Frequently Asked Questions

Here are some commonly asked questions. The list is not exhaustive and it is not meant to replace consultation with your allergist. Many of the questions deserve more than the brief answer that accompanies them. They are offered as food for thought and to prompt further question. If you have any comments or questions, please contact us.

Questions and answers written by Jane Salter with editorial input from Milton Gold MD and Peter Vadas MD.

Click on the question to access its answer.


What is anaphylaxis?














Medic Alert





A) What is anaphylaxis?

What is anaphylaxis?

In the early 1900's, when vaccination was still a novelty, a group of scientists were trying to induce immunity in dogs ('prophylaxis'). When subsequent doses of certain proteins led to death, rather than immunity, the term 'anaphylaxis' (the opposite of 'prophylaxis') was coined. While there is no universally accepted definition of anaphylaxis (Anna-fill-axis), most physicians would agree that it is a life-threatening allergic reaction to a specific trigger (food, insect sting, medication, exercise, and latex) in a person who has become sensitized. There is disagreement, however, about the constellation of symptoms by which it can be recognized. The commonest food allergens are peanuts, tree nuts, seafood, egg and milk products.

Anaphylaxis affects multiple body systems: skin, upper and lower respiratory, gastro-intestinal and cardiovascular. Anaphylactic shock is an explosive overreaction of the body's immune system to a triggering agent (allergen). It can be characterized by swelling, difficulty breathing, abdominal cramps, vomiting, diarrhea, circulatory collapse, coma and death.

Symptoms of anaphylactic shock tend to develop rapidly although the initial presentation can be delayed and/or deceptively mild. The victim may become uneasy, upset and red in the face. They may also develop a rapid heartbeat, prickling and itchiness in the skin, throbbing in the ears, sneezing, coughing and difficulty breathing. Shock may then follow, in which blood vessels become leaky, blood pressure falls and the person becomes cold, clammy and faint.


If you experience a first time reaction where symptoms appear suddenly or are moderate to severe, seek immediate medical attention and request a follow-up consultation with a qualified allergist. Always err on the side of caution.

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How common is anaphylaxis?

A conservative estimate is that 2% of the population (approximately 600,000 Canadians) may be affected by potentially life-threatening allergies. The incidence may be higher in children and it has increased dramatically in the last decade.

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What is the difference between anaphylactic and anaphylactoid?

Anaphylactic and anaphylactoid reactions are similar in their clinical presentation and treatment. The only difference is the chemical reactions that are taking place. Anaphylactic reactions are mediated by IgE (an immunoglobulin) and anaphylactoid reactions are not.

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B) Reactions

How can I recognize a reaction?

Each allergic individual will react in a specific way (i.e. with specific symptoms). This tends to be consistent from reaction to reaction unless the mode of contact is altered (i.e. ingestion, injection, inhalation). The severity of reaction, however, is less predictable. The quantity of allergen (trigger), asthma, the use of beta-blockers (cardiovascular medication) can affect it and this is why strict avoidance and the immediate use of epinephrine are imperative. You should discuss your/your child's particular signs and symptoms with your allergist and make sure that caregivers are aware of these. Many people watch for hives to develop, but these may not be present.

Signs and symptoms can include:

Mild Symptoms

  • tingling, numbness, pain in the lips and tongue;
  • itchy eyes, nose, face;
  • flushing of the face and body;

Moderate to Severe Symptoms

  • swelling of the eyes, face, lips, tongue and throat;
  • difficulty swallowing;
  • hives;
  • abdominal cramps, vomiting, diarrhea;
  • wheezing, coughing, difficulty talking and breathing;
  • a sense of foreboding, fear and apprehension;
  • weakness and dizziness;
  • drop in blood pressure, loss of consciousness, death.

Most serious reactions occur rapidly and respond quickly to epinephrine. Some life-threatening reactions may have a delayed onset or recur several hours after seemingly effective treatment. This is why it is imperative that people remain in hospital for 3-4 hours following a mild reaction and longer following moderate to severe reactions (Sampson). Most biphasic reactions recur up to 8-12 hours later, but some have been seen 25 hours later. The initial symptoms may also be masked or muted if the patient has been taking steroids or antihistamines.

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What happens during a reaction?

An allergic individual produces antibodies (IgE) which recognize specific proteins (allergens). These antibodies are present on the outside of mast cells and basophils. When an allergen couples with the IgE antibodies, histamine and other mediators of anaphylaxis are released from the mast cells and basophils. These mediators cause blood vessels to leak (which leads to swelling and drop in blood pressure) and airways to narrow (wheezing). Antihistamines cannot reverse all the effects of these mediators and their onset of action is too slow. Epinephrine, however, counters all the sequelae of anaphylaxis and must be given at the earliest sign. Mast cells and basophils can also release mediators via direct stimulation. This can occur with certain drugs (morphine) and exercise.

