Anaphylaxis is the most severe form of allergic reaction, often affecting several parts of the body, including either breathing difficulties, a sudden drop in blood pressure, or both.
Symptoms typically occur within 30 minutes of exposure, often within five minutes, and usually develop rapidly. It is rare for the onset of symptoms to be delayed for hours after exposure.
If you are at risk of anaphylaxis, you should be prescribed an adrenaline auto-injector, such as Anapen or EpiPen, and you will need an Anaphylaxis Management Plan,
which you can download below.
More information on adrenaline auto-injectors is further down the page.
What are the symptoms?
The symptoms of anaphylaxis can include a combination of some of the following.
• swelling of throat and mouth
• difficulty in swallowing or speaking
• difficulty in breathing, or noisy breathing
• alterations in heart rate
• wheeze or persistent cough
• abdominal pain, nausea and vomiting
• sense of impending doom
• sudden feeling of weakness (drop in blood pressure)
• collapse and unconsciousness
• palor and floppiness (in young children)
You would not necessarily experience all of these symptoms.
In some cases, anaphylaxis is preceded by less dangerous allergic symptoms, which can include:
• Swelling of face, lips and eyes
• Hives or welts on the skin
• Stomach pain, vomiting
Several factors can influence the severity of anaphylaxis, including asthma, exercise, heat, alcohol and, in people with food allergies, the amount eaten, and how it is prepared and consumed.
What are the most common causes of anaphylaxis?
Common causes include foods such as peanuts, tree nuts, sesame seeds, fish, shellfish, d
airy products and eggs. However, many other foods can also cause severe reactions.
Non-food causes include wasp or bee stings, natural latex (rubber), penicillin or any other drug or injection. In some people, exercise can trigger a severe reaction - either on its own or in combination with other factors such as food or drugs (e.g. aspirin). Exposure to cold (usually cold water) can also trigger anaphylaxis. In some cases, a trigger can’t be found and this is referred to as idiopathic anaphylaxis.
What exactly is going on?
Any allergic reaction, including the most extreme form, anaphylactic shock, occurs because the body's immune system reacts inappropriately in response to the presence of a substance that it wrongly perceives as a threat.
An anaphylactic reaction is caused by the sudden release of chemical substances, including histamine, from cells in the blood and tissues. These cells are mast cells and basophils.
The release is triggered by the reaction between the allergic antibody (IgE) with the substance (allergen) causing the anaphylactic reaction. The released chemicals act on blood vessels, resulting in dilatation (opening up) of the vessels.
The skin can become red and, with fluid leakage from the vessels, tissues may become swollen. This is common around the eyes and mouth. There may be a fall in blood pressure and, especially in asthmatics, there may be wheezing and narrowing of the airways. Not all anaphylaxis is caused by allergy (IgE) antibodies.
Some reactions are caused by direct effects on the mast cells/basophils, e.g. allergic reactions to aspirin and other anti-inflammatory drugs.
Why does adrenaline work?
Adrenaline works by strengthening the heartbeat, opening up the airways and raising blood pressure.
Adrenaline (epinephrine) is the recommended first aid drug for anaphylaxis.
Antihistamines treat hives and runny nose but not anaphylaxis and should never be used instead of adrenaline for anaphylaxis. If you have an asthma inhaler (e.g. Ventolin) use this after your adrenaline auto-injector (EpiPen or Anapen) for breathing problems, not before.
How likely is a person to die from anaphylaxis?
Although anaphylaxis is not uncommon and can be life-threatening, deaths are rare. The risk can be reduced with proper precautions: avoiding your triggers and prompt treatment with adrenaline. Overseas studies have found that co-existing asthma has a major part to play in deaths, so it’s important that you keep your asthma well controlled, even if it’s mild. Be careful, not fearful.
How do I know if I am at risk from anaphylaxis?
If you have suffered a severe allergic reaction in the past – whatever the cause – then any future reaction may be severe. If you have suffered a significant reaction to a tiny dose, or have reacted on skin contact, this might also be a sign that a larger dose may trigger a severe reaction. If you have asthma as well as allergies, this can put you in a higher risk category. Where foods such as peanuts, nuts, seeds, shellfish and fish are concerned, even mild symptoms should not be ignored because future reactions may be severe.
How do I get a diagnosis?
Your doctor will normally ask a series of questions that may help to narrow down the list of likely causes such as foods or medicines consumed that day, or insect stings. This approach will also help to exclude conditions that can sometimes be confused with anaphylaxis, like fainting or panic attacks. If allergy is suspected, this may be followed by allergy tests, usually by skin prick tests or blood tests (CAP/RAST), to help confirm or exclude potential triggers.
How can I avoid problems?
The two main steps in managing anaphylaxis are to avoid triggers while at the same time being prepared for a severe reaction.
Once you know what the trigger for your anaphylaxis is, you will need to know where and how you may be exposed to it and minimise this risk as far as possible. Your doctor may be able to provide information and advice. If you have a food allergy, you may be referred to a dietitian.
