Anaphylactic Attacks: What They Are and How to Handle Them

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An anaphylactic attack comes on fast and it can be disorientating, scary and pretty exhausting. But if you know how to recognise the symptoms and to respond to them, the chances of something going horribly wrong are so small that they have to be measured in millions of person-years.

And now for the details, which include:

What happens to your body during an allergic reaction

Allergic reactions are normally caused by IgE antibodies activating an immune system (immunologic) response. They can be provoked by a range of different things including foods, venoms, medications, natural rubber latex, radiocontrast media, semen and aeroallergens like grass, cat dander and horse dander as well as airborne food allergens from milk or seafood

Medications like non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics and radiocontrast media (substances like iodine that are used to increase the contrast of X-ray images) can also trigger immune system responses that involve immune system components other than IgE, such as IgG antibodies and complement proteins.

Allergic reactions can also be ‘non-immunologic’ and not involve an immune system response at all. These are provoked by an antigen—e.g. medications, alcohol and physical factors such as cold, heat or sunlight—that directly activates the body’s mast cells or basophils (and possibly other immune system cells). Both mast cells and basophils are types of white blood cell that release inflammatory mediators—chemical messengers that act on blood vessels and/or cells to produce an inflammatory response which looks just like an allergic response.

Severe reactions that occur via mechanisms that don’t involve IgE antibodies have traditionally been called ‘anaphylactoid’ or ‘pseudoallergic’ reactions, but several international allergy organisations recommend that the terms are scrapped and that everything is put under one ‘anaphylaxis’ umbrella, seeing that these types of reactions all look (and feel) the same.

When a reaction is not related to the immune system, your body does not have to have encountered the allergen before you have a reaction; you can have a severe reaction the first time you encounter it.

Some antigens— e.g. insect venom and certain medications like NSAIDs and opiate drugs—can provoke reactions via several immunologic and/or non-immunologic mechanisms simultaneously.

The clinical symptoms of allergic reactions mainly derive from the chemicals that are released by the body’s mast cells and, to a lesser extent, basophils. Once activated, these white blood cells release a veritable cascade of inflammatory mediators which cause physiological changes, activate other immunology pathways and attract other immune system cells to the ‘fight’. The most abundant and well-known of these mediators is histamine.

The signs and symptoms that accompany an allergic reaction have been shown to correlate with the concentration of histamine in the blood plasma. Histamine is created by your body to perform daily functions like regulating your sleep-wake cycle and releasing stomach acid. But it has also long been considered the principal mediator of anaphylaxis because, in high amounts, like those produced during a severe allergic reaction, it can also cause unwanted side-effects.

Skin (cutaneous) & mucosal symptoms

Localised histamine release in the skin causes sensory nerves to release neuropeptides which produces:

• Hives (urticaria)

Histamine circulating around the body causes blood vessels to expand (vasodilation)—to help white blood cells reach foreign invaders more rapidly—and to become more leaky (permeable)—to help white blood cells travel through the walls of the vessels to reach injured tissues. This, in turn, causes:

• Flushing (erythema) and a warm sensation throughout the body
• Itching (pruritus)
• Swelling of the face (angio-oedema), lips and tongue (which can make breathing difficult if it becomes severe)

Myth: ‘There are no hives so it can’t be anaphylaxis.’ NO, in fact, a lack of skin symptoms is a bad sign when it comes to anaphylaxis.

Skin and mucosal symptoms occur in the vast majority of cases of anaphylaxis. However, the presence of systemic skin symptoms—e.g. generalised hives—is not anaphylaxis unless they are accompanied by either respiratory and/or cardiovascular symptoms and/or persistent gastrointestinal symptoms (according to certain definitions of anaphylaxis).

However, skin symptoms are absent in around 10 to 20% of anaphylactic reactions, and an absence of symptoms is especially common in cases of fatal anaphylaxis.

Breathing (respiratory) symptoms

Histamine causes the smooth muscle in the throat to contract and the upper airways to narrow. As fluid leaks out of the blood vessels, the layer of tissue that lines the body’s interior (the mucosa) starts to swell up (mucosal oedema). Histamine also increases mucus secretion, making it even harder to breathe.

Upper airway symptoms include:

• Blocked nose (nasal congestion) or runny nose (rhinorrhœa)
• Sneezing
• Itchy throat (throat pruritus)
• Persistent coughing
• The sensation of swelling or tightness in the throat/around the larynx (laryngeal oedema)
• Difficulty talking or hoarse voice (dysphonia)
• Difficulty swallowing (dysphagia) or painful swallowing (odynophagia)
• A harsh sound when breathing (stridor)

In the lower airways, histamine causes the smooth muscle in the airways of the lungs (the bronchi) to constrict (bronchoconstriction), causing contractions in the airways that make it hard for someone to catch their breath (bronchospasm). The bronchi can become plugged up with mucus and the tissue can also start to swell (bronchial oedema). Fluid can collect in the air sacs in the lungs (pulmonary oedema).

Lower airway symptoms include:

• Chest tightness
• Shortness of breath (dyspnea)
• Difficulty breathing
• High-pitched or wheezing sounds when breathing

If the reaction goes unchecked, it can end in respiratory failure, which is when when your lungs can’t get enough oxygen into your blood or remove enough carbon dioxide, resulting in too little of the first (hypoxemia) and too much of the second (hypercarbia) in your body. Finally there is respiratory arrest; you stop breathing.

Gastrointestinal (GI) symptoms

Histamine initiates contraction of the intestinal smooth muscle and alterations in water and electrolyte absorption which produce:

• Stomach pain and/or cramping
• Diarrhoea

Histamine also acts as a neurotransmitter, stimulating the vomiting centre in the medulla oblongata (part of the brain stem) to provoke:

• Nausea
• Vomiting (emesis)

Heart & circulation (cardiovascular) symptoms

The expansion of the blood vessels coupled with their increased permeability—which can result in around a third of your blood plasma leaking into the surrounding tissues in a matter of minutes—can cause them to empty rapidly, resulting in a sudden and dramatic drop in blood pressure (hypotension), making it more difficult for the heart to fill up and pump blood around the body.

Cardiovascular symptoms include:

• Dizziness
• Fainting (syncope)
• Rapid heartbeat (tachycardia)
• Heart palpitations (arrhythmia)—the feeling of a skipped beat, a rapid fluttering, ‘flip-flopping’ or pounding sensation in the chest
• Slow heartbeat (bradycardia)—although a rapid heartbeat is the most common form of irregular heartbeat seen during anaphylaxis, a slow heartbeat or an initial rapid heartbeat followed by a reduction (‘relative bradycardia’) is occasionally seen, often in venom-induced reactions
• Pallor and floppiness (hypotonia, in very young children)

The healthy human heart also contains a lot of mast cells and the inflammatory mediators released from these mast cells during anaphylaxis contribute to vasoconstriction, coronary artery spasm and the rupture of atherosclerotic plaque (the hard build-up of fat, calcium and cellular waste that can line the artery wall), which can provoke cardiac arrest (which is not the same as and slightly more urgent than a heart attack).

