What Are Allergies And Who Is At Risk?

Rarely is a medical term used as frequently and casually as "allergy." It pops up in everyday conversation to describe what we don't like - school, work or just about anything else. But medically speaking, allergy has a very specific meaning: it is a biologic reaction to something your body doesn't like.

Allergies are an abnormal sensitivity to allergens, which can be ingested, inhaled or touched, and which most other people can tolerate without trouble. Usually, the immune system does not waste its time by reacting against nontoxic substances in our environment, using its various weapons to instead fight the viruses, bacteria, fungi and other parasites that threaten health.

One set of weapons in your immune system (including IgE antibodies, mast cells, eosinophils, and type 2 helper T cells) is your body's branch of defense against worms, parasite larvae, and certain fungi. In some areas of the world, we couldn't live in full health without this function of our immune system. But in people with allergies, this set of weapons launches attacks against a perfectly harmless substance, such as ragweed pollen, animal dander or certain foods or drugs. The word allergy comes from the Greek allos, meaning other. It was first used in 1906 to refer to an altered reaction in the body's immune system.

Mild allergies are more of a nuisance than a threat. They can requiring your vigilance so that you avoid exposure, or they may require medical treatment. Occasionally, allergies can be life threatening.