ICD-10 Code B05.0 – Measles complicated by encephalitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B05.0 – Measles complicated by encephalitis
What it is
B05.0 identifies measles with encephalitis, meaning the patient has measles infection plus inflammation of the brain. Use it when the record links neurologic involvement directly to measles.
Clinical signs
Typical measles findings include fever, cough, coryza, conjunctivitis, and rash. Encephalitis may add altered mental status, seizures, headache, or focal neurologic deficits; clinical features vary, refer to documentation.
When to use this code
Use B05.0 when the provider documents measles encephalitis, measles with brain inflammation, or a measles complication affecting the central nervous system. The diagnosis should clearly connect encephalitis to measles. If the record only states suspected encephalitis, check documentation before coding.
Do not use for
Do not use this code for uncomplicated measles or for encephalitis without documented measles. Also avoid it when the neurologic problem is attributed to another cause. Check documentation.
Coding tip
Assign B05.0 only when both measles and encephalitis are documented together and causally linked.