Ulcerative colitis (UC) is an autoimmune disease associated with both intestinal and extraintestinal manifestations. The latter may include heart complications, such as myopericarditis leading to life-threatening arrythmias. Nowadays, UC is commonly treated with biologic medications and infliximab is the first line therapy in an outpatient setting, while it is also used as rescue therapy in acute severe UC. However, it has been associated with severe immunosuppression, cytomegalovirus (CMV) reactivation and drug-induced hepatitis. We report a case of UC flare in a biologic naïve patient admitted with myopericarditis, which was further complicated by positive CMV biopsies and infliximab-induced transaminitis. In acute inflammatory bowel disease (IBD) flare presentation with tachycardia and chest pain, an underlying myocardial injury should be investigated.Mucosal healing should be evaluated endoscopically in cases of partial response to biologics.Both cytomegalovirus (CMV) infection and infliximab-induced liver injury may lead to acute hepatitis.