United European Gastroenterology (UEG) said an analysis presented at UEG Week 2026 in Barcelona found an association between earlier antibiotic prescriptions and irritable bowel syndrome (IBS) at age 24.
The UEG release said researchers compared prescription records with IBS assessments for 2,853 participants in Sweden’s BAMSE cohort. Records came from Sweden’s Prescribed Drug Register, starting in 2005, when participants were 9 to 11 years old, and ending one year before their assessment at age 24. UEG reported that 10% of participants had IBS; prior antibiotic use appeared in records for 87.8% of those with IBS and 80.2% of those without it.
After adjusting for sex and family socioeconomic status, UEG reported an association estimate of 1.5 for participants with any antibiotic prescription compared with those with none (95% confidence interval: 1.0–2.2). The announcement did not identify the statistical measure behind the estimates. By prescription count, estimates versus no prescriptions were 1.3 for one or two prescriptions (95% CI: 0.9–2.0), 1.6 for three to five (1.0–2.4) and 1.7 for six or more (1.1–2.6). The intervals for the first two groups included or touched 1.0, and the release did not report a trend test.
UEG also reported an estimate of 1.4 for any tetracycline use (95% CI: 1.1–1.8) and 6.0 for three or more cephalosporin prescriptions (1.9–18.8). The release described the cephalosporin interval as wide.
The researchers did not investigate why antibiotic use was associated with IBS, UEG said. Lead author Dr. Jessica Sjölund cited earlier studies on antibiotics’ effects on gut microbiota as one possible explanation. She said the findings should not deter antibiotic treatment when it is needed for bacterial infections.
Karolinska Institutet says BAMSE is a prospective cohort that has followed more than 4,000 children born in Sweden from 1994 to 1996; this analysis covered a subset. A separate nationwide Swedish case-control study published in 2023 in Alimentary Pharmacology & Therapeutics also reported an association among adults. It found an adjusted odds ratio of 2.21 (95% CI: 2.14–2.28) among 29,111 patients and 135,172 controls. That study involved a different population, and neither study establishes that antibiotics cause IBS.
UEG says an abstract book is expected about three weeks after the congress.
