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How to decide whether or not to use an EpiPen Illustration: Two epinephrine autoinjectors, one with a Not sign over it and the other with a green circle around it, separated by a question mark in between them.

But is it anaphylaxis?

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While it may sound strange to those of us who know anaphylaxis all too well, one of the more common questions I hear is, How do I know if I'm having anaphylaxis?

In this article, I follow the now-standard practice [Simons FER. Anaphylaxis: Recent advances in assessment and treatment. J Allergy Clin Immunol. 2009; 124:625–36; quiz 37–8] of not distinguishing between anaphylaxis [a whole-body IgE-mediated hypersensitivity reaction] and anaphylactoid [resembling anaphylaxis but not IgE-mediated] reactions since they have the exact same symptoms and outcomes.

Doctors are confused, too

And it’s not just patients who are confused about just what constitutes anaphylaxis. I've had people tell me things like: “My doctor said it couldn’t have been anaphylaxis because…

  • I didn’t pass out.
  • My throat didn't close up.
  • It didn’t come on fast enough.

A 1995 study [Klein JS, Yocum MW. Underreporting of anaphylaxis in a community emergency room. J Allergy Clin Immunol 1995; 95:2] confirms that even emergency room (ER) doctors often misdiagnose anaphylaxis. Researchers examined all of the visits to a particular ER, finding 17 cases of what the authors felt was anaphylaxis. However, the ER doctors had diagnosed the patients’ condition as anaphylaxis in only four of the 17 cases! In three of the four cases that the ER doctors diagnosed as anaphylaxis, the patients were admitted to the hospital, but only five of the 17 patients were given epinephrine. Ten of the 17 patients were given corticosteroids either in the ER or as prescriptions — even though there is no evidence to support this treatment. Reference [Sampson HA, Muñoz-Furlong A, et al. Symposium on the definition and management of anaphylaxis: Summary report. J Allergy Clin Immunol 2005; 115:8]. The authors of the 1995 study conclude that the ER doctors tended to misdiagnose anaphylaxis as less serious allergic reactions, which could lead to improper treatment and follow-up of this life-threatening condition. Reference [Klein JS, Yocum MW. Underreporting of anaphylaxis in a community emergency room. J Allergy Clin Immunol 1995; 95:2].

As one researcher [Golden DB. What is anaphylaxis? Curr Opin Allergy Clin Immunol. 2007 7(4):331–336] recently summarized the current state of affairs, "Anaphylaxis is underrecognized, underreported, under-treated and poorly understood."

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Symptoms of anaphylaxis

Most doctors and patients can agree on a basic list of symptoms that are most often seen in cases of anaphylaxis. The problem comes in deciding which symptoms are necessary to say, Yup, this anaphylaxis!

While anaphylaxis is a whole-body reaction, it tends to focus on four particular systems of the body: skin, breathing, circulation, and digestion. Table 1 outlines the systems and symptoms that are most often part of anaphylaxis.

Table 1. The symptoms of anaphylaxis

SystemSubsystemSymptomsMedical terminology
Skin (cutaneous, subcutaneous, or mucosal tissue) General Flushing, itching, hives, swelling, measles-like rash, goose bumps or raised hair on neck, back, arms, etc. Erythema, pruritus, urticaria, angioedema, morbilliform rash, piloerection
Mouth Itchiness or tingling of lips, tongue, and roof of mouth; metallic taste in mouth; swelling of lips, tongue, and dangling edge of soft palate Pruritus of lips, tongue, and palate; metallic dysgeusia; edema of lips, tongue, and uvula
Eyes Itchiness, redness, and swelling around eyes, red eyes, tearing Periorbital pruritus, erythema and edema, conjunctival erythema, tearing
Breathing (respiratory) Laryngeal Itching and tightness in the throat, swallowing difficult or impossible, hoarseness or difficulty speaking, dry disjointed cough, high-pitched sound when inhaling, inability to take in enough oxygen, itchiness in the ears Pruritus and tightness in the throat, dysphagia, dysphonia, dry staccato cough, stridor, asphyxia, sensation of pruritus in the external auditory canals
Lung Shortness of breath, labored breathing, chest tightness, deep cough and wheezing, lack of oxygen Shortness of breath, dyspnea, chest tightness, deep cough and bronchospasm (decreased peak expiratory flow), hypoxemia
Nose Itching, congestion, runny nose, sneezing Pruritus, congestion, rhinorrhea, sneezing
Circulation (cardiovascular) Blood pressure Symptoms of low blood pressure (dizziness, light headedness, blurred vision, increased pulse), collapse, loss of bladder or bowel control Hypotension, hypotonia, incontinence
Faintness Feeling of faintness, fainting, confusion Near-syncope, syncope, altered mental status
Heart Chest pain, abnormal heart beat Chest pain, dysrhythmia
Digestion (gastrointestinal) GI Sick to stomach, painful abdominal cramps, throwing up, diarrhea Nausea, crampy abdominal pain, vomiting (stringy mucus), diarrhea
Other Labor-like contractions in women. A feeling of impending doom. Seizures. Uterine contractions in women. Aura of doom. Seizures.

