G44.021 Chronic cluster headache, 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)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 339.02 Chronic cluster headache (approximate)

Code annotations containing back-references to G44.021

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 G44.021

• Headache › cluster › chronic › intractable

Nearby codes

• 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
• G44.021 Chronic cluster headache, intractable (this code)
• G44.029 Chronic cluster headache, not intractable
• G44.03 Episodic paroxysmal hemicrania
• G44.031 Episodic paroxysmal hemicrania, intractable
• G44.039 Episodic paroxysmal hemicrania, not intractable
• G44.04 Chronic paroxysmal hemicrania