These chemicals include histamine and leukotrienes. They act on tissues in the body and create the allergic response. Allergies can affect nearly any part of the body. The nose, sinuses, eyes, lungs, and skin are most affected. No one knows for sure why some people have allergies and others do not.
Family history appears to play a part in a person's development of allergies.
There is little that can be done to prevent allergies from developing. Once they have developed, flare-ups can be reduced by allergy shots. These shots decrease a person's sensitivity to the allergen. Allergies are generally diagnosed with a medical history and physical examination. Blood tests and skin testing can be done to identify specific allergens.