ICD-10 Code B10.01 – Human herpesvirus 6 encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B10.01 – Human herpesvirus 6 encephalitis
What it is
B10.01 identifies encephalitis caused by human herpesvirus 6, an infection that inflames the brain. Use it when documentation specifically links HHV-6 to the encephalitis.
Clinical signs
Clinical features vary; refer to documentation. Typical encephalitis findings include altered mental status, confusion, seizures, fever, or focal neurologic deficits, but the record should support HHV-6 as the cause.
When to use this code
Use B10.01 when the provider documents HHV-6 encephalitis, HHV-6 meningoencephalitis, or encephalitis due to human herpesvirus 6. It is appropriate for confirmed infectious encephalitis, not for nonspecific viral illness. Check documentation if the organism is suspected but not stated.
Do not use for
Do not use this code for encephalitis caused by another virus or for unspecified viral encephalitis. If the record only says HHV-6 infection without brain involvement, this code is not supported.
Coding tip
Code the organism only when the provider clearly documents HHV-6 as the encephalitis cause.