Allergic diseases are due to a sensitivity, which certain persons develop to normally harmless substances. A susceptible person who is exposed to these substances has a symptom of the disorder in the respiratory organs, the digestive organs or the skin. The most common of these disorders are hay fever, asthma, stomach and intestinal disturbances, rashes due to contact, eczema, and hives.

Allergic diseases are due to a sensitivity, which certain persons develop to normally harmless substances. A susceptible person who is exposed to these substances has a symptom of a disorder in the respiratory organs, the digestive organs or the skin. The most common of these disorders are hay fever, asthma, stomach and intestinal disturbances, rashes due to contact, eczema, and hives.

Substances capable of producing allergy are called allergens. When a particular allergen is absorbed by the body, the minute cells in the tissues manufacture special substances antibodies which interact with it. This produces an irritation in the susceptible tissues; for example, the nose, the bronchial tubes or the skin.

The range and variety of things to which susceptible persons may become sensitive are almost endless. Sensitivity usually occurs only after repeated exposure to the substance. Allergy patients may be sensitive to more than one allergen.

ALLERGENS ENTER THE BODY BY VARIOUS ROUTES:

1. By being swallowed-food, drinks and drugs.
2. By being inhaled-dust, pollens, fumes.
3. By external contact-clothes, cosmetics, industrial products.
4. By injection-drugs and serums.

The tendency to become sensitized or allergic to some foreign substance is usually inherited. It is a peculiarity of the constitution just as the coloring of the eyes. It also appears that what one will become sensitive to depends in part upon the amount of exposure to any foreign substance or allergen. Thus, an individual who has inherited this tendency to become sensitive to foreign substances may become sensitive to cow’s milk shortly after birth, may become sensitive to dog hair at the age of six years after acquiring a dog and throughout his life may develop new sensitivities as his new environment subjects him to new exposures. The previous sensitivities may remain or may be lost.