The management of Inflammatory Bowel Disease (IBD), encompassing Crohn's disease and ulcerative colitis, has been revolutionized by the advent of biologic therapies. These targeted agents have provided unprecedented control over disease activity for many patients. However, a significant challenge persists: not all patients respond initially (primary non-response), and a substantial proportion lose response over time (secondary non-response). This clinical dilemma has propelled Therapeutic Drug Monitoring (TDM) from a niche investigative tool to a cornerstone of modern, precision medicine in IBD. TDM moves beyond empirical dose adjustments, using objective data to guide therapy, ensuring patients receive the right drug at the right dose at the right time.