Anaphylaxis is the most severe form of allergic reaction. It usually occurs quickly after exposure to something the person is allergic to, and is potentially life threatening.

On this page, you can find the following information:

Key points about anaphylaxis

  • Someone having anaphylaxis needs immediate treatment and medical attention.
  • Life-threatening symptoms are those that affect your airways making it hard to breathe, or your circulation system, causing dizziness or collapse.
  • Signs to watch for are:
    • difficult/noisy breathing
    • swelling of the tongue
    • swelling or tightness in the throat
    • difficulty talking or hoarse voice
    • wheeze or persistent cough
    • persistent dizziness or collapse
    • pale and floppy (young children)
    • abdominal pain or diarrhoea (can be a sign of anaphylaxis in bee/wasp sting reaction).
  • Treat anaphylaxis immediately by following the steps below.

If you or someone you care for experiences the following symptoms, give adrenaline if available and call 111 for an ambulance: 

  1. Lie the person down – they should NOT stand or walk. If they have breathing difficulties, you can allow them to sit.
  2. Remove any trigger if it is still present (eg, a bee sting).
  3. Give adrenaline using an autoinjector (eg, EpiPen) if the person has one. Make sure you know how to use it correctly before you administer it* (or help the person to administer it themselves).
  4. Call 111 for an ambulance. Stay with them until the ambulance arrives.


  • If there is no adrenaline on hand, follow the other 3 steps
  • Don’t get up even if you feel better after having adrenaline, wait for the ambulance.

*The instructions will be on the side of the EpiPen, and the person may have an Anaphylaxis Action Plan with the EpiPen.

What are the causes of anaphylaxis?

Anaphylaxis is a serious whole body allergic response to exposure to an allergen. It's an over-reaction by your immune system to the allergen trigger. It can make your airways tighten, which restricts your breathing, or affect the circulation of blood in your body, and it can be life threatening.

An allergen can be anything, but common triggers of anaphylaxis include:

  • food
  • insect venom
  • medicines.

In some cases, the cause may take some time to be identified.


  • Milk, eggs, peanuts, tree nuts, sesame, fish, shellfish, wheat and soy are the most common food triggers, and cause 90% of allergic reactions. However, any food can trigger anaphylaxis.
  • In some cases, mild or moderate  allergic symptoms can happen before the above symptoms, such as
  • swelling of your face, lips or eyes
  • hives, welts or body redness
  • tingling of your mouth
  • tummy pain or vomiting (being sick).
  • Having asthma can also increase the risk of having a severe reaction if you accidentally eat even a small amount of the food you are allergic to.

Insect venom

Bee and wasp stings are the most common causes of anaphylaxis from insect stings in New Zealand.


Both over-the-counter and prescribed medicines, such as antibiotics or painkillers, can cause life-threatening allergic reactions. You can also have anaphylactic reactions to herbal or alternative medicines. Anaesthetics and contrast agents used in imaging tests can also cause anaphylaxis.


Other triggers such as latex or exercise-induced anaphylaxis are less common. Occasionally the trigger cannot be identified.  

How is anaphylaxis diagnosed?

Anaphylaxis may be diagnosed following a severe reaction for which you went to an emergency department at the hospital. 

Your doctor will ask you questions related to your symptoms, examine you and do some tests to find out your triggers, and/or rule out other conditions that can be similar to anaphylaxis, such as fainting, severe asthma attacks or panic attacks. 

Tests that may be done include:

  • blood test to look for an antibody called IgE or an enzyme called mast cell tryptase
  • skin prick testing to find out triggers.

You may also be diagnosed as at risk of anaphylaxis because of an allergy you have been diagnosed with e.g. to a food, even though you may only have had mild to moderate reactions to it previously. 

If you are diagnosed at risk of anaphylaxis, your doctor or nurse specialist will give you an anaphylaxis action plan that outlines the steps to take. They will also prescribe you an EpiPen (see below for more information). 