References for Table 1: Sampson-05 [Sampson HA, Muñoz-Furlong A, Bock SA, Schmitt C, Bass R, Chowdhury BA, et al. Symposium on the definition and management of anaphylaxis: Summary report. J Allergy Clin Immunol 2005; 115:8], Wyatt [Wyatt R. Anaphylaxis: How to recognize, treat, and prevent potentially fatal attacks. Postgraduate Medicine Online 1996; 100:87–104], Sampson-06 [Sampson HA, Muñoz-Furlong A, et al. Second symposium on the definition and management of anaphylaxis: Summary report - Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006; 117:7], Simons [Simons FER. Anaphylaxis. J Allergy Clin Immunol. 2010; 125:S161–81], and Alcoceba [Alcoceba E, Gonzalez M, Gaig P, Figuerola E, Auguet T, Olona M. Edema of the uvula: Etiology, risk factors, diagnosis, and treatment. [Case report] J Investig Allergol Clin Immunol. 2010;20(1):80–83].


As you look at Table 1, there are two things you may notice:

  1. Many of those same symptoms can characterize the mast cell attacks that people with mastocytosis often call "leaking," and
  2. Those of us who have had anaphylaxis many times may report symptoms that are not listed in that table.

The second issue — people having symptoms not included in the table — is easy enough to explain. Anaphylaxis sets off a chain reaction of events, and which organs are most sensitive to those changes can vary from one individual to another and from one attack to another.

For example, I have had attacks in which I was so weak that I found it hard to use an EpiPen®, and I have heard the same thing from other people. So why isn’t weakness listed as symptom? Well, the weakness is secondary to the collapse of our circulation. Some of us get more or less shaky — that’s an individual difference.

The first issue, however, is trickier. So let’s talk about criteria that can be used for saying that an attack is full-blown, systemic anaphylaxis, as opposed to partial degranulation or leaking of mast cell contents. But before we even do that, let’s talk about why defining anaphylaxis is so difficult.

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It’s not easy to define anaphylaxis

A number of different groups have developed criteria for deciding whether or not a reaction is anaphylaxis. The problem is that for a long time there has not existed a universal consensus on the definition and diagnostic criteria for anaphylaxis. Reference [Clark, Camargo. Epidemiology of anaphylaxis. Immunology and Allergy Clinics of North America 2007; 27:145–63.].

In April of 2004, the National Institute of Allergy and Infectious Diseases (NIAID) and the Food Allergy and Anaphylaxis Network (FAAN) together sponsored a two-day Symposium on the Definition and Management of Anaphylaxis, hoping to gather experts from different disciplines that deal with anaphylaxis. Reference [Sampson HA, Muñoz-Furlong A, et al. Symposium on the definition and management of anaphylaxis: Summary report. J Allergy Clin Immunol 2005; 115:8.]. And in 2005, the same groups sponsored a Second symposium on the definition of and management of anaphylaxis. Reference [Sampson HA, Muñoz-Furlong A, et al. Second symposium on the definition and management of anaphylaxis: Summary report - Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006; 117:391–7]. The summary report of the second symposium offers a very carefully crafted set of criteria for diagnosing anaphylaxis.

So what’s the problem? Well, if I thought I might be having anaphylaxis and I paused to see if my symptoms matched the second symposium’s criteria, I am quite certain that I would be dead before I could figure it out. You see, the consensus criteria are a bit like a menu from a Chinese restaurant. You can have three or more from column A, three or more from column B, or two from column C.

Anaphylaxis, it appears, is more complicated than many life-threatening conditions.

Let me see if I can explain the second symposium criteria in a way that will make sense to you. The criteria presuppose that a person is becoming ill rapidly. What does rapidly mean? The criteria specify that rapidly can be anywhere from minutes to several hours. So, it’s not something that comes on over the period of a week or a few days.

Next, the criteria assume that you fall into one of three categories:

  1. You are reacting to a known allergen
  2. You are reacting to a likely allergen
  3. You have no idea why you are reacting.

