What s allergy

In rare cases, an allergy can lead to a severe allergic reaction, called anaphylaxis or anaphylactic shock, which can be life threatening.

This affects the whole body and usually develops within minutes of exposure to something you’re allergic to.

Signs of anaphylaxis include any of the symptoms above, as well as:

Anaphylaxis is a medical emergency that requires immediate treatment.

Read more about anaphylaxis for information about what to do if it occurs.

Sheet final reviewed: 22 November 2018
Next review due: 22 November 2021

It was early morning in early summer, and I was tracing my way through the woods of central North Carolina, steering cautiously around S-curves and braking hard when what looked love a little rise turned into a narrow bridge.

I was on my way to meet Tami McGraw, who lives with her husband and the youngest of their kids in a sprawling development of ancient trees and wide lawns just south of Chapel Hill. Before I reached her, McGraw emailed. She wanted to feed me when I got there.

“Would you love to attempt emu?” she asked. “Or perhaps some duck?”

These are not normal breakfast offerings. But for years, nothing about McGraw’s life has been normal. She cannot eat beef or pork, or drink milk or eat cheese or snack on a gelatine-containing dessert without feeling her throat shut and her blood pressure drop.

Wearing a wool sweater raises hives on her skin; inhaling the fumes of bacon sizzling on a stove will knock her to the ground. Everywhere she goes, she carries an array of tablets that can beat back an allergy attack, and an auto-injecting EpiPen that can jolt her system out of anaphylactic shock.

McGraw is allergic to the meat of mammals and everything else that comes from them: dairy products, wool and fibre, gelatine from their hooves, char from their bones. This syndrome affects thousands of people in the US and an uncertain but likely larger number worldwide, and after a decade of research, scientists own begun to understand what causes it.

It is created by the bite of a tick, picked up on a hike or brushed against in a garden, or hitchhiking on the fur of a pet that was roaming outside.

The illness, which generally goes by the name “alpha-gal allergy” after the component of meat that triggers it, is a trial that McGraw and her family are still learning to manage with. In much the same way, medicine is grappling with it, too. Allergies happen when our immune systems perceive something that ought to be familiar as foreign. For scientists, alpha-gal is forcing a remapping of basic tenets of immunology: how allergies happen, how they are triggered, whom they put in harm and when.

For those affected, alpha-gal is transforming the landscapes they live in, turning the dependable comforts of home – the plants in their gardens, the food on their plates – into an uncertain terrain of risk.


In 1987, Dr Sheryl van Nunen was confronted with a puzzle.

She was the head of the allergy department at a regional hospital in the suburbs of Sydney, Australia, and had a reputation among her colleagues for sorting out mysterious episodes of anaphylaxis. This time, a man had been sent to see her who kept waking up, in the middle of the night, in the grip of some profound reaction.

Van Nunen knew at once that this was out of the ordinary, since most allergic reactions happen soon after exposure, rather than hours later. She also knew that only a few allergens affect people after they own gone to bed. (Latex, for instance – someone sensitive to it who has sex using a latex condom might drop asleep and wake up in the midst of an allergy attack.) She checked the man for the obvious irritants and, when those tests came up negative, took a thorough glance at his medical history and did a skin test for everything he had eaten and touched in the hours before bedtime.

The only potential allergen that returned a positive result was meat.

This was weird (and dismaying, in barbecue-loving Australia).

What s allergy

But it was the only such case Van Nunen had ever seen. She coached the patient on how to avoid the meals that seemed to be triggering his reactions, put it below to the unpredictability of the human immune system, and moved on.

Then a few more such patients came her way. There were six others during the 1990s; by 2003, she had seen at least 70, every with the same problem, every apparently affected by meat they had eaten a few hours before. Groping for an explanation, she lengthened the list of questions she asked, quizzing the patients about whether they or their families had ever reacted to anything else: detergents, fabrics, plants in their gardens, insects on the plants.

“And invariably, these people would tell to me: ‘I haven’t been bitten by a bee or a wasp, but I’ve had lots of tick bites,’” Van Nunen recalls.


As she remembers it, Tami McGraw’s symptoms began after 2010.

That was the year she and her husband, Tom, a retired surgeon, spied a housing deal in North Carolina, a development next to a nature reserve whose builder had priced the large houses to sell. The leafy spread of streams and woodland pockets was everything she wanted in a home. She didn’t realise that it offered everything that deer and birds and rodents – the main hosts of ticks – desire as well.

She remembers one tick that attached to her scalp, raising such a welt that the spot was red for months afterwards, and a swarm of baby ticks that climbed her legs and had to be scrubbed off in a boiling bath laced with bleach.

