SummaryBackgroundFatigue is a common symptom of chronic inflammation, including inflammatory bowel disease (IBD), resulting in significant impairment in quality of life.AimsTo identify the prevalence of fatigue in a large IBD cohort compared to the general population, address risk factors, and evaluate its impact on daily life.MethodsWe evaluated 1208 IBD patients from the Swiss Inflammatory Bowel Disease Cohort Study (SIBDCS) and 414 healthy controls. Significant fatigue was defined as a visual analogue scale (VAS‐F, range 0‐10) score ≥ 4. Secondary endpoints were severity of fatigue and its impact on daily activities with the Fatigue Severity Scale (FSS), with a score ≥ 4 indicative of fatigue. Demographic, IBD‐related and psychiatric symptoms were assessed with a multivariate analysis of variance (MANOVA) model optimised for prediction of VAS‐F (primary outcome) and FSS scores.ResultsOverall, 672 IBD patients (55.6%) reported significant fatigue compared to 145 (35%) controls (OR 2.71; 95% CI 2.08‐3.54; P < 0.001). In IBD, fatigue also significantly affected daily activities (FSS ≥ 4; 405 (33.5%) IBD patients vs 81 (19.6%) controls, P < 0.001). In the MANOVA model, fatigue levels were associated with female gender (coefficient 0.839; 0.556 ‐ 1.123; P < 0.001), younger age at diagnosis (−0.031 per year; −0.042– −0.019; P < 0.001), shorter disease duration (−0.036 per year; −0.050– −0.022; P < 0.001), nocturnal diarrhoea (0.718; 0.295‐1.141; P = 0.001), low educational level (P = 0.034) and symptoms of depression and anxiety.ConclusionsFatigue is both more frequent and more severe in patients with IBD than in the general population.