SIBO (Small Intestinal Bacterial Overgrowth) is the abnormal proliferation of bacteria in the small intestine — an area that normally has relatively low bacterial counts (10³–10⁴ CFU/mL) compared to the colon (10¹¹–10¹² CFU/mL). When bacteria colonize the small intestine in large numbers, they ferment carbohydrates before absorption, producing gas (hydrogen and/or methane) and causing bloating, belching, diarrhea or constipation, malabsorption, and fatigue.
The most common mistake in SIBO treatment: addressing the bacteria without correcting the underlying cause. SIBO is almost always a symptom of an upstream problem — impaired migrating motor complex (MMC) activity, low stomach acid, structural abnormalities, or post-infectious dysmotility. Without fixing the root cause, relapse is near-inevitable.
Dose: 550mg TID (three times daily) × 14 days. Rifaximin is a minimally absorbed antibiotic that acts locally in the small intestine — <0.4% systemic absorption, meaning it doesn't affect systemic microbiome substantially and has a good safety profile for repeat courses.
For methane/IMO: Rifaximin 550mg TID + neomycin 500mg BID × 14 days simultaneously. The dual approach is essential — neomycin provides broader coverage against methanogens that rifaximin alone doesn't reach.
Success rate: ~70% for H2, ~50–60% for IMO. Relapse is common without addressing root cause.
The Chedid et al. 2014 study (n=104) compared rifaximin to herbal antimicrobials (FC Cidal + Dysbiocide from Biotics Research, or Candibactin-BR + Candibactin-AR from Metagenics) and found equivalent SIBO clearance rates: 46% with herbals vs. 34% with rifaximin (herbals were actually numerically superior, though the difference wasn't statistically significant).
Common herbal protocols (4 weeks): Oregano oil + berberine + allicin (for H2-dominant); allicin high-dose (450mg TID) as add-on for methane. Lower cost than rifaximin, no prescription needed, but requires strict compliance over 4 weeks vs. 2 weeks for antibiotics.
An elemental diet (Vivonex, Physicians' Elemental, or homemade versions) provides all nutrition as pre-digested amino acids, simple sugars, and MCT fats — absorbed entirely in the proximal small intestine before bacteria can ferment them, effectively starving the SIBO. Two weeks of elemental diet: ~80–90% SIBO clearance rate — higher than any antibiotic protocol. The catch: it tastes terrible, is expensive ($400–800 for 2 weeks), and requires iron discipline to complete. Used for severe, antibiotic-resistant cases or when antibiotics are contraindicated.
SIBO returns in ~46% of patients within 9 months because antibiotics kill the overgrowth but don't fix why it developed. The migrating motor complex (MMC) — the "housekeeper" wave that sweeps the small intestine clean between meals — is impaired in most SIBO cases. Common causes of MMC dysfunction: post-infectious (after food poisoning, particularly Salmonella/Campylobacter), low thyroid function, opioid medications, chronic stress, adhesions/scar tissue from abdominal surgery, and connective tissue disorders (EDS).
Post-treatment motility support: Prokinetic agents — low-dose naltrexone (LDN, 1–5mg at bedtime), iberogast, ginger, 5-HTP (after treatment), or prescription prokinetics (prucalopride) — are used post-treatment to maintain MMC function and prevent relapse. Not all practitioners address this; it's one of the most important factors in long-term SIBO management.
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