Allergies and Your Immune System

An allergy (also known as an "immediate hypersensitivity reaction") results when the immune system is sensitized to a foreign protein. The body responds and produces antibodies (IgE), which recognize and bind to the protein. This immune response is responsible for the allergic reaction.

What happens during an allergic reaction? In simple terms, the body's immune system reacts to a substance it mistakes for an invader. The immune system releases a chemical called immunogoblin E (IgE) that in turn triggers the release of histamines. The histamine reaction produces the symptoms associated with allergies.

The severity of the histamine reaction to these substances, called allergens, varies among individuals. Some people have very mild allergies. For others, even a trace amount of a particular allergen is enough to trigger a serious reaction in some people.

Common allergens include dust mites, mold, pollen, pet dander, bee venom, poison ivy, peanuts, certain antibiotics, and latex.

This section is divided into multiple articles covering topics such as common allergens in your home and food allergies, with each listed in the menu to the left. To research other allergy or health topics, please use the morefocus search tool, or see the related topics listed to the left.