Comment in Aliment Pharmacol Ther. 2021 Sep;54(6):845. Aliment Pharmacol Ther. 2021 Sep;54(6):843-844. BACKGROUND: With the advent of biological therapy in IBD, it is uncertain to what extent 5aminosalicylates (5ASA) are used. AIMS: To explore whether or not 5ASA is continued once biological or immunomodulator therapy is initiated, and the outcomes in those who continued the 5ASAs. METHODS: We conducted a retrospective cohort study using the population-based University of Manitoba IBD Epidemiologic Database which includes prescription drug dispensation from 1996 through 2018. We assessed outcomes among 5ASA users who continued versus discontinued 5ASA after initiation of anti-TNF therapy or immunomodulators. RESULTS: In all, 8379 (77%) of persons with IBD received at least one 5ASA dispensation (85% of ulcerative colitis, UC and 68% of Crohn's disease, CD). There was a reduction in later years, particularly for CD. The most common pattern of 5ASA use was intermittent at 65.1% (stopping and restarting use) versus one-time (4.1%), previous continuous (13.8%) and persistent (17%). Among the total IBD population use was 59% oral, 3% rectal and 14% combination. Of all 5ASA starts, only 25% were continued longer than 20 months. After immunomodulator or anti-TNF initiation, there was no difference in either UC or CD for negative outcomes (hospitalisation, surgery, corticosteroid starts, colorectal cancers or drug-related adverse events) between those who continued 5ASA versus those who discontinued. CONCLUSIONS: 5ASA remains commonly prescribed in UC and CD. Rates of persistent use in UC are low. Once an anti-TNF or immunomodulator is initiated, continuation of 5ASA seems to add no benefit. © 2021 John Wiley & Sons Ltd.