These are recognized as causes of asthma because they cause inflammation of the respiratory passages and ‘over-reactiveness’ of the airways. The symptoms caused by inducers normally last longer, and are less easily reversible than those caused by triggers.
The most common inducers are allergens and respiratory viral infections. Allergens are substances that cause an allergic reaction in the body. Allergic reactions in the lungs play an active role in inducing asthma. More than seventy-five per cent of children with asthma also have allergies. They are more likely to develop allergic conditions such as eczema or the common cold. Eczema is a skin disease that results in dry and scaling skin patches.
Asthma combined with allergy normally occurs before the age of thirty, but about half the adults above thirty with asthma also have allergy. Sometimes the allergy may build up gradually in the body over several years. When it becomes strong, symptoms of asthma develop. Some people develop an allergy when they change their jobs or shift to another geographical location.
It is important to remember that not everyone who has asthma has allergies. The reason for this is not clear. However, lifestyle, living conditions and work environment can affect chemical reactions that cause allergy and asthma.
An allergy often affects several members of the same family. Although people are not born with allergies, they can inherit the tendency to develop allergies. Environmental factors play a very important role in the development of allergy with asthma.