For at least some of us, this is already complicated. Why? Well, most people have allergy attacks, which are hypersensitivity reactions that are mediated by an allergen and our body's immunoglobulin E (IgE). But many of us who have idiopathic anaphylaxis (IA) or mastocytosis can have allergic-like reactions that are fast but which are not mediated by allergens or are not mediated by IgE.

For example, many people with mastocytosis can have reactions to substances (for example, insect stings or medications) to which they have never been exposed before. For a reaction to be truly allergic in nature, a person must have been exposed to the substance at least once before so that their body could form the reactive substances that are activated when the person later encounters the substance again.

So, for some of us, we may react to specific things without those reactions being true allergies. For example, an easy way for me to have anaphylaxis is to smell or eat a freshly chopped onion, and yet RAST testing suggests that I do not have an allergy to onions! That’s why I call onions a trigger rather than an allergen.

Do the second symposium’s criteria address the issue of triggers? Nope. Hopefully, at some point, someone will explain to these people that it takes more than allergies to make the world of anaphylaxis go round.

In the meantime, I would suggest that you mentally change allergen to allergen/trigger in the criteria above. If something has definitely made you sick in the past, you probably belong in category 1 above, or if you are pretty sure it has, then assume that you fall into category 2.

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Anaphylaxis to a known allergen or trigger

If you have been exposed to a known allergen (or trigger) and you become sick rapidly (that is, within minutes to several hours), check your blood pressure. If your systolic blood pressure has dropped significantly from what it usually is, then you are having anaphylaxis. Period.

What is systolic blood pressure?

As the heart beats, it rhythmically contracts and relaxes. These two phases of the heartbeat are called systole (contraction) and diastole (relaxation). In measuring blood pressure, two numbers are noted — the higher number measures systolic blood pressure, while the lower number measures the diastolic blood pressure. For example, if your blood pressure were normally 130 over 80, then 130 would be your systolic blood pressure and 80 would be your diastolic blood pressure.

 
The next table explains what is meant by a “significant drop in blood pressure.”

Table 2. A significant drop in blood pressure means…

Age Systolic blood pressure is Or
Adult Less than 90 mm Hg More than a 30% decrease from baseline (normal) systolic blood pressure
11 to 17 years old
10 years old
9 years old Less than 88 mm Hg
8 years old Less than 86 mm Hg
7 years old Less than 84 mm Hg
6 years old Less than 82 mm Hg
5 years old Less than 80 mm Hg
4 years old Less than 78 mm Hg
3 years old Less than 76 mm Hg
2 years old Less than 74 mm Hg
1 year old Less than 72 mm Hg
1 month to 1 year Less than 70 mm Hg

Reference for Table 2: Sampson [Sampson HA, Muñoz-Furlong A, et al. Second symposium on the definition and management of anaphylaxis: Summary report - Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006; 117:391–7.]

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Anaphylaxis to a suspected allergen or trigger

But what if you’ve recently (minutes to a few hours) been exposed to something that you aren’t sure is an allergen or trigger? What if you only suspect that it is?

In that case, according to the second symposium’s criteria, you are having anaphylaxis if you have two or more of the following categories of symptoms:

  1. Skin-mucosal symptoms
  2. Symptoms of respiratory compromise
  3. Cardiovascular symptoms
  4. Persistent digestive symptoms

So, if you think you’re reacting to a specific substance and you have, say, hives and diarrhea or vomiting, you’re having both skin and digestive symptoms. But what are “persistent” GI symptoms? Good question. Since all this has to happen in less than “several hours,” I would guess that you need to have diarrhea or vomiting more than once — but not necessarily all day!

And what is respiratory compromise? I would say that your respiration is compromised when it’s clear that you aren’t really getting enough oxygen, that is, you are displaying asthmatic symptoms (coughing, wheezing, stridor and/or excessive mucus production), your throat is swelling shut, or you're experiencing persistent "air hunger."

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Anaphylaxis for no particular reason

The final category is someone having a rapid (minutes to several hours) reaction to, well, anything or nothing.

In that case, it’s anaphylaxis if you have involvement of skin or mucosal tissue (or both) plus either respiratory compromise or reduced blood pressure or related symptoms.

Summarizing the second symposium criteria

In Table 3 I’ve attempted to summarize the second symposium criteria.

