Ulcerative colitis (UC) is a chronic inflammatory condition characterized by diarrhea, abdominal pain, rectal bleeding, and weight loss. Upadacitinib is an oral, selective, small molecule Janus Kinase (JAK) inhibitor that was recently approved in the United States for moderate to severe UC. Clinical trials evaluating the efficacy of upadacitinib excluded patients with a previous exposure to tofacitinib, a nonselective JAK inhibitor; therefore, the efficacy of upadacitinib in patients with previous exposure to tofacitinib remains largely unknown.