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J20.4 vs J45.909

J20.4 (Acute bronchitis due to parainfluenza virus) compared with J45.909 (Unspecified asthma, uncomplicated), from the official CMS tabular data.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Summary

These codes can be reported together when both conditions are documented, because J20.4 lists J45.909 under Excludes2, which marks them as distinct conditions.

Official rule
What is different?

The conditions named.J20.4 is “Acute bronchitis due to parainfluenza virus”; J45.909 is “Unspecified asthma, uncomplicated”.

Registry fact

Can these codes be reported together?

Yes, when both are documented.J20.4 lists J45.909 under Excludes2: “allergic bronchitis NOS (J45.909)”. Excludes2 marks distinct conditions that may both be reported when both are documented.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

None.Neither entry carries an Excludes1 note that names the other code. J20.4 carries 2 Excludes1 notes and J45.909 carries 5 Excludes1 notes covering other codes; the side-by-side table quotes them.

Official rule

Is there an Excludes2 relationship?

Yes.J20.4’s tabular entry: “allergic bronchitis NOS (J45.909)”. The note covers J45.909.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Informational

Excludes2 relationship

J20.4
Acute bronchitis due to parainfluenza virus
↔
J45.909
Unspecified asthma, uncomplicated

What we found

Yes, when both are documented.J20.4 carries an Excludes2 note covering J45.909: “allergic bronchitis NOS (J45.909)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2027

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

Similar descriptions do not make codes interchangeable. The documentation and the official instructions decide which code applies.

Official descriptionDiffers
J20.4

Acute bronchitis due to parainfluenza virus

J45.909

Unspecified asthma, uncomplicated

StatusSame for both
Billable
Excludes1Differs
J20.4
  • bronchitis NOS (J40)
  • tracheobronchitis NOS (J40)
J45.909
  • detergent asthma (J69.8)
  • miner's asthma (J60)
  • wheezing NOS (R06.2)
  • wood asthma (J67.8)
  • bronchitis due to chemicals, gases, fumes and vapors (J68.0)
Excludes2Differs
J20.4
  • acute bronchitis with bronchiectasis (J47.0)
  • acute bronchitis with chronic obstructive asthma (J44.0)
  • acute bronchitis with chronic obstructive pulmonary disease (J44.0)
  • allergic bronchitis NOS (J45.909)
  • bronchitis due to chemicals, fumes and vapors (J68.0)
  • chronic bronchitis NOS (J42)
  • chronic mucopurulent bronchitis (J41.1)
  • chronic obstructive bronchitis (J44.-)
  • chronic obstructive tracheobronchitis (J44.-)
  • chronic simple bronchitis (J41.0)
  • chronic tracheobronchitis (J42)
  • chronic obstructive pulmonary disease with acute lower respiratory infection (J44.0)
J45.909
  • lung diseases due to external agents (J60-J70)
  • asthma with chronic obstructive pulmonary disease (J44.89)
  • chronic asthmatic (obstructive) bronchitis (J44.89)
  • chronic obstructive asthma (J44.89)
  • other specified chronic obstructive pulmonary disease (J44.89)
  • cystic fibrosis (E84.-)
Use additional codeDiffers
J20.4

None at this code

J45.909
  • code to identify:
  • eosinophilic asthma (J82.83)
  • exposure to environmental tobacco smoke (Z77.22)
CategoryDiffers
J20.4

J20 Acute bronchitis

J45.909

J45 Asthma

ChapterSame for both

J00-J99 — Diseases of the Respiratory System (J00-J99)

IncludesDiffers
J20.4
  • acute and subacute bronchitis (with) bronchospasm
  • acute and subacute bronchitis (with) tracheitis
  • acute and subacute bronchitis (with) tracheobronchitis, acute
  • acute and subacute fibrinous bronchitis
J45.909
  • allergic (predominantly) asthma
  • allergic bronchitis NOS
  • allergic rhinitis with asthma
  • atopic asthma

No Code first, Code also and 7th character note at either code.

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on. In a row that differs, notes every code shares are dimmed.

Edit this comparisonCheck a whole claim

Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources