ICD-10 Code K63.8211 – Small intestinal bacterial overgrowth, hydrogen-subtype (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K63.8211 – Small intestinal bacterial overgrowth, hydrogen-subtype
What it is
K63.8211 identifies small intestinal bacterial overgrowth with a hydrogen-predominant subtype. Use it when documentation specifies SIBO and indicates hydrogen as the dominant gas pattern.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings include bloating, abdominal discomfort, excess gas, diarrhea, or malabsorption concerns, but the record should support the hydrogen subtype.
When to use this code
Use this code when the provider documents small intestinal bacterial overgrowth and clearly identifies the hydrogen subtype. It may also apply when testing or specialist notes explicitly state hydrogen-predominant SIBO, and the diagnosis is confirmed in the chart.
Do not use for
Do not use this code for nonspecific bloating, irritable bowel symptoms, or suspected SIBO without documentation. If the subtype is not stated, check documentation before assigning K63.8211.
Coding tip
Assign K63.8211 only when the hydrogen subtype is documented; otherwise, query or code the more general SIBO diagnosis if supported.