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Background and Importance Therapeutic drug monitoring (TDM) is broadly used in the management of patients with inflammatory bowel disease (IBD). Proactive strategy, which involves regularly scheduled measurements of drug levels and anti-drug antibodies, even when the patient is asymptomatic, is increasingly used to guide dose adjustments, maintain optimal drug exposure, and prevent future treatment issues.Aim and Objectives To analyse the experience of a proactive TDM approach for infliximab (IFX), adalimumab (ADA) and ustekinumab (UST) in patients with Crohn’s disease (CD) or Ulcerative colitis (UC), and to assess the acceptance of the pharmaceutical recommendations.Material and Methods Prospective, single-centre study including patients with IBD treated with IFX, ADA or UST from April 2025 to September 2025. TDM was performed using the population pharmacokinetic models of Sánchez-Hernández (2019), Sánchez-Hernández (2020) and Xu et al (2020) for IFX, ADA and UST, respectively, through the software PKS. Variables recorded: demographic (sex and age), drug, sort of intervention (reinduction, dose change, shorten the dosing interval, treatment switch, and to measure a new trough serum concentration), and acceptance rate of the pharmaceutical interventions.Results During the study period, 48 patients were included, 26 (54.2%) female. The median (interquartile range (IQR)) age was 47 (33-63) years. Most patients had CD (81.3%) and nine had UC. Twenty-seven patients were treated with IFX (56.3%), 12 with ADA (25.0%) and nine with UST (18.7%). The main interventions in patients treated with IFX were to shorten the dosing interval (37,0%), to measure an additional through level (33.3%), and to increase the dose (22,2%). In the case of ADA, the most repeated interventions were to measure a new trough serum concentration (33.3%), to shorten the dosing interval (33.3%) and to restart the drug (25.0%). In patients with ustekinumab, the main interventions were to shorten the dosing interval (55.6%) and to restart ustekinumab (33.3%).The total degree of acceptance of the recommendations was 79.2%.Conclusion and Relevance Proactive TDM approach involves a range of pharmaceutical interventions, with a high degree of acceptance among prescribing physicians. Future research will be essential in our hospital to determine whether proactive strategies effectively have an impact on pharmacological treatment outcomes in patients with IBD.Conflict of Interest No conflict of interest