2027 ICD-10-CM Diagnosis Code G44.009Cluster headache syndrome, unspecified, not intractable
ICD-10-CM Codes›G00–G99›G40-G47›G44
- Billable — Valid for Submission
- Chronic Condition
G44.009 is a billable ICD-10-CM diagnosis code for cluster headache syndrome, unspecified, not intractable. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 102 through 103. Coders also document this condition as atypical cluster headache. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Headache; including migraine.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Atypical cluster headache
- Ciliary neuralgia
- Cluster headache
- Cluster tic syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G44.009: its own notes plus those printed at G44 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Cluster headache syndrome NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G44.009, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming G44.009: they are not reported together with it, unless the two conditions are unrelated.
Excludes2 4
These codes carry an Excludes2 note naming G44.009: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Cephalgia, cephalalgia See Also: Headache;
histamine G44.009
not intractable G44.009
cluster G44.009
not intractable G44.009
histamine G44.009
not intractable G44.009
Neuralgia, neuralgic (acute) M79.2
ciliary G44.009
not intractable G44.009
migrainous G44.009
not intractable G44.009
Syndrome See Also: Disease;
cluster headache G44.009
not intractable G44.009
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Cluster Headache
a primary headache disorder that is characterized by severe, strictly unilateral pain which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15-180 min. occurring 1 to 8 times a day. the attacks are associated with one or more of the following, all of which are ipsilateral: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, facial sweating, eyelid edema, and miosis. (international classification of headache disorders, 2nd ed. cephalalgia 2004: suppl 1)
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 G44.009 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G44.009Overview
What is the ICD-10 code for cluster headache syndrome, unspecified, not intractable?
The ICD-10-CM code for cluster headache syndrome, unspecified, not intractable is G44.009 (sometimes written as G44009). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G44.009 (Cluster headache syndrome, unspecified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report cluster headache syndrome, unspecified, not intractable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G44.009 group to?
When cluster headache syndrome, unspecified, not intractable is the principal diagnosis on an inpatient stay, it groups to MS-DRG 102, 103, with relative weights from 0.8219 to 1.1200 depending on complications. Higher weights mean higher Medicare reimbursement.
Can G44.009 be reported with R51.9?
Not as a rule. The Excludes1 note at G44, which applies to G44.009, lists "headache NOS (R51.9)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of G44.009?
Under the General Equivalence Mappings, cluster headache syndrome, unspecified, not intractable converts to ICD-9-CM 339.00 (cluster headache syn NOS). The mapping is approximate, so confirm the match fits the documentation.
