SIBO: The Hidden Cause of Bloating, Gas, and IBS-Like Symptoms
- AGG
- May 19
- 2 min read
Bloating. Chronic gas. Diarrhea or constipation that won't resolve. Symptoms that have been labeled 'IBS' for years without a clear answer or effective treatment.
For a significant number of patients living with these complaints, the underlying cause may be small intestinal bacterial overgrowth — SIBO. It's one of the most underdiagnosed GI conditions, and it's also one of the most treatable once it's properly identified.
What Is SIBO?
The small intestine is supposed to be a relatively bacteria-free zone. The colon — the large intestine — is where the vast majority of our gut bacteria live and do their important work. When bacteria from the colon migrate to or proliferate excessively in the small intestine, the result is SIBO.
Those misplaced bacteria ferment carbohydrates that should be absorbed before they reach the colon, producing hydrogen and/or methane gas. The result: bloating (often severe and worsening as the day goes on), excess gas, and disrupted bowel habits — symptoms that closely mimic IBS.
How Common Is SIBO?
Research suggests that SIBO may be present in 6–15% of healthy adults and in 30–85% of patients with IBS — a striking finding that suggests many patients diagnosed with 'IBS' may actually have an undetected bacterial overgrowth driving their symptoms. In patients with certain risk factors, the prevalence is even higher.
Who Is at Risk?
Prior abdominal or bariatric surgery (especially gastric bypass)
Conditions affecting gut motility: diabetes, hypothyroidism, scleroderma, Parkinson's disease
Structural abnormalities: adhesions, strictures from Crohn's disease
Chronic proton pump inhibitor (PPI) use — reducing stomach acid may allow more bacteria to survive in the upper GI tract
Older adults — motility naturally slows with age
Diagnosing SIBO
The standard test for SIBO is a hydrogen/methane breath test — a simple, non-invasive test we offer in our offices. You drink a lactulose or glucose solution and breathe into collection tubes at intervals over approximately two hours. Elevated hydrogen or methane readings indicate abnormal bacterial fermentation in the small intestine.
The test is straightforward, but preparation matters: you'll need to follow a low-fermentation diet the day before and fast overnight. We provide complete instructions when you schedule.
Treating SIBO
SIBO is typically treated with rifaximin — a gut-specific antibiotic with minimal systemic absorption and an excellent safety profile. Patients with methane-predominant SIBO (more likely to present with constipation) may require a combination of rifaximin and neomycin.
Dietary modifications — particularly a low-FODMAP diet during and after treatment — can reduce recurrence. Equally important is identifying and addressing the underlying condition predisposing you to SIBO in the first place. Without treating the root cause, SIBO often returns.
What If You've Been Told You Have IBS?
If you have been living with an IBS diagnosis for years and have not responded well to standard IBS treatments, SIBO testing is a reasonable next step. The two conditions frequently co-occur, and treating SIBO in the appropriate patient can dramatically improve symptoms that have been resistant to other approaches.
📅 Ask us about SIBO breath testing at your next visit — call (908) 851-2770 or book online.
Medical Disclaimer: This blog post is intended for general informational and educational purposes only and does not constitute medical advice.
