ICD-10 Code G44.53 – Primary thunderclap headache (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G44.53 – Primary thunderclap headache
What it is
G44.53 identifies a sudden, severe headache that reaches peak intensity within seconds to minutes and is not explained by another condition. Use it only when the chart supports a primary thunderclap headache diagnosis.
Clinical signs
Typical documentation describes an abrupt “worst headache,” often with rapid onset and intense pain. Because secondary causes can mimic this pattern, clinical features vary; refer to documentation.
When to use this code
Use G44.53 when the provider explicitly diagnoses primary thunderclap headache and notes that no secondary cause has been identified. It may also apply when the record documents a thunderclap presentation with appropriate evaluation excluding other causes. Check documentation if the diagnosis is uncertain.
Do not use for
Do not assign this code for migraine, tension-type headache, or headache due to another disorder. If the chart points to subarachnoid hemorrhage, stroke, infection, or another cause, code that condition instead.
Coding tip
Verify that “primary” is documented or that secondary causes were ruled out before assigning G44.53.