ICD-10 Code J45.31 – Mild persistent asthma with (acute) exacerbation (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J45.31 – Mild persistent asthma with (acute) exacerbation
What it is
This code identifies mild persistent asthma that has worsened into an acute flare. It applies when the record documents both the chronic asthma severity and the current exacerbation.
Clinical signs
Typical findings include wheezing, cough, chest tightness, and shortness of breath. Clinical features vary; refer to documentation, especially when the note states an asthma exacerbation.
When to use this code
Use J45.31 when the provider documents mild persistent asthma and also describes an acute exacerbation or flare. The chart should support the persistent severity level, not just a general asthma diagnosis.
If the note only says asthma exacerbation without severity, check documentation before assigning this code. You should code the more specific asthma type only when it is clearly stated.
Do not use for
Do not use this code for asthma without an exacerbation, or for a different asthma severity such as intermittent, moderate persistent, or severe persistent asthma. Check documentation.
Coding tip
Verify that both “mild persistent asthma” and “acute exacerbation” appear in the provider’s documentation before reporting J45.31.