The First Major Guideline for Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth, or SIBO, happens when too many bacteria accumulate in the small intestine, often causing bloating, gas, and discomfort. For years, doctors lacked a unified standard for diagnosing it. This 2020 guideline filled that gap.

What the guideline covers

Using a structured evidence-review process, the authors evaluated how SIBO should be diagnosed and treated. The central diagnostic tool is the breath test, in which a person consumes a sugar (glucose or lactulose) and then breathes into a device that measures the gases produced as gut bacteria ferment it.

Key points

• A rise in breath hydrogen of more than 20 ppm within 90 minutes is considered a positive result for SIBO.
• A methane level of 10 ppm or higher signals a distinct condition the guideline names intestinal methanogen overgrowth, which is strongly linked to constipation.
• Hydrogen sulfide was recognized as a third gas produced by gut bacteria, though no validated commercial test existed at the time.
• Antibiotics such as rifaximin were recommended as first-line treatment, with an added agent for the methane-dominant form.

“Hydrogen sulfide is a third gas produced by gut bacteria, but a commercial testing system is not yet available.”

The guideline highlights a broader theme in gut health: the gases our microbes generate are meaningful, measurable indicators. This summary is educational and not a substitute for medical advice.