RecruitingPhase 4Drug trialUpadacitinib Combined With Corticosteroids vs Corticosteroid Monotherapy Induction for Inpatients and Outpatients With Acute Severe Ulcerative ColitisThis trial is being conducted to learn more about the optimal sequence of various medications in the management of acute severe ulcerative colitis (ASUC). This research is studying multiple drugs already approved by the Food and Drug Administration (FDA). The goal of this study is to test the early efficacy and safety of upadacitinib (Rinvoq) and corticosteroids compared to corticosteroids alone as induction therapy for both inpatients and outpatients with ASUC.