Table 3. Second symposium criteria made easy

It’s anaphylaxis if with… You have rapid onset and…
Known allergen/trigger Significant BP drop
Suspected allergen/trigger Two or more of:
  • Skin involvement
  • Respiratory compromise
  • Reduced BP or associated symptoms
  • Persistent GI symptoms
?? Skin/mucosal involvement AND (Respiratory compromise OR Reduced BP or associated symptoms)

Reference for Table 3: Sampson [Sampson HA, Muñoz-Furlong A,et al. Second symposium on the definition and management of anaphylaxis: Summary report - Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006; 117:391–7].

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Grading anaphylaxis

Before there was a first or second symposium, a group of researchers [Ring-2004 [Ring J, Brockow K, Behrendt H. History and classification of anaphylaxis. Novartis Foundation Symposium 2004; 257:6–16; discussion –24.]] offered “a simple scoring system from I to IV which is immediately useful with regard to acute therapy without need for long reflection….” I have modified this system by using everyday words for the medical terms, and the result is in Table 4.

Table 4. Grading of anaphylactic reactions according to severity of clinical symptoms

Grade Symptoms
Skin Digestion Breathing Circulation
I Itching, tingling, flushing, hives, swelling      
II Itching, tingling, flushing, hives, (swelling is optional) Nausea, cramping Runny nose, hoarseness, shortness of breath or labored breathing Rapid heartbeat (> 20 bpm (abbreviation for "beats per minute") increase), blood pressure change (> 20 mm Hg systolic), irregular heartbeat
III Itching, tingling, flushing, hives, (swelling is optional) Vomiting, defecation, diarrhea Larynx swelling, wheezing, coughing, turning blue Shock
IV Itching, tingling, flushing, hives, (swelling is optional) Vomiting, defecation, diarrhea Breathing stops Heart stops

Reference for Table 4: Ring [Ring J, Brockow K, Behrendt H. History and classification of anaphylaxis. Novartis Foundation Symposium 2004; 257:6–16; discussion –24].

Ring’s criteria are much easier to work with. At the point when you’ve only got skin or mucosal symptoms, you’re at stage I. Since at stage IV you’re dying, it would be wisest to take action as you swing into stage II or III.

Let’s put this into plain English: If you are having skin or mucosal symptoms, as soon as you notice changes in your breathing, circulation, or digestion, you can assume that you’re having anaphylaxis.

When I first saw Ring’s grading system, I wondered if he was right in stating that, essentially, anaphylaxis always begins with skin or mucosal symptoms. So, I ran an informal poll in my idiopathic anaphylaxis support group. Every single person who responded reported that their attacks began with some kind of skin or mucosal symptoms: Itching, burning, tingling, flushing, a metallic taste in the mouth, hives or nettle rash, and/or swelling.

Another thing I like about Ring’s grading system is that it talks about blood pressure change, rather than just low blood pressure. This is important because while the attack can be causing us to lose much of our circulation to third-spacing, our body is working very hard to try to keep circulation going. That’s why some of us initially see an increase in blood pressure, instead of an immediate crash. So under this system any significant change in systolic blood pressure suggests that you’re entering stage II.

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Frequency of anaphylactic symptoms

A 2006 article by Webb and Lieberman [Webb LM, Lieberman P. Anaphylaxis: a review of 601 cases. Annals of Allergy, Asthma, & Immunology, 2006; 97:39-43] did a review of medical records spanning 25 years to collect data on 601 cases in which a patient presented with anaphylaxis. What they found when they analyzed the frequency of various symptoms is shown in Table 5.

Table 5. Incidence of symptoms in anaphylactic reactions

Symptom Incidence (%)
Hives or swelling 87
Shortness of breath 59
Fainting or dizziness 33
Diarrhea or abdominal cramps 29
Flushing 25
Laryngeal 21
Nausea or vomiting 20
Low blood pressure 15
Runny nose 8
Swelling around eyes 8
Chest pain 6
Headache 3
Itch without rash 5
Blurry vision 1
Seizure 1

Table reference [Webb LM, Lieberman P. Anaphylaxis: a review of 601 cases. Annals of Allergy, Asthma, & Immunology, 2006; 97:39-43].

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But what if it’s “just” diarrhea?

Some of us with mast cell-related illnesses have diarrhea all day, every day. Does that mean that we’re having anaphylaxis all the time? Not necessarily.

If you are having skin or mucosal symptoms, diarrhea, and no other symptoms, an epinephrine autoinjector is not usually the recommended route. My doctor has told me to use an EpiPen® if it appears that my breathing or circulation is becoming compromised — and that includes feeling faint.

However, other patients might be given different rules of thumb for a very good reason: We’re all different. I am among those who are often able to interrupt an attack with a quick big dose of Benadryl. But when some people start to have an attack, it’s an unstoppable toboggan into circulatory or respiratory collapse. For those people, it’s wisest to use an epinephrine autoinjector immediately.

