Antibiotic exposure is associated with a significantly increased risk of developing irritable bowel syndrome (IBS), according to a systematic review and meta-analysis presented at Digestive Disease Week in Chicago May 2-5.

 Conducted by researchers from institutions in India and the United States, the study synthesizes evidence across observational studies to clarify class-specific risks, potential dose-response patterns, and the impact of antibiotic indications.

Study Findings

The meta-analysis included 14 observational studies encompassing 377,943 adults without pre-existing IBS. Using random-effects modeling, investigators found that antibiotic exposure nearly doubled the risk of incident IBS (odds ratio [OR] 1.96; 95% CI, 1.35–2.82; p=0.0003), though heterogeneity was high (I²=98.2%).

Class-specific analysis revealed the highest IBS risk associated with tetracyclines (OR 2.26) and fluoroquinolones (OR 2.10). Cephalosporins (OR 1.93), penicillins (OR 1.69), and macrolides (OR 1.66) were also linked to elevated risk. Studies evaluating mixed indications for antibiotic use showed a higher pooled risk (OR 2.14; 95% CI, 1.60–2.86) compared with those focused on gastrointestinal (GI) infections (OR 1.47; 95% CI, 0.78–2.77), although subgroup differences were not statistically significant (p=0.29).

Three studies assessed cumulative antibiotic exposure and consistently demonstrated a trend toward increased IBS risk with a higher number of antibiotic courses, suggesting a possible dose-response relationship. Sensitivity analyses restricted to adjusted estimates showed attenuated associations, indicating that confounding factors may partially explain the observed effects. However, the association remained significant in low-risk-of-bias studies (OR 1.41; 95% CI, 1.05–1.63), and leave-one-out analyses confirmed the stability of results.

Clinical Implications

These findings reinforce the role of gut microbiota disruption in IBS pathogenesis and highlight antibiotics as a potentially modifiable risk factor. The stronger associations observed with tetracyclines and fluoroquinolones—agents known for broader microbiome disruption—support the hypothesis that microbial dysbiosis contributes to IBS development.

For clinicians, the results underscore the importance of antibiotic stewardship, particularly in noncritical indications. While causality cannot be definitively established due to observational design and residual confounding, minimizing unnecessary antibiotic exposure may reduce downstream gastrointestinal complications.

The lack of a significantly higher risk in GI infection–specific studies suggests that antibiotics may not independently amplify post-infectious IBS risk, though evidence remains inconclusive.

Antibiotic exposure is associated with increased IBS risk, particularly with microbiota-disruptive classes. Emerging dose-response signals warrant further investigation. Prospective, standardized studies are needed to clarify causal pathways and inform targeted prevention strategies in clinical practice.

Reference:

Nandakishor N, Panda S, Sharma A, et al. Antibiotic exposure and IBS risk: a systematic review and meta-analysis of class-specific risk, indication effects and emerging dose-response signals. Presented at: Digestive Disease Week; May 2–5, 2026; Chicago, Illinois.