Myth: ‘If you haven’t passed out, you haven’t had an anaphylactic attack.’ NO.

There are several grades of anaphylaxis (see next section), equivalent to mild, moderate and severe anaphylaxis. The least severe—which I have called ‘mild’, but is still a serious reaction which needs to be treated immediately with adrenaline—does not involve passing out.

The moderate and severe versions of anaphylaxis do include fainting or loss of consciousness (note: fainting is temporary whereas loss of consciousness tends to be prolonged) as possible symptoms, but you don’t have to suffer from every possible symptom to experience (severe) anaphylaxis.

The most severe form of anaphylaxis can involve loss of consciousness due to a sudden, massive drop in blood pressure; this is called anaphylactic shock. At this point, your blood pressure has dropped to dangerously low levels and there is inadequate blood flow to your vital organs and tissues, which can lead to organ failure.

The most severe form of anaphylaxis can also involve not being able to breathe properly (respiratory failure), during which you will probably still be conscious, if lethargic. If left untreated, this will lead to respiratory failure and you will stop breathing, at which point you will lose consciousness and your prognosis is not looking good.

The very (very) vast majority of people who experience anaphylaxis will not experience anaphylactic shock, respiratory failure or respiratory arrest.

Nervous system (neurological) symptoms

Neurological symptoms are mostly a result of not enough blood getting to the organs and include:

• Lethargy
• Headaches
• Mental confusion
• Slurred speech
• Seizures or strokes (extremely rare)
• Anxiety or an impending sense of one’s death—in medical-speak, this is referred to as angor animi, or ‘soul anguish’, a feeling that ‘something isn’t right’, or more commonly ‘a feeling of impending doom’
• Behavioural change (‘infants’ and young children) such as irritability, stopping play or clinging to their parent

Other symptoms

Other symptoms can occasionally be associated with an allergic reaction.

These include:

• A metallic taste in the mouth
• Uterine cramps with or without vaginal bleeding (metrorrhagia)—essentially, something that feels and can look like you’re having your period—which is very rarely experienced by women

Timing and severity of symptoms

As a rule of thumb, the quicker the onset of allergic symptoms, the more severe the reaction is likely to be. The onset of anaphylaxis is usually sudden, with symptoms often developing within seconds to minutes of exposure to a trigger. Since the skin, respiratory and digestive tracts are rich in mast cells, which are generally considered the most important cell in driving allergic reactions, these organs systems are the ones that tend to be primarily affected in the reaction.

Most cases of anaphylaxis start within 30 minutes of being exposed to the trigger. The length of time it takes to react depends on the trigger. On average, severe reactions to injected drugs take around 5 minutes to reach peak severity, those to venom take about 15 minutes, and those to food around 30 minutes.

Some severe reactions, however, take longer to develop; notably, in cases of alpha-gal syndrome, the now-notorious allergy to red meat, symptoms generally appear 3 to 6 hours after eating.

Symptoms are often dose-dependent; the more of the allergen a person has been exposed to, the worse the reaction will be. They also seem to be directly related to the amount of histamine that’s released (especially skin symptoms)

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When is it anaphylaxis?

Allergic reactions can start off with mild symptoms before becoming more serious—however, there is still no absolute consensus about the point at which a reaction becomes anaphylaxis. There have been several attempts at coming up with a definition and description of anaphylaxis by various organisations including the American National Institute of Allergy and Infectious Disease and Food Allergy and Anaphylaxis Network—whose revised ‘NIAID/FAAN Consensus Criteria for Anaphylaxis’ were published in 2021—and the World Allergy Organization (WAO) who came up with an ‘Updated grading system for systemic allergic reactions’ in 2024.

A European panel of experts—GA²LEN, the Global Allergy and Asthma Excellence Network—attempted to create an international consensus by ‘resolving the differences’ in the criteria specified by those organisations and developed a ‘definition, overview, and clinical support tool’ that was published in 2025.

It states that anaphylaxis is likely when any one of these criteria are fulfilled:

1. After no known allergen exposure:
   • There is the sudden onset of illness, with skin or mucosal symptoms and EITHER of:
     • Respiratory symptoms
     • Cardiovascular symptoms
2. After likely allergen exposure:
   • There is the sudden onset of TWO or more of the following:
     • Skin or mucosal symptoms
     • Respiratory symptoms
     • Cardiovascular symptoms
     • Severe gastrointestinal symptoms
       • Note that vomiting just once or twice or experiencing diarrhoea does not count in cases of food-related anaphylaxis because these symptoms are caused by the allergen being in the gut itself. However, if someone vomits once or twice during another type of reaction, for example, after a bee sting, it does count, since the GI tract is remote from the site of the bite, therefore part of a systemic reaction which could lead to anaphylaxis
3. After known allergen exposure:
   • There is the sudden onset of EITHER
     • Respiratory symptoms after exposure to a non-inhaled allergen
     • Cardiovascular symptoms

Using the various signs and symptoms experienced by their patients, different teams of experts have classified allergic reactions into 4 or 5 categories. The grading systems range from mild allergic reactions to severe anaphylaxis and they look something like this:

	Grade 1 (mild, transient reaction)	Grade 2 (systemic reaction)	Grade 3 (‘mild’ anaphylaxis) Any 2 of	Grade 4 (‘moderate’ anaphylaxis) Any 2 of	Grade 5 (‘severe’ anaphylaxis)
Skin symptoms (any of)	Mild itching Patches of flushed skin Localised hives Mild facial (e.g. lip) swelling	Widespread itching and protracted scratching Generalised flushing (covering over half the body area) Systemic (numerous or widespread hives) Moderate facial swelling	(Skin symptoms may be present but don’t count towards the classification)	(Skin symptoms may be present but don’t count towards the classification)	(Skin symptoms may be present but don’t count towards the classification)
	OR	AND/OR
GI symptom (any of)	Nausea Mild stomach cramps	Persistent (over 20 minutes) and significant (non-distractable) stomach pain Vomiting (once or twice) Diarrhoea (once or twice)	Severe and persistent crampy stomach pain Repetitive vomiting (more than twice) Defecation (more than twice)	(GI symptoms may be present but don’t count towards the classification)	(GI symptoms may be present but don’t count towards the classification)
	OR	AND/OR	AND/OR	AND/OR	AND/OR
Respiratory symptoms (any of)	Sneezing, Runny, Itchy or blocked nose Itchy, uncomfortable throat that needs clearing Repetitive coughing	Runny, itchy or blocked nose	Throat tightness Painful swallowing Repetitive coughing Hoarseness High-pitched voice (stridor) Mild to moderate wheezing Shortness of breath	Tongue swelling Difficulty swallowing Severe wheezing and shortness of breath that does not respond to 2 doses of adrenaline High-pitched voice (stridor) and difficulty breathing; can be recognised by abnormally rapid and shallow breathing, the skin around the neck, between the ribs or under the breastbone pulling inward with each breath, nasal flaring Bluish skin/lips/nails discolouration caused by a lack of oxygen in the blood (cyanosis) Pale skin (pallor)	Respiratory failure requiring ventilation Respiratory arrest (breathing stops but the heart is still beating)
			AND/OR	AND/OR	AND/OR
Cardiovascular symptoms (any of)			Sudden change of behaviour or level of activity, indicating dizziness or weakness	Floppiness (hypotonia) Fainting Rapid (or sometimes slow) heartbeat Irregular heartbeat	Loss of consciousness Anaphylactic shock (widespread dilation and permeability of blood vessels requiring immediate infusion) Cardiac arrest (heart stops beating)
	OR		AND/OR	AND/OR
	Red, itchy or watery eyes Metallic taste in mouth		Women: Uterine cramps with or without bleeding	Neurological symptoms: * Signs of reduced alertness: (drowsiness, confusion) Feeling of ‘impending doom’

