Bronchiolitis: Symptoms, Causes, and Treatment
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick answer
Bronchiolitis is a viral lung infection that swells and fills the smallest airways with mucus, most often in children under age 2. Cold-like symptoms are followed by wheezing and harder breathing. Call right away for babies under 12 weeks old and seek urgent care for blue skin or very fast breathing. Antibiotics don't work; treatment is fluids and rest. [1] [2]
What the research says
According to PubMed:
A single antibody shot before RSV season lowered the risk of RSV chest infections in healthy babies. In a trial of 1,490 late-preterm and term infants, 1.2% (12 of 994) given nirsevimab had a medically attended RSV lower respiratory tract infection versus 5.0% (25 of 496) given placebo, an efficacy of 74.5% (95% CI 49.6 to 87.1); the difference in RSV hospitalizations (0.6% vs 1.6%) was not statistically significant. (Hammitt et al., DOI).
Epinephrine and steroid medicines are not routinely recommended. Finnish national guidelines concluded that nebulised adrenaline and inhaled or oral glucocorticoids did not reduce hospitalisation rates or relieve symptoms in infants with bronchiolitis and should not be used routinely. (Tapiainen et al., DOI).
In hospital, how oxygen is given matters. A systematic review–based practice guideline found high-flow nasal cannula therapy safe and more effective than low-flow oxygen for infants with moderate to severe bronchiolitis, and recommended an oxygen saturation target of 90% to 97% for infants and children with bronchiolitis. (Napolitano et al., DOI).
Study details are from PubMed abstracts.
Key facts at a glance
Key fact | What to know |
What it is | A viral lung infection of the bronchioles, the smallest airways of the lungs [1] |
Who gets it | Mostly children under age 2; infants under 3 months have the highest risk [1] |
Main cause | Respiratory syncytial virus (RSV), which infects nearly every child by age 2 [1] |
Typical duration | |
Usual care setting | |
Main symptoms | Cold-like start, then cough, wheezing, and harder breathing [1] |
Can it recur? | Yes. A child can get RSV more than once [1] |
What exactly is the condition called bronchiolitis?
In your lungs, the main airways, called bronchi, branch into smaller and smaller passageways. The smallest airways, called bronchioles, lead to tiny air sacs called alveoli, where oxygen enters the bloodstream. [1]
Bronchiolitis is a common lung infection in young children and infants. It causes swelling and irritation, plus a buildup of mucus, in these smallest airways. [1]
The infection is almost always caused by a virus. Bronchiolitis usually affects children under the age of 2, and rarely, adults can get it. [1]
Symptoms start much like a common cold but then get worse, causing coughing and a high-pitched whistling sound when breathing out called wheezing. Sometimes children have trouble breathing. [1]
What are the symptoms of bronchiolitis?
For the first few days, the symptoms of bronchiolitis look much like a common cold. This early phase is easy to mistake for any ordinary cold. [1]
Early signs
Runny nose, stuffy nose, and cough appear first, sometimes with a slight fever. Within about a week, the breathing itself becomes the problem. [1]
Later, your child may have a week or more of working harder than usual to breathe, which may include wheezing, a high-pitched whistling sound made when breathing out. [1]
Many infants with bronchiolitis also have an ear infection called otitis media. [1]
Symptom | What it looks like |
Runny or stuffy nose | Early cold-like sign in the first few days [1] |
Cough | Persists and can worsen over a week or more [1] |
Wheezing | High-pitched whistling sound when breathing out [1] |
Working harder to breathe | Fast, short, shallow breaths over a week or more [1] |
Slight fever | Sometimes present in the early phase [1] |
Ear infection (otitis media) | Common in many infants with bronchiolitis [1] |
When should you see a doctor about bronchiolitis?
