Background: Small intestinal bacterial overgrowth (SIBO) contributes significantly to the pathogenesis and symptom severity of irritable bowel syndrome (IBS). It is associated with microbial dysbiosis, abnormal intestinal gas fermentation, altered motility, and systemic metabolic and neurocognitive effects, including brain fogginess. Diagnostic uncertainty and lack of a universally accepted gold standard complicate clinical management. Aim: This review synthesizes current evidence on disease mechanisms, diagnostic challenges, therapeutic strategies, and the impact on patient quality of life in SIBO-associated IBS. Methods: A literature search was conducted in PubMed, Scopus, and Google Scholar for full-text articles published between 2000 and 2025. Clinical studies, systematic reviews, and meta-analyses addressing pathophysiology, diagnostics, and treatment outcomes were included. Results: Microbial dysbiosis exacerbates gastrointestinal symptoms through excessive gas production and disrupted motility. Patients frequently report cognitive impairments, including brain fogginess, alongside gastrointestinal distress. Targeted therapy with nonabsorbable antibiotics provides significant symptom relief and improves functional capacity. Persistent diagnostic challenges underscore the need for standardized breath testing and microbial assessments to guide management. Conclusion: Incorporating specific microbial diagnostics into routine gastroenterological practice is essential for optimizing treatment in SIBO-associated IBS. Recognizing the multifaceted impact of bacterial overgrowth enables clinicians to implement targeted therapies, address both intestinal and systemic consequences, and improve long-term patient outcomes.
Dąbrowska et al. (Tue,) studied this question.