Unpredictably, at strange intervals, she began to feel dizzy and sick.

“I’d own unexplained allergic reactions, and I’d break out in hives and my blood pressure would go crazy,” she told me. The necklines of every her T-shirts were stretched, because she tugged at them to relieve the feeling that she couldn’t take a deep breath. She trekked to an array of doctors who diagnosed her with asthma or early menopause or a tumour on her pituitary gland.

They prescribed antibiotics and inhalers and steroids. They sent her for MRI scans, pulmonary function tests, echocardiograms of her heart. Nothing yielded a result.

Looking back, she realises she missed clues as to the source of her problem. She always seemed to need to use an asthma inhaler on Wednesdays – the day she spent hours in her car, delivering steaming-hot dinners for meals on wheels. She would feel short of breath, and need to visit an urgent-care clinic, on Saturdays – which always started, in her household, with a large breakfast of eggs and sausages.

Then a shut friend had a scary episode: after going for a run, she arrived home and passed out on the boiling concrete of her driveway.

Once the friend had recovered, McGraw quizzed her. Her friend said: “They thought I got stung by a bee while I was running. But now they ponder maybe I own a red-meat allergy.”

McGraw remembers her first reaction: that’s crazy. But her second was: maybe I own that too. She did some searching online, and then asked her doctor to order a little-known blood test that would show if her immune system was reacting to a component of mammal meat. The test result was so strongly positive that her doctor called her at home to tell her to step away from the stove.

The test launched her on an odyssey of discovering just how much mammal material is present in everyday life.

One time, she took capsules of liquid painkiller and woke up in the middle of the night, itching and covered in hives provoked by the drug’s gelatine covering.

When she bought an unfamiliar lip balm, the lanolin in it made her mouth peel and blister. She planned to spend an afternoon gardening, spreading fertiliser and planting flowers, but passed out on the grass and had to be revived with an EpiPen.

What s allergy

She had reacted to manure and bone meal that had been added as enrichments to the bagged compost she had bought.

She struggled with the attacks’ unpredictability, and even more with the impact on her family. “I ponder I’m getting better, and then I realise I’m not,” she says. “It’s just that I’m more knowledgable about what I can and can’t do.”


The discovery of new diseases often follows a pattern. Scattered patients realise they are experiencing strange symptoms. They discover each other, face to face in a neighbourhood or across the world on the internet. They bring their experience to medicine, and medicine is sceptical. And then, after a period of pain and recalcitrance, medicine admits that, in fact, the patients were right.

That is the tale of the discovery of CFS/ME and Lyme disease, among others.

But it is not the tale of alpha-gal allergy. An strange set of coincidences brought this bizarre illness to the attention of researchers almost as soon as it occurred.

The tale begins with a cancer drug called cetuximab, which came on to the market in 2004. Cetuximab is a protein grown in cells taken from mice. For any new drug, there are likely to be a few people that react badly to it, and that was true for cetuximab. In its earliest trials, one or two of every 100 cancer patients who had it infused into their veins had a hypersensitive reaction: their blood pressure dropped and they had difficulty breathing.

That 1-2% stayed consistent as cetuximab was given to larger and larger groups.

And then there was an aberration. In clinics in North Carolina and Tennessee, 25 of 88 recipients proved hypersensitive to the drug, with some so ill that they needed emergency shots of adrenaline. At about the same time, a patient who was receiving a first dose of cetuximab in a cancer clinic in Bentonville, Arkansas collapsed and died.

The manufacturers, ImClone and Bristol-Myers Squibb, checked every obvious thing about the trial: the drug’s ingredients, the cleanliness of the manufacturing plants, even the practices at the medical centres where cetuximab had been istered.

Nothing stood out. The most that researchers could guess at the time was that the recipients might own some helpful of mouse allergy.

Then the first coincidence occurred: a nurse whose husband worked at the Bentonville clinic mentioned the death to Dr Tina Hatley, an immunologist in private practice in Bentonville. Hatley had recently finished postgraduate training at the University of Virginia’s allergy centre, and she mentioned the death to her previous supervisor, Dr Thomas Platts-Mills.

The bad responses to the drug looked love allergic reactions, and they were common enough – and far enough from the manufacturer’s expectations – to be an intriguing research opportunity.

Platts-Mills pulled together a team, looping in Hatley and several current research fellows as well.

Fairly quickly, they discovered the source of the problem. People were reacting to the drug because they had a pre-existing sensitivity, indicated by a high level of antibodies (called immunoglobulin E, or IgE for short), to a sugar that is present in the muscles of most mammals, though not in humans or other primates. The name of the sugar was galactose-alpha-1,3-galactose, known for short as alpha-gal.

