Bronchiolitis - What is it?

Bronchiolitis is an infection of the small tubes (bronchioles) inside the lungs. The infection is usually caused by a virus and often affects children under 2 years.

Bronchiolitis means that small tubes called bronchioles have become swollen and full of mucus. This can make it harder to breathe. Air normally enters the lungs through the windpipe, down larger branching tubes (known as bronchi) and then into the smallest tubes (bronchioles).

The air passes from the bronchioles into millions of tiny air sacs (alveoli) in the lung and then into the bloodstream.

A child with bronchiolitis has inflamed bronchioles.[1] The bronchioles become swollen and full of mucus. This makes it harder for oxygen to reach the lungs and get into the bloodstream. Your child may wheeze and breathe faster to try to get the air they need.

Bronchiolitis is caused by a virus. Respiratory syncytial virus (RSV) is the most common type. It causes bronchiolitis in 7 in 10 children with the illness. In winter, nearly all bronchiolitis is caused by this virus.

RSV is also a common cause of colds, and usually causes only mild symptoms in adults. It's spread in the air by coughing and sneezing. By the age of 2 years, almost all children have had an infection caused by RSV.[2]

For most children, an RSV infection isn't serious. But in about 1 in 5 babies and young children, the virus can infect the airways lower down and cause bronchiolitis.

In early spring, a virus called parainfluenza virus type 3 is often the cause.[3] This virus also causes croup. Croup is when a child's voice box or windpipe becomes inflamed. The child usually has a 'barking' cough.

Some things make it more likely that your child will get bronchiolitis. They include being:[4]

Six months of age or younger
Born prematurely (before 37 weeks in the pregnancy)
Exposed to cigarette smoke
In crowded living conditions
Bottle-fed rather than breast-fed.

The symptoms of bronchiolitis aren't severe for most young children. Your child probably won't need to go to hospital. But the illness can become serious for babies and infants who have other lung diseases or heart diseases.

Your child is more likely to get bronchiolitis severely if he or she:[5]

Has close contact with other infected children
Has a heart disease from birth
Has a long-term lung disease
Was born prematurely
Has low oxygen levels because of any of the conditions above
Has difficulty fighting infections (an immune problem)
Is less than 6 weeks old.

You can't easily prevent your baby getting bronchiolitis. The viruses that cause it are common and all around us. There's no vaccine available yet to protect your baby against RSV.

But if you have a cold, you can try to stop the virus from spreading. You should wash your hands often, especially before you pick up or touch your child.

References

Juan Manuel Lozano. Bronchiolitis. October 2007. Clinical evidence. (Based on October 2006 search). Available at http://clinicalevidence.bmj.com/ceweb/conditions/chd/0308/0308.jsp (accessed on 12 November 2007).
Navas L, Wang E, de Carvalho V, et al. Improved outcome of respiratory syncytial virus infections in a high-risk hospitalized population of Canadian children. Journal of Pediatrics. 1992; 121: 348-354.
Phelan P, Olinsky A, Robertson C. Respiratory illness in children. 4th edition. Blackwell Scientific Publications, London, UK; 1994.
U.S. National Library of Medicine. Medline Plus: bronchiolitis. November 2005. Available at http://www.nlm.nih.gov/medlineplus/ency/article/000975.htm (accessed on 12 November 2007).
Purcell K, Fergie J Driscoll Children's Hospital respiratory syncytial virus database: risk factors, treatment and hospital course in 3308 infants and young children, 1991 to 2002. The Pediatric Infectious Disease Journal. 2004; 23: 418-423.

Glossary

inflammation: Inflammation is when your skin or some other part of your body becomes red, swollen, hot and sore. Inflammation happens because your body is trying to protect you from germs, from something that's in your body and could harm you (like a splinter) or from things that cause allergies (these things are called allergens). Inflammation is one of the ways in which your body heals an infection or an injury.

This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.