ICD-10 Code G44.0 – Cluster headaches and other trigeminal autonomic cephalgias (TAC) (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G44.0 – Cluster headaches and other trigeminal autonomic cephalgias (TAC)
What it is
G44.0 identifies cluster headache and related trigeminal autonomic cephalalgias. Use it for a primary headache disorder with severe unilateral pain and autonomic features, not for nonspecific headache complaints.
Clinical signs
Typical findings include repeated attacks of very severe, usually one-sided head pain with eye watering, nasal congestion, eyelid swelling, or facial flushing. Clinical features vary; refer to documentation.
When to use this code
Use G44.0 when the provider documents cluster headache or another trigeminal autonomic cephalalgia as the diagnosis. It also fits charted TAC subtypes when the record supports that classification. If the note only says headache without a specific type, check documentation.
Do not use for
Do not use this code for migraine, tension-type headache, or headache caused by another condition. Do not assign it when the diagnosis is uncertain or when documentation only states “headache.”
Coding tip
Match the code to the exact headache type documented and capture laterality or subtype details only when the record clearly supports them.