And the ugly truth is that some of us skate uncomfortably close to the line frequently. In those cases, I would suggest that you work with your doctor to try to find a medication regime that will better control your day-to-day symptoms.

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If it’s not anaphylaxis, what else could it be?

It is important to remember than there are some other conditions that can closely mimic at least some of the symptoms of anaphylaxis. And the situation is made more complex by the fact that not every person has every symptom of anaphylaxis every time.

In diagnosing anaphylaxis, doctors consider a number of other conditions in making their differential diagnosis. Table 6 lists many of the other conditions that can cause at least some of the symptoms of anaphylaxis.

Table 6. Differential diagnosis

Condition Description
Anaphylaxis
Anaphylaxis to external agents Allergies, drugs and insect stings
Anaphylaxis to physical factors Reactions to exercise, cold, heat, or sunlight
Idiopathic anaphylaxis Unknown cause
Excess internal production of histamine
Systemic mastocytosis Infiltration of organ systems by mast cells with varied clinical manifestations, which can include fever, weight loss, and characteristic symptoms of mast cell activation.
Urticaria pigmentosa Cutaneous (skin-related) mastocytosis resulting from excess numbers of mast cells in the skin, producing characteristic eruptions that are flat or slightly elevated brownish papules (well-delineated solid elevation on skin up to 1 cm in size) that can react when touched. Children can outgrow the disease, but adults rarely do. Adults may also form systemic symptoms or lesions.
Basophilic leukemia Granulocytic (white blood cells having granules, which include neutrophils, basophils and eosinophils) leukemia in which the number of basophils, both in blood and tissue, greatly increase. The numbers of basophils, both mature and immature, can become as high as 40 to 80% of the total numbers of white blood cells
Acute promyelocytic leukemia Leukemia (disease in which numbers of abnormal white blood cells greatly increase) that presents as a severe bleeding disorder
Hyatid cyst Cyst formed most often in the liver by the larva of Echinococcus granulosus (unilocular and osseous forms) or Echinococcus multilocularis.
Other forms of shock
Cardiogenic shockShock due to a decline in cardiac output secondary to heart disease, usually a myocardial infarction (heart attack), but sometimes cardiac arrhythmia (irregularity or loss of rhythm in the beating of the heart, which can be caused by a variety of conditions).
Pulmonary embolism Obstruction of the pulmonary artery or one of its branches
Hemorrhagic shockShock caused by a reduction in blood volume due to bleeding, characterized by low blood pressure, rapid heartbeat, pale, cold, clammy skin, and low urine production.
Insulin reaction For example, shock produced by extremely low blood sugar
Septic ShockShock caused by the release of endotoxin from gram-negative bacteria, especially Escherichia coli (species of bacteria normally found in the intestines).
Vasodepressor (lowering blood pressure via vasodilation) reactions
Autonomic epilepsyEpisodes of autonomic dysfunction due to seizure activity can cause palpitations, chest pain, rapid, slow or irregular heartbeat, high or low blood pressure, changes in breathing, dyspepsia, gastric pain, nausea, vomiting, belching, incontinence, flushing, blanching, perspiration, salivation, tearing, and more.
Flushing syndromes Such as flushing related to menopause, being overheated, various medications, carcinoid syndrome, chlorpropamide-alcohol flushing (CPAF), etc.
Medullary carcinoma thyroidMalignant thyroid neoplasm (abnormal tissue growth)
Orthostatic hypotension Decrease in systolic blood pressure of 20 mm Hg or more or decrease in diastolic blood pressure of 10 mm Hg or more within five minutes of standing upright — in other words, the person's blood pressure falls suddenly when he or she stands up. This can cause dizziness, fainting, visual or auditory disturbances, weakness, sweating, paleness, GI upset, or urinary incontinence. Orthostatic hypotension is more common in older adults.
Vasovagal syncope These are classic fainting spells, which most often result from blood pooling in peripheral areas of the body. Precipitating causes include: prolonged standing, stressful stimuli (fear, pain, invasive instrumentation), increased ambient or core body temperature, lack of food, and rapid early morning rising. Typical early symptoms include lightheadedness, fatigue, blurred vision, sweating, nausea, and palpitations. A negative history of heart problems makes vasovagal syncope a more likely explanation, especially in younger adults.
"Restaurant syndromes"
Choking/inhaled food Inhaled food or food that is stuck in someone's throat may result in symptoms that may occasionally be mistaken for anaphylaxis.
Monosodium glutamate (MSG)Flavor enhancer that has been known to cause "Chinese restaurant syndrome" which can include burning sensation at back of neck, forearms and chest, facial pressure or tightness, chest pain, headache, nausea, upper body tingling and weakness, palpitations, numbness in the back of thte neck, arms and back, bronchospasm (in asthmatic patients only), and drowsiness. MSG has also been known to induce asthma in a few cases.
Scrombroid poisoningIllness that occurs after eating improperly stored fatty dark-fleshed scombroid fish (tune, mackerel, skipjack, etc.) and can include itching, throbbing headache, flushing, hives, oral burning or tingling, palpitations, and GI disturbances. Symptoms occur very soon after eating and usually do not last more than three to six hours.
