Asthma is the term which describes a specific type of breathing problem that arises due to narrowing of the airways. This narrowing is caused when certain natural chemicals within the body are released, usually in response to infection or when the patient comes into contact with something that they are allergic to. The same release of chemicals also leads to inflammation of the airways.

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If the breathing tubes are narrow it is more difficult to get air in and out of the lungs. This causes a sensation of breathlessness and tightness in the chest. With the narrowed airways there may be wheezing and a dry irritating cough, which can sometimes be triggered in the cold, extreme heat, or with exercise. It can sometimes just occur at night, disturbing sleep. In some people (especially children), a cough may be the main symptom.

When do these symptoms arise?

One of the characteristics of asthma is that the symptoms are variable, with some days being better, and others worse. This will relate to both the treatment that is being given (to increase number of good days) and the environmental exposure to triggers that may worsen asthma (increase number of bad days). In addition to this symptoms may vary spontaneously throughout the day. Everyone's airways are narrowest in the small hours of the morning so this will be the worst time in asthma. If the asthma is not well controlled with treatment, waking at night due to breathlessness, wheeze, chest tightness or cough is often present.

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What triggers make asthma worse?

Some substances specifically trigger asthma; other substances just act as irritants when the airways are already over-reactive due to asthma. These irritants usually only transiently worsen the asthma (i.e. 30-60 minutes) whereas those specific factors that trigger asthma may do so for days or weeks.

Specific factors include allergens such as house dust mite droppings in dust, pets such as cats and dogs, pollens such as tree and grass, and moulds, as well as infection such as the common cold. The allergens mentioned will only worsen asthma if a person is specifically sensitive to that substance. Exposure to chemicals in the work environment can also lead to the development of asthma in some people.

Non-specific irritants include cigarette smoke, car exhaust fumes, perfumes, aerosol sprays such as hair lacquer or furniture polish, change in temperature - especially going from a warm to a cold environment - paint or cooking odours, and exercise.

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Who gets asthma?

Asthma can arise at any age but about half of asthmatics develop symptoms before the age of 10 years. It then tends to become less severe in teenagers but can come back in later life. Much of the asthma in young children relates to cold viruses, and children are the most likely to 'grow out of it' as they get older.

Asthma is twice as common in boys as girls, perhaps because infant boys have smaller airways.

It tends to run in families so if there is a family history of asthma or of other allergies such as hay fever or eczema, an individual may be more likely to develop asthma. In adults who develop asthma for the first time in their 30s, 40s and 50s (late onset asthma) allergy is much less common. In late onset asthma a proportion may have asthma related to exposure to chemicals in their work environment, and some may be sensitive to chemicals in drugs or their diet (i.e. aspirin-sensitive asthma or salicylate intolerance). In some it may follow a severe chest infection.

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Is asthma serious?

It is important to understand that while asthma can be very troublesome, a majority of people with the condition either do not require treatment or have symptoms which are easily controlled on very little medication. There are many successful sportsmen and women who have asthma. If you have recently been diagnosed with asthma, you should not panic.

Symptoms may not present all the time and there may be no signs of the condition between attacks. If you attend your doctor when well, he or she may not find any evidence of the disease. However, he or she will be able to exclude other chest problems and arrange further tests for asthma.

There are some people whose asthma does not respond fully to treatment and this can result in some chronic symptoms despite regular medication. The majority lead active lives despite their condition. Usually it is possible to avoid troublesome asthma by avoiding trigger factors such as allergens, and by using medication.

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How is asthma diagnosed?

The diagnosis of asthma is based on two main features: the presence of those symptoms already described, and the variability in the airway narrowing and symptoms. This
variability is usually measured by home monitoring of lung function with a peak flow meter - a simple device to measure the flow of air out of the lungs. If, over a period of time, the morning and evening values vary by more than 15%, or treatment for asthma improves the readings by more than this value, this is indicative of asthma. As the airways are narrower at night, the morning value is usually lower than the evening measurement.

Lung function tests are useful in assessing the breathing in more detail. These involve breathing into machines which record the air flow and volumes during various breathing manoeuvres. A reversibility test may be used to assess your response to an asthma inhaler such as salbutamol. In asthma there is usually a marked improvement in lung function measurements after a dose of medication. Your GP may be able to perform or arrange lung function tests but they are not always necessary. More complex lung function tests are only available in hospital laboratories and are indicated in special circumstances.

Allergy skin tests are vital in finding out whether your asthma is due to inhalant allergens. You may need a referral to a specialist centre although some GPs are able to offer these tests. Drops of a number of allergen extracts are placed on the skin (usually the forearm) and the skin is pricked lightly through the drops. A positive reaction will cause some itching and a bump at the site within 10 minutes. A blood test for allergic antibodies to various allergens is an alternative but in some cases can be less likely to detect an allergy than skin tests.

Sometimes, challenge tests may be necessary. These are used in more difficult asthma cases, in specialist centres, and are very carefully controlled to avoid excessive wheeziness. Test substances which can cause wheezing may be administered in gradually increasing doses as a fine mist (nebulised). Exercise or aspirin challenges may also be used occasionally.

A chest x-ray may be indicated to confirm that there is no other cause for your symptoms.

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How should asthma be treated?

The treatment of allergic asthma is based on allergen avoidance and drug treatment.

Allergen avoidance should concentrate on reducing exposure to housedust mite, mould spores, animal dander and (in some people) pollens. Remember that many chemicals will irritate airways in the asthmatic patient, and exposure to cigarette smoke, traffic fumes, sprays, perfumes, solvents, paint fumes and cleaning chemicals should also be considered.

Drug treatment is directed towards the two main components of asthma: the airway inflammation and the muscle narrowing around the airways. For very mild asthma in which symptoms only arise occasionally, a reliever inhaler to relax the airway muscles when needed is all that is required. If this is needed more than once a week then a regular steroid inhaler to suppress the airway inflammation should be used. If it is not possible to use inhalers then tablets may be available, but inhalers are more effective. In some people with persistent asthma more than one type of preventer therapy, and additional tablet medication, may be needed.

Many asthmatics also suffer from rhinitis ('hay fever' symptoms, for either part of the year, or all year). Proper treatment of their rhinitis can lead to an improvement in their asthma (see our fact sheet Allergic rhinitis).

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Management plans

Your medication requirements may alter over time. If you are going through a period of worsening symptoms, you need to act to control them. It is unwise to allow unusual symptoms to continue as this could lead to an asthma attack. Sometimes it is enough just to increase your inhaled steroid for a few days, which will control the airway inflammation. It will help if you monitor your progress using a peak flow meter (you can get one on prescription). If you are not making good progress, or your symptoms are suddenly worse, you should see your doctor to review your medication. Your doctor or asthma nurse will be able to advise you on the most appropriate management plan for your individual case.

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Asthma clinics

Most GPs review their asthmatic patients from time to time to ensure that their asthma is well-controlled on the most appropriate medication. You should make time to go to appointments. Sometimes asthma control can deteriorate slowly over time so that you do not notice a problem and this can be picked up at your clinic appointment.

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Is there a cure for asthma?

There are new drugs that can help when a patient does not get relief from the usual treatments, but at present none of the treatments for asthma cure the condition. In rare cases of severe allergy, desensitising injections may help but are only available through specialist centres.


Last updated: March 2012