2026 ICD-10-CM Diagnosis Code K59.00Constipation, unspecified

ICD-10-CM Codes›K00–K95›K55-K64›K59

ICD-10-CM K59.00
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K59.00 is a billable ICD-10-CM diagnosis code for constipation, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified gastrointestinal disorders.

Code Identity

ICD-10-CM Code
K59.00
Billable Status
Yes — Valid for Submission
Code Describes
Constipation, unspecified
Short Description
Constipation, unspecified
Same as the full description in the CMS dataset.
Parent Code
K59.0
Constipation

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK59Other functional intestinal disorders
This CodeK59.00Constipation, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute constipation
  • Acute constipation in childhood
  • Acute constipation in infancy
  • Alteration in bowel elimination
  • Alteration in bowel elimination: constipation
  • Atonic constipation
  • Chronic constipation
  • Chronic constipation without overflow
  • Constipation
  • Constipation alternates with diarrhea
  • Constipation due to neurogenic bowel
  • Constipation due to spasm of colon
  • Constipation during pregnancy
  • Defecation reflex abnormal - constipated
  • Defecation reflex finding
  • Drug-induced constipation
  • Encopresis
  • Encopresis with constipation AND overflow incontinence
  • Infant dyschezia
  • Obstipation
  • Perceived constipation
  • Simple constipation
  • Spurious diarrhea - overflow
  • Therapeutic opioid induced constipation

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Constipation(atonic) (neurogenic) (simple) (spastic)
    • Dyschezia

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG025
Other specified and unspecified gastrointestinal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Constipation

    infrequent or difficult evacuation of feces. these symptoms are associated with a variety of causes, including low dietary fiber intake, emotional or nervous disturbances, systemic and structural disorders, drug-induced aggravation, and infections.

  • Opioid-Induced Constipation

    constipation associated with the use of opioids.

  • Encopresis

    incontinence of feces not due to organic defect or illness.

  • Encopresis

    an elimination disorder characterized by fecal incontinence, whether involuntary or intentional, which is not due to a medical condition and which occurs in someone who is toilet trained.

Patient EducationClinical

Constipation

Constipation means having fewer than three bowel movements a week. The stool (poop) can be hard and dry. Sometimes it is painful to pass. At one time or another, almost everyone gets constipated. In most cases, it lasts a short time and is not serious.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K59.00 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
564.00 Constipation NOS
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K59.00Overview

Is K59.00 (Constipation) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report constipation, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K59.00 group to?

When constipation, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K59.00?

Under the General Equivalence Mappings, constipation, unspecified converts to ICD-9-CM 564.00 (constipation NOS). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.