Introduction
Bronchiolitis is inflammation of the smallest airways (bronchioles), most often in infants and young children during viral season. Respiratory syncytial virus (RSV) is the leading cause; rhinovirus, adenovirus, and parainfluenza can also trigger it.
Illness usually starts like a cold—runny nose and mild cough—then progresses over a few days to wheeze, fast breathing, and feeding difficulty. Most children recover with supportive care at home or in hospital; a minority need oxygen or intensive support.
Highest risk groups include babies under six months, premature infants, and children with heart, lung, or immune problems. Smoke exposure and crowded living increase infection and severity risk.
This page is general education for caregivers. Blue lips, severe work of breathing, poor feeding, or dehydration signs require emergency care—do not wait for “another day of watching.”
Overview
Bronchiolitis is a viral lower-airway illness of early childhood, not the same as adult chronic bronchitis or asthma—though wheeze can look similar.
Diagnosis is usually clinical; tests mainly exclude other problems or assess oxygen needs.
Treatment centers on hydration, oxygen when needed, and monitoring—not routine antibiotics.
- Viral inflammation of bronchioles, chiefly in infants
- RSV is the most common pathogen; other viruses also cause outbreaks
- Peak severity often days 3–5 of illness
- Supportive care is the mainstay; most recover in one to three weeks
- Prematurity and chronic disease raise hospitalization risk
- Prevention: hygiene, smoke avoidance, and immunization strategies as locally recommended
What happens in the body
Virus infects airway lining cells, causing swelling, mucus, and debris that narrow tiny bronchioles. Air trapping and uneven ventilation produce wheeze and low oxygen in more severe cases.
Young infants have narrow airways and limited reserve, so the same viral swelling that older children tolerate can cause marked distress, poor feeding, and apnea in babies.
- Viral injury → bronchiolar swelling and mucus
- Airflow obstruction → wheeze and tachypnea
- Infant airways more easily critically narrowed
- Hypoxemia appears when gas exchange is impaired
Signs and symptoms
Symptoms typically evolve over several days. Caregivers may notice:
- Runny or stuffy nose at the start
- Persistent cough, often worse at night
- Wheezing (high-pitched whistling with breathing)
- Fast breathing or visible chest retractions
- Shortness of breath or pauses in breathing (apnea) in young infants
- Mild to moderate fever
- Reduced feeding or fewer wet nappies
- Irritability or unusual sleepiness
- Vomiting after coughing fits
- In severe disease: grunting, nasal flaring, or blue color around lips
- Dehydration signs: dry mouth, no tears, sunken eyes
- Older toddlers may describe chest tightness; infants show distress instead
Causes and risk factors
Bronchiolitis is primarily infectious; environment and host factors shape severity:
- RSV—most common cause in infants
- Other viruses: rhinovirus, adenovirus, parainfluenza, and others
- Spread by respiratory droplets and contaminated hands/surfaces
- Age under six months (highest risk)
- Premature birth with underdeveloped lungs
- Exposure to tobacco smoke or indoor air pollution
- Crowded households or daycare exposure during outbreaks
- Underlying heart, lung, neuromuscular, or immune disease
- Lack of breastfeeding may increase infection risk in some settings
Diagnosis and evaluation
Clinicians diagnose mainly from age, season, and exam; extra tests are selective:
- History of cold symptoms progressing to wheeze and fast breathing
- Exam for wheeze, crackles, oxygen need, and work of breathing
- Pulse oximetry to measure oxygen saturation
- Nasal swab for viral testing when it changes isolation or public-health decisions
- Chest X-ray if pneumonia, foreign body, or alternative diagnosis is suspected—not routine for classic mild cases
- Blood tests only when bacterial sepsis or another complication is a concern
- Differential includes asthma, pneumonia, croup, and congenital airway problems
Treatment and management
Most care is supportive. Medicines are used selectively—do not give leftover antibiotics or adult cough formulas to infants:
- Frequent smaller feeds and extra fluids to prevent dehydration
- Nasal saline and gentle suction to clear the nose before feeds
- Humidified air and upright positioning for comfort
- Supplemental oxygen if saturations are low
- Hospital monitoring for apnea, poor feeding, or rising oxygen need
- Bronchodilators or steroids only in selected cases after clinician judgment—not blanket therapy
- Antibiotics only if a bacterial complication is diagnosed
- ICU care and ventilatory support for respiratory failure
- Follow local guidance on RSV immunization/monoclonal antibody for eligible infants
Prevention, self-care, and lifestyle
Not every condition is fully preventable, but the steps below may lower risk or recurrence:
- Handwashing before handling infants
- Keep newborns away from people with colds when practical
- Eliminate household tobacco smoke exposure
- Breastfeeding when possible for immune support
- Stay up to date with influenza and other recommended vaccines for household contacts
- Ask about RSV prevention products recommended for your infant’s age and risk
- Clean shared toys and high-touch surfaces during outbreak season
Possible complications
Delay, missed care, or unsafe self-medication can raise the chance of complications in some cases:
- Dehydration from poor feeding
- Hypoxemia requiring oxygen
- Apnea in young or premature infants
- Secondary bacterial pneumonia
- Respiratory failure needing intensive care
- Hospitalization and rare need for mechanical ventilation
- Later recurrent wheeze or higher asthma risk in some children after severe episodes
- Caregiver stress and sleep disruption during prolonged illness
When to see a doctor or seek emergency care
Seek prompt medical advice or emergency care if any of the following apply—it is safer not to wait and see:
- Any infant under three months with fever
- Fast, labored, or irregular breathing
- Blue or gray color of lips, tongue, or face
- Pauses in breathing
- Poor feeding, fewer wet nappies, or signs of dehydration
- Extreme lethargy or difficulty waking
- Wheeze with increasing distress at home
- Known premature or cardiac/lung disease child with any breathing change—seek care early
Living with the condition
At home, count wet nappies, watch breathing effort, and keep nasal passages clear before feeds. Nighttime worsening is common; have a plan for when to go to emergency.
Cough can linger after the worst breathing phase improves. Follow-up is wise if wheeze keeps returning between viral illnesses.
Siblings and caregivers should practice hygiene; adults usually get a cold-like illness rather than classic infant bronchiolitis, but they can still transmit virus.
Frequently asked questions
Is bronchiolitis the same as bronchitis?
No. Bronchiolitis affects the tiniest airways and mainly infants. Bronchitis involves larger bronchi and is discussed differently in older children and adults.
Do antibiotics cure bronchiolitis?
No. It is usually viral. Antibiotics help only if a bacterial complication is confirmed.
How long does recovery take?
Many children improve within one to two weeks; cough may last longer. Severe cases needing oxygen take longer to bounce back fully.
Is bronchiolitis contagious?
Yes. The viruses spread through droplets and hands. Hygiene and limiting close contact with vulnerable infants reduce spread.
Can my child get it more than once?
Yes. Different viruses—or the same virus in another season—can cause another episode, though severity varies.
Will my child develop asthma?
Most recover without chronic disease. Severe bronchiolitis is linked with higher later wheeze/asthma risk in some children; discuss persistent wheeze with your clinician.
Important caution
This article is for general health education only. It is not personal medical advice or a substitute for pediatric assessment.
Supportive care decisions—including oxygen and hospital admission—should follow examination of work of breathing, feeding, and oxygen levels.
Seek emergency care for blue lips, severe breathing effort, apnea, or an infant who cannot feed or stay hydrated.