Asthma symptoms happen when your airways become swollen. This makes them narrower, causing breathing problems.

In people who have asthma, symptoms can be triggered by different things, such as allergies, exercise, smoke, cold air or infections.

It's not fully understood what causes asthma. You may be more likely to get asthma if:

• you have allergies such as eczema, hay fever or food allergies
• other people in your family have asthma, hay fever, eczema or allergies
• you were born prematurely or had a low birth weight
• you were exposed to things like high levels of air pollution or cigarette smoke as a child
• you had illnesses as a child that affected your breathing, such as bronchiolitis or croup
• you're overweight

Asthma can also be caused by breathing in substances such as certain chemicals at work.

Help and support for asthma

As well as support from your healthcare team, you may find it helpful to get support from other people with asthma, either at a local support group or online.

There are also national charities that can offer support and information about asthma.

Asthma and Lung UK

Information and support for anyone affected by lung conditions including asthma.

• Website: www.asthmaandlung.org.uk
• Helpline: 0300 222 5800
• Asthma and Lung UK: support in your area
• Asthma and Lung UK: living with a lung condition

Allergy UK

Information and support for people living with allergies.

• Website: www.allergyuk.org
• Helpline: 01322 619898
• Allergy UK: asthma

Beat Asthma

Website for children and young people with asthma.

• Website: www.beatasthma.co.uk
• Beat Asthma: information for families and children