Acute Severe Ulcerative Colitis (ASUC): Clinical Features, Initial Management, and the Role of Advanced Therapies.

Acute severe ulcerative colitis (ASUC) is a medical emergency affecting up to 25% of patients with ulcerative colitis (UC), with colectomy required in approximately 25-30% of cases during the initial admission. Intravenous corticosteroids remain the first-line therapy, though one-third of patients do not respond, necessitating rescue with infliximab or calcineurin inhibitors, which are both supported by randomized trials and guideline recommendations. Comparative studies and meta-analyses have shown similar efficacy between these agents, while sequential use is associated with higher adverse event rates and should be restricted to specialized centers. Recent data have refined infliximab use, with the PREDICT-UC trial showing no superiority of intensified dosing over standard regimens. Emerging therapies are under investigation: vedolizumab has been used as maintenance following calcineurin induction; ustekinumab has shown benefits in retrospective UC cohorts, particularly after cyclosporine; and Janus kinase (JAK) inhibitors represent the most recent addition. The randomized TACOS trial and the prospective TRIUMPH study demonstrated an improved short-term response with tofacitinib in steroid-refractory ASUC, and real-world reports suggest promising outcomes with upadacitinib. While infliximab and cyclosporine remain as standard rescue therapies, ongoing trials with novel agents are likely to broaden treatment options. This review summarizes the clinical features, initial management, and the role of advanced therapies in ASUC.