Alpha-gal is familiar to numerous scientists because it is responsible for an enduring disappointment: its tendency to trigger intense immune reactions is the reason that organs taken from animals own never successfully been transplanted into people.

The puzzle was why the drug recipients were reacting to it. To own an allergic reaction, someone needs to own been primed with a prior exposure to a substance – but the trial recipients who reacted badly were every on their first dose of cetuximab.

Team members scrutinised the patients and their families for anything that could explain the problem. The reactions appeared regional – patients in Arkansas and North Carolina and Tennessee experienced the hypersensitivity, but ones in Boston and northern California did not.

They investigated parasites, moulds and diseases that happen only in pockets of the US such as rural Tennessee.

The question then became: what in rural Tennessee could trigger a reaction love this? The answer arose from a second coincidence. Dr Jacob Hosen, a researcher in Platts-Mills’s lab, stumbled across a map drawn by the Centers for Disease Control and Prevention (CDC) showing the prevalence of an infection called Rocky Mountain spotted fever. It exactly overlapped the boiling spots where the cetuximab reactions had occurred.

Rocky Mountain spotted fever is transmitted by the bite of a tick: Amblyomma americanum, one of the most common ticks in the south-eastern US.

It’s known as the lone star tick because of the blotch of white that appears on the back of the female’s body.

The researchers wondered – if the mystery reactions shared a footprint with a disease, and ticks caused the disease, could ticks be linked to the reactions, too?

It was an intriguing hypothesis, and was reinforced by a new set of patients who came trickling into Platts-Mills’s clinic at about the same time. They were every adults, and that was strange to start with, because allergies tend to show up in childhood. They had never had an allergic reaction before, but now they were experiencing allergy symptoms: swelling, hives and, in the worst cases, anaphylactic shock.

They too had high levels of IgE antibodies to alpha-gal.

Dr Scott Commins, another postgraduate fellow in Platts-Mills’s group, took it upon himself to phone every new patient to enquire whether they’d ever suffered a tick bite. “I ponder 94.6% of them answered affirmatively,” he says. “And the other few would tell, ‘You know, I’m outdoors every the time. I can’t remember an actual tick that was attached, but I know I’d get bites.’”

Meat from mammals inevitably contains alpha-gal – so in already sensitised individuals, eating meat may constitute a second exposure, in the same way infusing cetuximab had been.

If tick bites had sensitised them, then the alpha-gal reaction might be a food allergy as well as a drug reaction.

But the connection was speculative, and cementing cause and effect would take one final, extraordinary coincidence.

As it happens, Platts-Mills likes to hike. One weekend he took off across the central Virginia hills, tramping through grassy underbrush. He came home five hours later, peeled off his boots and socks, and found that his legs and feet were speckled with tiny dots. They looked love ground pepper, but were dug into his skin – he had to use a dull knife to scrape them off – and they itched fiercely. He saved a few, and sent them to an entomologist.

What s allergy

They were the larval form of lone star ticks.

This, he realised, was an chance. When he returned to the lab, he had his team draw his blood and check his IgE levels. They were low to start with, and then week by week began to climb. Platts-Mills is British – his dad was an MP – and in the midst of having his IgE tracked, he went to an event at the Royal Society of Medicine in London. “And at that point,” he says cheerfully, “I ate two lamb chops and drank two glasses of wine.”

In the middle of the night, he woke up covered in hives.


The lone star tick doesn’t get much attention in the US.

It’s the black-legged tick, Ixodes scapularis, that has the dubious honour of being the most well-known, as it’s the carrier of Lyme disease, which causes an estimated 300,000 cases of illness in the US each year.

What s allergy

The lone star tick doesn’t transmit Lyme disease, but is the vector for other serious illnesses, including Q fever, ehrlichiosis, Heartland virus, Bourbon virus and tularaemia, an infection so serious that the US government classifies the bacteria that cause it as a potential agent of bioterrorism.

While Lyme clusters in the north-east and the northern midwest US, diseases carried by Amblyomma stretch from the coast of Maine to the tip of Florida, the Atlantic to the middle of Texas, and the southern shores of the Grand Lakes every the way to the Mexican border. And that range appears to be expanding. “The northern edge of where these ticks are abundant is moving,” says Dr Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies, north of New York City.

“It is now well-established further north, into Michigan, Pennsylvania, New York and well up into New England.

“Climate change is likely playing a role in the northward expansion,” Ostfeld adds, but acknowledges that we don’t know what else could also be contributing.

