2026 ICD-10-CM Diagnosis Code J21.0Acute bronchiolitis due to respiratory syncytial virus
ICD-10-CM Codes›J00–J99›J20-J22›J21
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
J21.0 is a billable ICD-10-CM diagnosis code for acute bronchiolitis due to respiratory syncytial virus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 202 through 203. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. Coders also document this condition as acute bronchiolitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute bronchitis and Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute bronchiolitis
- Acute bronchiolitis caused by respiratory syncytial virus
- Acute lower respiratory infection caused by respiratory syncytial virus
- Acute viral bronchiolitis
- Respiratory syncytial virus bronchiolitis
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Acute bronchiolitis due to RSV
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Acute Bronchiolitis
acute inflammation of the bronchioles usually caused by the respiratory syncytial virus.
Patient EducationClinical
Bronchial Disorders
When you breathe in, the air travels down through your trachea (windpipe). It then goes through two tubes to your lungs. These tubes are your bronchi. Bronchial disorders can make it hard for you to breathe.
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Convert J21.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About J21.0Overview
What is the ICD-10 code for acute bronchiolitis due to respiratory syncytial virus?
The ICD-10-CM code for acute bronchiolitis due to respiratory syncytial virus is J21.0 (sometimes written as J210). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is J21.0 (Acute bronchiolitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report acute bronchiolitis due to respiratory syncytial virus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does J21.0 group to?
When acute bronchiolitis due to respiratory syncytial virus is the principal diagnosis on an inpatient stay, it groups to MS-DRG 202, 203, with relative weights from 0.6700 to 0.9712 depending on complications. Higher weights mean higher Medicare reimbursement.
Is J21.0 a CC or MCC?
CMS lists J21.0 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.
What is the ICD-9 equivalent of J21.0?
Under the General Equivalence Mappings, acute bronchiolitis due to respiratory syncytial virus converts to ICD-9-CM 466.11 (acu broncholitis d/t RSV). The mapping is a direct match.
