BACKGROUND: Treatments for inflammatory bowel disease (IBD) remain limited, and cannabis-based medicinal products (CBMPs) provide promise in addressing inflammation and pain. However, long-term data on CBMP efficacy in IBD are scarce. This study examines health-related quality of life (HRQoL) changes in IBD patients treated with CBMPs. RESEARCH DESIGN AND METHODS: Patients with IBD were identified from the UK Medical Cannabis Registry. Primary outcomes were changes in the short IBD questionnaire (SIBDQ), EQ-5D-5L, single-item sleep quality scale (SQS), and generalized anxiety disorder-7 (GAD-7), from baseline to 18-months after CBMP treatment started. Secondary outcomes were adverse event prevalence. RESULTS: Analysis of 116 patients with IBD included 94 males (81.03%) with a mean age of 39.52 +/- 9.12 years. There were improvements in the SIBDQ, GAD-7, SQS, and EQ-5D-5L Index (p < 0.001). At 18-months, 30 (25.86%) patients achieved a minimal clinically important difference (MCID) in the SIBDQ. Patients with severe baseline anxiety and above-median THC doses were more likely to achieve this MCID (p < 0.050). Twenty (17.24%) patients reported 155 (133.62%) adverse events. CONCLUSIONS: CBMP treatment was associated with improvement in IBD-specific outcomes in patients and general HRQoL over 18-months. However, causation cannot be inferred. Hence, randomized controlled trials are still required.