The lone star tick is a sturdy, stealthy predator. It isn’t picky about conditions – it tolerates the damp of Atlantic beaches, and its western expansion only stopped when it ran up against the Texas desert – and is content to feed from dozens of animals, from mice every the way up.

It loves birds, which may own helped it move north so rapidly, and it has a special lust for the white-tailed deer that own colonised numerous American suburbs. And, unlike most ticks, it bites humans in every three stages of its lifecycle: as an adult, as a nymph and as the poppy seed-sized larvae that attacked Platt-Mills, which linger on grass stalks in clusters and spring off hundreds at a time.

Ticks detect scent with organs embedded in their first pair of legs, and what they’re sniffing for is carbon dioxide, the exhaled breath of an animal full of warm, oxygenated blood.

When lone star ticks catch wind of it, they take off. “The Lyme disease tick is a slow tick,” says Dr William Nicholson, a microbiologist at the CDC. “Amblyomma will run to you.”

There has been so little research into alpha-gal allergy that scientists can’t consent on exactly what stage of the bite starts victims’ sensitisation. One aspect of its epidemiology is becoming clear, though: the allergy isn’t only caused by the lone star tick.

In Australia, Van Nunen (who is now a clinical associate professor at the University of Sydney School of Medicine) couldn’t understand how her patients’ tick bites solved the mystery of their meat allergy.

But she could see something else. The beaches that fringe the coast north and south of Sydney are rife with ticks. If bites from them were putting people at risk of a profound allergy, she felt compelled to get the expression out.

In 2007, Van Nunen wrote up a description of 25 meat-allergic patients whose reactions she had confirmed with a skin-prick test. Every but two had had severe skin reactions to a tick bite; more than half had suffered severe anaphylaxis.

The crucial detail in Van Nunen’s research was that her cases were caused by bites from Ixodes holocyclus, called the paralysis tick. Alpha-gal allergy was not just an strange occurrence in one part of the US. It had occurred in the opposite hemisphere, making it literally a global problem.

And so it has proved. Wherever ticks bite people – everywhere other than the Arctic and Antarctic – alpha-gal allergy has been recorded.


It was a sunny early morning at the University of North Carolina Medical Middle in Chapel Hill. Scott Commins, who moved here in 2016 to become an associate professor, had 11 patients to see before the finish of the day.

Seven of them had alpha-gal allergy.

Laura Stirling, 51, was fretting over a list of questions. In 2016, she found a fat lone star tick attached to her, and afterwards had fierce indigestion whenever she ate or smelled pork – a challenge, because her husband likes to tinker with a smoker on weekends. In 2017, she was bitten again, and her symptoms worsened to midnight hives and lightheadedness that sent her to her doctor’s office. She immediately cut every meat and dairy from her diet.

A year later, she wanted to know if she could add anything back.

“Can I eat dairy?” she asked. “Can I cook dairy? Can I eat it if it doesn’t own animal rennet in it?” She paused. “I’ve been symptom-free, because I don’t take risks.”

Commins walked her through a protocol he has developed, a method for adding back mammal products one dose at a time. He has a hypothesis that alpha-gal reactions are linked to the fat content of food; that might explain why they take so numerous hours to happen, because the body processes fat via a slower metabolic pathway than protein or carbs.

He recommends that patients start with a spoonful of grated dry cheese, because its fat content is low, and graduate by slow steps up to full-fat yoghurt and milk and then to ice-cream.

If those foods don’t provoke reactions, he suggests tiny doses of lean meat, starting with deli ham. Stirling lit up at that. “I dream of charcuterie,” she sighed.

Because Commins was part of Platt-Mills’s earliest research, he has been seeing alpha-gal patients for more than a decade now. He estimates he has treated more than 900 men and women; five new patients reach every week. He has coached a significant number of them back to eating some mammal products and managing their exposures to the things they can’t handle, so their worst experience is hunting for an emergency antihistamine tablet, not being rushed to hospital.

Commins and Platts-Mills named alpha-gal allergy a decade ago, and Van Nunen saw her first patient 20 years before that.

A lab test for the allergy, the one that Tami McGraw received, has been on the market since 2010. (Platts-Mills and Tina Hatley, now Merritt, share the patent.) That makes it hard to understand why patients still struggle to be diagnosed and understand the limits of what they can eat or permit themselves to be exposed to. But alpha-gal allergy defies some of the bedrock tenets of immunology.

Food allergies are overwhelmingly caused by proteins, tend to surface in childhood and generally trigger symptoms quickly after a food is consumed.

