BACKGROUND & AIMS:We estimated the prevalence of social determinants of health (SDH, food insecurity and social support) in adults with inflammatory bowel diseases (IBD) in the United States and evaluated associations with financial toxicity and healthcare use. METHODS:In the National Health Interview Survey 2015, we identified adults with IBD and estimated the prevalence of food insecurity and/or lack of social support. We evaluated associations with financial toxicity (financial hardship due to medical bills, personal and health-related financial distress, cost-related medication nonadherence, healthcare affordability) and emergency department use. RESULTS:Of estimated 3.1 million adults with IBD in the US, 42% or estimated 1,277,215 patients with IBD reported at least one negative SDH, with 12% reporting both food insecurity and lack of social support. On multivariable analysis adjusting for age, sex, race, family income and comorbidities, patients with food insecurity were significantly more likely to experience financial hardship due to medical bills (odds ratio [OR], 3.31; 95% CI, 1.48-7.39), financial distress (OR, 6.92; 95% CI, 2.28-21.0) and cost-related medication non-adherence (OR, 8.07; 95% CI, 3.16-20.6). Similarly, patients with inadequate social support were significantly more likely to experience financial hardship due to medical bills (OR, 2.98; 95% CI, 1.56-5.67), financial distress (OR, 3.05; 95% CI, 1.64-5.67) and cost-related medication non-adherence (OR, 2.71; 95% CI, 1.10-6.66). Food insecurity and/or lack of social support was not associated with increased risk of emergency department use. CONCLUSIONS:In an analysis of data from the National Health Interview Survey 2015, we found that 1 in 8 patients with IBD have food insecurity and lack social support, which is associated with higher financial toxicity. Patients with IBD should be assessed for SDH to tailor healthcare delivery and improve population health.