ICD-10 Code G44.00 – Cluster headache syndrome, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G44.00 – Cluster headache syndrome, unspecified
What it is
G44.00 identifies cluster headache syndrome when the specific type is not documented. It is used for a severe primary headache disorder with recurring attacks, but the record does not give a more precise cluster headache subtype.
Clinical signs
Clinical features vary; refer to documentation. Typical cluster headache attacks are unilateral, severe, and often occur with autonomic findings such as tearing, nasal congestion, or eye redness.
When to use this code
Use this code when the clinician documents cluster headache syndrome but does not specify whether it is episodic, chronic, or another defined form. It also fits when the note confirms cluster headache and no further detail is available. If the subtype is stated, code that more specific option instead.
Do not use for
Do not use G44.00 for migraine, tension-type headache, or other headache disorders. Check documentation if the provider describes a more specific cluster headache type or another diagnosis.
Coding tip
Look for wording such as “cluster headache” plus any subtype details; if none are documented, G44.00 is the correct unspecified choice.