Vedolizumab-Induced Interstitial Lung Disease: A Case of Delayed-Onset Pulmonary Toxicity.

Vedolizumab, a monoclonal antibody targeting α4β7 integrin, is widely used for the treatment of moderate to severe inflammatory bowel disease (IBD) and is generally well tolerated. Pulmonary toxicity is exceedingly rare, with only a small number of interstitial lung disease (ILD) cases reported. We describe a 46-year-old woman with ulcerative colitis (UC), managed with vedolizumab for two years, who developed progressive dyspnea and cough. Despite corticosteroid therapy, her symptoms worsened. Imaging demonstrated diffuse centrilobular nodules consistent with hypersensitivity pneumonitis. Infectious, autoimmune, and other secondary causes were excluded. Following another vedolizumab infusion, her symptoms deteriorated further. Vedolizumab was permanently discontinued, leading to marked clinical, functional, and radiological improvement within months. Drug-induced ILD is a challenging diagnosis due to its nonspecific clinical and radiological features. In this case, the temporal association, exclusion of alternative causes, relapse on re-challenge, and improvement after drug withdrawal strongly supported vedolizumab-induced ILD. A review of published literature confirms this as a rare but potentially serious adverse effect. Vedolizumab-induced ILD, though uncommon, should be considered in patients presenting with new-onset respiratory symptoms during biologic therapy. Early recognition and discontinuation of the offending drug are critical to prevent long-term pulmonary complications.