Leflunomide as a cause of collagenous colitis: an entity to consider.

Leflunomide belongs to the group of disease-modifying anti-rheumatic drugs (DMARDs) used in the treatment of psoriatic, rheumatoid, and reactive arthritis. Approximately 20% of patients will experience some adverse event, highlighting weight loss, abdominal pain and diarrhea. We describe the clinical, endoscopic, and histological findings in a patient with psoriatic arthritis (PA) who developed severe chronic diarrhea after drug use.