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ICD-10-CM 2027 diagnosis code

G44.009Cluster headache syndrome, unspecified, not intractable

✓ Billable / specific

G44.009 is a valid, billable ICD-10-CM code for cluster headache syndrome, unspecified, not intractable. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for Cluster headache, ICD-10 code for Ciliary neuralgia, ICD-10 code for Histamine headache, ICD-10 code for Histamine cephalgia.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About G44.009

G44.009 is the ICD-10-CM diagnosis code for cluster headache syndrome, unspecified, not intractable. It belongs to category G44 (other headache syndromes), block G40-G47 (episodic and paroxysmal disorders) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within G44.00 (cluster headache syndrome, unspecified), G44.009 is specifically for cluster headache syndrome, unspecified, not intractable. Related codes cover intractable (G44.001).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 102 (Headaches with MCC, relative weight 1.1201) and DRG 103 (Headaches without MCC, relative weight 0.822), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 339.00 (cluster headache syndrome, unspecified).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Cluster headache syndrome NOS

Notes that apply from higher levels

Instructions written at a parent level also apply to G44.009.

› From G44 Other headache syndromes
Excludes1
Excludes2
  • atypical facial pain (G50.1)
  • headache due to lumbar puncture (G97.1)
  • migraines (G43.-)
  • trigeminal neuralgia (G50.0)

Broader instructions also apply from Chapter 6: Diseases of the nervous system.

Alphabetic index entries

12 entries

Terms in the official ICD-10-CM index that lead to G44.009.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 01 · Diseases and Disorders of the Nervous System

ICD-9-CM equivalent

Converter →
  • 339.00Cluster headache syndrome, unspecifiedapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about G44.009

Is G44.009 billable?

Yes. G44.009 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can G44.009 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict G44.009 as a principal diagnosis.

Is G44.009 a CC or MCC?

No. G44.009 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does G44.009 group to?

G44.009 is used in the MS-DRG v44.0 logic for MS-DRG 102 (Headaches with MCC) and MS-DRG 103 (Headaches without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for G44.009?

The CMS General Equivalence Mappings map G44.009 to ICD-9-CM 339.00.