What s allergy

Alpha-gal is a sugar; alpha-gal patients tolerate meat for years before their reactions begin; and alpha-gal reactions take hours to happen. Plus, the range of reactions is far beyond what’s normal: not only skin reactions in mild cases and anaphylaxis in the most serious, but piercing stomach pain, abdominal cramps and diarrhoea as well.

But alpha-gal reactions are definitely an allergy, given patients’ results on the same skin and IgE tests that immunologists use to determine allergies to other foods. That leads both Van Nunen and Commins to wonder whether the syndrome will assist to reshape allergy science, broadening the understanding of what constitutes an allergy response and leading to new concepts of how allergies are triggered.

Merritt, who estimates she has seen more than 500 patients with alpha-gal allergy, has it herself; she has had bad reactions to meat every her life, since being bitten by seed ticks at girl scout camp, and was re-sensitised by a lone star tick bite final year.

She is sensitive enough to react not only to meat, but to other products derived from mammal tissues – and as she has discovered, they are threaded throughout modern life.

The unrecognised dangers aren’t only sweaters and soaps and face creams. Medical products with an animal origin include the clotting drug heparin, derived from pork intestines and cow lung; pancreatic enzymes and thyroid supplements; medicines that include magnesium stearate as an inert filler; vaccines grown in certain cell lines; and other vaccines, and intravenous fluids, that contain gelatine.

“We own huge difficulty advising people about this,” Van Nunen says. “Sometimes you own to sit below for seven hours, record seven emails and own four telephone conversations to be capable to tell to a 23-year-old lady who’s about to travel: ‘Yes, you may own this brand of Japanese encephalitis vaccine because they do not use bovine material.

The vaccine is made in [cells from] the African green monkey and I own looked up that monkey and it does not contain alpha-gal.’”

Some replacement heart valves are grown in pigs; they may cause alpha-gal sensitisation that could trigger an allergy attack later. And cardiac patients who own alpha-gal allergy seem to use up replacement heart valves more quickly than normal, putting them at risk of heart failure until they can get a replacement.

There’s also a growing sense that alpha-gal may be an occupational hazard.

Final year, researchers in Spain treated three farm workers who developed hives and swelling and had difficulty breathing after being splashed with amniotic fluid while they were helping calves to be born. Every three of them – a 36-year-old lady, a 56-year-old lady and a 53-year-old man – already knew they had alpha-gal sensitivity, but had never imagined that skin contact would be risky. In the two main groups where patients collect, it’s common to hear school cafeteria workers fret about reactions from breathing the fumes of meat cooking.

It’s hard to know how numerous people may be sensitised to alpha-gal without knowing it.

A project at the US National Institutes of Health (NIH) that studies unexplained occurrences of anaphylaxis found final year that 9% of the cases weren’t unexplained after all: they were alpha-gal patients whose sensitivity had never been diagnosed.

Platts-Mills points out that the prevalence of high levels of alpha-gal IgE in his earliest studies was up to 20% in some communities, “but that was absolutely not the prevalence of allergic reactions to meat,” he says. “So there are clearly plenty of people out there who’ve got the antibody but don’t own this syndrome.”

What this every means is that there are almost certainly people for whom a meat-containing meal or medical intervention could trigger an alpha-gal reaction of unknown severity.

This is an edited version of an article first published by Wellcomeon Mosaic and is republished here under a Creative Commons licence.

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Anywhere from 40 to 50 million people in the U.S. own allergies or asthma. These diseases are so common that it might seem love the diagnosis and treatment are straightforward and that any doctor should be capable to ister the most effective therapies. However, allergists are experts in their field with specialized training that allows them to:

  1. Treat more than just your symptoms
  2. Identify the source of your suffering
  3. Accurately diagnose your condition
  4. Perform allergy testing
  5. Develop a personalized plan that eliminates your symptoms
  6. Provide you with the most cost-effective care that produces the best results

Two key steps in the process of allergy diagnosis are the medical history and allergy test selection.

Allergists use their skills in these areas to assist more patients feel well, stay athletic during the day, and relax at night. And that’s nothing to sneeze at.

Why Take a Medical History?

When it comes to human allergic disease, an individual’s medical history is as significant as the results of an allergy test. Medical history is the critical link between allergy test results and allergic disease itself.

Allergy skin testing is the gold standard and is used along with the medical history to establish a diagnosis. Both blood and skin allergy tests can detect a patient’s sensitivity to common inhalants love pollen and dust mites or to medicines, certain foods, latex, venom, or other substances.

