Background Intravenous (IV) infliximab is a first line treatment for moderate or severe flare of inflammatory bowel disease. Recently a new formulation of infliximab with subcutaneous (SC) administration has been developed and approved for this indication. Methods From March 2021, 14 patients diagnosed with inflammatory bowel disease (Crohn’s disease-CD- or ucerative colitis-UC), in clinical remission for at least 6 months with infliximab IV who had needed previous intensification, either because of a reactive therapeutic drug monitoring and loss of response, or because of a proactive drug monitoring (trough levels <3µg/ml), were switched to SC infliximab. We analized retrospectively from the start of SC infliximab until week 8 after switch, fecal calprotectin levels (FC), C reactive protein (CRP), concomitant treatment, trough levels, treatment adherence, need for intensification or relapse, and adverse events. Results Four patients (28,57%) were diagnosed with CD, 10(71,4%) were diagnosed with UC (Table 1). Median duration of IV treatment was 53 months (IQR 33–59). Reasons for starting infliximab were corticodependence in 6 patients (42,8%), corticorefractoriness in 6(42,8%) and topdown strategy in B2 phenotipe with Crohn’s disease in 2 (14,3%). Reasons for intensification were: loss of response in 5 patients (35,7%), intensified induction in one (7,1%), proactive therapeutic drug monitoring in 8 (57,14%) (graphic 1). Intensification regimens are shown in graphic 2. Eleven patients (78,57%) were still in an intensified regimen when switched. All patients were in clinical and biochemical remission (FC<200 µg/g and CRP<10 mg/dl) before switch. Median basal infliximab trough levels before switch were 6,98µg/ml (IQR 2,4-10,5); median trough levels 8 weeks after switch were 14,12 (IQR 12,22-22,7) (p=0,003) (graphic 3). Thirteen patients (92,8%) followed treatment and stayed in clinical remission. One patient, treated with original IV infliximab before switch, relapsed after third subcutaneous administration, and did not respond to reintroduction of original IV infliximab. There were no adverse events. Conclusion In our centre, switching from IV to standard dose SC infliximab maintained clinical and biochemical remission in patients that previously needed intensified regimen, improving trough levels without any adverse events. These findings provide potential therapeutic insights into SC infliximab as a monotherapy agent for inflammatory bowel disease.