Croup vs Bronchiolitis: Key Differences
Content reviewed against published AAP, CDC guidelines
Last reviewed:
Both croup and bronchiolitis are common respiratory illnesses in young children caused by viruses. However, they affect different parts of the airway and have distinct symptoms.
Key takeaways
- Croup causes a barking cough and stridor; bronchiolitis causes wheezing
- Croup affects the upper airway; bronchiolitis affects the lower airways
- Croup responds to steroids; bronchiolitis does not respond to any medication
- Croup is typically worst at night; bronchiolitis progressively worsens over days
: Location
Croup: Upper airway (voice box & windpipe)
Bronchiolitis: Lower airway (small bronchioles in lungs)
: Typical age
Croup: 6 months to 3 years
Bronchiolitis: Under 12 months
: Key sound
Croup: Barking cough + stridor (harsh sound breathing in)
Bronchiolitis: Wheezing + crackles
: Cough type
Croup: Barking, seal-like
Bronchiolitis: Wet or productive
: Worse at
Croup: Night
Bronchiolitis: Any time, gradually worsens over days
: Onset
Croup: Often sudden (middle of the night)
Bronchiolitis: Gradual over 2-3 days
: Duration
Croup: 2-3 days of barking cough
Bronchiolitis: 7-10 days, peaks day 3-5
: Treatment
Croup: Steroids (dexamethasone), cool air
Bronchiolitis: Supportive only (suctioning, fluids)
: Main concern
Croup: Airway obstruction from swelling
Bronchiolitis: Breathing difficulty + dehydration from poor feeding
| Croup | Bronchiolitis | |
|---|---|---|
| Location | Upper airway (voice box & windpipe) | Lower airway (small bronchioles in lungs) |
| Typical age | 6 months to 3 years | Under 12 months |
| Key sound | Barking cough + stridor (harsh sound breathing in) | Wheezing + crackles |
| Cough type | Barking, seal-like | Wet or productive |
| Worse at | Night | Any time, gradually worsens over days |
| Onset | Often sudden (middle of the night) | Gradual over 2-3 days |
| Duration | 2-3 days of barking cough | 7-10 days, peaks day 3-5 |
| Treatment | Steroids (dexamethasone), cool air | Supportive only (suctioning, fluids) |
| Main concern | Airway obstruction from swelling | Breathing difficulty + dehydration from poor feeding |
When to Worry
- Either condition: blue lips, severe retractions, very rapid breathing
- Croup: stridor at rest when child is calm
- Bronchiolitis: baby unable to feed, fewer than 3 wet diapers in 24 hours
- Any baby under 3 months with breathing difficulty needs immediate evaluation
Frequently asked questions
What is the main difference between Croup and Bronchiolitis?
How can I tell if my baby has Croup or Bronchiolitis?
When should I worry?
Sources
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Bottom line
Both Croup and Bronchiolitis are common in young children. The key differences in symptoms can help you identify what your child may have, but when in doubt, consult your pediatrician.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.