Asthma is a long-term condition that can cause a cough, wheezing and breathlessness. The severity of the symptoms varies from person to person. Asthma can be controlled well in most people most of the time.
In the UK, 5.4 million people are currently receiving treatment for asthma. That is 1 in every 12 adults and 1 in every 11 children. Asthma in adults is more common in women than men.
If you are diagnosed with asthma as a child, the symptoms may disappear during your teenage years. However, asthma can return in adulthood. If childhood symptoms of asthma are moderate to severe, it is more likely that the condition will persist or return later in life. However, asthma does not only start in young people and can develop at any age.
The cause of asthma is not fully understood, but it is known that asthma often runs in families. You are more likely to have asthma if one or both of your parents has the condition.
What is asthma?
Asthma is caused by inflammation of the airways. These are 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). This makes it difficult to breathe and causes wheezing and coughing. It may also make your chest feel tight.
A severe onset of symptoms is known as an asthma attack or an 'acute asthma exacerbation'. Asthma attacks may require hospital treatment and can sometimes be life-threatening, although this is rare.
For some people with chronic (long-lasting) asthma, long-term inflammation of the airways may lead to more permanent narrowing.
Common triggers
A trigger is anything that irritates the airways and brings on the symptoms of asthma. These differ from person to person and people with asthma may have several triggers.
Common triggers include house dust mites, animal fur, pollen, tobacco smoke, exercise, cold air and chest infections.
Other types of asthma
There are other types of asthma that can be made worse by certain activities:
Work-aggravated asthma is pre-existing asthma that is made worse by dust and fumes at work.
Occupational asthma is caused by exposure to specific substances at work. For example, some nurses develop occupational asthma after exposure to latex, and some workers in the food-processing industry develop occupational asthma as a response of exposure to flour.
Outlook
While there is no cure for asthma, symptoms can come and go throughout your life. A number of treatments can help control the condition very effectively. Treatment is based on two important goals:
relief of symptoms
preventing future symptoms and attacks from developing
Successful prevention can be achieved through a combination of medicines, lifestyle advice and identifying and then avoiding potential asthma triggers.
Symptoms
The symptoms of asthma include:
feeling breathless (you may gasp for breath)
a tight chest, like a band tightening around it
wheezing, which makes a whistling sound when you breathe
attacks triggered by exercise, exposure to allergens and other triggers
You may have one or more of these symptoms. Symptoms that are worse during the night or with exercise can mean that asthma is getting worse. Talk to your doctor or asthma nurse about this.
When asthma gets worse
When asthma symptoms get significantly worse, this is known as an asthma attack. A severe asthma attack usually develops slowly, taking 6 to 48 hours to become serious. However, for some people, asthma symptoms can get worse quickly.
As well as symptoms getting worse, you can tell that an asthma attack is developing when:
you get more wheezy, tight-chested or breathless
the reliever inhaler is not helping as much as usual
there is a drop in your peak expiratory flow (see Asthma - diagnosis for more information)
If these things happen, do not ignore them. Contact your GP or asthma clinic or consult your asthma action plan, if you have one.
In a severe asthma attack, other things may happen such as:
The reliever inhaler, which is usually blue, does not help symptoms at all.
The symptoms of wheezing, coughing, tight chest are severe and constant.
You are too breathless to speak.
Your pulse is racing.
You feel agitated or restless.
Your lips or fingernails look blue.
Call 999 to seek immediate help if you or someone else has severe symptoms of asthma.
Causes
There is no single cause of asthma, but certain factors may increase the likelihood of developing it. These include genetic factors and the environment.
Who is at risk of developing asthma?
Factors that are known to increase the likelihood of developing asthma include:
a family history of asthma or other related allergic conditions (known as atopic conditions), such as eczema, food allergy or hay fever
developing another atopic condition such as a food allergy
having bronchiolitis as a child (a common lung infection among children)
being exposed to tobacco smoke as a child, particularly if your mother smoked during pregnancy
being born prematurely (especially if you needed a ventilator)
being born with a low birth weight (less than 2kg or 4.5 pounds)
The symptoms of asthma can have a range of triggers, but they do not affect everyone in the same way. Once you know your asthma triggers, you can try to avoid them.
Infections of the airways and chest. Upper respiratory infections, which affect the upper airways, are often caused by cold and flu viruses and are a common trigger of asthma.
Allergens. Pollen, dust mites, animal fur or feathers, for example, can trigger asthma.
