The term “Intrinsic” asthma was first introduced in 1940 in order to emphasize that this type is distinct from allergic extrinsic asthma with respect to the absence of an obvious precipitating exogenous cause.
Characteristically, “Intrinsic” asthmatics have a later onset of symptoms. A lot of them have “late-onset” asthma after middle-age. Often, the disease has a more severe clinical course than those with allergic asthma. Further, there is usually no family history of asthma or allergy and the female sex appears to be affected more often. In addition, a respiratory flu-like disease or cold often precedes the development of symptoms in intrinsic asthma. Moreover, nasal polyps and aspirin sensitivity seems to occur more frequently in this group of asthmatics. Finally, it appears to have a different immuno-pathological basis from extrinsic asthma. It is triggered by factors NOT related to allergies.
It is quite challenging to treat intrinsic asthma since the causative agent is not fully known, unlike in extrinsic asthma in which avoidance of allergens improves the situation. There are a number of triggers to intrinsic asthma:
- Chemicals like cigarette, smoke, aspirin, cleaning agents or other irritants
- Cold air, dry air
- Extreme of emotional feelings like laughing, crying, anxiety, stress