OBJECTIVES:  To assess the burden of IBS-D on health-related quality of life (HRQoL), activity impairment and healthcare resource utilisation (HCRU) based on disease severity among adults in the EU5 (Spain, France, Italy, Germany and United Kingdom). METHODS:  IBS-D patients were identified from the EU5 2013 National Health and Wellness Survey, a self-administered, internet-based general health survey. Patients reported the frequency and nature of their IBS symptoms and disease severity (mild/moderate/severe). HRQoL, activity impairment and HCRU were assessed using the Short Form-36 version 2 physical and mental component summary scores (PCS, MCS; range 0–100), Work Productivity and Activity Impairment Questionnaire General Health Version (higher percentages indicate greater impairment) and number of patient-reported visits to any healthcare provider in the past 6 months, respectively. Multivariable generalised linear models assessed HRQoL, activity impairment and HCRU by IBS-D severity, controlling for demographic and health characteristics. RESULTS: CONCLUSIONS:  Patients with more severe IBS-D experience greater impairments in HRQoL and daily activities, and higher HCRU, representing a substantial burden of illness and highlighting the need for effective treatments to manage IBS-D symptoms.