If symptoms become serious, call your child's healthcare provider. This is especially important if your child is younger than 12 weeks old or has other risk factors, such as being born too early or having a heart condition. [1]
Get medical attention right away if your child has blue or gray skin, lips, or fingernails due to low oxygen levels. A child who struggles to breathe and cannot speak or cry also needs urgent care. [1]
Other emergency signs include refusing to drink enough or breathing too fast to eat or drink, and breathing very fast, which in infants can be more than 60 breaths a minute, with short, shallow breaths. [1]
Watch the child's chest too. If a child cannot breathe easily and the ribs seem to suck inward when breathing in, or makes wheezing or grunting noises with each breath, seek care right away. A child who appears slow moving, weak, or very tired also needs urgent attention. [1]
What causes bronchiolitis and how does it happen?
Bronchiolitis happens when a virus infects the bronchioles, the smallest airways in the lungs. The infection makes these airways swollen and irritated, and mucus collects in them, which makes it difficult for air to flow freely in and out of the lungs. [1]
The infection is usually caused by the respiratory syncytial virus, or RSV. RSV is a common virus that infects just about every child by 2 years of age, and RSV outbreaks often happen during the colder months of the year in some locations or the rainy season in others. [1]
A person can get RSV more than once. Other viruses can also cause bronchiolitis, including the viruses that cause the flu and the common cold. [1]
How does bronchiolitis spread?
The viruses that cause bronchiolitis are easily spread between people. [1]
You can catch them through droplets in the air when someone who is sick coughs, sneezes, or talks. [1]
You can also catch them by touching shared items, such as dishes, doorknobs, towels, or toys, and then touching your eyes, nose, or mouth. [1]
What are the risk factors for bronchiolitis?
Bronchiolitis usually affects children under the age of 2 years. Infants younger than 3 months have the highest risk because their lungs and their ability to fight infections are not yet fully developed. [1]
Risk factor | Why it matters |
Age under 3 months | Lungs and immune defenses are not fully developed [1] |
Being born too early | Premature babies have less-developed lungs [1] |
Heart or lung condition | Underlying disease raises the risk [1] |
Weakened immune system | Harder to fight infections [1] |
Around tobacco smoke | Smoke exposure increases risk [1] |
Child care settings | Contact with lots of other children [1] |
Crowded places | More exposure to circulating viruses [1] |
Siblings in school | Siblings can bring the infection home [1] |
What complications of bronchiolitis should you watch for?
Most children recover well, but severe bronchiolitis can cause serious complications that require a hospital stay. [1]
Low oxygen in the body is one key complication. Pauses in breathing are another, and these are most likely to happen in babies born too early and in babies under 2 months old. [1]
Not being able to drink enough liquids can cause dehydration, when too much body fluid is lost. And not being able to get the amount of oxygen needed is called respiratory failure. [1]
If any of these happen, your child may need to be in the hospital. Severe respiratory failure may require that a tube be guided into the windpipe to help your child breathe until the infection improves. [1]
How is bronchiolitis diagnosed?
A child's healthcare provider can usually diagnose bronchiolitis by the symptoms and by listening to the child's lungs with a stethoscope. [2]
Tests and X-rays are not usually needed to diagnose bronchiolitis. A provider may recommend tests if the child is at risk of severe bronchiolitis, if symptoms are getting worse, or if there may be another problem. [2]
Diagnostic step | What it shows |
Stethoscope exam | Listening to the lungs confirms the diagnosis in most cases [2] |
Chest X-ray | Can show if there are signs of pneumonia [2] |
Viral testing | A nose swab tests for the virus causing bronchiolitis [2] |
Blood tests | White blood cell count and oxygen level in the bloodstream [2] |
If the child has been refusing to drink or eat or has been vomiting, the provider may look for symptoms of dehydration. These signs include a dry mouth and skin, extreme tiredness, and making little or no urine. [2]
What are the treatment options for bronchiolitis?