This table was created using the following papers:

1. 2024 paper: ‘Updated grading system for systemic allergic reactions: Joint Statement of the World Allergy Organization Anaphylaxis Committee and Allergen Immunotherapy Committee’
2. 2021 guidelines: ‘Guideline (S2k) on acute therapy and management of anaphylaxis: 2021 update’
3. 2021 paper: ‘A severity grading system of food-induced acute allergic reactions to avoid delay of epinephrine administration’

Practically-speaking, these are not clear cut stages that a person necessarily travels through; you don’t have to experience all of the symptoms in a life-threatening reaction and there’s no telling how long each stage will last (not long, if it’s a severe reaction). A person can also skip a stage or two and start off with the most severe type of reaction.

The signs and symptoms of anaphylaxis are unpredictable and can vary from one person to another and from one reaction to another. Some people only experience severe symptoms affecting one organ system, i.e. the respiratory system (they can’t breathe in enough oxygen) or the cardiovascular system (their heart can’t pump enough blood to their organs). Either of these difficulties can result in death and needs to be dealt with by medical professionals as soon as humanly possible.

People often experience reactions of a different level of severity; people with a history of mild reactions can suddenly experience a moderate or severe reaction, or vice versa. In these cases, cofactors will often be involved. Cofactors are things about a person or the situation they’re in that can make a reaction worse, such as exercise, medications, alcohol, stress or ambient temperature.

Infant anaphylaxis can be difficult to recognise because infants are incapable of telling us how they are feeling, so anyone facing an infant having an allergic reaction has to look for certain signs that could indicate anaphylaxis, such as:

• Tongue thrusting or pulling, repetitive lip licking, ear tugging, eye rubbing—indicating itchy/tingling mucosa
• Hoarse crying—indicating a swollen throat/larynx
• Spitting up, hiccups, back arching—indicating GI discomfort
• Persistent abnormally rapid and shallow breathing, noisy breathing or grunting—indicating difficulty breathing
• Abnormally slow breathing—could indicate an upcoming breathing emergency
• Rapid heartbeat, blue-tinged skin, mottled skin—indicating not enough oxygenated blood getting to tissues and organs
• Behavioural changes including persistent and unexplained irritability, persistent crying, clinging to caregiver, sudden drowsiness, unresponsiveness, going floppy (hypotonia)— indicating neurological involvement

The following sites have good pages on the signs and symptoms of anaphylaxis in infants and toddlers:

• The Allergy and Asthma Network (AAN)
• Asthma and Allergy Foundation of America (AAFA)
• Kids with Food Allergies (KFA)

Ultimately, death from anaphylaxis is normally the result of someone not getting enough oxygen-filled blood to their brain and other essential organs. So, when a person sounds like they are having difficulty breathing properly and/or maintaining consciousness or making sense, it’s time to act.

Myth: ‘Anaphylaxis often results in death.’ NO, it doesn’t.

People who experience an anaphylactic attack rarely ever end up dying, which is all the more remarkable when you consider the fact that the majority of anaphylactic attacks are not dealt with properly (see Common mistakes later).

You can read more about the prevalence of anaphylaxis, the most dangerous triggers and the people most at risk here.

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The many faces of anaphylaxis

Anaphylaxis looks different for every individual with allergies.

Different triggers, different ages groups, different symptoms

Symptoms of anaphylaxis differ according to the type of trigger; for example, people who experience anaphylaxis to drugs or venom are more likely to experience cardiovascular symptoms, whereas people—often children—who experience anaphylaxis to food are more likely to experience respiratory symptoms. Note that these are generalised observations; ultimately, anaphylaxis is a dynamic event during which all sorts of symptoms may come and go.

A person’s symptoms may also differ according to whether the offending substance has been inhaled, eaten or injected. For example, being injected with a medication that you are allergic to or applying it to your skin is more likely to cause an allergic reaction than swallowing it, and having it administered intravenously is more likely to cause the most severe symptoms.

However, it would be a mistake to think that you can predict the severity of a reaction depending on the route of exposure; although injected drugs and venoms tend to produce worse reactions than food, that’s not always the case. For some unlucky people, eating a tiny amount of peanut is just as likely to produce a life-threatening reaction as being stung by a wasp.

Triggers and symptoms also differ according to age group, with children under the age of 6 being more likely to have food allergies than older children and adults, who are, in turn, more likely to react to venom and drugs. Respiratory symptoms are also more common in young children, with teenagers and adults being more likely to experience cardiovascular symptoms.

Anaphylaxis can have two phases and it can be persistent

An anaphylactic reaction can be uniphasic, biphasic, protracted, or refractory.

A uniphasic reaction is one that occurs just once after exposure to the trigger. After the first set of symptoms have gone away, the allergic reaction is over. This is the case in the vast majority of anaphylactic reactions.

A biphasic reaction is when you have an initial episode of anaphylaxis which is then followed by a second wave of symptoms at least one hour after the first lothave subsided. Estimates of the number of biphasic reactions as a proportion of all anaphylactic reactions vary between less than 1% to 23%. 2 large reviews of patients with anaphylaxis have found an overall rate of biphasic reactions of around 5%.

The second wave of symptoms typically occurs around 11 hours after the first wave, although it can take as long as 72 hours to appear. In a study involving 103 patients who were contacted within 3 days of visiting the emergency department, the average time until the second wave hit was 10 hours, but around 4 in 10 people had had recurrent symptoms more than 10 hours after their initial reaction.

The early administration of adrenaline during the initial symptoms may help to prevent biphasic reactions.

The severity of the symptoms suffered the second time around is unpredictable, and the second phase often does not resemble the first. The majority of studies have found that the second round of symptoms tend to be less serious than the initial symptoms and severe (aka ‘clinically important’) reactions are rare, although about half of those who experience a second wave of symptoms will still need to be treated with adrenaline. Fatalities are almost unheard of.