Sulfites (substance frequently used as a food preservative) A variety of sulfite-related hypersensitivity reactions have been documented and anaphylactoid reactions have been observed in some cases.
Miscellaneous
AngioedemaWhile angioedema [swelling in the deeper layer skin] can be a symptom of anaphylaxis, there are people who can have serious attacks of angioedema without having anaphylaxis. For example, people who have hereditary angioedema (HAE) have attacks characterized by recurrent skin swellings, bouts of abdominal pain, tongue swelling, and laryngeal edema. Sometimes these attacks can lead to upper airway obstruction and death.
Catmenial (pertaining to a woman's menstrual cycle) anaphylaxisProgesterone-induced anaphylaxis can present as recurrent episodes of anaphylaxis that are related to a woman's menstrual cycle.
Cricoarytenoid joint fixationInflammation of this joint in the larynx can cause pain and hoarseness, and in severe cases, it can constrict the airway and make breathing difficult. Most common in people with inflammatory arthritis, such as RA (rheumatoid arthritis).
EUEdema of the uvula [edge of the soft palate that hangs at the back of the throat above the base of the tongue] (EU) is experienced as a fullness of the oropharynx [the area of the air/food passageway at the back of the mouth and throat between the soft palate and the upper area of the epiglottis] and difficulty in talking or breathing. EU can be a feature in anaphylaxis or angioedema or it can be a single-symptom idiopathic phenomenon.
Hyperimmunoglobulin E, urticaria syndromeA complex disease with highly elevated serum IgE levels, recurrent severe staphylococcal infections, dermatitis, and abnormalities of both skeleton and dentition. Both urticaria and anaphylaxis sometimes occur with this syndrome. (Also known as HIES or Job's syndrome.)
ISCLSIdiopathic systemic capillary leak syndrome (also known as Clarkson's disease) is characterized by repeated episodes of hypovolemic shock due to increased capillary permeability. For more info, see my blog entry on ISCLS.
NeurologicSeizure or stroke.
PheochromocytomaA catecholamine-producing tumor located in the adrenal gland that can also produce both norepinephrine and epinephrine. Common symptoms are hypertension, headache, palpitations, and profuse sweating. (Also known as pheochromoblastoma or chromaffin-cell tumor.)
PseudoanaphylaxisAdministering procaine penicillin to some patients causes fainting and neurological symptoms. These reactions are caused by the procaine rather than the penicillin. Administering lidocaine has also caused similar episodes.
Red man syndrome (vancomycin)An infusion rate-related reaction to vancomycin characterized by chest pain, breathing discomfort, itchiness, hives, flushing, and angioedema. Usually treated by stopping administration of vancomycin and administering diphenhydramine and fluids. This is not considered to be a true allergic reaction.
Urticarial vasculitisUnlike regular hives, lesions of urticarial vasculitis (UV) last longer than 48 hours and may take days to resolve completely. UV lesions do not blanch when pressed, and may cause hyperpigmentation of the area after they have healed. Also, they are often moderately painful and may feel both tender and burning, in addition to itchiness.
Vocal cord dysfunction syndromeClosure of the vocal folds during in-breathing leaving a characteristic small chink aperture through which air moved. Often misdiagnosed as asthma. Recent research suggests that other factors than psychological ones may contribute to the development of this behavior. (Also known as VCD or paradoxical vocal fold adduction.)
Non-organic disease
Globus hystericus A lump in the throat or sensation of choking associated with anxiety, hypertension, or panic attacks.
Panic attacksA panic attack is defined an episode of intense discomfort or fear during which the person experiences at least four of the following symptoms: Palpitations, sweating, tremulousness, sense of being smothered or shortness of breath, sensation of choking, chest pain, nausea or abdominal distress, dizziness or lightheadedness, burning or pricking sensations (paresthesia), chills or flushing, feelings of unreality or being detached from oneself, fear of losing control or of going crazy, and/or a fear of dying. The problem, of course, is that at least 11 of these 13 symptoms are common during anaphylaxis. (Note: On occasion this diagnosis has been erroneously assigned by ER staff to people actually having anaphylaxis who have effectively used an EpiPen® before arriving at the hospital.)
Undifferentiated somatoform anaphylaxisSituation in which a person believes his or her symptoms of shortness of breath, difficulty or distress in breathing, throat closure and fainting are anaphylaxis, when there is no objective evidence of upper or lower airway obstruction or hypotension. (Note: On occasion this diagnosis has been erroneously assigned by ER staff to people actually having anaphylaxis who have effectively used an EpiPen® before arriving at the hospital.)
Intentionally feigned attacks
Munchausen anaphylaxis Intentionally induced allergic reactions (for example, a person may consume a substance that he or she knows will cause an anaphylactic reaction). The patient may then deny either consuming the substance or being aware of the allergy to that substance.
Munchausen stridorNonorganic, loud, purposeful wheezing respirations, which may frighten medical personnel (because they fear anaphylaxis, etc.) and may be used to abuse the ER or hospital or result in the unnecessary administration of epinephrine.

