(Barcelona, Spain, Monday, 19 October 2026) Antibiotic use from childhood through early adulthood was 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 2026.1
IBS is a common digestive disorder that affects more than 60 million people across Europe, causing symptoms such as abdominal pain and changes in bowel habits.2,3 Whilst previous research has suggested a link between antibiotic use and IBS4, evidence on whether childhood exposure is associated with IBS in adulthood remains inconsistent.5-7 Much of the existing evidence relies on people recalling past antibiotic use, with a lack of population-based studies using objectively recorded antibiotic data across childhood.
To address this gap, researchers analysed data from 2,853 participants in the population-based 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. The researchers examined whether participants had received antibiotics, the total number of prescriptions received, and the classes of antibiotics prescribed.
At age 24, 10.0% of participants had IBS, of whom 79.4% were female. Antibiotic use was more common among those with IBS, with 87.8% having received antibiotics during the study period 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 progressively with the number of antibiotic prescriptions (P for trend <0.001). 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 individual 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).
Lead author Dr Jessica Sjölund said the study provides an important step forward in understanding the relationship between antibiotic exposure and IBS. "By examining a population-based group of young adults with antibiotic exposure objectively recorded from childhood and adolescence, we were able to address key limitations of earlier research, including reliance on recalled antibiotic use and specialist healthcare records to identify IBS, which may not capture the full spectrum of IBS in the general population."
"These findings strengthen the epidemiological evidence for a potential link between antibiotic exposure and IBS and support further research into this relationship, although it does not establish causality."
Whilst the study did not investigate why antibiotic exposure was associated with IBS, one possible explanation for the association involves the gut microbiome. Dr Sjölund explained, "Previous studies have shown that antibiotics can alter the gut microbiome, with observational research suggesting that these changes may persist for several years and may be more pronounced following repeated courses. As alterations to the gut microbiome are thought to play a role in IBS, this could be one possible pathway underlying the association we observed."
Discussing the next steps for research, Dr Sjölund said, "Larger, long-term studies with repeated assessment of IBS over time could help determine whether antibiotic exposure precedes IBS and whether the timing of exposure or type of antibiotic matters. Looking more closely at infections, other health conditions and psychological and family factors could also help clarify what is contributing to the association. Alongside this, repeated assessments of the gut microbiome could offer further insight into whether microbiome changes are involved."
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 and sometimes essential 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."
