The 3 Types of SIBO: Hydrogen, Methane & Hydrogen Sulphide
Not all SIBO is the same — and identifying which type you have can help tailor treatment.
1. Hydrogen-Dominant SIBO
The most common type. Bacteria ferment carbohydrates and produce hydrogen gas.
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Common symptom: Diarrhoea
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Testing: A spike in hydrogen levels on a breath test
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Treatment: Herbs like oregano, berberine, or prescription antibiotics such as rifaximin
2. Methane-Dominant SIBO (Now called IMO – Intestinal Methanogen Overgrowth)
Caused by archaea (not bacteria) that consume hydrogen and produce methane gas.
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Common symptom: Constipation
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Testing: Elevated methane on a breath test
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Treatment: More stubborn; often needs a combination of antimicrobials and diet
3. Hydrogen Sulphide SIBO
A newer form that produces rotten egg–smelling gas.
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Common symptoms: Bloating, gas, diarrhoea, body odour
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Testing: Not widely available yet, but increasingly recognised
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Treatment: Requires careful modulation, sometimes using binders and sulphur-reducing diets
Identifying your SIBO type can help you avoid one-size-fits-all solutions and get to the root faster.