About five percent of the population has a genetic tendency to develop allergies. The most common allergens are proteins which occur in nature. However, clinical allergy is diagnosed by a combination of history, physical examination, and special tests. Respiratory allergy is one kind of hypersensitivity. Once recognized, reactive airway patients can be helped with a lifelong medical program and strict avoidance of specific triggering substances.
Extrinsic asthma refers to a respiratory reaction to specific allergens in the environment.
Environmental allergens may include manmade substances such as chemicals and natural substances such as airborne mold from peanuts or cheese. There are allergic reactions to microbes, dander, insect venoms, house dust, and plant products such as pollens, wood dust, thorns and sap. Allergic responses to prescribed drugs are well known. Many causes of extrinsic asthma can be diagnosed with skin tests and can be corrected or modified by a series of shots called desensitization. There are at least five major types of skin reactions.