ICD-10 Code J11.0 – Influenza due to unidentified influenza virus with pneumonia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J11.0 – Influenza due to unidentified influenza virus with pneumonia
What it is
J11.0 identifies influenza when the virus is not specifically identified and pneumonia is documented as part of the illness. Use it for flu cases with lower respiratory involvement, not uncomplicated influenza.
Clinical signs
Typical findings include influenza symptoms such as fever, cough, sore throat, body aches, and fatigue, along with evidence of pneumonia. Clinical features vary; refer to documentation.
When to use this code
Use J11.0 when the provider documents influenza with pneumonia and does not name a specific influenza virus type or strain. It also fits cases where the record supports flu-related pneumonia, but the virus remains unidentified. Check documentation if the note is unclear about whether pneumonia is present.
Do not use for
Do not use this code for influenza without pneumonia, or when a specific influenza virus is identified and a more specific code applies. Do not assign it if the documentation only says viral pneumonia; check documentation.
Coding tip
Confirm both influenza and pneumonia are documented together, and code any additional complications or manifestations separately when the record supports them.