Can acute bronchiolitis occur without fever?

Can Acute Bronchiolitis Occur Without Fever?

Yes, acute bronchiolitis can absolutely occur without fever—fever is not required for diagnosis and many infants present with bronchiolitis without documented fever. 1, 2

Clinical Presentation of Bronchiolitis

Bronchiolitis is a clinical diagnosis based on respiratory symptoms, not fever. The typical presentation includes:

• Nasal congestion and rhinorrhea (upper respiratory symptoms for 1-3 days initially) 2, 3
• Tachypnea (rapid breathing) 1
• Wheeze and/or crepitations/crackles on lung examination 1
• Increased respiratory effort and cough 2
• Fever may or may not be present 2, 3

The American Academy of Pediatrics guidelines define bronchiolitis as a clinical syndrome in children under 2 years characterized by respiratory distress preceded by coryzal (upper respiratory) symptoms with or without fever. 4 This explicitly acknowledges that fever is not a necessary diagnostic criterion.

Why Fever Presence Matters (But Isn't Required for Diagnosis)

While fever is not required for bronchiolitis diagnosis, its presence does have clinical implications:

• Febrile infants with bronchiolitis have extremely low rates of serious bacterial infection (bacteremia or meningitis much less than 1%) 1
• The presence of fever in bronchiolitis patients historically led to overuse of antibiotics, but studies show children with the distinct viral syndrome of bronchiolitis have lower risk of bacterial co-infection than febrile infants without an identifiable source 1
• When fever is present, it typically occurs in the first 1-3 days along with upper respiratory symptoms, before lower respiratory tract signs develop 2, 3

Common Clinical Pitfall

Do not require fever to diagnose bronchiolitis. The diagnosis is based on the constellation of:

1. Age under 2 years
2. Preceding upper respiratory symptoms (congestion, rhinorrhea)
3. Lower respiratory tract findings (tachypnea, wheeze, crackles, increased work of breathing)

1, 2, 3

Many clinicians mistakenly associate all lower respiratory infections with fever, but bronchiolitis is fundamentally a clinical diagnosis based on respiratory findings, and documented fever occurs in only a subset of cases. 2