2026 ICD-10-CM Diagnosis Code G44.001Cluster headache syndrome, unspecified, intractable

ICD-10-CM Codes›G00–G99›G40-G47›G44

ICD-10-CM G44.001
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

G44.001 is a billable ICD-10-CM diagnosis code for cluster headache syndrome, unspecified, intractable. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 102 through 103. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Headache; including migraine.

Code Identity

ICD-10-CM Code
G44.001
Billable Status
Yes — Valid for Submission
Code Describes
Cluster headache syndrome, unspecified, intractable
Short Description
Cluster headache syndrome, unspecified, intractable
Same as the full description in the CMS dataset.
Parent Code
G44.00
Cluster headache syndrome, unspecified

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG44Other headache syndromes
This CodeG44.001Cluster headache syndrome, unspecified, intractable

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.

    • Cephalgia, cephalalgia
      • histamine
        • intractable
    • Headache
      • cluster
        • intractable
    • Headache
      • histamine
        • intractable
    • Neuralgia, neuralgic(acute)
      • ciliary
        • intractable
    • Neuralgia, neuralgic(acute)
      • migrainous
        • intractable
    • Syndrome
      • cluster headache
        • intractable

Clinical ClassificationClinical

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

CCSR NVS010
Headache; including migraine
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Headache

Almost everyone has had a headache. Headache is the most common form of pain. It's a major reason people miss days at work or school or visit the doctor.

Read the full article at MedlinePlus

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

Convert G44.001 to ICD-9-CMHistory

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

ICD-9-CM
339.00 Cluster headache syn NOS
Approximate The match is approximate rather than exact.

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 G44.001Overview

Is G44.001 (Cluster headache syndrome, unspecified) a billable code?

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

What MS-DRG does G44.001 group to?

When cluster headache syndrome, unspecified, intractable is the principal diagnosis on an inpatient stay, it groups to MS-DRG 102, 103, with relative weights from 0.8363 to 1.1209 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of G44.001?

Under the General Equivalence Mappings, cluster headache syndrome, unspecified, intractable converts to ICD-9-CM 339.00 (cluster headache syn NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.