A review of the data of 496 adults presenting to the emergency department in two Canadian hospitals with anaphylaxis found only 5 cases of ‘clinically important’ biphasic reactions. A similar review of adults patients seen at a hospital in Japan found that 18 of the 202 patients with anaphylaxis had biphasic reactions, 8 of which qualified as anaphylaxis but only 2 of which were severe.

A review of 14 years’ worth of admissions to a children’s hospital in America identified 108 cases of anaphylaxis, 6 of which were biphasic and 3 of which involved serious symptoms. A similar review of children seen at a hospital in Japan during a 7 years period identified 353 cases of anaphylaxis, 6 of which were biphasic and one of which required adrenaline.

Biphasic reactions among people receiving immunotherapy may be higher, with studies putting the rate at around 1 in 10 patients to 1 in 5.

Biphasic reactions can happen after provocation by any kind of trigger and it’s almost impossible to predict which cases of anaphylaxis will have 2 waves of reactions. But some researchers have made a stab at it.

Although biphasic reactions to food have been found to be both more and less likely than to other triggers, studies do seem to agree that biphasic reactions are more likely among people who are reacting to an unknown trigger (aka ‘idiopathic’ anaphylaxis).

Another things that studies agree on is that biphasic reactions are more likely among people whose initial symptoms are severe, include low blood pressure (hypotension) and need more than one dose of adrenaline.

A review of 315 anaphylaxis cases seen at 8 Australian hospitals reported that 55 patients had biphasic reactions, 29 of which required adrenaline. Their medical data revealed that a biphasic reaction was more likely in people with pre-existing lung disease (mainly asthma); these people may have less physical capacity (‘physiological reserve‘) to deal with the reaction.

Although the medical history and initial symptoms of people who have uniphasic and biphasic reactions are similar, a biphasic reaction may also be preceded by an initial wave of symptoms that last relatively longer than those of a uniphase reaction.

Some experts think that some reactions that are classed as biphasic and have a second wave of symptoms occurring soon after the first wave may just be long-drawn-out reactions whose symptoms are temporarily masked by treatment with adrenaline. Which brings us onto our next category of anaphylactic reaction.

A protracted (or prolonged/persistent) reaction is an episode of anaphylaxis that lasts for at least 4 hours, although in practice this is often several more hours, even days (21 days on one occasion) without completely resolving. The exact frequency of these types of reactions is unknown, but they seem to be very uncommon; rarer than biphasic reactions in any case.

Refractory anaphylaxis has no formal definition but it basically involves continued signs of anaphylaxis despite the appropriate use of adrenaline and other symptom-focused therapy—i..e respiratory or cardiovascular symptoms that stubbornly persist in spite of aggressive attempts to get rid of them. It’s highly likely in cases where the initial symptoms need 3 or more doses (or an IV infusion) of adrenaline. It’s a rare condition that’s probably due to the ongoing release of inflammatory mediators and insufficient circulating adrenaline.

An analysis of data from the European anaphylaxis registry identified 42 cases out of a total of 11,596 (0.0036%) and revealed that the most common triggers of these types of cases were drugs (notably antibiotics), followed by foods then insects, that bee venom was more likely to provoke refractory anaphylaxis than wasp venom and that people having some kind of operation (hence the drugs) were the group most at risk of experiencing them. Just over a quarter (26.2%) of cases were fatal.

A reaction can fit into more than one of these categories. Some people who have anaphylaxis to omalizumab (an anti-IgE antibody medicine that prevents the release of IgE, marketed as Xolair) suffer both a delayed onset (occurring over 2 hours after they take it) and a protracted progression of symptoms that lasts several hours.

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What happens next?

If your anaphylactic attack has been severe enough to warrant a trip to the hospital, you can expect further immediate help, including being given oxygen if you’re having problems with your breathing, and/or receiving further doses of adrenaline if your symptoms are not getting any better. If you’re at the hospital, you may be given adrenaline intravenously (i.e. straight into a vein) as well as fluids to help replace some of the ones you may have lost from your blood vessels during the attack, and any other type of emergency care the doctors think you need.

Monitoring

When all the action is over, you will probably be kept in to be monitored in case your symptoms worsen or you suffer a biphasic reaction.

There is no standard length of time for the period of monitoring, but as a very general rule of thumb, you will be kept in:

• at least 2 hours if you reacted well to the adrenaline, and your symptoms have completely disappeared, and you have an adrenaline auto-injector that you know how to use, and you can be properly supervised by someone else on your discharge
• at least 6 to 8 hours if you had a to moderate-severe reaction, or you needed 2 doses of adrenaline, or you have asthma and are still wheezing, or you’ve got a history which includes a previous biphasic reaction or a protracted/prolonged reaction
• at least 12 hours if you had a severe reaction which required more than 2 doses of adrenaline, or you have severe asthma or your reaction involved acute breathing problems, or you’ve had a reaction to food which is still being digested and could cause further problems, or it’s late at night and you may not be able to respond properly if your symptoms deteriorate further, or you live in an area with difficult access to emergency care
• 12 to 24 hours if you suffered from low blood pressure or anaphylactic shock

At a bare minimum, doctors should keep a close eye on your blood pressure, your heart rate and function and your blood oxygen level.

The management of anaphylaxis is not supposed to end with treatment of the anaphylactic episode. In a perfect world, long-term management for people who have experienced anaphylaxis should include:

• advice on what to do if you suffer a second wave of anaphylactic symptoms and advice on where to find information about anaphylaxis in case of future episodes
• a prescription for an adrenaline auto-injector (or two)
• (advice to see your doctor to get) a referral for specialist assessment
• advice on how to avoid the trigger (if identified)
• an individualised anaphylaxis action plan
• advice on getting a medical alert ID

Unfortunately, this is not a perfect world and the majority of people who are treated for anaphylaxis do not get most of these things. Luckily, there are still a lot of things you can do for yourself.

A (prescription for a)n auto-injector

If you’re lucky you may be given an auto-injector (or 2) when you’re discharged and, if not, at least a prescription.

Doctors have no absolute rules when it comes to prescribing auto-injectors. Guidelines on how many auto-injectors to prescribe vary per country (and practice varies within each country). In countries like the UK and Australia, doctors often prescribe one although, in the UK at least, the official guidance is to prescribe two (but the British Society for Allergy & Clinical Immunology (BSACI) recommends just one on the basis that one dose is usually all that’s needed for most reactions). In the US, doctors commonly prescribe two.

According to American guidelines, although agencies like the FDA recommend that people at risk of anaphylaxis carry 2 auto-injectors at all times, because these devices are costly, the advice is that people be prescribed 2 devices if they required multiple doses of epinephrine to treat their reaction and/or have a history of biphasic reactions.