Allergy New Zealand also has information, resources and support that may help (details below).
How can I be prepared?
• If you are prescribed adrenaline — either in the form of an auto-injector or an ampoule, needle and syringe — always carry it with you and make sure you know how to use it. Ask your doctor or pharmacist to show you. Auto-injector (EpiPen or Anapen) trainers are available.
• Make sure your adrenaline is up to date, and remember to replace it as soon as it expires.
• Have an Anaphylaxis Management Plan
signed by your allergy specialist, paediatrician or GP. This outlines mild, moderate and severe symptoms and exactly what to do when each of these develop. You can download a copy from the Australasian Society of Clinical Immunology and Allergy
. Have this available for family and friends — put it on the bulletin board at home; carry one in your pocket. If a child is the person at risk, make sure his or her teachers and friends’ parents have a copy - along with the adrenaline. Make sure everyone knows where the adrenaline is when you go out, or when you are at home.
• Do the e-anaphylaxis online training here
- it's FREE! And encourage your family and friends to do it.
• Be alert to all symptoms and take them seriously. Use adrenaline if you think you are beginning to show signs of a severe reaction. Do not wait until you are sure. Even if adrenaline is administered, you will still need to get to hospital as soon as possible. Someone must call an ambulance.
• Make sure others in your family know how to administer the adrenaline — and when. Do not be frightened of adrenaline. It is a well-understood drug. The dose you will administer has few side effects, which will pass quickly in any case. It is a safe drug for most people, although it may not be prescribed if you have a heart condition or are being treated for high blood pressure.
• Wear a MedicAlert bracelet
• Be open about your allergy problem with your family, friends and colleagues.
• If you are allergic to insect stings, your doctor may recommend allergen-specific immunotherapy, or desensitisation. Venom immunotherapy provides over 95 per cent protection against severe reactions. Immunotherapy consists of injecting increasing quantities of venom over several weeks, or in the case of “rush immunotherapy” over the course of a couple of days. Once a maintenance dose is reached, the injections can be spaced out over longer intervals. The advice of an allergy specialist should be sought prior to undertaking desensitisation. The cost of the venom vaccine is covered by Pharmac.
What should I do if I think I am having a serious reaction?
Follow your Anaphylaxis Management Plan. These are some key points:
• Is there any difficulty with breathing or swallowing? Is there weakness or floppiness? Is there a steady deterioration? Any of these are signs of a serious reaction.
• Administer adrenaline without delay if you believe the symptoms are serious, or becoming serious.
• Dial 111 and say you are having a severe allergic reaction or get someone else to do it.
What happens after I have been to hospital?
If you have a severe reaction, you will have to stay in hospital for at least four to six hours because life-threatening reactions can reoccur even after you have recovered. Before you are released from hospital, the following should happen:
• The hospital should refer you to an allergy/immunology service for a complete evaluation.
• You should be provided an Anaphylaxis Management Plan
• You should be prescribed an adrenaline auto-injector and shown how to use this.
• You should have an Accident Compensation Corporation (ACC) claim form filled out.
What does ACC cover?
ACC will not cover allergic reactions that are of a mild to moderate nature, such as (but not limited to) itching, rashes, sneezing and hay fever and all underlying allergic conditions.
ACC will provide cover if you have an anaphylactic reaction to an allergen caused by your employment, or if you have an anaphylactic reaction to food or insect venom out of the workplace.
Severe reactions triggered by treatment such as a standard antibiotic treatment are covered if it is not a necessary part or an ordinary consequence of the treatment.
Where cover has been approved, you may be entitled to the whole range of entitlements available under ACC, which includes weekly compensation, lump sum compensation, treatment, social rehabilitation and vocational rehabilitation.
ACC claims should be lodged by the doctor and/or emergency service involved at the time of the anaphylactic reaction. You should check as soon as possible if a claim has been made on your behalf. If an ACC claim was not lodged, you should query this with your GP and/or your local ACC office.
Cover should include the following:
• Cost of an ambulance and the emergency care and treatment
• Referral to an allergy specialist service for an assessment
• The cost of your adrenaline auto-injector reimbursed if you used it to treat your reaction. You will need a copy of your receipt in order to do this, and you will also need to make sure that medical records relating to the ACC claim show that your auto-injector was used.
Acknowledgements: We would like to thank Dr Penny Fitzharris, Clinical Immunologist, Auckland Hospital, and the Anaphylaxis Campaign, UK, on which this leaflet is based.
Allergy New Zealand
Allergy New Zealand Inc
PO Box 56-117, Dominion Road, Auckland, New Zealand
Admin: 09 623 3912 Fax: 09 623 0091
Let us know
While we continue to develop clearer guidelines with ACC for claims we would be grateful if people who have made or are making a claim to ACC for anaphylaxis for themselves or their child could let us know how they got on including good news and/or any issues that have arisen. We are also happy to assist with further information if possible. Just email us on firstname.lastname@example.org.