What is SIBO?

SIBO is today one of the most underdiagnosed causes of chronic gut complaints. Many patients live for years with symptoms without ever receiving a clear explanation. They are often labelled with "IBS" or told it's "stress" while there is a measurable, treatable mechanism behind it.

• Hydrogen SIBO — Associated with diarrhoea, bloating and food intolerances.
• Methane SIBO (IMO) — More often linked to constipation, slow transit and weight gain.
• Hydrogen sulfide overgrowth (ISO) — Intestinal Sulfide Overproduction. Often presents with diarrhoea, a "rotten egg" smell, bladder or skin symptoms and sulfur intolerance. Frequently missed on standard breath tests.
• Mixed form — A combination of the above, with fluctuating symptoms.

The type partly determines the recovery strategy. That is why a breath test measuring hydrogen, methane and — where possible — hydrogen sulfide is the foundation of a sound approach.

Not every case of bloating, food intolerance or chronic gut discomfort is bacterial. SIFO — Small Intestinal Fungal Overgrowth — is an overgrowth of fungi (usually Candida) in the small intestine. The symptoms overlap strongly with SIBO: bloating, gas, brain fog, fatigue and food sensitivities, which is why SIFO is often missed when only a breath test is done.

SIFO can occur on its own, but frequently coexists with SIBO — especially after repeated antibiotic courses, prolonged acid-suppressing medication or a long-standing motility problem. If your breath test is negative but your symptoms persist, SIFO deserves serious consideration.

At Beyond SIBO we also guide people through testing, interpretation and recovery support for suspected or confirmed SIFO, using the same structured, evidence-based pathway.

SIBO is rarely an isolated problem. One or more underlying factors usually play a role: slow motility (MMC dysfunction), prior antibiotic use, acid-suppressing medication, thyroid issues, adhesions after surgery, hormonal shifts or chronic stress. Sustainable recovery requires attention to that cause — not only to the bacteria themselves.

SIBO is complex. There is no "one-size-fits-all" pill. A good pathway combines diagnosis, eradication, gut repair and relapse prevention — and adapts based on your response. That is precisely the philosophy of SIBO International.