Antibiotics and IBS may be linked in a way that starts long before adulthood. According to a new study presented at UEG Week 2026 in Barcelona, young adults who had received antibiotics from childhood onward had higher odds of irritable bowel syndrome (IBS) at age 24, and the odds rose as the number of prescriptions went up. The data come from a Swedish birth cohort. They show an association, not proof that antibiotics cause IBS, and the lead researcher says the findings should not put anyone off antibiotics they genuinely need.
How the antibiotics and IBS study was done
The researchers analysed data from 2,853 participants in the Swedish BAMSE birth cohort. Antibiotic prescriptions were taken from the Swedish Prescribed Drug Register, starting in 2005, when participants were aged 9 to 11, and running until one year before IBS was assessed at age 24. At 24, 10.0% of participants had IBS.
What the study found about antibiotics and IBS
Antibiotic use was more common among people with IBS: 87.8% had received antibiotics, compared with 80.2% of those without IBS. After accounting for sex and family socioeconomic status, people who had received antibiotics had 1.5 times the odds of IBS (95% confidence interval 1.0 to 2.2) compared with those who had not.
The odds increased with the number of prescriptions. Compared with no antibiotics, one or two prescriptions went with 1.3 times the odds (95% CI 0.9 to 2.0), three to five with 1.6 times (1.0 to 2.4), and six or more with 1.7 times (1.1 to 2.6).
The researchers also looked at antibiotic classes. Tetracyclines and cephalosporins stayed significantly associated with IBS after adjustment. Any use of tetracyclines went with 1.4 times the odds (1.1 to 1.8), and three or more cephalosporin prescriptions with 6.0 times the odds (1.9 to 18.8). Odds are a statistical measure, not the same as the share of people who developed IBS.
Why might antibiotics and IBS be connected?
The study did not investigate why. Lead author Dr Jessica Sjölund pointed to one possible explanation: previous studies have shown that antibiotics can alter the gut microbiome, and changes in the gut microbiome are thought to play a role in IBS, so this could be one pathway behind the association. For another recent story about microbes and health, see our report on long Covid linked to different lung and mouth bacteria. For a different angle on antibiotics, see our story on an IISc cow gut enzyme that breaks down antibiotic-resistant biofilms.
Limits of the antibiotics and IBS findings
This is an observational study presented at a medical meeting, and the release does not say whether it has been peer reviewed. Several results come with wide uncertainty. The range for the overall result starts at 1.0, the range for one or two prescriptions (0.9 to 2.0) includes 1.0, and the cephalosporin estimate of 6.0 spans 1.9 to 18.8, which makes it imprecise. The release says the results were adjusted for sex and family socioeconomic status only, and it does not describe why the antibiotics were prescribed or whether the infections behind them were considered.
A health caution matters here. Antibiotics remain an important treatment for bacterial infections, and nobody should skip or stop a prescribed course because of this study. If you have ongoing bowel symptoms or questions about a prescription, speak to a doctor.
My view on antibiotics and IBS
As a writer, I think the most useful reading is the one the lead author gives. The findings do not argue against antibiotics when they are needed, but they add one more reason to avoid unnecessary prescribing. The pattern of higher odds with more prescriptions is interesting, yet observational data of this kind cannot easily separate the antibiotics from everything else that happens in childhood. I would want to see the full paper and follow-up work on the microbiome before drawing firmer conclusions.
FAQ: antibiotics and IBS
Do antibiotics cause IBS?
The study does not show that. It found an association between antibiotic use and higher odds of IBS at age 24, and the researchers say they did not investigate why.
Should I avoid antibiotics because of this study?
No. The lead author says the findings should not discourage antibiotic use when it is needed, though they add to the reasons for avoiding unnecessary prescribing. Talk to a doctor about any prescription.
Which antibiotics were linked most strongly to IBS?
Tetracyclines and cephalosporins remained significantly associated after adjustment, but the cephalosporin estimate was very imprecise, so it should be read with caution.