What Is Known and Objective: Infliximab is an anti-tumour necrosis factor agent used in the treatment of inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis. While the use of infliximab is well established in the treatment of IBD, there are now four recently FDA-approved infliximab biosimilars that are increasingly used due to their cost-benefit for patients, institutions and payors. In addition, shortening the length of infliximab infusions from 120 min (standard infusion) to 60 min or less (rapid infusion) has been shown to safely provide further cost-benefit while also improving patient convenience. The safety of rapid infusions has been well-established for the infliximab reference product, however, there are limited data available regarding the safety of rapid infusions for infliximab biosimilars. The purpose of this study was to compare the incidence and severity of infusion reactions among patients with IBD receiving rapid infusion of infliximab reference product compared with infliximab biosimilar.Methods: This was a retrospective analysis of electronic health record data of patients with a diagnosis of IBD receiving an infliximab reference product or infliximab biosimilar infusion between December 2020 and December 2021. Patient-level variables included demographics, immunomodulator use, IBD-related hospitalization and infliximab trough concentration and antibody levels. Infusion-related variables of interest included total number of infusions, drug, dose, dosing interval, infusion time and use of pre-medications. Infusion-related reactions were defined as safety concerns documented by the administering nurse (anaphylaxis, shortness of breath, hypotension, swelling, rash, pruritus, hives, flushing, chest pain, muscle pain, joint pain, fevers, chills, headache or hypertension) or administration of emergency medications. Fisher's exact test was used to compare reaction rates.Results and Discussion: A total of 188 patients met inclusion criteria for analysis, and a total of 1124 infusions were administered during the study period. There were no