Anaphylaxis - overview


IMPORTANT The information provided is of a general nature and should not be used as a substitute for professional advice. If you think you may suffer from an allergic or other disease that requires attention, you should discuss it with your family doctor. The content of the information articles and all illustrations on this website remains the intellectual property of Dr Raymond Mullins and cannot be reproduced without written permission.

Anaphylaxis is the most severe form of allergic reaction. It results in potentially life-threatening symptoms such as difficulty breathing or a drop in blood pressure (shock). Other symptoms include swelling of the face or throat, dizziness, difficulty thinking, an intense sense of fear, tightness in the chest, vomiting or diarrhoea. Use of injected adrenaline (epinephrine) should be considered as First Aid. Fortunately, deaths in Australia are very rare, particularly in young children.

Common causes of Anaphylaxis

Food Allergy: Most commonly peanut, tree nuts, seeds, fish and crustaceans in adults; cows milk, egg, peanut and tree nuts and sesame seeds in young children.

Medication (drug allergy): Particularly painkillers and antibiotics. Herbal medicatiuons such as Royal Jelly and Echinacea amongst others can also trigger serious allergic reactions, particularly in those who have other allergic conditions such as asthma or hay fever.

Insect stings(venom allergy) such as bee, wasp, "jumper ants".

Exercise (either alone or in combination with food allergy)

Idiopathic. When a cause cannot be identified, cases are called "idiopathic".

Tick bites

Latex allergy

Cold urticaria. Some patients who get hives when exposed to cold air or water, or go into shock if they swim in cold water.

How is anaphylaxis managed?
People who have had an episode of anaphylaxis need to:

1. Identify and avoid the cause (if possible)

2. Develop avoidance strategies

3. Wear a MedicAlert bracelet identifying your allergy & its treatment

4. Recognise the early symptoms of an allergic reaction

5. Know what to do if it happens again. ie. have an emergency action plan in place

Identifying the cause
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 exposure to stinging insects.

Anaphylaxis usually occurs within minutes of a sting, and within hours of a food allergen or drug. That means that the history of everything eaten or drunk in the previous 4-6 hours is of utmost importance. In children, however, most reactions occur within 2 hours and often within 15-30 minutes of eating a food they are allergic to.

This approach will also help to exclude conditions that can sometimes be confused with anaphylaxis. Skin or blood (RAST) allergy testing help confirm or exclude potential triggers.

So if you have an episode of what you think may be an allergic reactions, document the circumstances. ie. everything you have done, eaten or drunk (including medicines, herbal medicines or foods) in the previous 12 hours. The following event record can be completed for each episode you have had.

Severity can be influenced by a number of factors...

1. But the main one is how sensitive the person is to their particular trigger

2. The amount of food eaten (more food=more severe) is less commonly an influencing factor

The form of the food (e.g. liquid may be absorbed faster, resulting in more severe & rapid reactions)

3. Whether it is eaten on its own, cooked or mixed in with other foods (e.g. scrambled egg may cause immediate facial swelling, but that in cake is diluted may be more slowly absorbed and result in delayed reactions)

4. Exercise around the same time as the meal may worsen severity. Some patients will only react to a food if they exercise around the same time, a condition called food and exercise-induced anaphylaxis. In these circumstances, the severity of the reaction is usually determined by the amount of food eaten, the vigour of the exercise and the time between the two.

5. Cooking of the food may alter the structure of the food allergen and make it less likely to provoke severe reactions (sometimes seen with egg and milk, but rarely with nuts or seafood)

Other factors (such as hot days, alcohol or spicy food with the meal, pain killers or infection).

  1. 6.Asthma. Having regular asthma as well increases the likelihood that asthma may occur as part of the reaction.

It is important to note, however, that there is a difference between severity of some symptoms such as hives/rash (which may or not be dangerous) and potentially dangerous symptoms (e.g. difficulty breathing, dizziness or collapse).

Recognising the symptoms
Early symptoms of an allergic reactions often include an itchy mouth, hands or feet, followed by the more devastating symptoms previously described. Other symptoms include red, itchy and puffy eyes, and hives that start around the armpits and groin (see photos below). These should be considered as warning signals to get emergency medical help and to start treatment immediately until help arrives.

Develop an Emergency Action Plan
A well thought-out "Action Plan" is an essential part of management and should be practiced. It requires you to recognise early warning symptoms, to carry the medication you need and to know how to use it. The Australian Society for Clinical Immunology and Allergy has a number of online anaphylaxis resources, including regular updates of its Action Plans which can be downloaded and filled out by your GP, paediatrician or allergy specialist.

1. Remove the trigger & minimise the effect of co-factors (e.g. spit out the offending food to minimise further absorption of allergen, stop exercising).