References for Table 6: Alcoceba, Gonzalez, et al. [Alcoceba E, Gonzalez M, Gaig P, Figuerola E, Auguet T, Olona M. Edema of the uvula: Etiology, risk factors, diagnosis, and treatment. [Case report] J Investig Allergol Clin Immunol. 2010;20(1):80–83.]; Balkisson, Baroody & Togias [Balkissoon RD Baroody FM, Togias A. Diorders of the upper airways. In: Mason RJ, Murray JF, et al. Murray & Nadel's Textbook of Respiratory Medicine, 4th ed. Philadelphia, PA: Elsevier Saunders; 2005]; Bork [Bork K. Hereditary angioedema with normal C1 inhibitor activity including hereditary angioedema with coagulation factor XII gene mutations. Immunol Allergy Clin N Am. 2006; 26:709–724]; Bush and Taylor [Bush RK, Taylor SL. In: Adkinson NF, Bochner BS, et al., eds. Middleton's Allergy: Principles and Practice. 7th ed. Philadelphia, PA: Saunders-Elsevier; 2008; 1169–1188]; Cummings [Cummings CW, Flint PW, et al. Otolargyngology: Head & Neck Surgery. 4th ed. Philadelphia, PA: Elsevier Mosby. 2005.]; Dinauer & Coates [Dinauer MC, Coates TD. Disorders of phagocyte function and number. In: Hoffman R, Benz EJ, Shattil SJ, Furie B, Silberstein LE, McGlave P, Heslop HE. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, PA: Churchill Livingstone Elsevier; 2009]; Ferri [Ferri FF. Ferri's Clinical Advisor 2010. Philadelphia, PA: Mosby-Elsevier. 2009]; Givens, Caldera & Prueitt [Givens ML, Caldera JR, Prueitt R. Antibacterial and antifungal agents. In: Shannon MW, Borron SW, Burns MJ. Haddad and Winchester's Clinical Management of Poisoning and Drug Overdose 4th ed. Philadelphia, PA: Saunders Elsevier; 2007]; Greenberger [Greenberger PA. Idiopathic anaphylaxis. Immunol Allergy Clin N Am. 2007; 27:273–93.]; Lieberman [Lieberman PL. Anaphylaxis. In: Adkinson NF, Bochner BS, et al., eds. Middleton's Allergy: Principles and Practice. 7th ed. Philadelphia, PA: Saunders Elsevier; 2008; 1007–1050]; Marx [Marx JA, editor-in-chief. Rosen's Emergency Medicine: Concepts and Clinical Practice. 6th ed. Philadelphia: Mosby Elsevier; 2006.]; Schondorf [Schondorf R, Shen W. Syncope: Case studies. Neurol Clin. 2006; 24:215–231]; So [So YT. Effects of toxins and physical agents on the nervous system: Marine toxins. In: Bradley WG, Daroff RB, et al., eds. Neurology in Clinical Practice. 5th ed. Philadelphia, PA: Butterworth Heinemann Elsevier; 2008; 1682–1686]; Sreevastava & Tarneja [Sreevastava D, Tarneja V. Anaphylactic reaction: An overview. MJAFI 2003; 59:53-6.]; Stone [Stone JH. Immune complex-mediated small vessel vasculitis. In: Firestein GS, Budd RD, et al. Kelley's Textbook of Rheumatology. 8th ed. Philadelphia, PA: Elsevier; 2008]; and Wyatt [Wyatt R. Anaphylaxis: How to recognize, treat, and prevent potentially fatal attacks. Postgrad Med Online 1996; 100:87-104.].

