G44.009 Cluster headache syndrome, unspecified, not intractable

The ICD-10-CM code for Cluster headache syndrome, unspecified, not intractable is G44.009 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

6: Diseases of the nervous system (G00-G99)

Section

G40-G47: Episodic and paroxysmal disorders (G40-G47)

Category G44

60 codes (40 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G44.009:

• Headache › histamine
• Neuralgia, neuralgic (acute) › migrainous
• Neuralgia, neuralgic (acute) › ciliary
• Headache › cluster
• Syndrome › cluster headache
• Cephalgia, cephalalgia › histamine
• Headache › cluster › not intractable
• Cephalgia, cephalalgia › histamine › not intractable

Inclusion Terms

• Cluster headache syndrome NOS

U.S. Hospital Utilization

• An estimated 3,985 U.S. inpatient stays in 2023 included G44.009 among the documented diagnoses.
• 255 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)