According to the literature, ileocolonoscopy allows an accurate diagnosis of Crohn’s disease or ulcerative colitis in 90% of cases (Passos et al., 2018); therefore, it is recommended that patients with diarrhea, abdominal pain, bloody stools, or fever should be alerted to the possibility of IBD and undergo colonoscopy during IL-17 inhibitor treatment. Here, IL17A is linked to ulcerative colitis.