ICD-10 Code K63.8212 – Small intestinal bacterial overgrowth, hydrogen sulfide-subtype (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K63.8212 – Small intestinal bacterial overgrowth, hydrogen sulfide-subtype
What it is
K63.8212 identifies small intestinal bacterial overgrowth with a hydrogen sulfide subtype. Use it when documentation specifically names this SIBO variant; it reflects abnormal bacterial activity in the small intestine.
Clinical signs
Clinical features vary; refer to documentation. Typical SIBO notes may mention bloating, abdominal discomfort, gas, diarrhea, or malabsorption, but you should code only when the hydrogen sulfide subtype is clearly documented.
When to use this code
Use K63.8212 when the provider documents hydrogen sulfide–subtype SIBO, such as in a gastroenterology assessment, test interpretation, or problem list. Apply it when the record distinguishes this subtype from other SIBO patterns. If the subtype is not stated, check documentation before assigning this code.
Do not use for
Do not use this code for nonspecific bloating, irritable bowel syndrome, or general intestinal infection. If the record only says “SIBO” without subtype detail, check documentation.
Coding tip
Code this only when the hydrogen sulfide subtype is explicitly documented, since subtype specificity matters.