Home About Allergy Manifestation Anaphylaxis

  • Anaphylaxis
  • Causes
  • Signs and Symptoms
  • Treatment

When allergies can be severe and fatal?

Anaphylaxis is a severe allergic reaction - the extreme end of the allergic spectrum – and is potentially life-threatening. Anaphylaxis is a medical emergency, and requires immediate treatment.

In most allergic reactions the resulting chemicals are released locally into the tissues in a particular part of the body (skin, airways, eyes etc.). Thus the symptoms of the allergic reaction usually only occur in this area.

In anaphylaxis, the chemicals that cause the allergic symptoms (e.g. histamine) are released generally in the bloodstream. This causes symptoms around the whole body, usually within minutes of exposure to the trigger substance (allergen) but sometimes hours later. We do not understand why certain allergic people are affected in this way, rather than with 'normal' allergic reactions.


The most common causes of anaphylactic reactions include:

  • Certain foods (including peanuts, tree nuts or shellfish) - however, all foods can potentially cause anaphylaxis
  • Insect stings
  • Drugs and contrast agents (used in some x-ray tests), particularly those given by injection.
  • Difficulty talking and/or hoarse voice

It is important to know the signs and symptoms of anaphylaxis

Anaphylaxis occurs after exposure to an allergen (usually to foods, insects or medicines), to which a person is already extremely sensitive. The symptoms of anaphylaxis are potentially life threatening and include any one of the following:

  • Difficult/noisy breathing
  • Swelling of tongue
  • Swelling/tightness in throat
  • Difficulty talking and/or hoarse voice
  • Wheeze or persistent cough
  • Loss of consciousness and/or collapse
  • Pale and floppy (in young children)

In some cases, anaphylaxis is preceded by less dangerous allergic symptoms such as:

  • Swelling of face, lips and/or eyes
  • Hives or welts on the skin
  • Abdominal pain, vomiting

Several factors can influence the severity of the allergic reaction. These include exercise, heat, alcohol, and in food allergic people, the amount eaten and how it is prepared and consumed.



The first line treatment for severe symptoms is adrenaline (epinephrine) given by injection into the muscles. Adrenaline given in this way is a safe treatment and you should not hesitate to use it if required. It starts to work within minutes, reducing swelling, relieving wheeze and improving blood pressure. It is also the only medicine which can stop the cells activated in an allergic reaction from releasing further mediators (chemicals) into the blood.

Once adrenaline has been given, antihistamines can be given as well, but the adrenaline should be given first.


IND/04/17/ALGY/022/EXP 04/19