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Do reactions worsen with each exposure to allergen?

The severity of a reaction reflects a person's allergic sensitivity at the time of the event and the allergen load (quantity of triggering agent). Both of these can be extremely variable. Hence, ensuing reactions may be consistent, more severe or less severe. People who have had very mild reactions may suffer a severe reaction and vice versa. It is imperative to err on the side of caution and be prepared for a severe reaction at any time.

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Are some people more at risk of having a severe reaction?

Through an examination of fatal and near fatal allergic reactions, Dr. Hugh Sampson and others have noted a few risk factors for severe anaphylaxis. These include asthma, previous severe reaction, allergy to particular allergens (peanut, tree nut, seafood, fish) and concurrent medication with beta-blockers (these block the therapeutic effects of epinephrine). (Sampson, H.A. Metcalfe et al. Fatal and Near-Fatal Anaphylactic Reactions to Food in Children and Adolescents. New England Journal of Medicine, 327:380-84,1992)

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When is my child most at risk of an anaphylactic reaction?

Your child is likely at higher risk when under the care of other people. In Dr. Hugh Sampson's study, 4 out of 6 fatal reactions occurred outside of the home. (Sampson, H.A. Metcalfe et al. Fatal and Near-Fatal Anaphylactic Reactions to Food in Children and Adolescents. New England Journal of Medicine, 327:380-84,1992) Teen-agers and young adults are also at increased risk because they are more likely to tempt fate and take chances.

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I think that my child had an anaphylactic reaction, but we gave the epinephrine quickly and symptoms abated. Are there any tests to indicate whether or not this was a reaction?

If you are unsure about a reaction, there are two tests that can be done after the fact to answer this question. You need to check this with the physician in the emergency room. Methylhistamine is a breakdown product of histamine and can be found in the urine after a reaction and mast cell tryptase can be found in the blood.

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C) Treatment

What is the best treatment for anaphylaxis?

Epinephrine reverses the negative cardiovascular effects of an anaphylactic reaction and helps to dilate the airways. It is the initial treatment of choice for anaphylaxis and can be used also during a life-threatening asthma attack. For optimal effect, an injection of epinephrine must be administered at the very beginning of a reaction. Given the rapidity with which symptoms can develop and progress, epinephrine must be available immediately. For this reason it is recommended that anaphylactic people carry their epinephrine with them at all times. While life saving, epinephrine only provides supportive emergency treatment and cannot replace thorough assessment and treatment in hospital. If significant symptoms persist after the initial injection, repeat injections may be given at 10-20 minute intervals while en route to emergency care. Antihistamines cannot replace epinephrine in the treatment of an anaphylactic reaction.

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What else can I do during a reaction?

Have a routine worked out at school, work or home for handling an emergency. Practice it often. Take/administer epinephrine at the first sign of a reaction and call 911. It is best not to drive yourself and if you are driving someone, who is having a reaction, make sure you have an assistant with you. You cannot care for them and drive at the same time. You can take/administer an antihistamine as well, although this should be secondary to epinephrine. Make note of the time and be prepared to give a second injection in 10-20 minutes if you/your child are still symptomatic. If the individual is having difficulty breathing, try to support them in an upright position. If they are comatose, you need to position them on their side in order to protect their airway from vomit. Loosen restrictive clothing and try to remain calm.

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Is there a cure for anaphylaxis?

Effective desensitization programmes are available for insect sting induced anaphylaxis and for drug allergies. Such programmes do not yet exist for food induced anaphylaxis.

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D) Epinephrine

What is epinephrine?

Epinephrine is a hormone produced in the body by the adrenal glands. It is released at times of acute stress to enhance our capability of "fight or flight". We all know the symptoms…the pounding heart, anxiety, tremor. It increases heart rate, diverts blood to the muscles, constricts blood vessels and opens the airways. When you give yourself a dose of epinephrine, you are giving your body something that it is making already. You are just giving it faster and at a higher dose.

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When should I use my epinephrine auto-injector?

If you/your child are potentially anaphylactic, you need to give epinephrine at the first sign of a reaction without waiting to see if it will worsen. When someone who is known to be anaphylactic makes significant contact with their trigger, and they have demonstrated a rapid progression of symptoms in the past, epinephrine can be given even before the onset of symptoms.

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How long will one dose be effective for?

Studies suggest that significant absorption is still occurring from a subcutaneous injection site after one hour. The absorption time should be more rapid from an intramuscular site (at least in children). The epinephrine auto-injector delivers its dose directly into muscle. If symptoms are still present or worsening after 10-20 minutes, a second dose should be administered. Most anaphylactic reactions will be controlled by the early injection of one dose of epinephrine. It is recommended, however, that at least two doses be kept on hand at all times or one dose for every 10-20 minutes of travel time to a medical facility.

