Signs of Bronchiolitis in Babies
Content reviewed against published AAP, CDC, NIH guidelines
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If your baby has been diagnosed with or you suspect signs of bronchiolitis in babies, here is what the evidence says.
The short answer
Bronchiolitis is a common lower respiratory infection in babies under 2 years, most often caused by RSV. It typically starts like a cold with runny nose and cough, then progresses to wheezing and breathing difficulty over 2-3 days. Most cases are mild and resolve at home within 1-2 weeks, but young infants (under 3 months) and babies born prematurely are at higher risk for severe illness requiring hospitalization.
Key takeaways
- Bronchiolitis is a common lower respiratory infection in babies under 2 years, most often caused by RSV. It typically starts like a cold with runny nose and cough, then progresses to wheezing and breathing difficulty over 2-3 days. Most cases are mild and resolve at home within 1-2 weeks, but young infants (under 3 months) and babies born prematurely are at higher risk for severe illness requiring hospitalization.
- Usually normal when: Your baby has a runny nose and cough but is breathing comfortably and feeding reasonably well.
- Call your doctor if: Your baby is breathing very fast (over 60 breaths per minute), has chest retractions, or nasal flaring.
- Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
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When to Seek Immediate Care
- Your baby is breathing very fast (over 60 breaths per minute), has chest retractions, or nasal flaring.
- Your baby's lips, tongue, or fingernails turn blue or dusky.
- Your baby has pauses in breathing, is extremely lethargic, or cannot be roused for feeds.
By Age
What to expect by age
0-3 months
Young infants are at the highest risk for severe bronchiolitis. Their small airways are particularly vulnerable to swelling and mucus buildup. Warning signs include fast breathing (over 60 breaths per minute), nasal flaring, chest retractions (ribs visible with each breath), poor feeding, and pauses in breathing (apnea). Any infant under 3 months with breathing difficulty from bronchiolitis should be evaluated urgently, as hospitalization may be needed for oxygen support or IV fluids.
3-12 months
Bronchiolitis in this age group often begins with 2-3 days of cold symptoms before progressing to wheezing and increased breathing effort. The illness typically peaks around days 3-5 and then gradually improves over 1-2 weeks, though cough may linger longer. Home care includes nasal suctioning, humidified air, frequent small feedings, and monitoring breathing. There is no medication that shortens bronchiolitis -- antibiotics do not help since it is viral.
12-24 months
Toddlers generally handle bronchiolitis better than younger babies because their airways are larger. Symptoms may include persistent cough, wheezing, and mild breathing difficulty. Most can be managed at home with supportive care. However, if your toddler is breathing rapidly, refusing fluids, or has not had a wet diaper in 6-8 hours, medical evaluation is needed. Children with asthma, heart conditions, or immune deficiencies are at higher risk for complications.
What Should You Do?
When to take action
- Your baby has a runny nose and cough but is breathing comfortably and feeding reasonably well.
- Your baby has mild wheezing after the peak of illness but is improving day by day.
- Your baby's breathing rate is normal when calm (under 40-60 breaths per minute depending on age).
- Your baby under 6 months develops any wheezing or increased breathing effort.
- Your baby is feeding less than half of normal amounts.
- Your baby's cough is worsening after day 5 of illness or symptoms have lasted more than 2 weeks.
- Your baby is breathing very fast (over 60 breaths per minute), has chest retractions, or nasal flaring.
- Your baby's lips, tongue, or fingernails turn blue or dusky.
- Your baby has pauses in breathing, is extremely lethargic, or cannot be roused for feeds.
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Signs of Bronchiolitis in Babies.
Things to mention
- Your baby under 6 months develops any wheezing or increased breathing effort.
- Your baby is feeding less than half of normal amounts.
- Your baby's cough is worsening after day 5 of illness or symptoms have lasted more than 2 weeks.
Observations to share
- Your baby under 6 months develops any wheezing or increased breathing effort.
- Your baby is feeding less than half of normal amounts.
- Your baby's cough is worsening after day 5 of illness or symptoms have lasted more than 2 weeks.
Urgent signs to report immediately
- Your baby is breathing very fast (over 60 breaths per minute), has chest retractions, or nasal flaring.
- Your baby's lips, tongue, or fingernails turn blue or dusky.
