may begin within several weeks, but full benefits are often not seen until 6–12 weeks after starting treatment.

Regular blood tests are important while taking leflunomide, including monitoring liver function and blood counts. Patients with pre-existing liver disease, such as hepatitis or cirrhosis, should not take this medication. Alcohol should be avoided because it may increase the risk of liver damage. Leflunomide should also not be used during pregnancy because it can cause serious birth defects.

Side Effects

The most common side effect of leflunomide is diarrhea, which occurs in approximately 20% of patients. This symptom frequently improves with time or by taking medication to prevent diarrhea. If diarrhea persists, the dose of leflunomide may need to be reduced.

Less common side effects include nausea, stomach pain, indigestion, rash, and hair loss. In fewer than 10% of patients, leflunomide can cause abnormal liver function tests or decreased blood cell or platelet counts. Rarely, this drug may cause lung problems, such as cough, shortness of breath or lung injury.

Tell Your Rheumatology Provider

Patients who are pregnant, planning pregnancy, or breastfeeding should discuss this with their rheumatology provider before starting leflunomide. The medication should be stopped at least 24 months or check serum metabolite level and treat with cholestyramine washout, before trying to conceive. Effective contraception is strongly recommended while taking this medication.

Live vaccines should generally be avoided during treatment with leflunomide. Patients should discuss any planned vaccinations with their rheumatology provider beforehand. It is also important to inform your rheumatologist if you develop an infection or are planning surgery, as leflunomide may affect healing and recovery.

Updated May 2026 by Howard Yang, MD, RhMSUS, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.