Acute severe ulcerative colitis is a life-threatening medical emergency, which can be associated with significant morbidity and is preventable through prompt and effective management. Corticosteroids remain the cornerstone of initial therapy, although a third of patients will not respond. Further management hinges on timely decisions with use of rescue therapy with ciclosporin or infliximab, without compromising the health or safety of the patient, or timely surgery. Although such patients need specialist care, it is imperative that emergency care physicians are aware of the important principles of management of this condition to achieve successful outcomes. Risk stratification and the use of predictive models using clinical parameters have reduced the morbidity associated with this condition.We discuss current evidence and present a clinical approach to clinicians involved in the emergency care of patients with acute severe ulcerative colitis in this review.