ICD-10 Code J18 – Pneumonia, unspecified organism (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J18 – Pneumonia, unspecified organism
What it is
J18 identifies pneumonia when the organism is not specified in the record. Use it for a documented pneumonia diagnosis without a named bacterial, viral, fungal, or other cause.
Clinical signs
Typical findings include cough, fever, shortness of breath, chest pain, and abnormal lung exam or imaging consistent with pneumonia. Clinical features vary; refer to documentation.
When to use this code
Use J18 when the provider documents pneumonia but does not identify the infectious organism. It also fits cases where the chart confirms pneumonia and the cause remains unspecified at discharge. If the record names a specific organism, code the more specific option instead.
Do not use for
Do not use J18 for aspiration pneumonia, influenza with pneumonia, or pneumonia due to a specified organism. Check documentation if the note gives a more precise diagnosis.
Coding tip
Code from the provider’s final documented diagnosis, not from suspected causes or imaging alone.