AimsThe aim of the study is to evaluate the clinical and biochemical response of inflammatory bowel disease patients treated with vedolizumab, 16 weeks after transitioning from intravenous (iv) to subcutaneous (sc). MethodsAn observational, prospective, single-center cohort study was performed. Patients with inflammatory bowel disease and maintenance treatment with vedolizumab, stable for at least 4 months, were offered to switch to sc formulation. At the same time of treatment administration a blood test was performed, with vedolizumab levels and fecal calprotectin. ResultsForty-three patients were included, 12 of them (27.9%) chose to transition to sc formulation. All included patients remained in remission during follow-up. At week 16 no significant differences were found in terms of calprotectin levels in patients on iv treatment (mean 146.6±SD 45.9) vs. sc (159.26±53.9) (p=0.9). Vedolizumab serum levels at week 16 were higher in the sc group (22,364.3±5141.6) vs. iv (11,425.9±1514.2) (p=0.009). At week 16, 9 (75%) of the patients in the sc group were highly satisfied with the medication and 11 (91.7%) considered it easy to administer. Four patients (12.9%) in the iv group and 2 (16.6%) in the sc group presented mild adverse effects. The 2 cases (100%) of the sc group the adverse event was local inflammation at the injection site. ConclusionIn our experience, vedolizumab sc is a convenient alternative to iv administration. Vedolizumab serum levels in patients who transitioned to sc were higher than iv formulation.