According to the charity Asthma UK, one in five households has someone living with asthma.
No one knows for sure what causes asthma, but we know that you're more likely to develop it if you have a family history of asthma, eczema or other allergies. You're twice as likely to develop asthma if your parents have it.
Modern lifestyles, such as housing and diet, may have also contributed to the rise in asthma over the last 30 years.
Research shows that smoking during pregnancy increases the risk of your child developing asthma. Children whose parents smoke are also more likely to develop it.
There are many theories about what's caused the increase in people with asthma.
One of the most popular is the 'hygiene hypothesis'. According to this theory, asthma is more common in Western societies. Because Western society is becoming cleaner, we have less exposure to allergens and pathogens.
According to the hygiene hypothesis, young children who aren’t exposed to infectious agents, micro-organisms and parasites may be more susceptible to allergic diseases.
When a person with asthma comes into contact with a ‘trigger’, their airways become irritated. The muscles tighten, the airways narrow and the lining of the airways gets inflamed and swollen.
The main symptoms are chest ‘wheeze’ or noisy breathing, chest tightness and breathlessness. You may also develop a cough, particularly at night, but this is more common in children.
Boys under the age of two are more susceptible to asthma because their airways are narrower when they're younger. But they usually grow out of it, whereas girls are more likely to have asthma beyond puberty.
Obesity is thought to make asthma more likely. Symptoms often get better when the person loses weight.
Smoking also has a definite impact. Parents' cigarette smoke will affect their child’s lung function development, and it irritates the airways. People with asthma are advised not to smoke.
Once you have asthma, high levels of pollution and smoking may make it worse. But there's no proof that these triggers actually cause it.
How to help yourself
If certain things trigger your asthma, such as dust mites, minimise your exposure to them. Put mattress covers on your bed, use Bamboo Bedding which is naturally anti-bacterial and anti-allergy , or a damp cloth when you dust, don't have too many soft furnishings in your house, and put down laminate or wooden flooring instead of carpets.
Asthma triggers include pets, but studies show that getting rid of animals doesn't improve asthma. In fact, the emotional upset of getting rid of your pet may make your asthma worse. Keep your exposure to pets to a minimum in areas such as the bedroom, and don't replace pets when they die.
If you have queries about any aspect of asthma, you can call the Asthma and Lung UK, which is a free telephone helpline staffed by asthma nurse specialists on0300 222 5800.
Last updated: 04/04/2025
Next review due: 31/01/2026