Leflunomide
Leflunomide is an immunomodulatory medication used primarily to treat rheumatoid arthritis and psoriatic arthritis. It works by inhibiting dihydroorotate dehydrogenase, an enzyme essential for pyrimidine synthesis, thereby reducing the proliferation of immune cells that contribute to inflammation. This medication helps decrease joint pain, swelling, and progressive joint damage in patients with autoimmune conditions.
Leflunomide is an immunosuppressant used to treat rheumatoid and psoriatic arthritis by inhibiting immune cell proliferation.
This medication carries a boxed (black box) warning — the strongest type of FDA warning. Review the full prescribing information before use.
Key facts at a glance
- ATC
- L04AK01
- RxNorm
- 27169
- Generic
- Leflunomide
- Class
- atc-l04
- Brands
- Arava
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Leflunomide is indicated for the treatment of active rheumatoid arthritis in adults to reduce signs and symptoms, inhibit structural damage, and improve physical function. It is also used for psoriatic arthritis.
Leflunomide inhibits dihydroorotate dehydrogenase, a mitochondrial enzyme critical for de novo pyrimidine synthesis. This inhibition prevents the expansion of activated T-lymphocytes and other rapidly dividing immune cells, exerting an antiproliferative and anti-inflammatory effect.
Leflunomide has a long half-life and requires a washout procedure with cholestyramine or activated charcoal if discontinuation is needed. It is contraindicated in pregnancy due to teratogenicity, requires regular liver function monitoring, and may cause bone marrow suppression. Common side effects include diarrhea, nausea, liver enzyme elevations, and rash.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy