Allergy - This is when the body's immune response reacts in a way which is abnormal. It does this in response to tiny particles of something you come into contact with. The substance is called the allergen. There are many know allergens. Examples include pollen, dust and mould spores.

Asthma Assistant Application - This is a computer program which has been designed for you to monitor and record your asthma. This can help you in many ways including taking control of your asthma.

Atopy - This is the tendency to develop an allergy. It does not necessarily mean you will develop the allergy, but if you are atopic you have the tendency to do so. Allergic conditions include eczema and hayfever as well as asthma.

Breathlessness - This is one of the main symptoms of asthma. It can feel very frightening as you cannot get all the air you need. Different people describe in in different ways, such as 'gasping for breath', 'feeling suffocated' or 'feeling strangled'.

Brittle asthma - This is a rare form of asthma where people get little or no warning of an asthma attack. They can go from being perfectly well to having a severe life-threatening attack in the space of a few minutes.

Bronchiolitis - This is a chest infection which is caused by a virus and occurs in babies. It can leave the baby coughing and wheezing for many months or even years following the infection. It can sometimes be mistaken for asthma. It can also trigger the first episode of asthma.

Bronchoconstriction - This is tightening of the muscles (constriction) around the airways (called bronchi or bronchioles) which occurs in asthma. This constriction narrows the airways. You may hear it referred to as bronchospasm.

Cardiac Asthma - This term is now rarely used and is completely different to the asthma we are concerned with here. Cardiac asthma has the same symptoms but these are caused by heart failure and not the changes in the lungs which is the bronchial asthma we are concerned with here.

Complementary therapy - These are non-medical treatments which are used alongside conventional medications. They include Yoga, T'ai Chi and Acupressure.

Coughing - This is one of the main symptoms of asthma. The cough in asthma is the same as the cough you get if you have a cold or chest infection. It can be quite dry or mucus may produced.

Chest tightness - This is one of the main symptoms of asthma. Chest tightness is often described as a feeling of 'congestion' in the chest or a heaviness. Less commonly it can be felt as chest pain.

Cystic fibrosis - This is an hereditary condition which results in nutrients from food being poorly absorbed in the gut and too much mucus produced in the lungs.

Diurnal Variation - In the context of asthma, this is the difference between how wide the airways in the lungs are if measured twelve hours apart. Our airways narrow and open naturally over each 24 hour period even in people who do not have asthma. In people with asthma, the variation is much greater. Generally, the greater the diurnal variation, the more unstable the person's asthma. Diurnal variation is usually measured in asthma by taking morning and evening peak flow readings. There are a number of ways of calculating diurnal variation.

Eczema - This is an allergy of the skin, which shows patches of red, itchy inflammation which may weep or blister.

Evening peak flow - This is your peak flow measured in the evening. If you are monitoring your asthma at home, you would normally take peak flow at about the same time each day (morning and evening) before using any medications for asthma if you need them.

Exercise-induced asthma - If people exercise and it brings on their asthma symptoms, this is said to be exercise-induced asthma. Exercise is a very common trigger of symptoms affecting 70-80% of people with the condition.

Extrinsic asthma - People whose symptoms are brought on by one or more external factors such as pollen or dust, are said to have allergic or extrinsic asthma. This is particularly common in children who develop asthma.

Green zone - Different zones are often used in managing asthma to give people an idea as to how well they are. Most of the time the zone ranges are based on peak flow readings. There are usually three zones which are coloured green, yellow and red going from good to bad in the same order. If your peak flow remains in your green zone your asthma is well. The range used here is usually between 100% and 80% of your personal best peak flow.

hay fever - This is an allergy caused by pollens. It affects the eyes and nose.

Inflammation - This is the body's response to some kind of injury. It is the body's way of protecting itself and helping it to heal. In asthma, the linings of the airways become over-reactive and inflamed. This makes them very sensitive and irritable so that the slightest thing will trigger asthma symptoms.

Intrinsic asthma - People whose symptoms do not seem to be brought on by anything external are said to have non-allergic or intrinsic asthma. It is more common in people who develop asthma for the first time in adulthood. Symptoms are more likely to be triggered by, for example, exercise, emotion or some drugs such as aspirin.

Morning dip - People with asthma often showed a marked drop in peak flow in the morning: this is called the morning dip. The exact reason why this happens is unknown. There are many ideas as to why it may occur, including acid leaking from the gullet at night, posture during sleep, low levels of body steroids at night and other theories, but it still remains a mystery!

Morning peak flow - This is your peak flow measured in the morning. If you are monitoring your asthma at home, you would normally take peak flow at about the same time each day (morning and evening) before using any medications for asthma if you need them.

Mucus - This is a substance produced by certain cells (the building bricks of the human body) lining different parts of the body. In asthma, there is often too much mucus produced by the cells lining the airways; this is a direct result of the inflammation which is present. This mucus, which is often coughed up, can be much harder than normal, and can contribute to the narrowing of the airways in asthma.

