Child breathing & allergies

Bronchiolitis in Babies: What Parents Need to Know

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Bronchiolitis is a lower-airway infection common in babies under 12 months, most often caused by RSV. It starts like a cold, then may progress to fast or labored breathing around days three to five before improving. Most cases resolve at home with fluids and rest; premature and very young infants can need medical care.

Last updated: July 2026History

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What bronchiolitis is and what causes it

Bronchiolitis happens when a viral infection inflames the bronchioles — the small airways deep in the lungs. Respiratory syncytial virus (RSV) is the most common cause, but several other respiratory viruses can trigger the same pattern. It peaks in fall and winter, typically from October through March 1. Bronchiolitis is distinct from bronchitis, which affects larger airways; the small-airway involvement is why infants, whose airways are already narrow, tend to have more trouble than older children with the same virus.

How it typically progresses

The illness usually unfolds over about a week. The first two to three days look like a typical cold — runny nose, mild cough, possibly a low fever. Around days three to five, the cough often worsens and breathing may become faster, noisier, or more effortful as the smaller airways become involved. Most babies reach their worst point around day four or five, then gradually improve. The cough can linger for two to three weeks even after the baby is otherwise well 2.

Home care during bronchiolitis

There is no specific medication that shortens bronchiolitis; treatment is supportive 2. Medications that are NOT recommended include antibiotics (bronchiolitis is viral), bronchodilators such as albuterol, and systemic corticosteroids — these have not been shown to change the course of illness in clinical trials. A few supportive measures can help a baby stay comfortable: using saline nose drops followed by gentle bulb suctioning before feeds (deep suctioning should be avoided as it can cause airway irritation), offering smaller and more frequent feeds since breathing hard makes feeding tiring, and running a cool-mist humidifier. Fever can be addressed with age-appropriate doses of acetaminophen, though ibuprofen is not appropriate for infants under six months. Avoid smoke exposure, which worsens airway inflammation 1.

Who is at higher risk for a more serious course

Most healthy, full-term babies over two months old do well at home. Babies at higher risk of a more serious course include those born prematurely (especially under 32 weeks), newborns under two months, babies with chronic lung disease, and those with certain hemodynamically significant heart conditions 2. Pediatric providers may discuss whether preventive options — such as nirsevimab (Beyfortus), a newer RSV immunization — are appropriate for very-high-risk infants or all infants during RSV season, as current AAP guidance supports broader immunization.

What a provider visit looks like

If a baby is seen in clinic or the emergency department for bronchiolitis, the provider will watch the breathing, listen to the lungs, check oxygen levels with a pulse oximeter, and assess hydration 2. Most cases do not require X-rays or lab tests — diagnosis is clinical. Hospital admission is sometimes needed for infants who need supplemental oxygen (typically when oxygen saturation falls below 90–92%), cannot take enough fluids by mouth, or are breathing too hard to feed safely. The average hospital stay is two to three days.

Common questions

RSV is the most common virus that causes bronchiolitis, but bronchiolitis is the name for the clinical illness — the pattern of lower-airway inflammation. Other respiratory viruses can cause the same picture. Not every baby with RSV gets full bronchiolitis, and not every bronchiolitis case is RSV.

Yes. Because multiple viruses can trigger bronchiolitis, a baby can have more than one episode, particularly in a single cold-and-flu season. Each infection is usually milder as the immune system matures.

In general, a resting breathing rate above about 60 breaths per minute in a baby under two months, or above about 50 in an older infant, is considered fast. If the skin between or below the ribs pulls in with each breath, that is a sign of extra effort and warrants a call to the pediatrician or a same-day visit.

Some children who have had bronchiolitis in infancy go on to have recurrent wheezing episodes, though it is not clear whether bronchiolitis causes this or whether the two share underlying risk factors. Many children outgrow early wheezing tendencies as their airways grow larger.

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When to get care right away

  • —Breathing faster than normal at rest, or visibly working hard to breathe
  • —Skin pulling in at the neck, between the ribs, or below the ribs with each breath (retractions)
  • —Blue or gray color around the lips or fingertips
  • —Any infant under 2 months with fever of 100.4°F (38°C) or higher
  • —Baby is too breathless to feed — nursing or bottle-feeding takes much longer than usual or baby stops partway through
  • —Fewer wet diapers than normal, no tears when crying, dry mouth
  • —Baby is unusually limp, hard to wake, or very lethargic
  • —Breathing that pauses or becomes irregular

If your baby has blue lips, stops breathing, or is unresponsive, call 911. For severe retractions or a very lethargic infant, go to the emergency department.

This article is general health information for parents and is not a diagnosis or treatment plan for your child. Contact your pediatric provider with concerns about your specific child.

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References

  1. 1.American Academy of Pediatrics (2025). Bronchiolitis in Babies: Symptoms, Treatment & Prevention. HealthyChildren.org. link ✓Overview of bronchiolitis causes, symptoms, home supportive care, and warning signs requiring emergency evaluation
  2. 2.Ralston SL, Lieberthal AS, Meissner HC, et al.; American Academy of Pediatrics (2014). Clinical Practice Guideline: The Diagnosis, Management, and Prevention of Bronchiolitis. Pediatrics. doi:10.1542/peds.2014-2742 ✓Evidence-based recommendations against bronchodilators, corticosteroids, and antibiotics for bronchiolitis; supportive care principles; hospital admission criteria; and high-risk infant groups

2 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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