What is wheezing?
Wheezing occurs when lower airways are narrow or constricted – breathing
feels difficult and there is a whistling sound in the chest on breathing
out. Wheezing is a symptom of asthma and other lower respiratory conditions
(such as the viral condition bronchiolitis).
Narrowing in the lower airways can be caused by different things.
- In asthma, redness and swelling (inflammation) in the small airways
deep in the lungs causes over-production of mucus and tightening of
airway muscles. The combination of swelling, mucus, and muscle
tightening all cause narrowing of the airways.
- With a viral infection in the airways, excess mucus production can
build up and clog the airways. This is particularly likely in a child
born with narrow or abnormally shaped airways.
See the ‘Asthma and Lung Function Tests’ brochure for more information on
lung inflammation in asthma.
What is the link between asthma and wheezing?
Most people with asthma wheeze. But not everyone who wheezes has asthma.
| Wheezing is very common in the first few years
of life. For most children it is temporary and does not mean that
they have asthma. |
Studies of babies and children have shown us that there are different types
of wheezing in young children.
- Transient wheezing – In more than half of children who wheeze, the
wheezing occurs when the child has an infection and stops when the child
gets better. Transient wheezing usually stops altogether by about 3
years of age as the airways grow and widen.
- Bronchiolitis is a common virus causing transient wheezing in
babies, particularly those under 6 months of age. If your baby has a
lung condition such as bronchiolitis it does not necessarily mean that
he or she will develop asthma as a child.
- Persistent wheezing – Children with wheezing that continues beyond
the preschool years are more likely to have allergies than children
whose wheezing stops. Signs of allergy include having eczema, hay fever,
or a runny nose without a cold.
The combination of continuing wheezing and allergies, or parents having
allergies or asthma, further increases the chance that wheezing will
continue and asthma will develop.
Can we tell if wheezing is transient or persistent?
Even though we know about different types of wheezing, it is difficult to
tell whether a young child has transient or persistent wheezing.
| Predicting whether wheezing is due to asthma
involves gathering different types of information over time,
including family history, signs of allergy, and whether wheezing
continues. |
The doctor can’t be completely sure whether it is asthma until the child
has a lung function test (see brochure on lung function tests).
To identify which children will get asthma, we need to understand more
about how asthma develops.
