What causes allergy?

Allergy happens because of an educational error of the bodies’ immune system. Normally, the body uses its immune system to defend itself against foreign invaders like bacteria and viruses through experience – by encountering, battling, and then remembering one enemy after another. The immune system is better equipped to fight off invaders that it has seen before than those it first encounters. This process is accomplished through special ‘memory’ white blood cells and unique protein molecules called antibodies.

Although there are many classes of antibodies, only one is involved in all true allergic reactions: IgE (also known as ‘the allergy antibody’). National Jewish discovered the IgE antibody in 1965.

Allergic reactions occur when the immune system misidentifies harmless foreign substances and reacts to them as if they were as harmful. These substances are called allergens. Common pollens, mold spores, house dust mites, cockroaches, and animal dander (shed skin, fur, or feathers) are among the allergens that most frequently cause problems. Allergic reactions to allergens such as insect venom, latex, and certain types of food or medications are more rare.

Irritants like tobacco smoke, perfumes, or strong cleaning products can make allergy symptoms worse and trigger asthma, but are not considered true allergens themselves.

How did I become allergic?

To become allergic to anything, a person must first have a genetic predisposition for allergy. Then, at least two exposures to an allergen are required: the primary exposure, and the secondary exposure.

Read a short story about how a child in a small town becomes allergic to ragweed pollen.

Why am I allergic to only certain things?

Some people are allergic to lots of things, others to very few things. The environment, genetics, and the immune system all play a role.

Why are allergy and asthma on the rise?

Asthma and allergies have both been on the rise for several decades - especially in developed countries. The hygiene hypothesis is one explanation for this increase: compared with the past, children living in these countries today are exposed to fewer infectious organisms, which are necessary to properly train their developing immune systems. As a result, their immune systems overreact to relatively harmless allergens, leading to allergies and asthma.

This information has been approved by David Tinkelman, M.D. (February 2006).