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INTRODUCTION — Bronchiolitis is a lower respiratory tract infection that occurs in children younger than two years old. It is usually caused by a virus. The virus causes inflammation of the small airways (bronchioles) (figure 1). The inflammation partially or completely blocks the airways, which causes wheezing (a whistling sound heard as the child breathes out). This means that less oxygen enters the lungs, potentially causing a decrease in the level of oxygen in the blood.
Bronchiolitis is a common cause of illness and is the leading cause of hospitalization in infants and young children. Treatment includes measures to ensure that the child consumes enough fluids and is able to breathe without significant difficulty. Most children begin to improve a few days after first developing breathing difficulties, but wheezing can last for a week or longer. Bronchiolitis can cause serious illness in some children. Infants who are very young, born early, have lung or heart disease, or have difficulty fighting infections or handling oral secretions are more likely to have severe disease with bronchiolitis. It is important to be aware of the signs and symptoms that require evaluation and treatment.
This topic review discusses the causes, signs and symptoms, and usual treatment of bronchiolitis in infants and children. More detailed information about bronchiolitis is available by subscription. (See 'Professional level information' below.)
BRONCHIOLITIS CAUSE — Bronchiolitis is typically caused by a virus. Respiratory syncytial virus (RSV) is the most common cause, although other viruses can also cause bronchiolitis. In the northern hemisphere, RSV outbreaks usually occur from October to April with a peak in December, January, or February. In the southern hemisphere, wintertime epidemics occur from May to September, with a peak in May, June, or July. In tropical and semitropical climates, the seasonal outbreaks usually are associated with the rainy season. During the coronavirus disease 2019 (COVID-19) pandemic, RSV may occur earlier than usual. In the summer of 2021 during the COVID-19 pandemic, a large RSV outbreak occurred in the United States.
Virtually everyone will have been infected with RSV by the age of three years. It is common to be infected more than once, even in the same RSV season; however, after the first time, subsequent infections are usually milder.
Children older than two years typically do not develop bronchiolitis, although they are commonly infected with RSV. In this age group, RSV usually causes symptoms similar to those of the common cold or mild wheezing; in some cases, the illness is significant enough to require evaluation by a health care provider. (See "Patient education: The common cold in children (Beyond the Basics)".)
While RSV is the most common cause, bronchiolitis can also result if a young child is infected with the virus that causes COVID-19. Some children may have infection with both RSV and the virus that causes COVID-19, called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
BRONCHIOLITIS SYMPTOMS — Bronchiolitis usually develops following one to three days of common cold symptoms, including the following:
●Nasal congestion and discharge
●A mild cough
●Fever (temperature higher than 100.4°F or 38°C) – The table describes how to take a child's temperature (table 1). (See "Patient education: Fever in children (Beyond the Basics)".)
●Decreased appetite
As the infection progresses and the lower airways are affected, other symptoms may develop, including:
●Breathing rapidly (60 to 80 times per minute) or with mild to severe difficulty
●Wheezing, which usually lasts approximately seven days
●Persistent coughing, which may last for 14 or more days (persistent cough also may be caused by other serious illnesses that require medical attention)
●Difficulty feeding related to nasal congestion and rapid breathing, which can result in dehydration
Apnea (a pause in breathing for more than 15 or 20 seconds) can be the first sign of bronchiolitis in an infant. This occurs more commonly in infants born prematurely and infants who are younger than two months.
Signs of severe bronchiolitis include retractions (sucking in of the skin around the ribs and the base of the throat) (figure 2), nasal flaring (when the nostrils widen during breathing), and grunting. The effort required to breathe faster and harder is tiring. In severe cases, a child may not be able to continue to breathe on their own.
Low oxygen levels (called hypoxia) and blue-tinged skin (called cyanosis) can develop as the illness progresses. Cyanosis may first be noticed in the finger and toenails; ear lobes; tip of the nose, lips, or tongue; and inside of the cheek. Any of these signs or symptoms requires immediate medical evaluation.