Someone might ask, “How do you tell the difference between a menopausal flush and anaphylaxis?” Well, in my experience, menopausal flushes don’t include the intense itching, the swelling, or the desire to crawl out of my skin that I usually get at the beginning of anaphylaxis.

At the 2006 TMS conference, one of the panelists differentiated between “wet” and “dry” flushes. Menopausal flushes are often of the “wet” variety.

It’s important to remember that some medical personnel may have a hard time recognizing anaphylaxis, too. If you get stuck in an emergency room with someone who decides that your attack is just hysteria, you may need to do a quick reality check and use your EpiPen® anyway. This is one area where even the professionals occasionally get it wrong. Reference [Klein JS, Yocum MW. Underreporting of anaphylaxis in a community emergency room. J Allergy Clin Immunol 1995; 95:2].

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Before you use that EpiPen®

And what do you do if you do need to use an EpiPen®? The first thing you should do is to lie down, so that your feet are at least on a level with your heart, if not elevated higher than your heart. And the second thing you should do is to remain lying down.

The Trendelenburg Position is the name for the position in which someone is lying on his back (in a supine position), with his feet higher than his head. This position is used to maximize blood flow to the brain of a hypotensive patient, and while there has been some debate about how well it works (Reference [Bridges N, Jarquin-Valdivia AA. Use of the Trendelenburg position as the resuscitation position: To T or not to T? Am J Crit Care. 2005; 14 (5):364–8]), given Pumphrey's findings (below), I'd be inclined to give it a try.

Why? In a 2003 article [Pumphrey RS. Fatal posture in anaphylactic shock. J Allergy Clin Immunol 2003; 112:451-2.], Richard Pumphrey writes: “An important pattern has become clear from the 38 anaphylactic shock deaths that occurred outside hospital. In 10 of these cases, information was available to determine the postural history after onset of anaphylaxis. Four deaths occurred within seconds of a change to a more upright posture: in each of 2 cases of nut anaphylaxis, the individual stood up after sitting slumped or lying down; in 1 case of antibiotic anaphylaxis, the individual was made to sit in a chair after lying in bed; and in 1 case a driver stepped out of his vehicle during a reaction to a sting. In another 5 fatal anaphylactic reactions to stings and in another fatal reaction to an antibiotic, each individual had been supported sitting up after shock caused loss of consciousness. The postural history of the remaining 28 cases is unknown: nevertheless, the pattern being reported seems significant. It is unusual for patients to be supported upright while shocked; most shocked patients will either lie down or collapse. Patients with anaphylactic shock after being stung might recover consciousness while lying down, only to lose it again when they try to sit up: they therefore tend to remain supine [lying on one's back] while shocked.”

He goes on to hypothesize why this might happen: “During anaphylactic shock, the capacity of the veins and capillaries expands greatly. While a shocked person is lying down, sufficient blood might return to the vena cava [large veins that return blood to the heart] to maintain a reduced circulation, but on the person's sitting up or standing, this venous return stops; the vena cava will then become empty within seconds. There is then no flow through the right side of the heart, and within a few seconds more, no blood will return to the left side of the heart from the lungs. Pulseless electric activity continues, but in the absence of left ventricular filling there can be no contractions; this prevents coronary arterial flow and leads to myocardial ischemia [too little circulation of blood to the heart muscle]. In less extreme cases, too, the coronary circulation, which is dependent on the diastolic pressure, is likely to become inadequate, because the blood pressure is the product of the cardiac output and the systemic vascular resistance, both of which are low in cases of anaphylactic shock.” Ibid. [Pumphrey RS. Fatal posture in anaphylactic shock. J Allergy Clin Immunol 2003; 112:451-2.]

He also notes that once the heart is empty, epinephrine and heart massage will do nothing to reverse the situation. The simplest preventative measure is to lie down before you take the EpiPen®, and then — stay down!

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An earlier version of this article appeared in the Summer 2007 issue of The Mastocytosis Chronicles, the quarterly newsletter of the Mastocytosis Society (TMS).


Page last updated: May 16, 2011

 
All information contained in this site is one layperson's interpretation of medical journal articles, textbooks, seminars, presentations, and other materials. Nothing that is stated here should carry more weight than the informed and considered opinions of your own highly trained and qualified medical caregivers. The author of this site is not a doctor and has absolutely no authority to prescribe or diagnose.

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