- Your baby has pauses in breathing, is extremely lethargic, or cannot be roused for feeds.
My notes
From ismybabyalright.com — free, evidence-based baby health guides
Related Conditions
RSV in Babies: What to Know
RSV (respiratory syncytial virus) is a common virus that affects nearly all children by age 2. Most babies have mild cold-like symptoms, but some, especially young infants and those with underlying conditions, can develop breathing difficulties. Watch for fast breathing, flaring nostrils, or visible chest pulling - these are signs to seek medical care.
Baby Wheezing
Wheezing is a high-pitched whistling sound heard during breathing out, caused by narrowed airways. In babies, the most common cause is a viral infection like bronchiolitis (often RSV). Many babies wheeze once or twice during their first viral illnesses and never wheeze again. However, wheezing with breathing difficulty always warrants medical evaluation.
My Baby Is Breathing Fast
Babies normally breathe faster than adults. A normal respiratory rate for a newborn is 30-60 breaths per minute, slowing to 20-40 by age 1. Brief episodes of faster breathing during excitement, crying, or feeding are normal. However, persistently rapid breathing (tachypnea) at rest, especially with other signs of respiratory distress, may indicate a lung or heart problem that needs prompt evaluation.
Clesrovimab: New RSV Prevention for Infants
Clesrovimab is a long-acting monoclonal antibody being developed for the prevention of RSV (respiratory syncytial virus) lower respiratory tract disease in infants. Similar to nirsevimab (Beyfortus), it provides passive immunity against RSV by giving babies ready-made antibodies. This approach is especially important because RSV remains a leading cause of infant hospitalization, and infants under 6 months are too young for active vaccination. Consult your pediatrician about the latest RSV prevention options for your baby.
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Assess breathing concerns and know when to seek emergency care.
Month-by-Month Development
Detailed monthly development guides from birth through 24 months.
When to Call the Doctor
General guide on when to call the pediatrician, visit urgent care, or go to the ER.
Frequently asked questions
Is signs of bronchiolitis in babies normal?
When should I call the doctor about signs of bronchiolitis in babies?
When is signs of bronchiolitis in babies normal?
What causes signs of bronchiolitis in babies?
What should I mention to my pediatrician about signs of bronchiolitis in babies?
Is signs of bronchiolitis in babies normal at 0-3 months?
Is signs of bronchiolitis in babies normal at 3-12 months?
Should I go to the ER for signs of bronchiolitis in babies?
Does signs of bronchiolitis in babies go away on its own?
References
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources
Related Resources
Bottom line
Most cases of signs of bronchiolitis in babies are normal. Talk to your pediatrician if your baby is breathing very fast (over 60 breaths per minute), has chest retractions, or nasal flaring.
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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Related Medical Concerns
RSV in Babies: What to Know
RSV (respiratory syncytial virus) is a common virus that affects nearly all children by age 2. Most babies have mild cold-like symptoms, but some, especially young infants and those with underlying conditions, can develop breathing difficulties. Watch for fast breathing, flaring nostrils, or visible chest pulling - these are signs to seek medical care.
Baby Wheezing
Wheezing is a high-pitched whistling sound heard during breathing out, caused by narrowed airways. In babies, the most common cause is a viral infection like bronchiolitis (often RSV). Many babies wheeze once or twice during their first viral illnesses and never wheeze again. However, wheezing with breathing difficulty always warrants medical evaluation.
My Baby Is Breathing Fast
Babies normally breathe faster than adults. A normal respiratory rate for a newborn is 30-60 breaths per minute, slowing to 20-40 by age 1. Brief episodes of faster breathing during excitement, crying, or feeding are normal. However, persistently rapid breathing (tachypnea) at rest, especially with other signs of respiratory distress, may indicate a lung or heart problem that needs prompt evaluation.
Clesrovimab: New RSV Prevention for Infants
Clesrovimab is a long-acting monoclonal antibody being developed for the prevention of RSV (respiratory syncytial virus) lower respiratory tract disease in infants. Similar to nirsevimab (Beyfortus), it provides passive immunity against RSV by giving babies ready-made antibodies. This approach is especially important because RSV remains a leading cause of infant hospitalization, and infants under 6 months are too young for active vaccination. Consult your pediatrician about the latest RSV prevention options for your baby.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.