This raises the challenging possibility that we may be able to prevent asthma by altering our environment. Treating asthma by removing the allergic cause can be very successful when the cause is easy to remove, as when the allergic cause is a dust or vapour inhaled only at work. The same is true when the cause is a domestic pet such as a cat or dog, though reluctance to part with a loved pet commonly prevents success. But the commonest cause of asthma is allergy to house dust mites, and getting rid of mites sufficiently to make a big difference to asthma requires a major change in lifestyle and is expensive. There may be future treatments which abolish or diminish the allergy process in the body.
Asthma changes progressively during the lifetime of someone who has it.
Children may grow out of asthma, but some of these grow back into it later. In people who have lifelong asthma the obstruction to the airways comes to be less completely relieved by drugs. One of the aims of treatment, according to current concepts, is to minimise the inflammation in the lung airways which we believe causes this long-term worsening. We've provided a widely used chart from which you can read off your predicted normal Peak Flow for your sex, age and height. A cause is something without which you would not be asthmatic.