Bronchiolitis usually lasts for 1 to 2 weeks, but symptoms occasionally last longer. Most children can be cared for at home with comfort measures, and it is important to stay alert for problems with breathing that are getting worse. [2]
Because viruses cause bronchiolitis, antibiotics, which treat infections caused by bacteria, do not work against it. However, bacterial infections such as pneumonia or an ear infection can happen along with bronchiolitis, and in that case a provider may give an antibiotic for the bacterial infection. [2]
Medicines called bronchodilators that open the airways do not seem to help bronchiolitis, so they usually are not given. In severe cases, a provider may try a nebulized albuterol treatment, in which a machine creates a fine mist of medicine that the child breathes into the lungs, to see if it helps. [2]
Oral corticosteroid medicines and pounding on the chest to loosen mucus, a treatment called chest physiotherapy, have not been shown to be effective for bronchiolitis and are not recommended. [2]
Hospital care
A small number of children may need a stay in the hospital. [2]
Your child may receive oxygen through a face mask to get enough oxygen into the blood, and may get fluids through a vein to prevent dehydration. [2]
In severe cases, a tube may be guided into the windpipe to help breathing. [2]
Care at home
Though it may not be possible to shorten the length of the illness, you can make your child more comfortable with a few simple steps. [2]
Home measure | How to do it |
Humidify the air | A cool-mist humidifier in a dry room may loosen mucus and lessen coughing; keep it clean so bacteria and molds do not grow [2] |
Give liquids often | Infants should have formula or breast milk only; older kids can drink water, juice, or milk, in small amounts often, since they may drink more slowly [2] |
Saline nose drops | Over-the-counter drops are safe; put several drops in one nostril and use bulb suction right away, then repeat on the other side [2] |
Fever and pain relief | Ask your provider about infants' acetaminophen or ibuprofen; these are safer than aspirin for children [2] |
Avoid secondhand smoke | Smoke worsens respiratory symptoms; smokers should smoke outside the house and car [2] |
Never give aspirin to children. It is not recommended due to the risk of Reye's syndrome, a rare but potentially life-threatening condition, and children and teenagers recovering from chickenpox or flu-like symptoms should never take it. [2]
Do not use other over-the-counter cough and cold medicines in children under 6 years old, and consider avoiding them for children younger than 12; the risks to children outweigh the benefits. [2]
How can you prevent bronchiolitis?
Because the viruses that cause bronchiolitis spread from person to person, one of the best ways to prevent infection is to wash your hands often. This is especially important before touching your baby when you have a cold, flu, or other spreadable illness. Wear a face mask if you are sick. [1]
If your child has bronchiolitis, keep your child at home until the illness is past to avoid spreading it to others. [1]
To help prevent infection, limit contact with people who have a fever or a cold, especially for newborns in the first two months of life. Clean and disinfect surfaces and items that people often touch, such as toys and doorknobs, especially if a family member is sick. [1]
Wash your own hands and your child's hands with soap and water for at least 20 seconds, and keep an alcohol-based hand sanitizer with at least 60% alcohol handy. Cover coughs and sneezes with a tissue, throw it away, then wash your hands, or cough or sneeze into your elbow. Use your own drinking glass, and breastfeed when possible, since respiratory infections are less common in breastfed babies. [1]
Which immunizations and medicines help protect against bronchiolitis?
In the U.S., RSV is the most common cause of bronchiolitis and pneumonia in children who are less than a year old. Two immunization options can help prevent severe RSV in young infants, and your healthcare professional can help you choose. [1] [3]
The antibody product called nirsevimab is a single-dose shot given in the month before or during RSV season. It is for newborn babies and those younger than 8 months who are born during or entering their first RSV season. In the U.S., the RSV season typically runs November through March. [1] [3]
Nirsevimab should also be given to children 8 months through 19 months old who are at higher risk of severe RSV disease through their second season. Higher-risk conditions include chronic lung disease from being born prematurely, a severely weakened immune system, severe cystic fibrosis, and being an American Indian or Alaska Native child. [1] [3]
In rare situations when nirsevimab is not available or a child is not eligible, another antibody product called palivizumab may be given, but it requires monthly shots during the RSV season and is not recommended for healthy children or adults. [1]
A vaccine called Abrysvo is approved for pregnant people to prevent RSV in infants from birth through 6 months of age. A single-dose shot can be given from 32 weeks through 36 weeks of pregnancy, during September through January in the U.S., and it is not recommended for infants or children. [1] [3]
Because COVID-19 and influenza can also cause bronchiolitis, getting seasonal COVID-19 and flu shots every year is recommended for everyone older than 6 months. [1]
How should you prepare for a bronchiolitis appointment?