According to European guidelines, you should be prescribed 2 auto-injectors. This should definitely happen if:

• you’ve had anaphylaxis to food, latex, aeroallergens, exercise or an unknown trigger before
• you have moderate/severe persistent asthma and a food allergy
• you have Hymenoptera venom allergy and
  • have not had / are not having immunotherapy and you’ve had more than systemic skin reactions or are at high risk of re-exposure
  • are having / have had immunotherapy and you’ve had more than systemic skin reactions and your risk of relapse is high
• you’re an adult with an underlying mast cell disorder and any previous systemic allergic reaction
• you’re a child with an underlying mast cell disorder, severe skin symptoms and an elevated baseline concentration of tryptase (an enzyme stored in mast cells that may indicate an increased risk of severe anaphylaxis to non-food antigens when present in high concentrations) in the blood

You may get 2 AAIs if:

• you’ve had a mild-to-moderate reaction to food allergens known to be high-risk in your region (e.g. celery in northern Europe, peach in southern Europe, peanut and/or tree nut in the US, shellfish in Asia-Pacific, milk if you’re a child)
• you’re a teenager or young adult with previous mild-to-moderate reactions to food
• you’re remote from medical help and have had a mild-to-moderate allergic reaction to food, Hymenoptera venom, latex or aeroallergens
• you’ve had a mild-to-moderate allergic reaction to traces of food
• you have a Hymenoptera venom or drug allergy with more than systemic skin reactions and you have cardiovascular disease
• you’re having oral immunotherapy for food allergy

Adrenaline auto-injectors are only available in about a third of the world’s countries. If you live somewhere without access to adrenaline auto-injectors, you may be offered one of the following as an alternative option:

• A 1 mL ampule of adrenaline and syringe
• An unsealed prefilled syringe containing the correct dose of adrenaline drawn up in advance by your doctor; note: adrenaline is stable for only 3 to 4 months in an unsealed syringe

You should also get advice on how and when to use the auto-injector(s) or the opportunity to handle and use a dummy training syringe. Although using a syringe might, at first glance, seem more daunting than using an auto-injector, a 2018 study found that people who were trained to a syringe made fewer mistakes than those trained to use an auto-injector (14.0% made mistakes using the EpiPen vs. 2.3%, using the syringe). And practice makes people more comfortable about doing it.

If you are not given an auto-injector or a prescription for one and you have an anaphylactic reaction, remember to lie down and raise your legs, or to sit down and stretch your legs out in front of you if you can’t breathe easily.

Speaking from personal experience, lying down can help get you through a case of moderately severe anaphylaxis without medication. I had 4 anaphylactic attacks before I knew what they were, let alone anything about food allergy. Luckily, I also have a horror of passing out (I like to be on top of everything, except for the floor) so I knew that lying down and putting my feet up should prevent this from happening. I ended up lying down with my feet up for around an hour and a half each time which, though not as relaxing as it sounds, still enabled me to walk away without any lasting damage.

A referral to a specialist

You should get a referral to see a doctor, preferably an allergist. They will go through your medical history and carry out the tests necessary to try and determine (or confirm) what caused your reaction.

Some follow-up studies involving people who’ve had an allergic reaction to food or insect stings have found that only about 1 in 5 people take the opportunity to go to the specialist they have been referred to and find out more about their allergy.

Not seeing a specialist is a missed opportunity for several reasons.

For a start, you may have been misdiagnosed and, if you’re going to avoid your trigger(s) successfully, you need to know what they are. One study reported that 35% of patients referred to allergy/immunology had had their original diagnosis changed; a few (7%) were determined not to have suffered from anaphylaxis and, among those who had had a trigger identified, a few (6%) were told that a different allergen had actually triggered their reaction and 1 in 5 (20%) were told that their trigger was still unknown. About a third (32%) of those whose trigger was initially unknown found out what had caused their reaction.

Not seeing an allergist is very much a wasted opportunity for those who’ve had anaphylactic reaction to insect venom, because those people are great candidates for immunotherapy. Venom immunotherapy has been shown to be a safe and effective treatment for people who have suffered venom-provoked reactions. Although the therapy itself can, on rare occasions, provoke systemic reactions, no fatalities have been reported and it works about 98% of the time. For almost everyone, it’s effectively a cure which takes away the stress of having to carry an adrenaline auto-injector and be extra-vigilant.

Immunotherapy for certain essential medications like antibiotics and chemotherapeutics has also been shown to be highly effective.

Immunotherapy for food allergies is not as effective, and also not routinely available, but immunotherapy for peanut, milk and egg has been shown to achieve clinical desensitisation—a sort of temporary tolerance which is maintained as long as the person eats a small dose of the allergen every day—in most patients and it can often be made available to certain people who are at high risk of severe reactions.

However, a visit to an allergist has other benefits for the food-allergic, as illustrated by this 2021 study involving a group of peanut-allergic children aged 8 to 16. The study was designed to investigate the effect that undergoing a food challenge resulting in anaphylaxis would have on the children’s ‘health-related quality of life’ (HRQL)—that is, their emotional well-being with respect to their health. 56 children reacted during their peanut challenge, 16 of whom had anaphylaxis. These children were all encouraged to use an auto-injector to self-administer adrenaline. 14 of them did and the parents took care of the other 2.

The researchers found that experiencing an allergic reaction under clinical supervision improved the children’s (and their parents’) HRQL. The children who had experienced anaphylaxis and used an auto-injector also saw an improvement in their feelings of self-efficacy—their perceived ability to handle the situation. 12 of the children who were questioned a year later when they went back to the hospital for immunotherapy still felt just as good about being able to live with and handle their food allergy. Ultimately, what this study showed is that finding out exactly how you may react to your food trigger and how you can deal with it brings peace of mind for everyone involved.

People who’ve had severe reactions to a food that’s an important nutrient in their diet, like milk for example, or have to eliminate several foods from their diet, may also be offered a referral to see a dietician to make sure that they can maintain a balanced diet.

Some people may also be offered a referral to a psychologist if they have had a particularly traumatic experience. Having an anaphylactic attack can be a traumatic experience, even causing PTSD in some people who experience it, and anyone feeling anxiety or distress after an episode should not be ashamed to seek help!

Advice on allergen avoidance

If your trigger has been identified, you should be given advice on how to avoid it in future.

Advice on avoiding food allergens will depend on the actual allergen, but it will involve:

• reading ingredients labels carefully
• paying attention to ‘may contain’ labels and avoiding those foods entirely if you’re particularly sensitive to them.
• avoiding foods that may cross-react with the one you’re allergic to; for example, if you’re allergic to shrimp, you may be told to avoid eating all shellfish, or if you’re allergic to walnuts, you may be advised to avoid all nuts (although, strictly-speaking, this may be unnecessary, but you’d need to undergo a food challenge to be sure)

Advice on avoiding insect stings will include things like:

• Know your enemy: stinging insects are most active during the late spring, summer and autumn months. Bees tend to provoke symptoms in the spring and early summer whereas wasps are more numerous in the late summer and autumn. Yellow jackets nest in the ground and in walls. Hornets and wasps nest in bushes,
• Avoid wearing sandals or walking barefoot in the grass
• Never swat at a flying insect; gently brush it aside or wait for it to leave
• Do not drink from open drink cans
• Be alert when eating outdoors and try to keep food covered at all times
• Cover your outside bins with tight-fitting lids and avoid open bins in public areas
• Avoid sweet-smelling perfumes, colognes and deodorants
• Avoid wearing brightly-coloured clothing
• Garden with caution; wear shoes and socks and use work gloves
• Open your windows with caution during the months when your trigger pest is active; opening during the very early morning should minimise their chances of getting in your house
• Drive with your car windows closed
• Have nests or hives near your home removed

Whatever your trigger, you should get a handout that will give you tips on how to minimise your exposure to it. If you have another condition that could worsen your allergic reactions, such as asthma, eczema, cardiovascular disease or systemic mastocytosis, you should be given tips on how to keep it under control.

