Allergy may be defined as a hypersensitivity reaction in a person to an exposure that does not affect most people. 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.