Asthma is a common condition that affects the airways. The typical symptoms are wheeze, cough, chest tightness, and shortness of breath. Symptoms can range from mild to severe. Treatment usually works well to ease and prevent symptoms. Treatment is usually with inhalers. A typical person with asthma may take a preventer inhaler every day (to prevent symptoms developing) and use a reliever inhaler as and when required (if symptoms flare up). Asthma is a condition that affects the smaller airways (bronchioles) of the lungs. From time to time the airways narrow (constrict) in people who have asthma. This causes the typical symptoms. The extent of the narrowing, and how long each episode lasts, can vary greatly.

Asthma can start at any age but it most commonly starts in childhood. At least 1 in 10 children and 1 in 20 adults have asthma. Asthma runs in some families but many people with asthma have no other family members affected. The common symptoms are cough and wheeze. You may also become breathless and develop a feeling of chest tightness. Symptoms can range from mild to severe between different people and at different times in the same person. Each episode of symptoms may last just an hour or so, or persist for days or weeks unless treated.

The symptoms of asthma are caused by inflammation in the airways, which may be triggered by different things in different people. The inflammation causes the muscles around the airways to squeeze (contract). This causes narrowing of the airways. It is then more difficult for air to get in and out of the lungs. This leads to wheezing and breathlessness. The inflammation also causes the lining of the airways to make extra mucus which causes cough and further obstruction to airflow. Asthma symptoms may flare up from time to time. There is often no obvious reason why symptoms flare up. However, some people find that symptoms are triggered, or made worse, in certain situations. It may be possible to avoid certain triggers, which may help to reduce symptoms. Some people only develop symptoms when exposed to a certain trigger - for example, exercise-induced asthma.

Sometimes symptoms are typical and the diagnosis is easily made by a doctor. If there is doubt then some simple tests may be arranged. The two commonly used tests are called spirometry and assessment with a peak flow meter. Spirometry is a test which measures how much air you can blow out into a machine called a spirometer. Two results are important:

• The amount of air you can blow out in one second - called forced expiratory volume in one second (FEV1).
• The total amount you can blow out in one breath - called forced vital capacity (FVC).

Your age, height and sex affect your lung volume. So, your results are compared with the average predicted for your age, height and sex. A value is calculated from the amount of air that you can blow out in one second divided by the total amount of air that you blow out in one breath (called FEV1:FVC ratio). A low value indicates that you have narrowed airways which are typical in asthma (but a low value can occur in other conditions too). Therefore, spirometry may be repeated after treatment. An improvement in the value after treatment to open up the airways, is typical of asthma.

A peak flow meter is a small device that you blow into. A doctor or nurse will show you how. It measures the speed of air that you can blow out of your lungs. No matter how strong you are, if your airways are narrowed, your peak flow reading will be lower than expected for your age, size and sex. If you have untreated asthma then you will normally have low and variable peak flow readings. Also, peak flow readings in the morning are usually lower than in the evening if you have asthma. You may be asked to keep a diary over two weeks or so of peak flow readings. Typically, a person with asthma will usually have low and variable peak flow readings over several days. Peak flow readings improve when the narrowed airways are opened up with treatment. Regular peak flow readings can be used to help assess how well treatment is working.

Most people with asthma are treated with inhalers. Inhalers deliver a small dose of medicine directly to the airways. The dose is enough to treat the airways. However, the amount of medicine that gets into the rest of your body is small so side-effects are unlikely, or minor. A reliever inhaler is taken as required to ease symptoms. The medicine in a reliever inhaler relaxes the muscle in the airways. This makes the airways open wider and symptoms usually quickly ease. These medicines are also called bronchodilators, as they widen (dilate) the bronchi and airways (bronchioles). A preventer inhaler is taken every day to prevent symptoms from developing. The medicine commonly used in preventer inhalers is a steroid. Steroids work by reducing the inflammation in the airways. When the inflammation has gone, the airways are much less likely to become narrow and cause symptoms. It takes 7-14 days for the steroid in a preventer inhaler to build up its effect. Therefore, it will not give any immediate relief of symptoms. However, after a week or so of treatment, the symptoms have often gone, or are much reduced. It can take up to six weeks for maximum benefit. You should then continue with the preventer inhaler every day even when your symptoms have gone - to prevent symptoms from coming back. You should then not need to use a reliever inhaler very often (if at all).

A long-acting bronchodilator may be advised in addition to a preventer inhaler. Long-acting bronchodilators relieve symptoms as they widen the lung airways (bronchi) but work for longer than reliever inhalers. The medicines in these inhalers work for up to 12 hours after each dose has been taken. A long-acting bronchodilator may be needed if symptoms are not fully controlled by the preventer inhaler alone.

Spacer devices are used with some types of inhaler. They are commonly used by children; however, many adults also use them. A spacer is like a small plastic chamber that attaches to the inhaler. It holds the medicine like a reservoir when the inhaler is pressed. A valve at the mouth end ensures that the medicine is kept within the spacer until you breathe in. When you breathe out, the valve closes. So, you don't need to have good co-ordination to inhale the medicine if you use a spacer device. A face mask can be fitted on to some types of spacers instead of a mouthpiece. This is sometimes done for young children and babies who can then use the inhaler simply by breathing in and out normally through the mask.

Omalizumab is a medicine that is only used in a small number of people who have severe persistent allergic asthma that has not been controlled by other treatments. So, it is not a common treatment. It is given by injection. It works by interfering with the immune system to reduce inflammation in the airways which is present in asthma. Treatment with omalizumab can only be started by a specialist.

There is no once-and-for-all cure. However, about half of the children who develop asthma grow out of it by the time they are adults. For many adults, asthma is variable with some good spells and some spells that are not so good. Some people are worse in the winter months and some are worse in the hay fever season. Although not curable, asthma is treatable. Stepping up the treatment for a while during bad spells will often control symptoms.

More information can be found in the following ATS files below.