Asthma causes the airways of the lungs (the bronchi) to become inflamed and swollen.
The bronchi are small tubes that carry air in and out of your lungs. If you have asthma, the bronchi are more sensitive than normal and certain substances or triggers can irritate them.
Common triggers include house dust mites, animal fur, pollen, tobacco smoke, cold air and chest infections.
When the bronchi are irritated, they become narrow and the muscles around them tighten, which can increase the production of sticky mucus, or phlegm. This makes it difficult to breathe and causes wheezing and coughing, and it may make your chest feel tight.
The severity of the symptoms of asthma differs from person to person, from mild to severe. The narrowing of the airways is usually reversible – occurring naturally, or through the use of medicines. However, for some people with chronic (long-lasting) asthma, the inflammation may lead to an irreversible obstruction of the airways.
A severe onset of symptoms is known as an asthma attack, or 'acute asthma exacerbation'. Asthma attacks can be life-threatening and may require hospital treatment.
The symptoms of asthma may occur for no obvious reason. They may include:
- feeling breathless (you may gasp for breath),
- a tight chest (like a band tightening around your chest),
- wheezing (a whistling sound when you breathe), and
- coughing, particularly at night (this is less common in adults than in children).
The severity and duration of the symptoms of asthma are often variable and unpredictable, and are sometimes worse during the night or with exercise. The symptoms of a severe asthma attack often develop slowly, taking between six and 48 hours to become serious.
You should remain alert for any signs of worsening symptoms. These include:
- a drop in your peak expiratory flow rate (see the 'diagnosis' section for more information),
- an increase in your pulse rate,
- an increase in wheezing, and
- feeling agitated or restless.
If you notice your symptoms getting worse, do not ignore them. Instead, please contact us to make an appointment or alternatively contact your GP or go to the nearest Accident and Emergency if we are closed.
If you or someone else is having a severe asthma attack, and you or they are unable to breathe, you should dial 999 immediately to request emergency medical treatment.