Published: June 2011

Leflunomide - if in doubt wash it out

Prescriber Update 32(2): 10
June 2011

Leflunomide is a disease modifying anti-rheumatic drug indicated for the treatment of rheumatoid arthritis and active psoriatic arthritis.

Leflunomide can cause serious and potentially life-threatening adverse reactions involving the liver, blood, lungs and skin. Due to its immunosuppressant effects leflunomide can also cause life-threatening infections, particularly when given in combination with other immunosuppressant medicines.1 As leflunomide has a very long half life (usually 1-4 weeks), adverse reactions can occur or persist long after leflunomide is discontinued.

Prescribers are reminded that if serious adverse reactions occur, leflunomide must be stopped and a cholestyramine or charcoal wash-out procedure initiated immediately.2 In addition, rheumatology advice should be sought for all patients experiencing serious adverse reactions to leflunomide.

Prescribers are encouraged to familiarise themselves with the prescribing information for leflunomide, available on the Medsafe website at:,3

Safety information has recently been added to the data sheet including:

  • Side effects may occur more commonly if leflunomide is given concomitantly with other hepatotoxic or haematotoxic medicines. Monitoring guidelines contained in the leflunomide data sheet should be carefully followed.
  • Interstitial pneumonitis may occur more frequently with concomitant use of methotrexate.
  • A wash-out procedure should be used for all serious adverse reactions. This information is included in a new subsection of the data sheet “Washout procedure for severe adverse reactions”.

As with all medicines, healthcare professionals are encouraged to continue to report all suspected serious or unexpected adverse reactions to leflunomide to CARM.

  1. Savage R (2008). Leflunomide - Update on Serious Toxicity. Prescriber Update 29(1):13-14
  2. Sanofi-Aventis New Zealand limited. 14 April 2011. Arava data sheet (Warnings & Precautions section).