Anaphylaxis is a condition where there is a serious and rapid allergic reactions to a substance (food or medications) or insect bites and stings. The allergic reaction usually involves more than one part of the body. If severe enough this condition can kill. Allergic reactions that occur almost immediately tend to be the most severe.

Causes:

• Wasp and bee stings:

When a sting causes faintness, breathing difficulties, rashes or swelling on a part of the body which has not been stung. If you just get swelling at the sting site, you are probably not going to have anaphylaxis if stung again.
• Exercise: 
  Exercise can cause reactions in some and so may exercise after food.
• Foods:
  Especially nuts, some kinds of fruits like bananas, avocados, kiwi fruit, figs, oranges etc. Vegetables including potatoes and tomatoes.
  People may get anaphylaxis from fish and some spices.
• Drugs and Medications:
  Penicillin's, Anaesthetic drugs, Aspirin and other painkillers.
• Latex:
  Mainly latex gloves, condoms and medical products. but also in many things encountered in daily life. Sufferers are nearly always health care or food preparation workers who have occupational contact with latex.
• Unknown:
  Some sufferers have unexplained attacks where no cause is found. This is called 'idiopathic anaphylaxis'. This term means, "they don't know the cause".

• An itchy rash.
• Faintness and unconsciousness this is due to very low blood pressure.
• Swelling
• Swelling in the throat, causing breathing and swallowing difficulties
• Asthma symptoms
• Vomiting
• Abdominal pains, diarrhoea and cramping
• Swelling or tingling feeling in the lips or mouth.