BACKGROUND: Although depression is prevalent among people with inflammatory bowel diseases (IBD), the impact of treating depression is unknown. METHODS: We conducted a retrospective study in an electronic-health record-based cohort. We identified patients with IBD using >/= 2 diagnosis codes, and patients with depression using >/= 1 diagnosis code. The exposure was a medication for the treatment of IBD. We assessed IBD-related hospitalizations, surgery, and emergency room (ER) visits after the index date of depression code or initiation of depression medication. We constructed multivariable logistic regression models to determine the odds of the outcome. RESULTS: We identified 4052 patients with IBD and depression with a median age of 49 years. In this cohort, 39% did not receive medication for depression while 61% were treated with an antidepressant not commonly prescribed for pain. Patients with IBD treated for depression were less likely to have an IBD-related ER visit than patients with IBD and depression not treated for depression (aOR: 0.63, 95% CI: 0.44-0.90). However, patients who were treated for depression were also more likely to be hospitalised (aOR: 1.40, 95% CI: 1.20-1.62), be treated with a corticosteroid (aOR: 1.34, 95% CI: 1.16-1.55) and have surgery for IBD (aOR: 1.42, 95% CI: 1.17-1.71). CONCLUSIONS: Antidepressant use is associated with reduced ER utilisation in patients with IBD. There were also increased hospitalisations, corticosteroid treatment, and surgery, which may reflect a more aggressive disease course associated with depression. Treating depression in patients with IBD may reduce healthcare costs by decreasing ER visits.