Anaphylaxis

Anaphylaxis is a severe, sudden, potentially life-threatening allergic reaction. Anaphylaxis is a medical emergency that requires immediate treatment.

Anaphylaxis symptoms

Symptoms of anaphylaxis can develop within minutes of being exposed to an allergen (substance to which you are allergic). Sometimes symptoms do not occur straight away, but develop after 30 minutes or longer.

Symptoms of mild or moderate allergic reactions (which may precede the symptoms of anaphylaxis) include:

  • skin rash or hives;
  • swollen face, eyes and lips;
  • abdominal cramps;
  • vomiting; and
  • diarrhoea.

Symptoms of anaphylaxis can include:

  • flushed or pale skin;
  • swollen tongue;
  • difficulty breathing or noisy breathing;
  • wheezing and/or persistent coughing;
  • swelling and constriction of the throat and airways;
  • hoarse voice or difficulty speaking;
  • pale skin and floppy (in young children); and
  • dizziness, fainting or loss of consciousness.

Causes

Anaphylaxis is caused by your immune system over-reacting to a substance that is not normally harmful. Common triggers of anaphylactic reactions include:

  • foods (such as eggs, nuts or seafood);
  • insect stings (including stings from bees, wasps and jack jumper ants); and
  • certain medicines (such as penicillin).

Tests

Anaphylaxis can be diagnosed based on your description of symptoms and a physical examination. Your doctor may recommend tests (such as skin prick tests or blood tests) to determine what triggered the allergic reaction.

Treatment

Anaphylaxis requires immediate treatment, as it can be a dangerous, life-threatening condition. Treatment for anaphylaxis involves:

  • emergency treatment of the allergic reaction;
  • identifying what you are allergic to so that you can avoid (as much as possible) exposure in the future; and
  • having a written emergency anaphylaxis action plan (that usually involves self-injecting adrenaline) in case of future accidental exposures.

Emergency treatment

Adrenaline

Adrenaline – a hormone that is produced by the body in times of stress – is used as an emergency treatment for allergic reactions because it rapidly reverses the effects of anaphylaxis, reducing airway swelling, opening up the airways and helping to maintain your blood pressure and circulation.

People with known allergies, especially those with previous episodes of severe allergic reactions or anaphylaxis usually carry an adrenaline self-injecting device, or autoinjector (e.g. EpiPen or Anapen), with them at all times in case of accidental exposure to allergens. The autoinjector contains a set dose of adrenaline that can be injected into the thigh muscles – your doctor will show you how to use it.

An injection of adrenaline is the best way to quickly control the symptoms of a severe allergic reaction. After using an adrenaline autoinjector, you still need to seek emergency medical treatment. Medical supervision and ongoing treatment are needed if you have a severe allergic reaction.

Other medicines

Anti-histamines and corticosteroids may also be used in the treatment of allergic reactions. Although these medicines are not helpful in the emergency treatment of life-threatening anaphylaxis, antihistamines can help with itch and hives, and corticosteroids may reduce the risk of symptoms recurring. Corticosteroids may be used in the case of insect sting allergic reactions to reduce local swelling.

Long-term treatment

In cases of certain insect sting allergies, immunotherapy (desensitisation) therapy can help prevent further episodes of anaphylaxis.

Immunotherapy involves giving increasing doses of the allergen (via injection) with the aim of regulating your immune system to reduce your body’s reaction to that particular allergen.

First aid for anaphylaxis

To help a person having a severe allergic reaction, follow these steps.

  • Remove the allergen if it is still present (e.g. remove insect stings).
  • Stay with the person and call out for help.
  • Lie the person down flat. If they are having trouble breathing, they can sit up, but should not stand or walk.
  • If they have an adrenaline autoinjector, help the person to administer adrenaline to the outer thigh muscle.
  • Call 000 for an ambulance.
  • Perform CPR if necessary.

Prevention

Allergen avoidance is the key to preventing allergic reactions. While this is not always possible, it is important to take care to avoid allergens as much as you can.

  • People with food allergies should always check the ingredients on food labels and check ahead before eating out.
  • Take care when outdoors if you are allergic to insect stings – wear clothing and footwear that covers your skin, use insect repellent and try to avoid wearing perfume and brightly coloured clothing.
  • Wearing a MedicAlert bracelet is helpful if you are allergic to medicines or other substances.
Last Reviewed: 27 November 2013
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References

1. Australasian Society of Clinical Immunology and Allergy (ASCIA). Health professional information paper: Anaphylaxis (September 2013). http://www.allergy.org.au/health-professionals/hp-information/asthma-and-allergy/anaphylaxis (accessed Sep 2013).
2. Australasian Society of Clinical Immunology and Allergy (ASCIA). Anaphlyaxis (updated April 2010). http://www.allergy.org.au/patients/about-allergy/anaphylaxis (accessed Sep 2013).
3. Royal Children’s Hospital Melbourne. Clinical practice guidelines: Anaphlaxis (updated Aug 2011). http://www.rch.org.au/clinicalguide/guideline_index/Anaphylaxis/ (accessed Sep 2013).
4. Australasian Society of Clinical Immunology and Allergy (ASCIA). ASCIA Action plans for anaphylaxis (updated Dec 2012). http://www.allergy.org.au/health-professionals/anaphylaxis-resources/ascia-action-plan-for-anaphylaxis (accessed Sep 2013).
5. Australasian Society of Clinical Immunology and Allergy (ASCIA). Adrenaline for severe allergies (updated April 2010). http://www.allergy.org.au/patients/allergy-treatment/adrenaline-for-severe-allergies (accessed Oct 2013).
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