ICD-10 Code G44.021 – Chronic cluster headache, intractable (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G44.021 – Chronic cluster headache, intractable
What it is
This code identifies chronic cluster headache that does not respond well to usual treatment. It reflects a recurrent headache disorder with cluster-pattern attacks that persist over time.
Clinical signs
Clinical features vary; refer to documentation. Typical cluster headache features include severe unilateral head pain with autonomic symptoms such as tearing, nasal congestion, or eyelid droop.
When to use this code
Use G44.021 when the provider documents chronic cluster headache and states it is intractable or refractory. Apply it when the record supports a chronic pattern rather than an episodic cluster headache diagnosis. If the note only says “cluster headache” without chronicity or intractability, check documentation.
Do not use for
Do not use this code for episodic cluster headache or for headache types that are not clearly documented as cluster headache. Do not assume intractability unless the provider states it.
Coding tip
Code the condition exactly as documented, and confirm both chronicity and intractability before assigning G44.021.