If this is not the case, you can look up a lot of this type of advice online.

An anaphylaxis action plan

In ideal circumstances, you will be given a personalised emergency anaphylaxis action plan which should include information like:

• Personal identification data: name, address, contact number, maybe a photograph
• Names and phone number of emergency contacts (parents, guardian, or next of kin, close friend)
• Details of personal doctor/allergist
• Contact details for local emergency services
• Which allergens/triggers need to be avoided
  • Including the generic and proprietary names of drugs and possible cross-sensitivities—e.g. if allergic to walnut, avoid pecans—if relevant
  • any non-allergen triggers or cofactors (e.g. exercise) that should be avoided
• How to recognise the signs and symptoms of mild or moderate allergic reactions, and what to do
• How to recognise the signs and symptoms of anaphylaxis and what steps to take (i.e. position yourself/the person having the attack properly, administer adrenaline, call an ambulance)
• Other pertinent information like, for example, where extra medication is kept, whether the person having the attack has other conditions that have to be taken into consideration like, for example, asthma or heart problems

If you have been given an anaphylaxis emergency kit including medicines, you should be told when to use them:

• Use the adrenaline auto-injectors first; the plan should include detailed instructions on how to correctly administer the auto-injector device (in case carers have to use it)
• Antihistamines (for skin symptoms)
• Inhaled beta2-agonists (for asthma/bronchospasm)

A copy of plan should be kept by the person who had the reaction, any caregivers and the family doctor.

People who have a management plan for their allergy, who know which triggers to avoid and how to avoid them are less likely to have an accidental reaction. And if they do have an allergic reaction, it’s more likely to be a mild one.

A medical alert ID

People who’ve been treated for an anaphylactic reaction are often advised to get some form of Medic Alert ID. This, at least, is something that is fully under your control and if you are at risk of having severe reactions, you should seriously consider getting something to help first responders help you.

There are a whole range of companies out there who sell them, here are a few things to consider when you’re choosing one:

Visibility and convenience; emergency service personnel are trained to check wrists and necks for these types of IDs, so a bracelet or necklace is the best way ensure that they can see the vital information when it’s needed most. If you don’t want a bracelet or necklace, other options like shoe IDs that attach to laces or IDs that attach to sports watch bands are available.

Information needed and engraving space; the ID should have enough room to list all of the information needed to identify the wearer, contact their loved ones and perform treatment safely:

• First and last name
• Allergies and/or medical conditions
• Current medications
• Treatment considerations / restrictions
• Emergency phone numbers

Abbreviations such as ‘EPI’ for adrenaline, ‘T1D’ for Type 1 Diabetes or ‘NKA’ for no known allergies are universal terms (in English speaking countries) and can help to save space. Consult with your doctor to determine what essential information to include. If you have a complex medical condition, options to store more information in an emergency online profile are available.

Comfort; a medical ID is meant to be worn all of the time and should become second nature, so you’ll need it to be comfortable and easy to get on and off. If you have dexterity problems, look for styles that stretch or have easy release closures or magnetic clasps.

Durability and legibility; your ID should be easy to read with a clear, good-quality engraving and a smooth finish. It may have to survive sports and pastimes like swimming, break-dancing or spending time at the beach. Materials like surgical grade stainless steel and titanium are the most durable and scratch-resistant metals currently available. If you opt for a bracelet, make sure that the band is durable, too, you don’t want it breaking and falling off.

Style; medic IDs don’t have to be boring, there’s something out there for every occasion, from going to school to running an ultra-marathon or picking up your award for services to the arts. Just make sure whatever you pick is visible and clearly looks like a medic alert ID and not some fancy bit of jewellery that first responders will ignore.

Guarantee; a good product will have a lifetime guarantee. If you actually wear it out, they should replace the engraved ID part for free.

There are also Android and Apple apps that will enable first responders to access vital medical information from your gadgets.

Image by Polina Tankilevitch on Pexels

Common mistakes

When it comes to treating anaphylaxis, lots (and lots) of people make the same kind of mistakes.

Not administering adrenaline

By far the most common mistake made by people treating an anaphylactic reaction is not administering adrenaline on time, or even at all, instead relying on medications like antihistamines or corticosteroids alone to treat symptoms.

In fact, over 3 decades worth of research has singled out failure to use adrenaline, or to use it promptly, as an important and avoidable factor in severe and fatal reactions.

Health professionals are not much better than laypeople. Several reviews have found that paediatricians, first responders and emergency doctors do not use adrenaline often enough. In fact, like a lot of lay people, doctors with less medical experience are more likely to administer adrenaline when a patient is showing signs of hypotension (low blood pressure)—like dizziness or loss of consciousness—instead of administering it when someone is showing other signs of anaphylaxis, like difficulty breathing (see When is it anaphylaxis?).

That said, the use of adrenaline by health professionals has almost doubled over the past decade (to 30.6%) but the average person is still just as reluctant to use their auto-injector.

So, why don’t people use adrenaline as they should?

Not having an auto-injector handy

A common reason for not administering adrenaline that pops up in many surveys and studies is the simple fact that people don’t have their auto-injector on them.

Some people find it too bulky, some are uncomfortable with carrying it in public or think that the emergency services will provide them with the care that they need, if they need it. Some people are less likely to carry one if they are exercising, wearing tight-fitting clothes or in familiar places like friends’ homes or school.

In many cases, people are not actually prescribed an auto-injector after an anaphylactic reaction (especially if they live in countries in South America, Africa/Middle-East and Asia-Pacific (although the number of prescriptions does seem to be on the increase. Not that that really matters to the people who can’t afford to buy them.

While there’s not much you can do about the second option (except, of course, to ask your doctor, and you may receive) if you do have an auto-injector, it’s worth finding ways to carry it around with you, even if they’re not cool.

That said, although a fair few people don’t have their auto-injector handy when they need it, more of them do, but they still don’t use it. There are more reasons for that.

Being scared to use the auto-injector

Some people may be reluctant to administer adrenaline, perhaps misconstruing the advice to call the emergency services afterwards as being due to the dangers of the adrenaline itself, as opposed to the need for monitoring and (possibly) additional treatment.