Airborne irritants. Cigarette smoke, chemical fumes and atmospheric pollution may trigger asthma.
Medicines. The class of painkillers called non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin and ibuprofen, can trigger asthma for some people, although are fine for most. Children under 16 years of age should not be given aspirin.
Emotional factors. Asthma can be triggered by emotional factors, such as stress or laughing.
Foods containing sulphites. Sulphites are naturally occurring substances found in some food and drink. They are also sometimes used as a food preservative. Food and drinks that are high in sulphites include concentrated fruit juice, jam, prawns and many processed or pre-cooked meals. Most people with asthma do not have this trigger, but some may. Certain wines can also trigger asthma in susceptible people.
Weather conditions. A sudden change in temperature, cold air, windy days, poor air quality and hot, humid days are all known triggers for asthma.
Indoor conditions. Mould or damp, house dust mites and chemicals in carpets and flooring materials may trigger asthma.
Exercise. Sometimes, people with asthma find that their symptoms are worse when they exercise.
Food allergies. Although uncommon, some people may have allergies to nuts or other food items, known as an anaphylactic reaction. If so, these can trigger severe asthma attacks.
There is increased inflammation in the linings of the airways, which swell.
The airways produce sticky mucus or phlegm, which can further narrow the airways.
The passages of the airways narrow, making it more difficult for the air to pass through and, therefore, more difficult to breathe. This can cause the characteristic wheezy noise, although not everyone with asthma will wheeze. In a life-threatening attack, there may not be a wheezy sound.
An asthma attack can happen at any time. However there are usually warning signs for a couple of days before. These include symptoms getting worse, especially during the night, and needing to use the reliever inhaler more and more.
Asthma can be life threatening. See Asthma - treatment to find out more about how to manage your asthma. Speak to your doctor or asthma nurse for further advice.
If you or someone else is having a severe asthma attack and cannot breathe, dial 999 immediately for emergency medical treatment.
Diagnosis
There is no simple test to diagnose asthma. Your GP can normally diagnose asthma by asking you about your symptoms and doing tests in the surgery. They will want to know when symptoms happen and how often, and if you have noticed anything that might trigger them.
Your GP will want to know if you have been taking any medicines, what your occupation is, whether you smoke or are exposed to passive smoking, and details about your work and home environment. This could help identify the possible triggers of your asthma.
If your GP suspects you may have asthma, a number of tests can be carried out to confirm the diagnosis.
Spirometry
To assess how well your lungs work, a breathing test called spirometry is carried out. You will be asked to breathe into a machine called a spirometer.
The spirometer takes two measurements: the volume of air you can breathe out in one second (called the forced expiratory volume in one second or FEV1) and the total amount of air you breathe out (called the forced vital capacity or FVC).
You may be asked to breathe out a few times to get a consistent reading.
The readings are compared with normal measurements for your age, which can show if your airways are obstructed.
Sometimes an initial set of measurements is taken, then you are given a medicine to open up your airways (a reliever inhaler) to see if this improves your breathing. Another reading is taken and, if it is much higher after taking the medicine, this can support the diagnosis.
Peak expiratory flow rate test
A small hand-held device known as a peak flow meter can be used to measure how fast you can blow air out of your lungs in one breath. This is your peak expiratory flow rate (PEFR), and the test is usually called a peak flow test.
You may be given a peak flow meter to take home and a diary to record measurements of your peak flow. Your diary may also have a space to record your symptoms. This will help you recognise when your asthma is getting worse.
Other tests
Some people, but not all, may need more tests. The tests may confirm the diagnosis of asthma or help diagnose a different condition. This will help you and your doctor plan your treatment.
Airway responsiveness tests
This test is used to see how your airways react when they come into contact with a trigger. You will be asked to breathe in histamine or methacholine, which will deliberately trigger asthma symptoms and cause the airways to narrow. In children, exercise is sometimes used as a trigger.
You then blow into the spriometer to measure how much your FEV1 and FVC have changed in response to breathing in the trigger. If there is a significant decrease in these measurements, you may have asthma.
Tests of airway inflammation
Phlegm sample. The doctor may take a sample of phlegm to check whether you have inflammation in the lungs.
Nitric oxide concentration. As you breathe out, the level of nitric oxide in your breath is measured. A high level of nitric oxide can be a sign of airway inflammation.
Tests of allergy
Skin testing or a blood test can be helpful to confirm whether your asthma is associated with specific allergies, for example to dust mites, pollen or foods.
