J21

Acute bronchiolitis

Header / non-billable

This code does not map to a risk-adjusting HCC in the loaded models.

Coding notes

Excludes 1 never coded together · Excludes 2 may co-exist

This code · J21
Includes

acute bronchiolitis with bronchospasm

Excludes 2

respiratory bronchiolitis interstitial lung disease (J84.115)

Inherited from J20-J22Other acute lower respiratory infections
Excludes 2

chronic obstructive pulmonary disease with acute lower respiratory infection (J44.0)

Inherited from chapter 10Diseases of the respiratory system
Excludes 2

certain conditions originating in the perinatal period (P04-P96) certain infectious and parasitic diseases (A00-B99) complications of pregnancy, childbirth and the puerperium (O00-O9A) congenital malformations, deformations and chromosomal abnormalities (Q00-Q99) endocrine, nutritional and metabolic diseases (E00-E88) injury, poisoning and certain other consequences of external causes (S00-T88) neoplasms (C00-D49) smoke inhalation (T59.81-) symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Use additional

code, where applicable, to identify: exposure to environmental tobacco smoke (Z77.22) exposure to tobacco smoke in the perinatal period (P96.81) history of tobacco dependence (Z87.891) occupational exposure to environmental tobacco smoke (Z57.31) tobacco dependence (F17.-) tobacco use (Z72.0)

Note

When a respiratory condition is described as occurring in more than one site and is not specifically indexed, it should be classified to the lower anatomic site (e.g. tracheobronchitis to bronchitis in J40).

Official Guidelines for J21

FY 2026 ›