The development of new biological drugs for the treatment of advanced oncological processes or severe inflammatory diseases brings with it the appearance of new adverse effects. Vedolizumab, an α4β7 integrin inhibitor antibody, is approved for induction and maintenance therapy in both Crohn disease and ulcerative colitis. We report a case of severe acneiform eruption induced by vedolizumab in a 17-year-old woman with ulcerative colitis.