Nebuliser - This is a machine which breaks up a liquid form of asthma medication into a fine mist. The mist is then breathed in through a mask or mouthpiece. Nebulisers are usually used by people with severe or brittle asthma and also by doctors to treat and asthma attack. You should always have very careful instruction on how and when to use a nebuliser if you have one at home, as they can be dangerous if used incorrectly. This danger is because people can over-rely on them and not seek help early enough when their asthma is getting worse.

Nocturnal asthma - This term is often used to describe asthma symptoms which occur in the night. Disturbed sleep from asthma symptoms is a definite sign of poor asthma control.

Occupational asthma - This is asthma caused solely by something where you work. There are over 200 substances currently known and recognised as a cause of occupational asthma. Examples are: isocyanates, latex and some wood dusts.

Peak flow - This is a measure of how hard and fast you can blow the air out of your lungs. If your asthma is well and your airways are open, you will be able to blow out fast and your peak flow reading will be normal. If your asthma is not so good, your airways will be narrowed; you will not be able to blow out so fast and your peak flow reading be lower.

Peak flow meter - Peak flow is measured using a hand held instrument called a peak flow meter. When you blow down the meter it measures the speed of the air as it passes through the hollow centre of the meter; there is a scale in litres per minute (abbreviated to l/min).

Personal best peak flow - This is your highest peak flow when you are well and your asthma is as well controlled as possible. It is usually measured in the middle of the day after using your immediate reliever medication.

Predicted peak flow - Studies have been carried out measuring peak flow in people who do not have asthma, of different age, sex and height. These 'predicted peak flow' values are commonly used as a reference point for people who have asthma, to see how close they are to what is considered a 'normal' value i.e. what they would be expected to achieve if they did not have asthma.

Preventer - This is a medication which prevents asthma symptoms from coming on. It works by reducing the inflammation present in the airways which is responsible for asthma symptoms. Preventers must be used regularly every day for them to work effectively.

Red zone - Different zones are often used in managing asthma to give people an idea as to how well they are. Most of the time the zone ranges are based on peak flow readings. There are usually three zones which are coloured green, yellow and red going from good to bad in the same order. If your peak flow falls into your red zone it usually means your asthma is very severe and you need to get help. You should not spend any of your time in your Red Zone!

Reliever - This is a medication which is used to treat asthma symptoms. It works by relaxing the muscles around the airways to open them up, thereby relieving the symptoms and enabling you to breathe more easily.

Reversibility test - This is a test the doctor may carry out to help diagnose whether or not you have asthma. The doctor will measure your peak flow, then give you some reliever medication. When the reliever has had time to work maximally (usually about 20 minutes) s/he will then get you to repeat you peak flow. If the value has increased by 15% or more this may mean asthma.

Self-management plan - This is an agreed set of guidelines between you and your doctor or asthma nurse on 'what to do when.' It basically gives you some signs to work from so that you can identify when you asthma is getting worse. The plan tells you exactly what to do depending on how bad it is.

Spacer - This is a chamber which fits on to the end of an aerosol inhaler. Spacers come in different shapes and sizes, some with masks and others with mouthpieces. They are a very useful addition to the aerosol for taking medication, particularly suitable for young children and people suffering from an asthma attack. Other benefits include increasing the amount of medication which reaches the lungs and to help reduce the risk of side effects.

Spirometer - This is an instrument similar to a peak flow meter. It also measures how fast you can blow out but gives additional information compared to a peak flow meter. The spirometer is sometimes used by doctors when diagnosing asthma or at a check-up.

Stable peak flow - Your peak flow is stable when your readings remain in your green zone (usually between 80% and 100% of your personal best peak flow), you have no morning dip and your diurnal variation is not greater than 20%.

Thrush - Also called candida, this is a fungal infection in the mouth which can be caused by using steroid based inhalers. It is a localised infection and is unusual when low dose inhalers are used. It can be prevented by using a spacer, brushing teeth and rinsing the mouth following inhaler use.

Trigger - A trigger is anything which brings on or worsens the symptoms of asthma. Most people with asthma have more than one triggers. Different people may have different sets of triggers. Examples of common triggers are pollen, exercise, the common cold and the house dust mite.

Unstable peak flow - Your peak flow is unstable when your readings regularly fall into your yellow zone (usually between 50% and 80% of your personal best peak flow), you have signs of a morning dip and your diurnal variation is greater than 20%. An unstable peak flow means your asthma is uncontrolled and you are at risk of an asthma attack.

Yellow zone - Different zones are often used in managing asthma to give people an idea as to how well they are. Most of the time the zone ranges are based on peak flow readings. There are usually three zones which are coloured green, yellow and red going from good to bad in the same order. If your peak flow falls into your yellow zone it may mean your asthma is getting worse. The range used here is usually 80% to 50% of personal best peak flow.

Wheezing - This is a noise that can sometimes be heard in asthma. It is best described as a whistling or hissing sound. You might hear it all the time when breathing in and out or only some of the time during each breath. The noise can be quite musical and will vary in pitch.

Glossary of General Asthma Terms