A child who is grunting, appears to be tiring, stops breathing, or has cyanosis needs immediate medical attention. (See 'Emergency care' below.)
BRONCHIOLITIS TRANSMISSION — Respiratory syncytial virus (RSV) is transmitted (spread) through droplets that contain viral particles; these are exhaled into the air when an infected person breathes, talks, coughs, or sneezes. These droplets can be carried on the hands, where they survive and can spread infection for several hours. If a person with RSV on their hands touches a child's eye, nose, or mouth, the virus can infect the child. Adults infected with RSV can easily transmit the virus to children or other adults. This is also true for other viruses that cause bronchiolitis.
Anyone in contact with infants or young children should wash their hands regularly or use an alcohol-based hand sanitizer if soap and water are not available (table 2).
A child with bronchiolitis should be kept away from other infants and anyone else who is susceptible to severe respiratory infection (eg, people with chronic heart or lung diseases or a weakened immune system) until their symptoms have resolved.
BRONCHIOLITIS DIAGNOSIS — The diagnosis of bronchiolitis is based upon a history and physical examination. Blood tests and X-rays are not usually necessary. Tests that can identify the virus or viruses in children with bronchiolitis are available if it is important to determine the underlying cause; for example, if a bacterial infection (which would require treatment with antibiotics) is suspected.
If you think your child may have been exposed to the virus that causes coronavirus disease 2019 (COVID-19), let their health care provider know. They will ask you questions about the child's symptoms and whether they might be at risk, and tell you if the child should get tested for the virus or needs to quarantine at home.
When a child has bronchiolitis, the provider must determine if the illness is severe or if there is a risk of complications. In these cases, hospitalization is generally recommended to closely monitor the child and provide intravenous (IV) fluids or supplemental oxygen. (See 'Hospital care' below.)
BRONCHIOLITIS TREATMENT
Emergency care — Parents should seek medical attention if the child seems to be worsening. A child who is grunting, appears to be tiring, stops breathing, or has blue-colored skin (cyanosis) needs urgent medical attention. If your child has these symptoms, or if they are worsening, call emergency medical services (in the United States and Canada, dial 9-1-1). (See 'When to seek help' below.)
Severe bronchiolitis should be evaluated in an emergency department or clinic capable of handling urgent respiratory illnesses. This is a life-threatening illness, and treatment should not be delayed for any reason.
Relieving symptoms — There is no treatment that can get rid of bronchiolitis, so treatment is aimed at relieving symptoms until the infection resolves. Treatment at home usually includes making sure the child drinks enough and using saline nose drops (or bulb suctioning for infants) to keep the nose clear.
Monitoring — Monitoring at home involves observing the child periodically for signs or symptoms of worsening. Specifically, this includes monitoring for an increased rate of breathing, worsening chest retractions, nasal flaring, cyanosis, a decreased ability to feed, or decreased urine output. Contact the child's health care provider to determine if and when an office visit is needed or if there are any other questions or concerns. (See 'When to seek help' below.)
Treating fever — You can give acetaminophen (sample brand name: Tylenol) to treat fever if your child is uncomfortable. Ibuprofen (sample brand names: Advil, Motrin) can be given to children over six months of age. Aspirin should not be given to any child under age 18 years. If your child has a fever, speak with their health care provider about when and how to treat it or if they need to be seen in the office.
Nose drops or spray — Saline nose drops or spray might help with congestion and runny nose. For infants, you can try saline nose drops to thin the mucus, followed by bulb suction to temporarily remove nasal secretions (table 3). An older child may try using a saline nose spray before blowing their nose.
Encourage fluids — Encourage your child to drink enough fluids to stay hydrated; it is not necessary to drink more fluids than normal. Children often have a reduced appetite and may eat less than usual. If an infant or child completely refuses to eat or drink for a prolonged period, urinates less often than normal, or has vomiting episodes with cough, contact a health care provider.
