Causes of asthma
We do not know what causes asthma, but we do know that many things can make it more likely that someone will get asthma.
Asthma often runs in families and people who have allergies – especially those under the age of 16 – are at a higher risk.
There are different types of asthma. Asthma associated with allergy usually starts in children. But some people develop asthma as adults and this is often not associated with allergic triggers.
Some people can develop asthma by repeatedly breathing in certain substances, especially while they’re at work, for example when they’re paint spraying, baking and welding.