Anaphylaxis

Allergies are the body's response to a substance called an allergen. Allergens themselves may not be harmful. However, in some people, things that are usually harmless can provoke a reaction. Allergic reactions vary and include many different symptoms. Some reactions can be severe and threaten life - this is called anaphylaxis. Some people have a condition called atopy which makes them prone to allergies. Testing for allergies can be complicated, and is not always needed. Medication, including antihistamines, can work well for many types of allergy.

What is an allergy?

An allergy is a response by the body's immune system to something (called anallergen) that is not necessarily harmful in itself. Certain people are sensitive to this allergen and have a reaction when exposed to it. Some allergic reactions are mild and harmless, but others are severe and potentially life-threatening (anaphylaxis).