You will likely start by seeing your child's primary care provider or pediatrician. Before your appointment, make a list of any symptoms your child has, including any that may not seem related to a cold or flu, and when they started. [2]
Also list key personal information, such as whether your child was born prematurely or has a heart or lung problem or a weakened immune system, along with the questions you want to ask. [2]
Helpful questions include: What is likely causing my child's symptoms? Does my child need any tests? How long do symptoms usually last? Can my child spread this infection to others? What treatment do you recommend, and are there other options? Does my child need medicine, and is there a generic option? What can I do to make my child feel better? [2]
Expect the provider to ask when symptoms began, whether they come and go or are constant, how severe they are, and what seems to make them better or worse. Preparing for these questions helps you make the most of your time. [2]
Conclusion
Bronchiolitis is one of the most common respiratory infections of early childhood, and most children recover fully at home within one to two weeks. [1] [2]
The key is watching the breathing, not just the cough. Ribs pulling inward, grunting, blue or gray skin, very fast breathing, and refusing to drink are the signs that mean getting help right away. [1]
If you are caring for a sick baby, keep offering fluids, keep the air moist, and ask your healthcare professional before giving any medicine. And for infants under 3 months old, or those born prematurely, call early rather than waiting it out. [1] [2]
Next steps: Worried about your baby's breathing? See a healthcare professional right away, especially if your baby has blue or gray skin, grunting, ribs pulling inward, very fast breathing, or is refusing to drink.
Frequently asked questions
How do I know if my child has bronchiolitis or just a cold?
Bronchiolitis starts like a common cold with a runny nose, stuffy nose, and cough, but then gets worse with a week or more of working harder to breathe and a high-pitched whistling sound called wheezing. A healthcare professional can confirm the diagnosis by listening to the child's lungs with a stethoscope. [1] [2]
How long does bronchiolitis last?
Do antibiotics help bronchiolitis?
No. Bronchiolitis is caused by a virus, so antibiotics, which treat bacterial infections, do not work. An antibiotic may be given only if a bacterial infection such as pneumonia or an ear infection develops along with the illness. [2]
When should I take my child to the hospital?
Seek urgent care for blue or gray skin, lips, or fingernails, ribs pulling inward when breathing, grunting with each breath, very fast breathing in an infant, refusing to drink, or a baby who is slow moving, weak, or very tired. A small number of children need hospital care for oxygen or IV fluids. [1] [2]
Can my child get bronchiolitis more than once?
Yes. A child can get RSV, the most common cause, more than once, and other viruses such as those that cause the flu or the common cold can also cause bronchiolitis. [1]
This article is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your individual situation.
References
Mayo Clinic Staff. Bronchiolitis - Symptoms and causes. Mayo Clinic. May 4, 2024. https://www.mayoclinic.org/diseases-conditions/bronchiolitis/symptoms-causes/syc-20351565
Mayo Clinic Staff. Bronchiolitis - Diagnosis and treatment. Mayo Clinic. May 4, 2024. https://www.mayoclinic.org/diseases-conditions/bronchiolitis/diagnosis-treatment/drc-20351571
Centers for Disease Control and Prevention. RSV in infants and young children. CDC. February 20, 2026. https://www.cdc.gov/rsv/infants-young-children/index.html
Hammitt LL, Dagan R, Yuan Y, et al. Nirsevimab for prevention of RSV in healthy late-preterm and term infants. N Engl J Med. 2022;386(9):837-846. PMID 35235726. https://doi.org/10.1056/NEJMoa2110275
Tapiainen T, Aittoniemi J, Immonen J, et al. Finnish guidelines for the treatment of laryngitis, wheezing bronchitis and bronchiolitis in children. Acta Paediatr. 2016;105(1):44-49. PMID 26295564. https://doi.org/10.1111/apa.13162
Napolitano N, Berlinski A, Walsh BK, et al. AARC clinical practice guideline: management of pediatric patients with oxygen in the acute care setting. Respir Care. 2021;66(7):1214-1223. PMID 33790048. https://doi.org/10.4187/respcare.09006
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