What is anaphylaxis?

Anaphylaxis, also known as anaphylactic shock, is a very severe form of allergic reaction. Immediate and life-threatening symptoms, including breathing difficulties, can be the result of exposure to a trigger. Anaphylaxis is a serious but treatable medical condition.

Allergic reaction

A problematic physiological response to an allergen that comes into contact with the body.

Causes

When a foreign substance enters your body, your immune system mounts a defence by producing antibodies. Anaphylaxis occurs when your immune system overreacts to a trigger that would normally be harmless. When this occurs, a chemical chain reaction leads to severe allergy symptoms. These triggers are known as allergens and can include:

Food

Nearly any food can trigger a food allergy that can develop into an anaphylactic shock. Foods that commonly trigger anaphylaxis include:

  • Crustaceans (e.g., lobsters, prawns and crabs);
  • Nuts (e.g., peanuts, cashews, walnuts, pecans and almonds);
  • Eggs;
  • Fish;
  • Soy products;
  • Sesame products, and;
  • Milk.

Insect venom

  • Bees;
  • Wasps;
  • Ants, and;
  • Ticks.

Medications

  • Some prescription medications (e.g., penicillin);
  • Some over-the-counter medications (e.g., aspirin), and;
  • Herbal preparations.

Rare causes

Unknown causes

Sometimes, despite in-depth investigations, the trigger cannot be found in some people.

Allergens

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Anaesthetics

A medication or other substance that causes a temporary loss of sensations, including pain.

Antibodies

A protein molecule produced by the immune system. Antibodies bind specifically to foreign substances to neutralise them or target them for destruction.

Immune system

The organs and cells involved in protecting the body against infection.

Risk factors

Some risk factors associated with anaphylaxis may include:

History of anaphylaxis

If you have a personal history of experiencing anaphylaxis, you are at risk of having the allergic reaction again. These subsequent allergic reactions can be more serious than the first reaction. If there is a family history of anaphylaxis to a certain allergen, there is a higher risk of you developing anaphylaxis to this trigger.

Previous conditions

If you already have previous allergies, asthma or eczema, you have an increased risk of anaphylaxis.

Allergen

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Allergic reaction

A problematic physiological response to an allergen that comes into contact with the body.

Signs and symptoms

The symptoms of anaphylaxis may occur within minutes of being exposed to an allergen, with 20 minutes being the average amount of time for symptoms to appear. Some signs and symptoms can include:

  • Swelling of the face (e.g., the lips or eyelids);
  • Skin reactions (e.g. reddening of the skin, or hives);
  • Swollen tongue;
  • Swollen throat;
  • Tightening of the airways;
  • Hoarseness in the voice or an inability to talk;
  • Wheezing or coughing;
  • Nausea, vomiting or diarrhoea;
  • Reduction in blood pressure;
  • Dizziness, fainting or unconsciousness, and;
  • Paleness and floppiness in children.

Anaphylaxis.Symptoms of anaphylaxis can be swollen lips and eyelids, and skin reddening. 

Allergen

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Methods for diagnosis

To diagnose anaphylaxis or to identify an allergen that is affecting you, some tests can include:

  • Evaluation of medical history;
  • Examination of signs and symptoms during anaphylaxis;
  • Blood tests (e.g., for certain antibodies), and;
  • Skin prick tests to rule out or confirm suspected triggers.

Allergen

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Antibodies

A protein molecule produced by the immune system. Antibodies bind specifically to foreign substances to neutralise them or target them for destruction.

Types of treatment

Treatment of anaphylaxis can include:

First aid

As anaphylaxis is a very serious medical emergency, it is important that you call an ambulance immediately (000) and follow the medical personnel's instructions. If you have an adrenaline auto-injector (see below) and have been trained in how to use it, it is best to administer this first.

Adrenaline injection

This involves an injection of adrenaline, usually into the muscle of your outer thigh, to treat the reaction.

Adrenaline auto-injector

Once your doctor identifies that you are at risk of anaphylaxis, they will prescribe you adrenaline. This comes as an auto-injectable device, commonly known as Epipen®, which is designed to deliver a precise dose of adrenaline to treat anaphylaxis. There are different dosage levels for children and adults.

Adrenaline auto-injector.An adrenaline auto-injector is used to treat anaphylaxis. 

Allergy specialist

To help determine the specific cause of your anaphylaxis, your doctor may refer you to see an allergy specialist. They can help you create an anaphylaxis management plan.

Adrenaline

A substance secreted primarily by the adrenal glands that helps to prepare the body for exertion. It is involved in regulating blood pressure, heart rate and breathing. Adrenaline can also be used as a drug to treat a number of conditions, including cardiac arrest and anaphylaxis.

Potential complications

When severe anaphylactic shock occurs, life-threatening conditions can arise. These complications can include stopping of breathing or heart contractions. In this case, you will require cardiopulmonary resuscitation (CPR) and other emergency treatment immediately.

Cardiopulmonary resuscitation

An emergency lifesaving procedure that involves manually pumping air into the lungs, and compressing the chest to circulate the blood. This first aid technique is used when someone's breathing or heartbeat has stopped.

Prognosis

In some cases, children will grow out of their allergies. If you have been diagnosed with anaphylaxis caused by a certain allergen, you may be able to avoid the trigger and not experience anaphylaxis. However, it is important to carry an adrenaline auto-injector just in case you are exposed to an allergen that causes anaphylaxis.

Adrenaline

A substance secreted primarily by the adrenal glands that helps to prepare the body for exertion. It is involved in regulating blood pressure, heart rate and breathing. Adrenaline can also be used as a drug to treat a number of conditions, including cardiac arrest and anaphylaxis.

Allergen

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Prevention

In order to help prevent anaphylaxis, a management plan can be created. Some suggestions to consider include:

  • Avoiding triggers that are known to cause anaphylaxis;
  • Notifying your work colleagues and friends of your allergies and how they can help treat you in an emergency, and;
  • Wearing a medical bracelet that will alert ambulance officers to your condition, if you become unconscious.