BARCELONA, Spain, Oct. 19, 2026 /PRNewswire/ -- Antibiotic use from childhood through early adulthood is associated with higher odds of irritable bowel syndrome (IBS) at age 24, with the odds increasing as the number of antibiotic prescriptions rose, according to a new study presented today at UEG Week 2026.

Researchers analysed data from 2,853 participants in the Swedish BAMSE birth cohort. Antibiotic prescriptions were obtained from the Swedish Prescribed Drug Register from 2005, when participants were aged 9–11 years, until one year before IBS was assessed at age 24.

At 24, 10.0% of participants had IBS. Antibiotic use was more common among those with IBS, with 87.8% having received antibiotics compared with 80.2% of those without IBS. After accounting for sex and family socioeconomic status, those who had received antibiotics had 1.5 times the odds of IBS (95% CI 1.0–2.2) compared with those who had not.

The odds of IBS increased with the number of antibiotic prescriptions. Compared with those who received no antibiotics, participants receiving one or two prescriptions had 1.3 times the odds of IBS (95% CI 0.9–2.0), rising to 1.6 times (95% CI 1.0–2.4) with three to five prescriptions and 1.7 times (95% CI 1.1–2.6) with six or more.

When antibiotic classes were examined, tetracyclines and cephalosporins remained significantly associated with higher odds of IBS after adjusting for sex and family socioeconomic status. Any use of tetracyclines was associated with 1.4 times (95% CI 1.1–1.8) the odds of IBS, while three or more prescriptions of cephalosporins were associated with 6.0 times the odds (95% CI 1.9–18.8).

Whilst the study did not investigate why antibiotic exposure was associated with IBS, one possible explanation for the association involves the gut microbiome. Lead author Dr Jessica Sjölund explained, "Previous studies have shown that antibiotics can alter the gut microbiome. As alterations to the gut microbiome are thought to play a role in IBS, this could be one pathway underlying the association observed."

Reflecting on the practical implications of the findings, Dr Sjölund stressed the need to balance the essential role of antibiotics with careful prescribing. "Antibiotics remain an important treatment for bacterial infections, and our findings should not discourage their use when they are needed. Rather, they highlight the possibility of longer-term effects from repeated exposure and add to the reasons for avoiding unnecessary antibiotic prescribing."

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