What is anaphylaxis?

Anaphylaxis is sometimes life threatening and is always a medical emergency.
It is the worst kind of allergic reaction. It usually happens 20 minutes to 2 hours after with a food, insect or medicine. Often a person is already allergic to the thing they have an anaphylactic reaction to.
This kind of reaction often involves a person's breathing, blood flow and sometimes the stomach.
Immediate treatment with adrenaline (EpiPen) can help to decrease the reaction but urgent medical attention is still needed.