Other therapies — Other therapies, such as antibiotics, cough medicines, decongestants, and sedatives, are not recommended. Cough medicines and decongestants have not been proven to be helpful (and are not safe for use in young children), and sedatives can mask symptoms of low blood oxygen and difficulty breathing.
Coughing is one way for the body to clear the lungs and normally does not need to be treated. As the lungs heal, the coughing caused by the virus resolves. Smoking in the home or around the child should be avoided because it can worsen a child's cough; exposure to secondhand smoke can also lead to other health problems in children.
Antibiotics are not effective in treating bronchiolitis because it is usually caused by a virus (antibiotics are only effective against infections caused by bacteria). However, antibiotics may be necessary if the child also has a bacterial infection, like an ear infection (common) or bacterial pneumonia (very uncommon).
Sometimes, keeping the child's head elevated can make it easier for them to breathe. A child over the age of one year may be propped up in bed with an extra pillow. Pillows should not be used with infants younger than one year.
Hospital care — Approximately 3 percent of children with bronchiolitis will require monitoring and treatment in a hospital. Most children receive monitoring of vital signs and supportive care, including supplemental oxygen and intravenous (IV) fluids, if necessary. Other treatments are individualized, based upon the child's needs and response to therapy.
Isolation precautions — Because the viruses that cause bronchiolitis are contagious, precautions must be taken to prevent spreading the virus to other patients and/or children. Parents or primary caregivers may visit (and stay with the child), but siblings and friends should not. Toys, books, games, and other activities can be brought to the child's room. All visitors (nurses, doctors, parents) must wash their hands before and after leaving the room.
Feeding — Most infants and children can continue to eat, breastfeed, or drink normally while in the hospital. If the child is unable or unwilling to eat or drink adequately, breathing too fast, or having significant difficulty breathing, they may need to get fluids and nutrition into a vein (by IV).
Treatments — Supplemental (extra) oxygen may be needed for children who are unable to get enough oxygen from room air; this is usually given by placing a tube (called a nasal cannula) under a child's nose or by placing a face mask over the nose and mouth. For infants, an oxygen head box (a clear plastic box) may be used. The child is tested periodically to determine the blood oxygen level when oxygen is turned off. The goal is to slowly reduce and then discontinue supplemental oxygen when the child is ready.
If a child is severely ill and unable to breathe adequately on their own, or if the child stops breathing, a breathing tube (endotracheal tube) may be inserted into the mouth and throat. This is connected to a machine (called a ventilator) that breathes for the child at a regular rate. The use of an endotracheal tube and ventilator is a temporary measure that is discontinued when the child improves.
Discharge to home — Most children who require hospitalization are well enough to return home within three to four days. Children who require a machine to help them breathe usually need to stay in the hospital for four to eight days or longer before they are ready to go home.
Recovery — Most children with bronchiolitis who are otherwise healthy begin to improve within two to five days. However, wheezing persists in some infants for a week or longer, and it may take as long as four weeks for the child to return to their "normal" self. Recovery may take longer in younger infants and those with underlying medical problems (eg, prematurity, other lung diseases). The child should be kept out of day care or school until the fever and runny nose have resolved (ie, the time during which they are most contagious).
BRONCHIOLITIS PREVENTION — There are several ways to prevent severe bronchiolitis:
●Avoid smoking around the child, as this increases the risk of respiratory illness.
●Wash hands frequently with soap and water, especially before touching an infant. Hands should ideally be wet with water and plain or antimicrobial soap, and rubbed together for at least 20 seconds. Hands should be rinsed thoroughly and dried with a single-use towel. If you cannot wash your hands in a sink, use a gel with at least 60 percent alcohol.
●Stay away from other adults and children with upper respiratory infection. Keep infants or children home from school or day care when they are sick.
