Acute severe ulcerative colitis is a rapidly progressive severe form of colitis that can occur in 20-30% patients with ulcerative colitis. Early recognition, hospitalization at centers with experience and expertise and multidisciplinary treatment is the cornerstone of appropriate management of this condition. After excluding infections and other differentials, patients should be started on parenteral corticosteroids to control inflammation. ASUC patients are at high risk for thromboembolic complications and hence DVT prophylaxis is ideally started as soon as possible in the emergency room and continued throughout hospitalization. Objective criteria should be applied to assess improvement and identify patients who are unlikely to improve without second line/rescue therapy as early as 72 hours on steroid therapy. Infliximab and cyclosporine are the most used options for second line therapy and should be administered under direction by gastroenterologists. Disease progression despite aggressive treatment or non-response to second line therapy, complications such as megacolon, perforation, hemorrhage can occur requiring colectomy as a salvage option in those patients.