What are the recommended diagnostic tests for confirming SIBO in a primary care setting?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 17 August 2025Updated: 17 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

In a primary care setting, the provided UK guidelines, such as those for irritable bowel syndrome (IBS) and dyspepsia, do not explicitly recommend specific diagnostic tests for confirming small intestinal bacterial overgrowth (SIBO) ,,,. These guidelines primarily focus on ruling out other conditions that present with similar gastrointestinal symptoms ,,,. However, European guidelines indicate that hydrogen and methane breath tests are the recommended diagnostic methods for SIBO [Hammer et al., 2022]. These tests involve the ingestion of a substrate, such as glucose or lactulose, and subsequent measurement of hydrogen and methane gases in the breath [Hammer et al., 2022].

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