Bowel Prep Drink Clears Gut Bacteria Overgrowth for 6 Weeks
- Authors
- Kunihiko Yokoyama, Kentaro Tominaga, Yuichi Kojima, Yuzo Kawata, Naruhiro Kimura, Toru Setsu, Akira Sakamaki, Shuji Terai
- Journal
- Clinical Journal of Gastroenterology
- Year
- 2026
- DOI
- 10.1007/s12328-026-02412-2
- Study Type
- Human
- Outcome
- Neutral
- Peer Reviewed
- Yes
- Country
- Japan
- Health Condition
- Small Intestinal Bacterial Overgrowth (SIBO)
- Body System
- Gastrointestinal
TL;DR
A single patient’s SIBO resolved after polyethylene glycol bowel preparation and remained absent for 6 weeks, but this does not establish a treatment effect.
Key Finding
A patient's small intestinal bacterial overgrowth, detected by hydrogen breath testing, was normalized after a polyethylene glycol bowel preparation and remained normalized at 6-week follow-up without additional treatment.
Summary
A patient with liver disease and a bacterial overgrowth in the small intestine (detected by breath testing) underwent a standard bowel-cleaning procedure using polyethylene glycol before a colonoscopy. Surprisingly, the breath tests showed the bacterial overgrowth had resolved after the procedure and remained resolved 6 weeks later, without any additional treatment. This single case suggests that bowel-cleaning solutions might affect harmful bacteria in the small intestine, though much more research is needed to confirm this.
Practical Takeaway
This is a single case report, not a controlled study, so no conclusions about effectiveness can be drawn. While it suggests bowel preparation might influence intestinal bacteria in some patients with liver disease, this is very early, hypothesis-generating evidence that requires systematic research before any therapeutic claims can be made.
Abstract
Small intestinal bacterial overgrowth (SIBO) is a frequent complication of chronic liver disease with portal hypertension that often persists or recurs despite standard treatments. Polyethylene glycol (PEG)-based bowel preparations are routinely used before colonoscopy; however, their effects on SIBO have not yet been systematically evaluated. We report the case of a 44-year-old man with metabolic dysfunction-associated steatohepatitis, complicated by intrahepatic portal vein thrombosis and esophagogastric varices. Before colonoscopy, hydrogen and methane breath testing revealed hydrogen-positive and methane-negative SIBO, while the gastrointestinal symptoms were mild, with a Gastrointestinal Symptom Rating Scale score of 15. Subsequently, the patient underwent a standard bowel preparation using a PEG electrolyte solution. No antibiotics, probiotics, laxatives, or dietary interventions were administered before or after the procedure. Follow-up breath tests performed 1 week after bowel preparation demonstrated normalization of both hydrogen and methane levels. Importantly, repeat testing at 6 weeks confirmed sustained negativity without any additional interventions. This case highlights a previously unreported phenomenon, suggesting that transient luminal interventions, such as bowel preparation, may influence small intestinal microbial dynamics in selected high-risk patients. This observation should be considered hypothesis-generating, and no conclusions regarding therapeutic efficacy can be drawn from this single case.