Abstract Background Inflammatory bowel diseases (IBDs) are associated with substantial health care needs. We estimated the national burden and patterns of financial toxicity and its association with unplanned health care utilization in adults with IBD in the United States. Methods Using the National Health Interview survey (2015), we identified individuals with self-reported IBD and assessed national estimates of financial toxicity across domains of financial hardship due to medical bills, cost-related medication nonadherence (CRN) and adoption of cost-reducing strategies, personal and health-related financial distress (worry about expenses), and health care affordability. We also evaluated the association of financial toxicity with emergency department (ED) utilization. Results Of the estimated 3.1 million adults with IBD in the United States, 23% reported financial hardships due to medical bills, 16% of patients reported CRN, and 31% reported cost-reducing behaviors. Approximately 62% of patients reported personal and/or health-related financial distress, and 10% of patients deemed health care unaffordable. Prevalence of financial toxicity was substantial even in participants with higher education, with private insurance, and belonging to middle/high-income families, highlighting underinsurance. Inflammatory bowel disease was associated with 1.6 to 2.6 times higher odds of financial toxicity across domains compared with patients without IBD. Presence of any marker of financial toxicity was associated with higher ED utilization. Conclusions One in 4 adults with IBD experiences financial hardship due to medical bills, and 1 in 6 adults reports cost-related medication nonadherence. These financial determinates of health—especially underinsurance—have important implications in the context of value-based care.