Asthma is a growing worldwide problem. Asthma is classified in various ways. Traditionally, doctors have categorised asthma into two general groups, Extrinsic (allergic) asthma and Intrinsic (non-allergic) asthma, depending upon the types of stimuli that flare up these attacks.
Extrinsic (allergic) asthma:
More prevalent in the younger age group, extrinsic asthma is caused by the immune system’s response to inhaled allergens such as pollen, animal dander or dust mite particles. People with allergic asthma frequently have other allergy-related problems such as hay fever, rhinitis, skin rashes, eczema.
Extrinsic asthma responds quite well to the use of inhaled steroids as these suppress the immune system.
Intrinsic (non-allergic) asthma
Intrinsic asthma is caused by anything except an allergy. It may be caused by an infection, stress, laughter, exercise, cold air, food preservatives or a host of other factors.
Treatment of intrinsic asthma is not easy as it may not be known what triggers the asthma in the first place and therefore avoiding triggers can be impossible.
Mixed asthma
As the name suggests, mixed asthma is a mixture of intrinsic and extrinsic asthma. Not only do people react to some allergies but their asthma is also triggered by other factors.

It is common for someone with an extrinsic form of asthma to experience attacks when he has a chest infection - an intrinsic trigger.