Abstract Background Immunomodulators and biologicals are cornerstones in the management of Inflammatory Bowel Disease (IBD), but are associated with increased risk of infections. Post-marketing surveillance registries are pivotal to assess this risk, yet mainly focus on severe infections. Data on the prevalence of mild and moderate infections are scarce. We developed and validated a remote monitoring tool for real-world assessment of infections in IBD patients. Methods A 7-item Patient-Reported Infections Questionnaire (PRIQ) covering 15 infection categories was developed with a 3-month recall period. Infection severity was defined as mild (self-limiting or topical treatment), moderate (oral antibiotics, antivirals or antifungals) or severe (hospitalisation or IV treatment). Comprehensiveness and comprehensibility were ascertained through cognitive interviewing of 36 IBD outpatients. After implementation in telemedicine platform myIBDcoach, a prospective multicentre cohort study was performed between June 2020 and June 2021 in 584 patients to assess diagnostic accuracy. Events were cross-checked with GP and pharmacy data (gold standard). Agreement was evaluated using linear-weighted kappa with cluster-bootstrapping to account for within-patient level correlation. Results Patient understanding was good and interviews did not result in reduction of PRIQ-items. During validation, 584 IBD patients (57.8% female, mean age 48.6 [SD: 14.8], disease duration 12.6 years [SD: 10.9]) completed 1386 periodic assessments, reporting 1626 events. Linear-weighted kappa for agreement between PRIQ and gold standard was 0.92 (95%CI 0.89-0.94). Sensitivity and specificity for infection (y/n) were 93.9% (95%CI 91.8-96.0) and 98.5% (95%CI 97.5-99.4). Conclusions The PRIQ is a valid and accurate remote monitoring tool to assess infections in IBD patients, providing means to personalise medicine based on adequate benefit-risk assessments.