Generally skin testing is the most precise and preferred method used by trained allergists. Allergy blood tests may be ordered in certain specific situations, such as severe skin rashes, or if it is impossible to stop a medication that interferes with the interpretation of the skin test.

If the results of skin and blood allergy tests are not clear or are inconsistent with the patient’s medical history, allergists rely on their training and experience along with a patient’s medical history and a physical examination—not test results—to make the final diagnosis.

Research confirms what allergists already know: Allergy tests are valuable for their ability to give precise and dependable results that confirm information gathered in the medical history.

Why Is Allergy Test Choice Important?

An significant related consideration is for health practitioners to select the correct test, the one best capable to aid the diagnostic process.

For numerous reasons, that’s not an simple occupation. Allergy patients are often sensitized to numerous allergens, but are only clinically allergic to one or more specific substances. Allergists are trained to select tests that pinpoint the relevant allergen, which enables them to develop optimal therapies for each patient.

Board-certified allergists recognize that not every allergy tests are same. They regularly review the scientific literature to study which testing systems work better than others and the laboratory practices that may affect test results.

Allergy tests should not be ordered randomly, either. They are chosen based on symptoms, environmental and occupational exposures, age, and even hobbies.

Every results are then interpreted in the context of the patient’s medical history.

Get the facts: Discover answers with an allergist.

What is a Food Allergy? There Are Diverse Types of Allergic Reactions to Foods


If your kid has symptoms after eating certain foods, he or she may own a food allergy.

A food allergy occurs when the body’s immune system sees a certain food as harmful and reacts by causing symptoms. This is an allergic reaction. Foods that cause allergic reactions are allergens.

IgE Mediated Food Allergies

The IgE mediated food allergies most common in infants and children are eggs, milk, peanuts, tree nuts, soy and wheat.

The allergic reaction can involve the skin, mouth, eyes, lungs, heart, gut and brain. Some of the symptoms can include:

  1. Feeling love something terrible is about to happen
  2. Swelling of the lips, tongue or throat
  3. Stomach pain, vomiting, diarrhea
  4. Skin rash, itching, hives
  5. Shortness of breath, trouble breathing, wheezing
  6. Immunoglobulin E (IgE) mediated.

    Symptoms result from the body’s immune system making antibodies called Immunoglobulin E (IgE) antibodies. These IgE antibodies react with a certain food.

  7. Non-IgE mediated. Other parts of the body’s immune system react to a certain food. This reaction causes symptoms, but does not involve an IgE antibody. Someone can own both IgE mediated and non-IgE mediated food allergies.

Sometimes allergy symptoms are mild. Other times they can be severe. Take every allergic symptoms seriously. Mild and severe symptoms can lead to a serious allergic reaction called anaphylaxis (anna-fih-LACK-sis).

This reaction generally involves more than one part of the body and can get worse quick. Anaphylaxis must be treated correct away to provide the best chance for improvement and prevent serious, potentially life-threatening complications.

Treat anaphylaxis with epinephrine. This medicine is safe and comes in an easy-to-use device called an auto-injector. You can’t rely on antihistamines to treat anaphylaxis. The symptoms of an anaphylactic reaction happen shortly after contact with an allergen. In some individuals, there may be a delay of two to three hours before symptoms first appear.

Cross-Reactivity and Oral Allergy Syndrome

Having an IgE mediated allergy to one food can mean your kid is allergic to similar foods.

For example, if your kid is allergic to shrimp, he or she may be allergic to other types of shellfish, such as crab or crayfish. Or if your kid is allergic to cow’s milk, he or she may also be allergic to goat’s and sheep’s milk. The reaction between diverse foods is called cross-reactivity. This happens when proteins in one food are similar to the proteins in another food.

Cross-reactivity also can happen between latex and certain foods. For example, a kid who has an allergy to latex may also own an allergy to bananas, avocados, kiwis or chestnuts.

Some people who own allergies to pollens, such as ragweed and grasses, may also be allergic to some foods.

Proteins in the pollens are love the proteins in some fruits and vegetables. So, if your kid is allergic to ragweed, he or she may own an allergic reaction to melons and bananas. That’s because the protein in ragweed looks love the proteins in melons and bananas. This condition is oral allergy syndrome.

Symptoms of an oral allergy syndrome include an itchy mouth, throat or tongue. Symptoms can be more severe and may include hives, shortness of breath and vomiting.

Reactions generally happen only when someone eats raw food. In rare cases, reactions can be life-threatening and need epinephrine.

