K59.1
✓ Billable
Functional diarrhea
ICD-10-CM · FY2026 · Diseases of the Digestive System
Code
K59.1
System
ICD-10-CM
Billable
Yes — valid for submission
Effective
FY2026
Chapter
Diseases of the Digestive System
Source
CMS / CDC NCHS
⚠ Verify before billing. Confirm against the current CMS/NCHS ICD-10-CM files and your payer's rules before claims submission.
Frequently asked questions
What is ICD-10 code K59.1?
ICD-10-CM code K59.1 represents Functional diarrhea. It is a billable diagnosis code in the Diseases of the Digestive System chapter, effective October 1, 2025 – September 30, 2026.
Is K59.1 billable?
Yes. K59.1 is a valid billable ICD-10-CM code for insurance claims and clinical documentation.
What chapter is K59.1 in?
K59.1 belongs to the Diseases of the Digestive System chapter (K00–K95) of ICD-10-CM.
Related codes in the K59 category
K59
Other functional intestinal disorders
Non-billable
K59.0
Constipation
Non-billable
K59.2
Neurogenic bowel, not elsewhere classified
Billable
K59.3
Megacolon, not elsewhere classified
Non-billable
K59.4
Anal spasm
Billable
K59.8
Other specified functional intestinal disorders
Non-billable
K59.9
Functional intestinal disorder, unspecified
Billable
K59.00
Constipation, unspecified
Billable
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