ICD-10 Code J11.08 – Influenza due to unidentified influenza virus with specified pneumonia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J11.08 – Influenza due to unidentified influenza virus with specified pneumonia
What it is
This code identifies influenza caused by an unidentified influenza virus when the patient also has a specified type of pneumonia. Use it when the record links influenza and pneumonia, but the virus type is not named.
Clinical signs
Clinical features may include typical influenza symptoms such as fever, cough, sore throat, myalgia, and respiratory illness with pneumonia findings. Clinical features vary; refer to documentation.
When to use this code
Use J11.08 when the provider documents influenza with pneumonia and does not identify the influenza virus type. The pneumonia must be specified in the record, not implied. Check documentation if the note only says “flu” or “respiratory infection” without a clear pneumonia diagnosis.
Do not use for
Do not use this code when the influenza virus is identified, or when pneumonia is not documented as present. If the record does not support both conditions together, check documentation.
Coding tip
Match the influenza and pneumonia linkage in the provider note before assigning J11.08.