Two Categories of Food Allergies

  • Immunoglobulin E (IgE) mediated. Symptoms result from the body’s immune system making antibodies called Immunoglobulin E (IgE) antibodies. These IgE antibodies react with a certain food.
  • Non-IgE mediated. Other parts of the body’s immune system react to a certain food. This reaction causes symptoms, but does not involve an IgE antibody. Someone can own both IgE mediated and non-IgE mediated food allergies.

Non-IgE Mediated Food Allergies

Most symptoms of non-IgE mediated food allergies involve the digestive tract.

Symptoms may be vomiting and diarrhea. The symptoms can take longer to develop and may final longer than IgE mediated allergy symptoms. Sometimes, a reaction to a food allergen occurs up 3 days after eating the food allergen.

When an allergic reaction occurs with this type of allergy, epinephrine is generally not needed. In general, the best way to treat these allergies is to stay away from the food that causes the reaction.

Under are examples of conditions related to non-IgE mediated food allergies.

Not every children who react to a certain food own an allergy. They may own food intolerance. Examples are lactose intolerance, gluten intolerance, sulfite sensitivity or dye sensitivity. Staying away from these foods is the best way to avoid a reaction. Your child’s doctor may propose other steps to prevent a reaction.

If your kid has any food allergy symptoms, see your child’s doctor or allergist. Only a doctor can properly diagnose whether your kid has an IgE- or non-IgE food allergy. Both can be present in some children.

Eosinophilic Esophagitis (EoE)

Eosinophilic (ee-uh-sin-uh-fil-ik) esophagitis is an inflamed esophagus. The esophagus is a tube from the throat to the stomach. An allergy to a food can cause this condition.

With EoE, swallowing food can be hard and painful. Symptoms in infants and toddlers are irritability, problems with eating and poor weight acquire.

Older children may own reflux, vomiting, stomach pain, chest pain and a feeling love food is “stuck” in their throat. The symptoms can happen days or even weeks after eating a food allergen.

EoE is treated by special diets that remove the foods that are causing the condition.

What s allergy

Medication may also be used to reduce inflammation.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is another type of food allergy. It most often affects young infants. Symptoms generally don’t appear for two or more hours. Symptoms include vomiting, which starts about 2 hours or later after eating the food causing the condition. This condition can also cause diarrhea and failure to acquire weight or height. Once the baby stops eating the food causing the allergy, the symptoms go away. Rarely, severe vomiting and diarrhea can happen which can lead to dehydration and even shock. Shock occurs when the body is not getting enough blood flow.

Emergency treatment for severe symptoms must happen correct away at a hospital.

What s allergy

The foods most likely to cause a reaction are dairy, soy, rice, oat, barley, green beans, peas, sweet potatoes, squash and poultry.

Allergic Proctocolitis

Allergic proctocolitis is an allergy to formula or breast milk. This condition inflames the lower part of the intestine. It affects infants in their first year of life and generally ends by age 1 year.

The symptoms include blood-streaked, watery and mucus-filled stools. Infants may also develop green stools, diarrhea, vomiting, anemia (low blood count) and fussiness.

When properly diagnosed, symptoms resolve once the offending food(s) are removed from the diet.

Medical review December 2014.

Allergen Details:

Allergen name: Sus s 1
Lineage: Source: Animalia Chordata
Order: Cetartiodactyla
Species: Sus scrofa(Domestic pig)
Biochemical name: Serum albumin
MW(SDS-PAGE): 60 kDa
Allergenicity: 37 patients sensitized to cat, n=5 had IgE to Fel d 2 with n=1 having cross-reactive IgE to porcine SA (Sus s 1); 39 highly sensitized cat-allergic, n=9 had IgE to Fel d 2, every 9 had cross-reactive IgE to porcine SA (Sus s 1); 3 patients with pork-cat syndrome, every 3 had cross-reactive IgE to porcine SA (Sus s 1)
Allergenicity reference: 9105522 23352634 
Route of allergen exposure: Food
Date Created: 23-22-2015
Last Updated: 2019-09-26 07:24:52
Submitter Info:
Name: Christiane Hilger
Institution: Luxembourg Institute of Health, Infection & Immunity
City: Esch-sur-Alzette, Luxembourg
Email: [email protected]
Submission Date: 2015-09-15

Table of IsoAllergens Click +/- for additional information

Isoallergen and variants GenBank Nucleotide GenBank Protein UniProt PDB
Sus s 1.0101 M36787 AAA30988.1 P08835

Non-IgE Mediated Food Allergies

Most symptoms of non-IgE mediated food allergies involve the digestive tract.

Symptoms may be vomiting and diarrhea. The symptoms can take longer to develop and may final longer than IgE mediated allergy symptoms. Sometimes, a reaction to a food allergen occurs up 3 days after eating the food allergen.

