Inflammation of the small airways in the lungs caused by a viral infection

  • Most common under the age of 12 months
  • Parental smoking and living in overcrowded conditions are risk factors; babies who are not breast-fed are also at increased risk
  • Gender and genetics are not significant factors

Bronchiolitis is a common and usually mild condition that mainly occurs in babies under the age of 12 months. The small airways in the lungs, called bronchioles, become inflamed due to a viral infection and restrict the flow of air in and out of the lungs. In about 9 in 10 cases, the infection is caused by the respiratory syncytial virus, which can be transmitted from person to person in the airborne droplets from coughs and sneezes. By the age of 5, almost all children in the UK have been infected with this virus. Most of those affected only develop the symptoms of a common cold, but occasionally the infection leads to more severe breathing difficulties. During winter, bronchiolitis tends to occur in epidemics. The risk of a child having bronchiolitis is increased if his or her family lives in overcrowded conditions, in which a viral infection can spread more quickly, or if the child’s parents smoke. Babies who have never been breast-fed are also more likely to develop the condition.

Respiratory syncytial virus

This virus is the most common cause of bronchiolitis, in which small airways in the lungs are inflamed. In some cases, the infection causes severe breathing difficulties.

What are the symptoms?

Initially, an affected child may have symptoms resembling a common cold, such as a runny nose, fever, and sneezing. However, the following symptoms may develop after 2–3 days:

  • Cough.

  • Rapid breathing.

  • Wheezing.

  • Feeding difficulties.

If your child is under 1 year old and has these symptoms, you should contact the doctor. Occasionally, babies may experience severe breathing difficulties, especially if they are very young or have an underlying condition such as congenital heart disease. These babies may develop a blue tinge on the tongue, lips, and skin, a condition called cyanosis. In very small babies who have bronchiolitis, intervals of more than 10 seconds may occur between breaths. You should call an ambulance immediately if your baby is having difficulty breathing, if his or her tongue, lips, or skin become blue-coloured, or if he or she becomes drowsy at unexpected times because of the extra effort that is needed to breathe.

How is it diagnosed?

The doctor will probably suspect bronchiolitis from the symptoms and by listening to your child’s chest with a stethoscope. A chest X-ray may be arranged and the doctor may take samples of your child’s nasal secretions to look for evidence of infection with the respiratory syncytial virus.

What is the treatment?

If the bronchiolitis is mild, you will probably be able to treat your child at home. The doctor may prescribe inhaled bronchodilators to widen the airways and ease breathing. You may be advised to give your child liquid paracetamol (see Painkillers) to bring down a fever. You can help to ease your child’s breathing by increasing humidity in the bedroom. This can be done by placing a wet towel or a dish of water in the room close to a source of heat, such as a radiator. You should give your child small, frequent drinks and feeds so that he or she receives an adequate quantity of fluids to avoid dehydration, which can be serious.

Children with severe symptoms need to be treated in hospital, where they may be given an inhaled bronchodilator drug, sometimes via a nebulizer (a device that delivers a drug in aerosol form through a face mask). Intravenous fluids may be administered if the child is unable to feed. Oxygen is given if blood oxygen levels are low. Premature babies and those with problems such as heart disease may be given antiviral drugs to treat the infection and may need temporary mechanical ventilation to help them to breathe.

What is the prognosis?

Mild bronchiolitis usually improves within 5 days and clears up completely in about 10 days. Severe bronchiolitis may require several weeks of hospital treatment but causes no permanent damage. However, many children who have had bronchiolitis tend to suffer from wheezing when they have a cold.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

Back to top