●A yearly vaccination for influenza virus is recommended for everyone older than six months, especially for household contacts of children younger than five years, and out-of-home caregivers of children younger than five years. (See "Patient education: Influenza symptoms and treatment (Beyond the Basics)".)
●For adults and older children who are eligible, getting the COVID-19 vaccine will help to protect children in the home (or child care setting) who are not yet vaccinated.
●Infants who are younger than 24 months with specific types of chronic lung disease and infants who are younger than 12 months who were born before 29 weeks, have specific types of heart disease, or have other risk factors for severe respiratory syncytial virus (RSV) infection may be given a special medication (palivizumab) to prevent severe RSV infection requiring hospitalization. Palivizumab (brand name: Synagis) is a monoclonal antibody that protects the lungs from severe infection from RSV. It is given as an injection into the muscle once per month for five months. There is a low risk of serious side effects with palivizumab.
BRONCHIOLITIS AND ASTHMA — There is interest in the relationship between bronchiolitis in early childhood and later development of asthma. Infants hospitalized with bronchiolitis caused by respiratory syncytial virus and rhinovirus (a virus that is the most frequent cause of the common cold) have an increased risk of recurrent wheezing during the first 10 years of life. Some studies have also noted an increased risk of asthma following an episode of bronchiolitis, although it is unclear if the risk of asthma is increased due to bronchiolitis or other risk factors (eg, genetic predisposition to asthma, environmental irritants such as cigarette smoke).
The first time a child develops wheezing, it can be difficult to know if it is caused by bronchiolitis or asthma. Most cases of first time wheezing are caused by a virus. A history of recurrent wheezing episodes and a family or personal history of asthma, nasal allergies, or eczema help to support a diagnosis of asthma. Viruses frequently trigger asthma attacks in children with asthma.
After developing bronchiolitis, some infants will have recurrent episodes of wheezing during childhood. These wheezing episodes are triggered by viruses and may respond to the same treatments used in children with asthma.
WHEN TO SEEK HELP — If, at any time, a child develops features of worsening or severe bronchiolitis, the parent should seek immediate medical attention. This includes:
●Difficulty breathing or appearing overwhelmed by the work of breathing
●Pale or blue-tinged (cyanotic) skin
●Severe coughing spells
●Severe sucking in of the skin around the ribs and base of the throat (retractions) with breathing (figure 2)
●If the child stops breathing
Do not attempt to drive your child to the hospital yourself if the child is severely agitated, cyanotic, struggling to breathe, stops breathing, or is excessively drowsy (lethargic). In this situation, call emergency medical services (in the United States and Canada, dial 9-1-1).
Call the child's doctor or nurse if:
●The child has a fever (temperature higher than 100.4°F or 38°C), particularly for infants who are younger than three months (table 1)
●The child has signs or symptoms of bronchiolitis
●The child has difficulty feeding or has fewer wet diapers than usual
●You have any questions or concerns about the child's condition
WHERE TO GET MORE INFORMATION — Your child's health care provider is the best source of information for questions and concerns related to your child's medical problem.
This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients and caregivers, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient education: Bronchiolitis and RSV in children (The Basics)
Patient education: Cough in children (The Basics)
Patient education: Pneumonia in children (The Basics)
Patient education: Transient tachypnea of the newborn (The Basics)
Patient education: Mycoplasma pneumonia in children (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient education: The common cold in children (Beyond the Basics)
Patient education: Fever in children (Beyond the Basics)
Patient education: Influenza symptoms and treatment (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Approach to chronic cough in children
Bronchiolitis in infants and children: Clinical features and diagnosis
Bronchiolitis in infants and children: Treatment, outcome, and prevention
Causes of chronic cough in children
Respiratory syncytial virus infection: Clinical features and diagnosis
Respiratory syncytial virus infection: Treatment
The following organizations also provide reliable health information.
●National Library of Medicine
(www.medlineplus.gov/healthtopics.html)
●American Academy of Pediatrics
(www.healthychildren.org/English/health-issues/Pages/default.aspx)
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