Asthma is a common long-term condition that can cause coughing, wheezing, chest tightness and breathlessness.
The severity of these symptoms varies from person to person. Asthma can be controlled well in most people most of the time, although some people may have more persistent problems.
Occasionally, asthma symptoms can get gradually or suddenly worse. This is known as an "asthma attack", although doctors sometimes use the term "exacerbation".
Severe attacks may require hospital treatment and can be life threatening, although this is unusual.
Asthma is caused by inflammation of the small tubes, called bronchi, which carry air in and out of the lungs. If you have asthma, the bronchi will be inflamed and more sensitive than normal.
When you come into contact with something that irritates your lungs – known as a trigger – your airways become narrow, the muscles around them tighten, and there is an increase in the production of sticky mucus (phlegm).
Common asthma triggers include:
Asthma may also be triggered by substances (allergens or chemicals) inhaled while at work. Speak to your GP if you think your symptoms are worse at work and get better on holiday.
The reason why some people develop asthma is not fully understood, although it is known that you are more likely to develop it if you have a family history of the condition.
Asthma can develop at any age, including in young children and elderly people.
In the UK, around 5.4 million people are currently receiving treatment for asthma.
That's the equivalent of 1 in every 12 adults and 1 in every 11 children. Asthma in adults is more common in women than men.
While there is no cure for asthma, there are a number of treatments that can help control the condition.
Treatment is based on two important goals, which are:
For most people, this will involve the occasional – or, more commonly, daily – use of medications, usually taken using an inhaler. However, identifying and avoiding possible triggers is also important.
You should have a personal asthma action plan agreed with your doctor or nurse that includes information about the medicines you need to take, how to recognise when your symptoms are getting worse, and what steps to take when they do so.
For many people, asthma is a long-term condition – particularly if it first develops in adulthood.
Asthma symptoms are usually controllable and reversible with treatment, although some people with long-lasting asthma may develop permanent narrowing of their airways and more persistent problems.
For children diagnosed with asthma, the condition may disappear or improve during the teenage years, although it can return later in life. Moderate or severe childhood asthma is more likely to persist or return later on.