AHR and ulcerative colitis: <h4>Background</h4>The combination of curcumin and QingDai (CurQD) promotes aryl hydrocarbon receptor (AhR) activation and is effective in ulcerative colitis; however, its benefit in Crohn's disease (CD) has not been studied.<h4>Methods</h4>This is a retrospective, multicenter cohort study of patients who received CurQD for active CD, defined as the two-item patient-reported outcome (PRO2) stool frequency (SF) ≥ 2 and abdominal pain (AP) ≥ 1.