How is anaphylaxis managed? 

Anaphylaxis is a preventable and treatable event. Knowing the trigger(s) is the first step in prevention. Everyone at risk needs to know how to avoid food allergens and/or other triggers. 

However, because accidental exposure is possible, you and your child need to be able to recognise symptoms of anaphylaxis and be prepared to give adrenaline according to your anaphylaxis action plan. 

If you have had anaphylaxis for the first time, after those immediate steps and then getting emergency medical care, as part of your treatment plan you need to:

  • see a specialist to find out your triggers 
  • work out an anaphylaxis action plan with your doctor
  • attend follow-ups if required by your doctor
  • get educated on how to avoid triggers and use an adrenaline autoinjector if you are prescribed one
  • ask your doctor or nurse specialist for an asthma management plan if you or your child also has asthma. 

The Australasian Society of Clinical Immunology and Allergy (ASCIA) provides free online training on anaphylaxis for patients, families and the community.

Adrenaline is the first-line treatment for anaphylaxis

Adrenaline is the treatment for anaphylaxis. Adrenaline works by quickly reversing the effects of anaphylaxis.

Adrenaline can be easily given using an autoinjector such as an EpiPen (the only one available in New Zealand). The autoinjector injects a single, pre-measured dose of adrenaline into your muscle. If you are at risk of anaphylaxis, then your doctor might ask you to carry an autoinjector with you. Deaths from anaphylaxis are more common away from home and when adrenaline is either not used or is delayed.

If you or your child are prescribed an adrenaline autoinjector, it is important to learn and practise how to use it. You can register your EpiPen with and receive a free trainer pen.

Don't use antihistamines

Don’t use antihistamines to treat anaphylaxis – giving adrenaline quickly is the only treatment for anaphylaxis. Anaphylaxis is a potentially life threatening, severe allergic reaction and should always be treated as a medical emergency.

Read more about severe allergic reaction Choosing Wisely, NZ

How can I prevent anaphylaxis? 

Once you have had an anaphylactic reaction you will be referred to a specialist to help you work out your triggers. This may involve allergy testing or food/drug challenge.

Knowing your triggers for anaphylaxis is essential. In many cases avoidance is the only way to prevent anaphylaxis. Your specialist will help you work out ways to reduce the risk of anaphylaxis. This usually includes writing up an emergency anaphylaxis action plan. You will need to have regular reassessment, to check if the allergy is still present and to make sure your prevention plan is working for you.

Carrying your adrenaline autoinjector with you at all times if you have one and using it if you think you may have anaphylaxis can also help to prevent your anaphylaxis from getting worse.

What support is available with anaphylaxis?

It can be frightening if you have anaphylaxis. Talk through your feelings with your family/whānau members or health professionals taking care of you. Read more about how to talk about your feelings. 

Below are some support services and information for people affected by anaphylaxis and their family/whānau:

Allergy NZ Check their website or phone 0800 34 0800 for information and support. 
EpiPen Online educational resource where you can access additional information about anaphylaxis and EpiPen®.

Learn more

The following links provide further information about anaphlyaxis. Be aware that websites from other countries may have information that differs from New Zealand recommendations.    

Anaphylaxis Allergy NZ
Anaphylaxis (severe allergy) HealthInfo Canterbury, NZ
Anaphylaxis Australasian Society of Clinical Immunology and Allergy (ASCIA)
EpiClub NZ


  1. Anaphylaxis Auckland Regional HealthPathways, NZ, 2020
  2. Anaphylaxis Starship Clinical Guidelines, NZ, 2019
  3. Acute management of anaphylaxis ASCIA Guidelines, 2020
Credits: Health Navigator Editorial Team. Reviewed By: Penny Jorgensen, Allergy Advisor, Allergy New Zealand and Dr Tim Jefferies, GP and member of the NZ Child & Youth Allergy Clinical Reference Group Last reviewed: 15 Jan 2021