ICD-10 Code J21.0 – Acute bronchiolitis due to respiratory syncytial virus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J21.0 – Acute bronchiolitis due to respiratory syncytial virus
What it is
J21.0 identifies acute bronchiolitis caused by respiratory syncytial virus (RSV), a viral lower respiratory infection that inflames the small airways. Use it when the provider documents RSV bronchiolitis specifically.
Clinical signs
Typical findings include cough, wheezing, tachypnea, and increased work of breathing in an infant or young child. Clinical features vary; refer to documentation for the confirmed viral cause and severity.
When to use this code
Use J21.0 when the record states acute bronchiolitis due to RSV, RSV bronchiolitis, or equivalent wording. It is appropriate for confirmed or documented presumed RSV bronchiolitis in the encounter note. If the provider documents a different virus or only “bronchiolitis” without RSV, check documentation.
Do not use for
Do not use this code for RSV pneumonia, unspecified bronchiolitis, or bronchiolitis due to another organism. If the diagnosis is not clearly linked to RSV, choose the more specific documented code or check documentation.
Coding tip
Capture the exact organism and respiratory diagnosis wording from the provider note before assigning J21.0.