  1. 2.Seek urgent medical assistance (e.g. call an ambulance)

  2. 3.Lie down; many anaphylaxis deaths occur in people sitting or standing after an allergic reaction, including while being driven to hospital.

3. Inject adrenaline (epinephrine). Injected adrenaline works rapidly to reverse the effects of anaphylaxis and should be considered "First Aid" for its treatment.

4. Other medication. Some patients will be advised to take other medicines like antihistamines or cortisone tablets. It is important to realise that these will not prevent a life-threatening allergic reaction, as they take the best part of an hour to be absorbed.

5. Observe for relapse under medical supervision. This is because severe symptoms ("rebound") sometimes recur after apparent recovery.

Psychological issues
Anaphylaxis is a disorder where the threat of recurrence persists but the event itself (and its severity), unpredictable. Some patients (or their parents) will suffer considerable stress and anxiety. Review by your doctor after each relapse offers an opportunity to review appropriate management strategies including the correct use of adrenaline autoinjectors, to ensure that the device is renewed at appropriate intervals and to provide counselling where appropriate.

Other management issues

1. Patients who have had anaphylaxis should wear a Medic Alert bracelet. This increases the likelihood that adrenaline will be administered in an emergency. In general, this is more commonly recommended for adults and teenagers than young children.

2. Some types of heart and blood pressure medicines (such as Beta-blockers) can interfere with the drugs used in treatment. These are best avoided so check with your doctor if there are reasonable alternatives available.

3. Immunotherapy (desensitisation) injections are only useful for anaphylaxis caused by bee or wasp stings. This method is not yet useful for treating severe food allergy yet due to high rates of side-effects. THis is an area of active research and initial results are encouraging, but not yet the “cure” we are looking for.

  1. 4.Patients who go bushwalking to isolated areas should consider carrying an emergency satellite beacon (Eperb) to call for assistance if an emergency arises.

  2. 5.Those with symptoms triggered by exercise are best advised to not exercise alone, to carry a means of summonsing help (e.g. mobile telephone) or to pre-medicate. Nonetheless, patients with such symptoms need take advice about their specific condition from their allergy specialist.

Who should carry adrenaline (epinephrine)?
Food allergy in infancy is common (around 1 in 20 have at least a transient food allergy). While it is natural to be anxious about having another allergic reaction, serious allergic reactions fortunately occur much less often. Patients are normally advised to carry adrenaline (epinephrine) when they are considered to be at significant risk of having dangerous allergic reactions.

EpiPen and Anapen is subsidised in Australia under some circumstances

EpiPen adrenaline autoinjectors are subsidised by the Australian PBS system on Authority prescription, for patients considered at high risk of serious allergic reactions. There are a number of criteria attached to this subsidy. Guidelines for EpiPen se have been published at At this time, Authority must be prescribed in consultation with an allergy/immunology specialist, paediatrician, emergency specialist or respiratory physician. Only two devices are subsidised at any one time on the PBS. Those wanting to have a 3rd or 4th device need to pay the full private cost to do so. Extra EpiPens can be purchased privately across the counter in Australia and a prescription is not needed.

Adrenaline autoinjector expiry

The expiry date is approximately 1 year, although this may vary according to the date of importation. When it expires, it does not stop working, but rather becomes less potent as it ages. It is not unreasonable to keep the old expired ones for another 2 years as an extra backup device, then use the very old ones to practice on an orange so you get a feel for using a real device. Various studies have examined how much active adrenaline is available in expired EpiPens. One study estimated 75% active adrenaline 2 years AFTER the expiry date.

Autoinjectors comes in 2 sizes

Most allergy specialists prescribe EpiPen  Junior 0.15mg for children with a body weight less than 7.5 to 20 kg, and EpiPen “adult” 0.3mg size when the weight is greater than 20kg.

Travelling with food allergy, anaphylaxis and adrenaline autoinjectors

1. A website called SelectWisely ( produces a number of illustrated cards in different languages to use when travelling to communicate that one has food allergy. There may be other similar sites as well.

2. Contact your airline to determine their policies regarding food allergy well in advance of travel and before you book tickets. Some airlines have been known to throw travellers off planes at the last minute in recent years, refused boarding or have demanded that customers sign potentially expensive “disclaimer” documents before allowing them to travel, indemnifying the airline if they need to divert their plane in an emergency.

3. Ensure that you have all documents, letters and medicines needed prepared well in advance before you travel, including travel documents about carrying an EpiPen if needed. Your own GP can provide these. Do not leave such preparations to the last minute!

  1. 4.And have travel insurance!

  2. 5.And check out ASCIA resources including travel checklists and travel plans.

Last reviewed 5 June 2020