Anaphylaxis 101

21 May 2015

What is it?

Anaphylaxis the most severe allergic reaction that can rapidly become life threatening if it isn’t responded to or treated immediately. Anaphylaxis affects one or a combination of body systems –skin, respiratory, gastrointestinal and/or cardiovascular. The severe reaction generally occurs within 20 minutes to 2 hours after exposure to an allergen.

How does it occur?

An allergic reaction occurs when a person’s immune systems overreacts to an allergen – a substance or ‘trigger’ that is generally harmless to others. When someone comes into contact with an allergen, their immune system responds by creating an antibody to attack the allergen, which in turn sets off one or a number of reactions. If someone’s immune reaction is too intense, it is referred to as an anaphylactic reaction.

Why is it so dangerous?

Anaphylaxis is treated as a medical emergency because many of the symptoms can quickly become life-threatening.

During an anaphylactic reaction, the body suddenly releases chemical substances such as histamine, which are stored in the cells of blood and tissue. This sudden release is caused by the reaction between the antibody and the allergen. The chemicals released from the cells cause swelling, most commonly of the eyes, nose, and throat. These chemicals also cause other problems such as a dramatic fall in blood pressure. People with anaphylaxis are usually so sensitive to their allergens that even a minute exposure to it can trigger an anaphylactic reaction.

What are the signs of anaphylaxis?

Signs and symptoms can be subtle or severe, but include one or a combination of:

  • tightness of the throat from swelling
  • difficulty breathing
  • tongue, lips, eyes and facial swelling
  • hoarse voice and difficult speaking
  • wheeze or persistent cough
  • sudden feeling of weakness, collapse or falling unconscious
  • becoming pale or floppy (particularly in young children and infants)
  • abdominal pain, nausea and vomiting
  • hives, welts and flushed, hot skin or  body redness.

Common anaphylaxis triggers

There are many allergens that can cause anaphylaxis. The most common allergens in Australia are:

  • food, including milk, eggs, peanuts, all tree nuts, sesame, fish, shellfish, wheat and  soy
  • Venom from insects including bees, wasps and ants.

Read more on how to avoid anaphylactic triggers here.

First aid for anaphylaxis

Epipen and Anapen are normally carried by those who are at risk of anaphylaxis. These auto-injectors are designed to be used by anyone, including a parent, sibling, friend, passer-by, childcare worker, or the person suffering the reaction themselves. A person at risk of anaphylaxis should also always carry an Anaphylaxis Action Plan, which contains information on what to do in an anaphylactic emergency.

If you witness signs that suggest someone may be suffering from anaphylaxis, and are not already aware of their Anaphylaxis Action Plan, you should take the following steps:

  1. Lay victim flat, do not let them stand or walk. If breathing is difficult, allow them to sit
  2. Prevent further exposure to the trigger or allergen, if possible
  3. Administer adrenaline through auto-injector (Epipen and Anapen):
    * Child less than 5 years – 0.15 mg intramuscular injection.
    * Older than 5 years – 0.3mg intramuscular injection
  4. Call an ambulance
  5. Administer oxygen and / or asthma medication for respiratory symptoms.
  6. Further adrenaline should be given if no response after five minutes.
  7. If breathing stops follow resuscitation and life support procedures.

In accredited first aid training, the most common site to inject someone who might be going into anaphylactic shock is directly into their thigh. The adrenaline will reduce the effects of the reaction by constricting blood vessels, relaxing muscles in the lungs to improve the person’s breathing, stimulate the heart to continue beating and reduce any swelling to the face or throat. If adrenaline is administered, immediately call an ambulance to the site of emergency to continue further medical treatment.

For more information about anaphylaxis first aid management, read Guideline 9.2.7 by Australian Resuscitation Council. Taking an accredited first aid course in asthma and anaphylaxis will also educate you via theoretical and practical experience.

Guest writer: Zoe Perl
Australia Wide First Aid