SIBO is an acronym for small intestine bacterial overgrowth, a condition in which excessive bacteria are present in the small intestine rather than being confined primarily to the large intestine. It can be diagnosed with a breath test.
Research published in the Journal of Musculoskeletal Pain (2001; 9(3):107–113) suggests a possible connection between fibromyalgia and bacterial overgrowth in the small intestine. The study involved 815 subjects, including 152 individuals diagnosed with fibromyalgia. Of those with fibromyalgia, 29 also had inflammatory bowel disease and were excluded from further analysis.
Among the remaining 123 fibromyalgia patients, 96 tested positive for small intestine bacterial overgrowth using the lactulose hydrogen breath test. In addition, 107 of these patients met diagnostic criteria for irritable bowel syndrome, highlighting a strong overlap between fibromyalgia, gastrointestinal symptoms, and altered gut bacteria.
A subset of 25 patients underwent follow-up testing after antibiotic therapy. Of these, 11 showed complete eradication of bacterial overgrowth, while 14 had incomplete eradication. Overall, 57% of these patients reported global improvement in symptoms following treatment.
The authors noted correlations between fibromyalgia symptoms and specific bacterial species. Certain organisms, including some species of Chlamydia and Borrelia, may produce endotoxins capable of contributing to systemic symptoms. These findings support the idea that gut bacteria may play a role in the symptom pattern seen in at least some individuals with fibromyalgia.
