Anaphylaxis is a severe allergic reaction that may begin with itching of the eyes or face, according to WebMD. Then, the condition may progress to more serious symptoms such as difficulty swallowing and breathing, abdominal pains, vomiting, nettle rashes and swelling beneath the skin.
This condition occurs when the immune system develops an allergen-fighting antibody toward a substance that is normally harmless such as food. In severe cases, a person may go into shock which can be fatal. The most common trigger of anaphylaxis is food including tree nuts, peanuts, shellfish, sesame, fish, dairy products and eggs, explains the Anaphylaxis Campaign.