During the COVID-19 pandemic many IBD units chose Budesonide MMX (Cortiment) as the first-line treatment for flares of ulcerative colitis (UC) in outpatients for its favourable side effect profile. This retrospective study of all UC patients treated with oral steroids between 1 March 2019–30 June 2019 and 1 March 2020–30 June 2020 aimed to compare Cortiment with Prednisolone in routine clinical practice. Outcomes included the need for hospitalisation for acute severe ulcerative colitis, symptoms at four weeks and end of treatment, and the need for rescue Prednisolone. The 2019 and 2020 cohorts did not differ at the baseline. Cortiment prescriptions rose from 24.5% in 2019 to 70.1% in 2020 (p < 0.001). At week four there were significant differences between 2019 and 2020 in mean bowel frequency (3.49 vs. 5.85, p = 0.001), rectal bleeding <50% (89.7% vs. 73.1% of patients, p = 0.039), and physician global assessment (PGA) (39.2% vs. 19.8% in remission, p = 0.045). There was no significant difference in hospital admissions, rectal bleeding, and PGA at week eight. Rescue Prednisolone was required in 10% of Cortiment patients in 2019 vs. 31.3% in 2020 (p = 0.058). Active IBD is associated with worse COVID-19 outcomes prompting the careful evaluation of the choice of first-line steroid for UC, as Cortiment was associated with worse outcomes at four weeks.