Some Drugs Have Two Faces: Paradoxical Colitis in a Patient with Psoriatic Arthritis Previously Treated with Etanercept and IL-17 Inhibitors.

Tumor necrosis factor-alpha (TNF-α) and interleukin-17 (IL-17) inhibitors are among the most potent treatments for inflammatory arthropathies including rheumatoid arthritis, psoriasis, and spondyloarthropathies. The availability of these biologic agents have revolutionized the management of these conditions and improved patient outcomes. Though generally safe, these biologics may contribute to the induction or exacerbation of colitis. This paradoxical colitis has been observed in patients on TNF-α inhibitor etanercept and IL-17 inhibitors (secukinumab and ixekizumab). We report a case of a 46-year-old female with psoriasis and psoriatic arthritis who presented with gastrointestinal symptoms after treatment with etanercept and IL-17 inhibitors. She was later diagnosed with paradoxical indeterminate colitis that was masked and treated by subsequent biologics given for her RA and psoriatic arthritis. In this report, we will discuss the importance of considering paradoxical colitis in the differential diagnosis for patients even several years after TNF-α/IL-17 inhibitor initiation and explain why careful consideration must be made when initiating these colitis-inducing agents to treat patients with inflammatory disorders.