ICD-10-CM 2027
ICD-10 code for bronchiolitis
From the official ICD-10-CM alphabetic index entry “Bronchiolitis (acute) (infective) (subacute)”. Page updated September 29, 2026.
About coding bronchiolitis
The ICD-10-CM code for bronchiolitis is J21.9 (Acute bronchiolitis, unspecified). The official index lists 16 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on J21.9.
Within J21, choose J21.9 (unspecified) only when documentation doesn't support a more specific option: due to respiratory syncytial virus (J21.0), due to human metapneumovirus (J21.1) and due to other specified organisms (J21.8).
Don't report J21.9 together with the conditions in its Excludes1 note: chronic bronchiolitis (J44.89).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
More specific bronchiolitis codes (official index)
- with
- bronchospasm or obstruction J21.9 — Acute bronchiolitis, unspecified
- influenza, flu or grippe
- chemical (chronic) J68.4 — Chronic respiratory conditions due to chemicals, gases, fumes and vapors
- acute J68.0 — Bronchitis and pneumonitis due to chemicals, gases, fumes and vapors
- chronic (fibrosing) J44.89 — Other specified chronic obstructive pulmonary disease
- obliterative J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- due to
- external agent
- human metapneumovirus J21.1 — Acute bronchiolitis due to human metapneumovirus
- respiratory syncytial virus (RSV) J21.0 — Acute bronchiolitis due to respiratory syncytial virus
- specified organism NEC J21.8 — Acute bronchiolitis due to other specified organisms
- fibrosa obliterans J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- influenzal
- obliterans J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- with organizing pneumonia (BOOP) J84.89 — Other specified interstitial pulmonary diseases
- syndrome J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- obliterative (chronic) (subacute) J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- due to chemicals, gases, fumes or vapors (inhalation) J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- due to fumes or vapors J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome
- respiratory, interstitial lung disease J84.115 — Respiratory bronchiolitis interstitial lung disease
Don't confuse with (Excludes1 for J21.9)
- chronic bronchiolitis (J44.89)
Common questions about bronchiolitis ICD-10 codes
What is the ICD-10 code for bronchiolitis?
- J21.9 — Acute bronchiolitis, unspecified. More specific codes apply when the documentation supports them: J21.9, J68.4, J68.0, J44.89 and others below.
What is the ICD-10 code for chemical bronchiolitis?
- J68.4 — Chronic respiratory conditions due to chemicals, gases, fumes and vapors.
What is the ICD-10 code for chronic bronchiolitis?
- J44.89 — Other specified chronic obstructive pulmonary disease.
What is the ICD-10 code for fibrosa obliterans bronchiolitis?
- J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome.
What is the ICD-10 code for obliterans bronchiolitis?
- J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome.
What is the ICD-10 code for obliterative bronchiolitis?
- J44.81 — Bronchiolitis obliterans and bronchiolitis obliterans syndrome.
Is J21.9 billable?
- Yes. J21.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can J21.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict J21.9 as a principal diagnosis.
Is J21.9 a CC or MCC?
- J21.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.