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What are the side effects of epinephrine?

Transient and minor side effects of epinephrine can include palpitation (pounding heartbeat), pallor (paleness), dizziness, weakness, tremor (trembling), headache, throbbing, restlessness, anxiety and fear.

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What are the risks of epinephrine?

When used to treat a life-threatening reaction, there are no real contraindications to the use of epinephrine. There are few risks attached to the correct use of this drug, especially in children. Adults who are on medication or have significant health problems need to check with their physician about the potential for adverse effects.

While sulfites are present in the epinephrine solution as a preservative, they are not considered to be of concern for people with sulfite sensitivity.

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What happens if I inject epinephrine into the wrong site?

If used correctly, significant injury is unlikely. Directions for use are on the package insert. The lateral (outer) aspect of the thigh is the safest site for intramuscular injection as there is minimal risk of injection into major blood vessels or nerves in this area. Intravascular injection (which could occur on the front of the thigh) could lead to acute cardiovascular compromise. Injection into a major nerve (which could occur on the posterior thigh or buttock) can cause significant damage. Accidental injection into the hand, particularly the digits, can cause serious injury and possibly gangrene. This injury needs to be urgently assessed and treated in an emergency room.

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Are there different forms of epinephrine?

Epinephrine can be administered via an auto-injector, a preloaded syringe, a regular syringe, or a metered-dose inhaler. Epinephrine inhalation from a metered-dose inhaler is not recommended as an alternative to injectable epinephrine in the treatment of anaphylaxis.

The Epipen® is the only auto-injector currently available in Canada. It is easy to use and comes in two strengths. The Epipen® Jr. delivers 0.15mg of epinephrine intramuscularly and the adult auto-injector delivers 0.30mg. Dosage should be worked out with your physician, but the current general recommendation is that children begin to use the adult Epipen® when their weight approaches 25 kg (55 lbs.).

The Epi E×Z Pen™ and Epi E×Z Pen™ Jr. have been withdrawn from the market but may be reintroduced at some time in the future.

The Ana-Kit® (Bayer) contains a pre-loaded syringe with two 0.30mg doses of epinephrine, 4 chewable 2 mg tablets of chlorpheniramine (antihistamine), 2 sterilizing alcohol swabs and a tourniquet. The Ana-Kit® is more difficult to self-administer, especially for children, but it presents additional options. It can be used to deliver low doses of epinephrine (for very small children) as well as multiple doses. The dosage of chlorpheniramine is also adjustable.

Injectable epinephrine is available in 1ml (mg) ampuls for administration by regular syringe. Its use can be mastered with instruction from your physician and it can provide a valuable back up when travelling.

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When does my child switch from Epipen Jr.® to a regular Epipen®?

Dosage should be worked out with your physician, but the current general recommendation is that children begin to use the adult Epipen® when their weight approaches 25 kg (55 lbs.).

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Where should I keep my Epipens®?

Given the rapidity with which symptoms can develop and progress, epinephrine must be available immediately. For this reason it is recommended that anaphylactic or potentially anaphylactic people carry their epinephrine with them at all times. It makes no sense for the auto injector to be in the office while a food allergic child is eating in the lunchroom or an insect sting allergic child is playing outside.

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How many Epipens® should I carry?

There should be at least two doses of epinephrine available at all times. A second dose could be required 10-20 minutes after the first if the reaction is continuing. This situation could occur if the reaction is very severe, the dose given is inadequate or the injector is faulty. This needs to be discussed with your allergist.

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At what age should my child carry his/her own Epipen®?

This will vary from child to child. When they are very little, pre-school children or their friends could injure themselves while playing with an Epipen® in a fanny pack. At this stage, a caretaker would always be close at hand and could carry the child's medication for them. This could also be the case for children in nursery school and kindergarten. As children progress through school, however, they move to different classrooms, the lunchroom, gym, recess, and assembly. The only reliable/consistent place for epinephrine is with the child. This does not mean that young children would be expected to inject themselves. While children can and must learn how to do this from a very young age, they should still have our help. The child could become too dizzy, confused or frightened to deal with the situation. Life-long habits are also easiest to establish early on. Many older children, who have not carried their medication, find it difficult to start taking responsibility for this.

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How reliable is epinephrine?

If given correctly at the outset of a reaction, epinephrine is extremely reliable.

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Do I have to take any precautions with the epinephrine?

Epinephrine is light sensitive and needs to be stored at a temperature between 15-30° C. It should not be refrigerated and it can't be left in a car during a heat wave or a cold snap. You should check your solution regularly to ensure that there is no brown discoloration or precipitate. You also need to keep an eye on the expiry date. The shelf life for the Epipen® is somewhere from 18-24 months. Make sure that you are getting the best available date when you are making your purchase. Used Epipens® need to be discarded in a needle proof container to minimize any chance of injury.