Myth: ‘Adrenaline is dangerous.’ NO it isn’t.

Adrenaline is a hormone made by the two adrenal glands in your body primarily in response to stress so that you’re ready to act in ‘fight or flight’ situations. Some people enjoy the heart-pounding thrill of an adrenaline rush so much that they try things like running with bulls or jumping out of perfectly good planes just so that they can have more of it.

Auto-injectors contain the drug form of the hormone which is perfectly safe when injected into the thigh. Although adrenaline often causes mild adverse effects such as anxiety, fear, restlessness, headache, dizziness, palpitations, pallor and tremor—symptoms similar to those that happen during the physiologic ‘fight or flight’ response that occurs normally in sudden scary or life-threatening situations—they are temporary.

Myth: ‘Adrenaline is particularly dangerous for people with heart problems.’ NO it isn’t.

Adrenaline can cause some serious adverse effects—such as heart problems, pulmonary oedema (fluid in the lungs) or a sudden increase in blood pressure, all of which can be caused by anaphylaxis itself—but these effects tend to occur because of overdosing, which almost never happens with an auto-injector (even when a child uses an adult EpiPen, the adverse effects tend to be mild).

The vast majority of the very rare cases of overdose involve adrenaline given by hospital staff intravenously with an IV.

A 2017 study investigating cardiac complications among adult patients with anaphylaxis determined that older patients (over 50 years) were more likely to suffer from heart problems when they received adrenaline because they had it administered through an IV. The authors of the study suggested that this could be because doctors were reluctant to give them adrenaline in the first place and, somewhat ironically, instead of injecting them, which would be safer, they ended up giving it intravenously, which is more dangerous and therefore resulted in more problems.

In this study, 9.1% of the older patients experienced heart problems after having adrenaline given to them via IV, versus 0.3% when it was injected. (In the younger group, these figures were 0.4% and 0.005%, respectively).

What this tells us is that adrenaline suffers from a bad reputation with regard to heart problems (mostly) because of bad IV technique, and that middle-aged and older people with anaphylaxis would be better off using their auto-injectors before they got to hospital, because this would most likely resolve their symptoms and prevent them from having adrenaline administered intravenously.

Although the risk of adverse effects is greater in people with certain pre-existing cardiovascular, central nervous system, or thyroid diseases, and in people who use certain medications, the heart, which is jammed with mast cells, is a target organ in anaphylaxis.

Anaphylaxis itself can cause serious vasospasm (the temporary narrowing of blood vessels), irregular heart beat, and heart attacks.

The benefits of using adrenaline during an anaphylactic attack, especially when injected, always outweighs the risks.

Not knowing when to use the auto-injector

People also don’t know when to use their auto-injector. In what is a typical story, a British study of teenagers found that only 16.7% of them had used their auto-injector during an anaphylactic attack, the most common reason being that they didn’t realise that their reaction needed treatment with adrenaline. Hopefully, if you’re reading this page, you now have a good idea of when to use your auto-injector.

Not knowing how to use an auto-injector

Auto-injectors are designed to be given by non-medical people but quite a few people—even doctors—don’t know how to use them properly. One of the most common mistakes is people accidentally injecting themselves in the hand because they don’t know which side of the auto-injector the needle comes out of and they have their thumb over the (wrong) tip.

Another common cause of accidents is not holding a child still when administering adrenaline. A study investigating auto-injector injuries involving children found 22 cases, 17 of which were leg lacerations caused by the child kicking or moving their leg during the administration of adrenaline. (Only 3 of them required stitches).

The authors of the study noted that none of the auto-injectors available in America included instructions to immobilise the child’s leg. The study ended up being instrumental in getting the manufacturer of the Epipen to change their instructions to advise a 3-second (instead of a 10-second) hold time (followed by a quick massage) to reduce the risk of injury.

Ways to reduce the chance of injury include:

• Holding the auto-injector in the palm of your hand with your thumb over your index finger. The needle is generally activated when the device is pressed against your thigh, you shouldn’t have to press any buttons, so there’s no need to have your thumb on either end
• Firmly immobilising a person’s leg before administering the adrenaline
• Placing the auto-injector against the thigh and pressing it against it, rather than using a ‘swing and jab’ motion
• Holding the device in place for the shortest period of time recommended by the manufacturer
• Not re-inserting the needle if it is dislodged before the recommended hold time passes

A study reviewing voluntary self-reports sent to the USA Poison Control Centers between 1994 to 2007 found 15,190 unintentional injections from auto-injectors. Among the injured, 57% were children and 18% were under 5 years old. Only 15% of the injuries were classified as ‘moderate’ and 0.2% as ‘severe’, and only 7.8% were treated. And only 40% occurred when someone was trying to inject themselves or another person during an allergic reaction. The others happened when someone was inspecting the device (13%), disposing of the device (11%), training to use the device (8%) or reaching into an enclosed space like a pencil case or a bag (7%). 2% mistook it for a highlighter.

Research to date has always found that the benefits of using an auto-injector outweigh the risks.

There are several different brands of auto-injector available in English-speaking countries, including Adrenaclick, Allerject, Altellus, Anapen, Auvi-Q, Emerade, EpiPen, Fastjekt, and Jext. You can find videos on how to use all of these devices (and others) online.

Emergency action plans also often include diagrams of how to use whichever device you’ve been prescribed and there are plenty of other online resources that can explain how to use auto-injectors, when to use them and how to take care of them.

Ultimately, if you know how to use the auto-injector that you have, you’ll be more likely to use it (properly).

Having an expired auto-injector

Another common mistake is not checking the expiry date and finding yourself with an auto-injector that’s past its ‘use by’ date.

Current American guidance is to use it anyway, as research has found that expired auto-injectors retain substantial (80% to 90%) potency, well beyond their expiration dates. One study found that the adrenaline remained sterile and pure more than 2.5 years after expiration. (Note: that said, although the contents of the auto-injector may appear to be clear and without apparent discolouration, this does not mean that the adrenaline is still pure.)

While the adrenaline may become less effective after its expiry date, it’s not harmful (unless it’s been into space), so it’s better to use an expired auto-injector than none at all. That was also the view of the British health department when the UK ran out of EpiPens a few years back.

Which is no excuse not to keep your auto-injector up to date. It’s the only way you’ll know for sure that it will work properly.

Ignoring the early symptoms of a reaction

Because serious reactions frequently start off in the same way as milder reactions, people who are about to experience a life-threatening reaction may not initially realise the potential severity. Early signs of anaphylaxis such as flushing and systemic hives are often ignored but they could be the just the first stage of a reaction that’s about to get rapidly worse.

Similarly, it’s not uncommon for mild wheezing following exposure to a food allergen to be mistaken for ‘routine symptoms’ in people who have asthma, especially when it is poorly controlled. In these cases, people often think that the reaction is due to an exacerbation of their symptoms and go for the asthma inhaler. If the symptoms persist even after the inhaler has been used, anaphylaxis should be suspected and adrenaline given—this should make the symptoms go away, although this may well be temporary and a call the emergency services should be made for further treatment and monitoring.

