Overview: Leflunomide is an oral tablet used for rheumatoid arthritis. This medicine may help reduce joint swelling and damage. Common side effects include diarrhea, nausea, and headaches. Stop. Leflunomide is used to treat active rheumatoid arthritis. This medicine works by stopping the body from producing too many of the immune cells that are responsible for the swelling and inflammation. Leflunomide is an immunomodulatory drug that achieves its effects by inhibiting the mitochondrial enzyme dihydroorotate dehydrogenase (DHODH), which plays a key role in the de novo synthesis of uridine monophosphate (rUMP), which is required for the synthesis of DNA and RNA. What is leflunomide? Leflunomide affects the immune system and reduces swelling and inflammation in the body. Leflunomide is used to treat the symptoms of rheumatoid arthritis. Leflunomide may also be used for purposes not listed in this medication guide. Leflunomide is a medicine used to treat rheumatoid arthritis and psoriatic arthritis. It is an immunosuppressive medicine, which means that it works by reducing the activity of the immune system. Leflunomide (Larava) is a disease-modifying anti-rheumatic drug (DMARD) used to treat rheumatoid arthritis and psoriatic arthritis. Leflunomide is used alone or in combination with other medications to treat rheumatoid arthritis (a condition in which the body attacks its own joints, causing pain, swelling, and loss of function). Leflunomide is in a class of medications called disease-modifying antirheumatic drugs (DMARDs). 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 is a medication that treats rheumatoid arthritis. Rheumatoid arthritis occurs when your immune system attacks the tissue lining the joints on both sides of your body. The brand name of this medication is Arava®. You can take this medication by mouth with a glass of water as directed. Learn about the side effects of leflunomide, from common to rare, for consumers and healthcare professionals.