K59.1

Billable

Functional diarrhea

K59.1 is the ICD-10-CM code for Functional diarrhea. It is a billable, specific code valid for reimbursement.

Status
Billable
Chapter
K00-K95
Parent
K59
Edition
FY2026

K00-K95 Diseases of the digestive system

What this means — in plain language

MedlinePlus · NIH

What is diarrhea? Diarrhea is loose, watery stools (bowel movements). You have diarrhea if you have loose stools three or more times in one day. Acute diarrhea is diarrhea that lasts a short time. It is a common problem. It usually lasts about one or two days, but it may last longer. Then it goes away on its own. Diarrhea lasting more than a few days may be a sign of a more serious problem. Chronic diarrhea --…

Read more about Diarrhea at MedlinePlus ↗

Source: U.S. National Library of Medicine (MedlinePlus). Informational only — not medical advice.

Excludes1 — not coded here

  • diarrhea NOS (R19.7)
  • irritable bowel syndrome with diarrhea (K58.0)

Medications indicated for this condition

FDA labeling

Drugs whose FDA labeling lists this condition's category among its indications. Informational only — not a treatment recommendation or medical advice.

Conditions mapped to this code

MedlinePlus · NIH

Plain-language health-topic references grounded in MedlinePlus (NIH/NLM).

Frequently asked questions

What is ICD-10 code K59.1?
K59.1 is the ICD-10-CM code for "Functional diarrhea". It falls under K00-K95 Diseases of the digestive system.
Is K59.1 a billable code?
Yes — K59.1 is a billable, specific ICD-10-CM code valid for reimbursement.
What is excluded from K59.1?
Excludes1 (not coded here): diarrhea NOS (R19.7); irritable bowel syndrome with diarrhea (K58.0).

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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