Food-allergic children, especially, are more likely to have respiratory symptoms and may have to wait for an extra half an hour before someone recognises that they are having an anaphylactic reaction and give them the appropriate treatment, even when those children have had anaphylactic reactions before.

In fact, it’s not unusual for a person having an anaphylactic reaction to only get help after they suffer very severe symptoms, like a heart attack. Even doctors are more likely to wait for someone to show signs of heart problems or collapse before acting, but it could be too late by then.

If you suspect that you (your child) have (has) just been exposed to an allergen and you start to experience mild symptoms, pay close attention to them and be prepared to act if they start to get worse.

Thinking you’re safe because you have a history of mild reactions

What happened during your previous allergic reaction generally says nothing about what will happen during your next one, if indeed you actually have another one. For example, a study of Swedish children readmitted to emergency departments for food-related reactions reported that about 2 in 5 had reactions of comparable severity, 2 in 5 had reactions that were less severe and 1 in 5 had worse reactions. Another study of Australian children concluded that a history of anaphylaxis did not predict a repeat performance during food challenges to peanut.

It’s very common for people with a history of only mild reactions to have an anaphylactic reaction. In Italy, doctors noted that the severity of allergic episodes was similar only in patients who had had mild or moderate reactions; in other words, severe reactions tended to occur without a previous history of anaphylaxis and were unlikely to be repeated. Similarly, a review of 5 years’ worth of anaphylaxis cases seen at American children’s hospital emergency department noted that most of the children diagnosed with anaphylaxis had no record of having reacted to that trigger before.

Studies of fatal reactions are particularly telling, finding them to be unpredictable. One analysis of food-related fatalities occurring in the UK reported that over half involved people who only had a history of very mild reactions. A subsequent analysis of Brits who had died of food-related anaphylaxis during a 20-year period found that around 4 in 5 had not previously had an anaphylactic attack. A similar analysis of fatal cases in America reported that many of the people who died had neither been hospitalised for previous reactions nor had they needed adrenaline.

As for having another anaphylactic reaction, most people who experience one episode of anaphylaxis will never have another one.

People who are more likely to suffer from recurrent episodes of anaphylaxis include:

• people who are allergic to wheat and/or exercise
• people (notably children, but also adults) who are allergic to food, which is more likely than drugs or venom to cause more than one episode of anaphylaxis, although recurrent anaphylaxis to venom is more likely in geographic areas where people are more likely to be exposed to stinging insects, like Australia.
• people who are allergic to latex
• people who experience idiopathic anaphylaxis

If you are allergic to food, anaphylactic attacks are more likely to surprise you if you are also vulnerable to cofactors; an analysis of 74 food-induced reactions seen in Spanish patients that probably also involved either exercise, alcohol or NSAIDs revealed that in round 8 in 10 (82.4%) of the cases, the person had experienced a previous mild reaction, most commonly hives, before suffering the reaction that got a doctor’s attention (which was anaphylaxis in 85% of the cases). Most of those people were able to tolerate their food without the presence of cofactors, experiencing at most mild oral allergy syndrome (i.e. an itchy mouth).

Basically, having had only mild reactions to a trigger does not mean that you can afford to be complacent about exposing yourself to it again.

Image by Brett Jordan on Unsplash

The bottom line: expect the unexpected

Another common mistake is thinking that you won’t be surprised by an anaphylactic attack. Every day, hundreds of people all around the world are surprised by one, and there’s no reason to think that you can’t be, too.

For a start, food can surprise you in a myriad of ways—prepared food can be mislabelled, shop or restaurant personnel can be wrong about what’s in their products, your favourite dish can be new and improved with a different ingredient, a diner could fry their fish and their chips in the same oil, etc., etc.—and it’s most likely to surprise you in an environment in which you feel safe.

A range of studies have found that about half of all unexpected allergic reactions to food tend to occur at home and about half outside, in places like the homes of friends or relatives. Other common situations in which people are surprised by their food allergies include at school or at work, when eating out, (especially buffets) when eating takeaways and when on holiday.

Accidental exposure to food allergens occurs when people share food or eat food that has been cross-contaminated and when they eat prepared food that contains their trigger food—so-called ‘hidden allergens’—and either didn’t ask what was in it or didn’t read/ignored the label.

An analysis of the UK’s Anaphylaxis Campaign data collected over a 12-year period from 2001–2013 found that the majority of anaphylaxis reactions were triggered by exposure to known food allergens.

Of course, food is not the only thing that’s out to get you. You could be surprised by an invasive species of insect that can now live in your area thanks to climate change. Or someone could give you a type of painkiller that they don’t know you’re allergic to.

Between 1 in 5 and 1 in 2 of all people who’ve had an anaphylactic episode will go on to have another one. Both adults and children are more likely to have a second episode provoked by food, rather than venom or drugs, and those most at risk are the people who are allergic peanuts, tree nuts, wheat and/or exercise.

The best thing you can do to protect yourself is to make sure that you’re prepared for things to go sideways. If you don’t know what your triggers are, a trip to an allergist is a really good idea. If you’re allergic to venom, immunotherapy could provide you with a cure, and if you’re allergic to food, knowing what to avoid helps you to take control of your condition and gives peace of mind.

If you know you could potentially have a severe reaction, be prepared to deal with it:

• Have an emergency action plan; even if you’ve not been given a plan by a health professional, make your own, it could save your life
• If you have an auto-injector, carry it with you everywhere you might need it (along with your action plan) and be prepared to use it if you come into contact with your trigger and develop the initial signs of anaphylaxis—don’t wait to see if you end up on the floor
• Tell the people you see every day about your allergy and your triggers. Educate the people who are normally around you—those you live, exercise and/or work with—to recognise the symptoms and show them where your auto-injector is and how to use it
• If you have drug allergies, tell any healthcare provider who treats you (including your dentist) about them before any test or treatment
• Consider getting a medical alert ID if you’re particularly sensitive to your trigger
• Considering ICEing your phone; iPhone and Android phones have an In Case of Emergency (ICE) programme to which you can add important medical information (allergies, blood group, health conditions) and an emergency contact that’s accessible even from a locked screen. Note, the ICE feature is not without its critics. If you don’t have one of these smartphones, you can try this workaround to at least make your emergency contact obvious
• Consider getting a chef’s card; a wallet-sized printed paper or notecard that states your specific food allergies and their severity that you can hand to the food service staff to give to the chef when you eat out. Some cards also state hidden sources of specific foods and/or the need to avoid cross-contamination of work surfaces and utensils. You can buy these cards from various retailers and or you can make your own based on free templates available from a variety of sources. You can get translated version for eating out on holiday and allergy cards are available for non-food triggers, too. And there’s always an app for that.

Be safe, live long and prosper.

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