ICD-10-CM > K00-K95 > K55-K64 > K63 > K63.8 > K63.82 > K63.821 K63.821 Small intestinal bacterial overgrowth Non-Billable/Non-Specific Codes K63.8211Small intestinal bacterial overgrowth, hydrogen-subtypeK63.8212Small intestinal bacterial overgrowth, hydrogen sulfide-subtypeK63.8219Small intestinal bacterial overgrowth, unspecified