Antibiotics Linked to Irritable Bowel Syndrome at Age 24
A study presented at UEG Week in Barcelona links antibiotics taken from age 9 to 11 onward to higher odds of irritable bowel syndrome. Causation has not been shown.
Antibiotics taken from age 9 to 11 onward are associated with higher odds of irritable bowel syndrome at age 24, and the odds rise with the number of prescriptions. That is the finding of a Swedish study presented on Monday, October 19, 2026, at UEG Week 2026 in Barcelona by Dr. Jessica Sjölund, a physician at Sahlgrenska University Hospital and a researcher at the University of Gothenburg. The congress is organized by United European Gastroenterology (UEG), which is based in Vienna.
This is an association, not a proven cause. In the UEG press release, the author herself stresses that the finding does not establish causality.
How many people were analyzed, and how?
The team analyzed data on 2,853 participants from BAMSE, a Swedish population-based birth cohort. Antibiotic prescriptions were taken from the Swedish Prescribed Drug Register, starting in 2005, when the participants were 9 to 11 years old, and running until one year before they were assessed for irritable bowel syndrome at age 24. The researchers looked at three things: whether a person received antibiotics at all, how many prescriptions they had in total, and which drug classes those prescriptions belonged to.
The antibiotic data, in other words, do not depend on what participants remember. Sjölund points to that difference as the main strength of the study:
“By studying a population-based group of young adults with objectively recorded antibiotic exposure from childhood and adolescence, we were able to address key limitations of earlier research, including reliance on recalled antibiotic use and on specialist healthcare records to identify irritable bowel syndrome, which may not capture the full spectrum of the condition in the general population.”
According to UEG, more than 60 million people in Europe live with irritable bowel syndrome. Earlier studies had already hinted at a link with antibiotics, but the evidence on whether childhood exposure affects the condition in adulthood was, as UEG puts it, inconsistent.
What did the numbers show?
At age 24, 10.0 percent of participants had irritable bowel syndrome, and 79.4 percent of them were women. In the period studied, 87.8 percent of those with the syndrome had received antibiotics, compared with 80.2 percent of those without it.
After adjusting for sex and the family’s socioeconomic status, antibiotic use carried 1.5 times higher odds of the syndrome (95 percent confidence interval of 1.0 to 2.2). The lower bound of that interval touches 1.0, which means the result is on the edge of statistical significance.
The odds rise with the number of prescriptions (P for trend below 0.001):
- one to two prescriptions: 1.3 times higher odds (confidence interval 0.9 to 2.0, so it includes 1.0)
- three to five prescriptions: 1.6 times (interval 1.0 to 2.4)
- six or more prescriptions: 1.7 times (interval 1.1 to 2.6)
When drug classes were examined one by one, a significant association remained for tetracyclines and cephalosporins. Any use of tetracyclines carried 1.4 times higher odds (interval 1.1 to 1.8), and three or more cephalosporin prescriptions carried as much as 6.0 times higher odds. The confidence interval for cephalosporins is wide, from 1.9 to 18.8, which means the estimate is unreliable.
Odds are not the same as risk: 1.5 times higher odds do not mean the probability of the disease is 50 percent higher.
What could explain the link?
The study did not examine why antibiotics and irritable bowel syndrome occur together. The authors point to changes in the gut microbiota as one possible route. Sjölund explains:
“Previous studies have shown that antibiotics can alter the gut microbiome, and observational research suggests these changes may persist for several years and be more pronounced after repeated courses. As changes in the gut microbiome are thought to play a role in irritable bowel syndrome, this could be one possible pathway underlying the association we observed.”
What does this not prove?
Sjölund is just as clear about the practical message:
“Antibiotics remain an important and sometimes essential treatment for bacterial infections, and our findings should not discourage their use when needed. Rather, they point to the possibility of long-term consequences of repeated exposure and add a further reason to avoid unnecessary antibiotic prescribing.”
The limitations are built into the design. The study is observational, so it cannot rule out that a third factor, for example the frequent infections that lead to antibiotic prescriptions in the first place, lies behind both the drugs and the symptoms. Prescription data begin only at age 9 to 11, so earlier life is not covered, even though the press release title speaks of childhood. The syndrome was assessed once, at age 24, so it cannot be said whether the exposure came before the illness.
In the sources available to us, there is no indication that the work has been published in a peer-reviewed journal. It was presented at the congress, and the author calls for larger studies as the next step:
“Larger, long-term studies with repeated assessments of irritable bowel syndrome over time could help determine whether antibiotic exposure precedes the syndrome and whether timing or type of antibiotic matters. More detailed information on infections, other health conditions, and psychological and family factors could also help clarify what contributes to this association. In addition, repeated measurements of the gut microbiome could provide further insight into whether microbiome changes are involved.”
