G44.001 Cluster headache syndrome, unspecified, intractable

Billable ICD-10-CM code, FY2026.

Applies from G44 Other headache syndromes

Excludes1 (never code together)

• headache NOS (R51.9)

Excludes2 (not included here)

• atypical facial pain (G50.1)
• headache due to lumbar puncture (G97.1)
• migraines (G43.-)
• trigeminal neuralgia (G50.0)

Applies from G44.00 Cluster headache syndrome, unspecified

Applicable to

• Ciliary neuralgia
• Cluster headache NOS
• Histamine cephalgia
• Lower half migraine
• Migrainous neuralgia

MS-DRG index

Defines the logic of DRG(s) 102-103 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 339.00 Cluster headache syndrome, unspecified (approximate)

Code annotations containing back-references to G44.001

Back-references to G44.00

• Type 1 Excludes: G43 Migraine ("lower half migraine (G44.00)")

Back-references to G44.0

• Type 2 Excludes: G44.1 Vascular headache, not elsewhere classified ("cluster headache (G44.0)")

Back-references to G44

• Type 2 Excludes: G43 Migraine ("headache syndromes (G44.-)")
• Type 2 Excludes: G89 Pain, not elsewhere classified ("headache syndromes (G44.-)")
• Type 2 Excludes: R51 Headache ("migraine and other headache syndromes (G43-G44)")

Diagnosis Index entries for G44.001

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

Nearby codes

• G44 Other headache syndromes
• G44.0 Cluster headaches and other trigeminal autonomic cephalgias (TAC)
• G44.00 Cluster headache syndrome, unspecified
• G44.001 Cluster headache syndrome, unspecified, intractable (this code)
• G44.009 Cluster headache syndrome, unspecified, not intractable
• G44.01 Episodic cluster headache
• G44.011 Episodic cluster headache, intractable
• G44.019 Episodic cluster headache, not intractable
• G44.02 Chronic cluster headache