ICD-10 Code J09 – Influenza due to certain identified influenza viruses (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J09 – Influenza due to certain identified influenza viruses
What it is
J09 identifies influenza caused by a specific, confirmed influenza virus subtype. Use it when the record names the virus rather than documenting flu in general.
Clinical signs
Typical influenza features include abrupt fever, cough, sore throat, body aches, headache, and fatigue. Clinical features vary; refer to documentation.
When to use this code
Use J09 when the provider documents influenza due to an identified virus, such as avian or other named influenza strains. Code the confirmed organism as documented. If the chart only says “flu” or “influenza” without identification, check documentation before assigning J09.
Do not use for
Do not use this code for unspecified influenza or for a suspected influenza infection without documented viral identification. Check documentation if the record does not clearly name the virus.
Coding tip
Look for the exact virus name in the assessment, lab report, or discharge summary before assigning J09.