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I used the Epipen®, but there seemed to be some solution still in the device. Did I not inject it properly?

It may be worth noting that as each Epipen® and Epipen® Jr. contains 2 ml of solution there will be 1.7 ml remaining after injection.

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E) Allergens

What are the most common allergens?

The commonest allergens include food (peanut, tree nuts, fish and seafood in adults and milk, eggs, peanut, soy, tree nuts, fish and seafood in children), medication (penicillin), insect venom, latex and exercise. After investigation, a few reactions will still be labeled 'idiopathic' or 'cause unknown'.

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I developed a rash after Penicillin. Am I allergic to it?

Not necessarily. Penicillin allergy can be severe, but it is also over diagnosed. It's best to check with an allergist and, if necessary, be tested in a clinic setting.

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I have been told that my child has a "mild" peanut allergy. Do they really need to carry epinephrine?

The severity of reaction is not necessarily consistent. A much more severe reaction may follow a mild one. Most allergists recommend that all people with peanut allergy consider themselves to be at risk for anaphylaxis and prepare themselves accordingly.

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Is peanut oil safe to eat?

In North America, peanut oil is highly refined and the production is believed to remove or denature all of the protein (allergen) either by filtration or heat processing. In Europe and in North American specialty shops (especially health food stores), peanut oil may be cold pressed, and intact protein could be present. Allergic individuals must avoid these oils. Canadian peanut oil manufacturers, however, do not use cold pressed peanut oil as it is expensive, has a short shelf life and is potentially allergenic. In Canada, peanut oil must always be listed on the label if it is used as an ingredient or part of an ingredient. The same standards, however, do not apply to imported products. As manufacturing or manufacturing sources can change, and there is no designation of this on labels, we recommend that peanut oil be avoided by peanut/nut allergic people.

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If my child is allergic to peanuts, should they avoid tree nuts and vice versa?

A significant number of children who are sensitive to peanuts are also sensitive to tree nuts. Allergies can also develop over time. It is recommended that allergic individuals avoid both groups, as the risk of cross contamination is high. Members of the Canadian Nut Council are aware of this issue and have instituted manufacturing and training programmes to help reduce the risk.

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Is hydrolyzed plant protein now safe for allergic individuals?

Hydrolyzed plant protein is protein that may have originated in corn, soy, peanut or wheat and has been split by either acid hydrolysis or enzymatic digestion. Plant source is not delineated on food labels. A pilot study by Dr. Peter Vadas, et al has suggested that completely hydrolyzed plant protein may not be allergenic. Products containing partially hydrolyzed HPP are clearly allergenic. Until further studies have confirmed these findings, we recommend that allergic individuals continue to avoid eating hydrolyzed plant protein.

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F) Prevention

How can I prevent anaphylaxis?

Avoidance is the keystone of anaphylaxis management. In the case of food-induced reactions, get to know your sources of allergen, alternate names, safe manufacturers and restaurants. Even with scrupulous care, however, reactions may still occur. Be prepared to manage them.

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We are thinking of having another child. Is there anything we can do to prevent allergy for this child?

While the studies are not yet conclusive, it is recommended that pregnant and nursing mothers try to avoid potentially offensive allergens, particularly peanuts and nuts, and that they not be introduced to the child before the age of three years. When they are introduced, this should be done cautiously and under an allergist's guidance.

Delay introducing solid foods until your baby is 6 months old and try to breast feed until your baby is at least one year. If you are using formula, check with your doctor to make sure you are using the best one. Avoid cow's milk until your child is one year old.

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G) Children

Will my child outgrow their allergy?

Children who are sensitive to milk or egg tend to lose their allergy over time. Allergy to peanut, tree nuts, fish and seafood tends to persist. There is some suggestion, however, that the rate of persistence may be lower than previously thought.

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How can I tell if my other children are affected?

It is generally recommended that siblings avoid the food in question until the age of three years. They can be skin tested at one year of age or younger and you should discuss this with your allergist.

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H) Medic Alert

Should I wear a Medic Alert?

We recommend that all potentially anaphylactic individuals wear Medic Alert identification. In young children, this will serve as a reminder of the child's allergy for caregivers. In adults, coma could prevent self-administration of epinephrine or a description of medication allergy to hospital personnel. The Medic Alert should state the individual's anaphylactic sensitivity and that they carry an epinephrine autoinjector (e.g. Epipen®) in order to alert bystanders to look for and administer the device.

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I) Travel

How can I travel safely with anaphylaxis?

Please see our travel tips for some ideas.

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