Bronchiolitis (brong-kee-o-LYE-tis) is an infection that causes inflammation of the lung's smaller airways, also called the bronchioles (BRONG-kee-oles). It is common among very young children, particularly during the winter months.


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Pneumonia Respiratory

syncytlal virus (RSV)


What Is Bronchiolitis?

Bronchiolitis is caused by a virus that infects the bronchioles, the smallest airways that carry air through the lungs. The linings of these airways swell and become blocked with fluid and mucus * , making it difficult to breathe. The virus that most often causes bronchiolitis is called respiratory syncytial virus * (RSV). Other viruses, such as rhinovirus, parainfluenza * virus, influenza A * , and adenovirus * , also can cause bronchiolitis. Bronchiolitis is most common in late fall, winter, and early spring. It typically affects younger children, with most cases occurring in children 2 years old or younger. About 90,000 children are hospitalized for bronchiolitis each year in the United States.

How Does Bronchiolitis Spread?

The viruses that cause bronchiolitis are contagious. They usually are spread through the air when infected drops of fluid are released during a sneeze or cough. RSV stays alive on surfaces, such as countertops and toys, for long periods of time. 'When children touch these infected surfaces, they can easily pick up the virus. A child who is infected with RSV, however, may just get a bad cold and may not experience the symptoms of bronchiolitis.

Signs and Symptoms of Bronchiolitis

An infected child typically has a runny nose, mild cough, and low fever for a few days. Then the infection peaks; at this stage the cough may worsen, and breathing sometimes becomes difficult. The child may have rapid breathing and begin to wheeze. The child usually will not eat or sleep well because of these symptoms. The nostrils may flare (that is, they will open wide when the child breathes) and the upper belly and the skin covering the chest may retract (that is, it will look as though it is caving in) with each intake of breath. Sometimes the symptoms of bronchiolitis are so severe that the child needs extra oxygen and inhaled medications. If the child is not getting enough oxygen, cyanosis * may develop.

* mucus (MYOO-kus) is a thick, slippery substance that lines the insides of many body parts.

* respiratory syncytial (RES-puh-ruh-tor-e sin-SIH-she-ul) virus, or RSV, is a virus that infects the respiratory tract and typically causes minor symptoms in adults but can lead to more serious respiratory illnesses in children.

* parainfluenza (pair-uh-in-floo-EN-zuh) is a family of viruses that cause respiratory infections.

* influenza (in-floo-EN-zuh) A, is one member of a family of viruses that attack the respiratory tract.

* adenovirus (ah-deh-no-VY-rus) is a type of virus that can produce a variety of symptoms, including upper respiratory disease, when it infects humans.

* cyanosis (sye-uh-NO-sis) is a bluish or purplish discoloration of the skin and mucous membranes due to a lack of oxygen in the blood.

How Is Bronchiolitis Diagnosed and Treated?

It is important for children who have breathing problems to be examined by a doctor to make sure that they are getting enough oxygen. The doctor also will check for signs of dehydration * . The child's nasal fluid can be examined for the presence of RSV in a laboratory with the rapid antigen * detection test. This test often is used to diagnose the infection in the emergency room during the winter months.

Most children can be treated at home. Doctors typically recommend that children with bronchiolitis drink lots of fluids and sleep with a cool-mist vaporizer or humidifier in the bedroom, to ease breathing. Over-the-counter medications for pain and fever, such as acetaminophen (uh-SEE-teh-MIH-noh-fen), also can help children feel better. Antibiotics do not help bronchiolitis, because a virus causes the illness and antibiotics treat only infections caused by bacteria. Decongestants (medications that decrease the amount of mucus) should not be used, because they often produce unwanted side effects in very young children. Instead, a child's nose can be cleared of mucus with suction from a rubber bulb and saltwater nose drops. Occasionally, a child with bronchiolitis, especially one who was born prematurely or who has heart or lung problems, may have to be hospitalized so that extra oxygen and fluids can be given. Sometimes breathing treatments are required.

What to Expect

Most children with bronchiolitis do well with treatment at home guided by the child's doctor. A doctor should be called right away if the child has any signs of difficulty in breathing, such as breathing very fast or experiencing retractions or if the skin or lips turn pale or bluish. The doctor also should be called if the child is not able to take and hold down fluid by mouth. Most children get better after about a week, but the cough may last longer. In some cases the cough may not clear up for several weeks, even though the child is back to normal otherwise. Complications of bronchiolitis include pneumonia * , apnea * , and respiratory failure * . These are more common in children who are born prematurely or who have heart, lung, or other health problems. Children who have had bronchiolitis are more prone to asthma * later in childhood.

* dehydration (dee-hi-DRAY-shun) is a condition in which the body is depleted of water, usually caused by excessive and unreplaced loss of body fluids, such as through sweating. vomiting, or diarrhea.

* antigen (AN-tih-jen) is a substance that is recognized as a threat by the body's immune system. which triggers the formation of specific antibodies against the substance.

* pneumonia (nu-MO-nyah) is inflammation of the lung.

* apnea (AP-nee-uh) is a temporary stopping of breathing.

* respiratory failure is a condition in which breathing and oxygen delivery to the body are dangerously altered. This may result from infection, nerve or muscle damage, poisoning, or other causes.

* asthma (AZ-mah) is a condition in which the airways of the lungs repeatedly become narrowed and inflamed, causing breathing difficulty.

How Can Bronchiolitis Be Prevented?

The viruses that cause bronchiolitis, especially RSV, are spread easily. It is almost impossible to keep children away from others who are sick, but it is important to wash the hands often (children as well as the people caring for them, as in day care centers) to prevent the spread of RSV. Keeping sick children home from school and day care can help control the spread of infection to others. Children who are considered to be at high risk of becoming seriously ill from bronchiolitis, such as premature infants and those with chronic heart or lung disease, can be immunized against RSV to prevent infection.

See also
Bronchitis, Infectious
Common Cold



American Academy of Family Physicians, 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. The American Academy of Family Physicians posts information about bronchiolitis at its website.
Telephone 800-274-2237

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