Isotretinoin and the risk of inflammatory bowel disease and irritable bowel syndrome: A large-scale global study

Introduction: Risk of inflammatory bowel disease under isotretinoin is a scope of a long-standing controversy. The burden of isotretinoin-related irritable bowel syndrome has not been investigated. Objective: To evaluate the risk of Crohn's disease, ulcerative colitis (UC), and irritable bowel syndrome in patients with acne starting isotretinoin vs oral antibiotics treatment. Methods: A global population-based retrospective cohort study assigned 2 groups of patients with acne initiating isotretinoin (n = 77,005) and oral antibiotics (n = 77,005). Comprehensive propensity-score matching was conducted. Results: The lifetime risk of Crohn's disease (hazard ratio [HR], 1.05; 95% CI, 0.89-1.24; P = .583) and UC (HR, 1.13; 95% CI, 0.95-1.34; P = .162) was comparable between study groups, whereas the lifetime risk of irritable bowel syndrome was lower in isotretinoin-prescribed patients (HR, 0.82; 95% CI, 0.76-0.89; P < .001). In time-stratified analysis, isotretinoin-related risk of UC was significantly increased during the first 6 months following drug initiation (HR, 1.93; 95% CI, 1.29-2.88; P = .001), but decreased afterward to level the risk of the comparator group. The absolute risk difference within the first 6 months was clinically marginal (5.0 additional UC cases/10,000 patients starting isotretinoin; 95% CI, 2.5-7.7). Limitations: Retrospective data collection. Conclusion: Isotretinoin does not confer an elevated risk of Crohn's disease, whilst it might be associated with a slight and transient increase in UC risk.