5-Aminosalicylic Acid-induced Colitis in a Patient with Rheumatoid Arthritis without Inflammatory Bowel Disease

This report presents a rare case of 5-aminosalicylic acid (5-ASA)-induced colitis in a 76-year-old man with no history of inflammatory bowel disease (IBD). The patient, who was undergoing treatment for rheumatoid arthritis, developed persistent diarrhea and fever following sulfasalazine (SASP) administration and later experienced a high fever shortly after taking mesalazine. The drug-induced lymphocyte stimulation test result was positive for mesalazine and weakly positive for SASP, thereby supporting the diagnosis of 5-ASA intolerance. This case emphasizes that 5-ASA-induced colitis may occur in patients without IBD. Clinicians should consider this possibility when unexplained gastrointestinal symptoms appear after starting 5-ASA therapy even in patients without any prior IBD.