Reviewed by: HU Medical Review Board | Last reviewed: February 2019 | Last updated: November 2020

Leflunomide is a slow-acting anti-rheumatic drug (SAARD) that may be used to treat people with inflammatory conditions like ankylosing spondylitis (AS) and rheumatoid arthritis.1 SAARDs were used more frequently in the past. Current treatment guidelines for AS recommend against using SAARDs like leflunomide to manage AS because there is little to no evidence for the effectiveness of SAARDs in treating AS. In addition, newer medications like biologics are now available and have demonstrated more effectiveness.2 However, some rheumatologists might recommend SAARDs like leflunomide in some patients who can not take biologics. SAARDs are inexpensive so can be a good option for patients who don’t have insurance coverage for drugs.

Leflunomide is available as a generic and is also sold under the brand name Arava®.

What is the active ingredient in leflunomide?

Leflunomide is the active ingredient in this medication.

How does leflunomide work?

Leflunomide blocks the formation of DNA, which normally occurs as cells replicate. This action can reduce the inflammation produced by the immune system and help reduce pain and swelling.3

What are the possible side effects of leflunomide?

The most common side effect experienced by patients taking leflunomide is diarrhea, which usually improves with time or with anti-diarrheal medication. In some cases, the dosage of leflunomide may be reduced to reduce diarrhea. Less common side effects that may be experienced with leflunomide include nausea, stomach pain, indigestion, skin rash, hair loss, changes in liver function tests, or decreased blood cell counts.3

Rarely, leflunomide may cause more serious side effects, such as lung problems. Lung problems may cause symptoms including cough or shortness of breath.3 Leflunomide also decreases the immune system slightly and may increase risk for infections.

Things to know about leflunomide

Before taking leflunomide, patients should talk to their doctor about all medications, vitamins, and supplements they are taking. Some medications can interact negatively with leflunomide or cause it to not work as well.

Prior to starting treatment with leflunomide, patients should talk to their doctor about all their health conditions, especially if they:1,3

  • Are pregnant or planning to become pregnant
  • Are breastfeeding or planning to breastfeed
  • Have an infection or signs of an infection (fever, chills, cough, muscle aches, shortness of breath, sores, diarrhea, burning during urination)
  • Are planning to have surgery
  • Have a history of alcohol abuse
  • Have hepatitis, jaundice (yellowing of the whites of the eyes or skin), or other liver disease

Leflunomide can cause birth defects in the children of both men and women, and effective birth control must be used while taking leflunomide and up to 2 years after the medication is stopped. A prescribed medication (cholestyramine) may be used to help remove leflunomide from the body after treatment is completed.1,3

People taking leflunomide should not get live vaccines and should talk to their doctor before getting any vaccines.3

Dosing information

Leflunomide is available as a tablet to be taken by mouth once a day. The usual dosage is 20 mg daily.1 Patients should talk to their doctor about any questions on their dosing regimen.

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