It's an extreme response to an allergen.

A life-threatening allergic reaction (anaphylaxis) is a severe reaction to a specific allergen, or allergic trigger. Common triggers can include but are not limited to food, biting or stinging insects, medications and latex. Exercise-induced anaphylaxis is also possible, and sometimes anaphylaxis has no apparent cause at all (this is known as idiopathic anaphylaxis).

Click on one of the following triggers to learn more about it:

What happens inside the body when anaphylaxis occurs?

Anaphylaxis occurs when the body perceives a trigger as a threat and starts forming antibodies (special proteins made by the body’s immune system) to defend itself. These antibodies cause the release of certain molecules that produce the immediate symptoms of anaphylaxis.