When an allergic reaction occurs with this type of allergy, epinephrine is generally not needed.

What s allergy

In general, the best way to treat these allergies is to stay away from the food that causes the reaction. Under are examples of conditions related to non-IgE mediated food allergies.

Not every children who react to a certain food own an allergy. They may own food intolerance. Examples are lactose intolerance, gluten intolerance, sulfite sensitivity or dye sensitivity. Staying away from these foods is the best way to avoid a reaction. Your child’s doctor may propose other steps to prevent a reaction. If your kid has any food allergy symptoms, see your child’s doctor or allergist. Only a doctor can properly diagnose whether your kid has an IgE- or non-IgE food allergy.

Both can be present in some children.

Eosinophilic Esophagitis (EoE)

Eosinophilic (ee-uh-sin-uh-fil-ik) esophagitis is an inflamed esophagus. The esophagus is a tube from the throat to the stomach. An allergy to a food can cause this condition.

With EoE, swallowing food can be hard and painful. Symptoms in infants and toddlers are irritability, problems with eating and poor weight acquire. Older children may own reflux, vomiting, stomach pain, chest pain and a feeling love food is “stuck” in their throat.

The symptoms can happen days or even weeks after eating a food allergen.

EoE is treated by special diets that remove the foods that are causing the condition. Medication may also be used to reduce inflammation.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is another type of food allergy. It most often affects young infants. Symptoms generally don’t appear for two or more hours.

Symptoms include vomiting, which starts about 2 hours or later after eating the food causing the condition. This condition can also cause diarrhea and failure to acquire weight or height. Once the baby stops eating the food causing the allergy, the symptoms go away. Rarely, severe vomiting and diarrhea can happen which can lead to dehydration and even shock. Shock occurs when the body is not getting enough blood flow.

Emergency treatment for severe symptoms must happen correct away at a hospital. The foods most likely to cause a reaction are dairy, soy, rice, oat, barley, green beans, peas, sweet potatoes, squash and poultry.

Allergic Proctocolitis

Allergic proctocolitis is an allergy to formula or breast milk. This condition inflames the lower part of the intestine. It affects infants in their first year of life and generally ends by age 1 year.

The symptoms include blood-streaked, watery and mucus-filled stools. Infants may also develop green stools, diarrhea, vomiting, anemia (low blood count) and fussiness.

When properly diagnosed, symptoms resolve once the offending food(s) are removed from the diet.

Medical review December 2014.

Allergen Details:

Allergen name: Sus s 1
Lineage: Source: Animalia Chordata
Order: Cetartiodactyla
Species: Sus scrofa(Domestic pig)
Biochemical name: Serum albumin
MW(SDS-PAGE): 60 kDa
Allergenicity: 37 patients sensitized to cat, n=5 had IgE to Fel d 2 with n=1 having cross-reactive IgE to porcine SA (Sus s 1); 39 highly sensitized cat-allergic, n=9 had IgE to Fel d 2, every 9 had cross-reactive IgE to porcine SA (Sus s 1); 3 patients with pork-cat syndrome, every 3 had cross-reactive IgE to porcine SA (Sus s 1)
Allergenicity reference: 9105522 23352634 
Route of allergen exposure: Food
Date Created: 23-22-2015
Last Updated: 2019-09-26 07:24:52
Submitter Info:
Name: Christiane Hilger
Institution: Luxembourg Institute of Health, Infection & Immunity
City: Esch-sur-Alzette, Luxembourg
Email: [email protected]
Submission Date: 2015-09-15

Table of IsoAllergens Click +/- for additional information

Isoallergen and variants GenBank Nucleotide GenBank Protein UniProt PDB
Sus s 1.0101 M36787 AAA30988.1 P08835


Main allergy symptoms

Common symptoms of an allergic reaction include:

  1. swollen lips, tongue, eyes or face
  2. itchy, red, watering eyes (conjunctivitis)
  3. a raised, itchy, red rash (hives)
  4. sneezing and an itchy, runny or blocked nose (allergic rhinitis)
  5. wheezing, chest tightness, shortness of breath and a cough
  6. tummy pain, feeling ill, vomiting or diarrhoea
  7. dry, red and cracked skin

The symptoms vary depending on what you’re allergic to and how you come into contact with it.

For example, you may have a runny nose if exposed to pollen, develop a rash if you own a skin allergy, or feel sick if you eat something you’re allergic to.

See your GP if you or your kid might own had an allergic reaction to something. They can assist determine whether the symptoms are caused by an allergy or another condition.

Read more about diagnosing allergies.


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