When Is A "Food Allergy" Really An Allergy?
Robert Eitches
Food allergies are often misunderstood. There is a great deal of general confusion about them, and they constitute a controversial area within the allergy field of medicine. Oftentimes, what is at first thought to be a food allergy is found to be something else. For example, many people who think they are allergic to foods are merely sensitive to these foods. Others may have enzyme deficiencies which cause them to react adversely to a food in a non-allergic way. In the following article, I hope conquer these and other common misunderstandings about food allergies one at a time.
The Classic Food Allergy
Let's look first at "true" (or "classic") food allergies and how to prevent and treat them. Classic food allergies include allergies to milk, soy, egg whites, shellfish and peanuts. Peanut allergy is a good example to examine, since it is one of the most widely known food allergies and is becoming more and more common. (It is also the food allergy most likely to be fatal). With classic food allergies, your body forms antibodies against the offending food. Even the smell of the food can cause a reaction in a highly allergic person. That's why peanut allergic persons do not like to fly in planes where nuts are served. I recently treated two different people who had severe reactions to peanuts while on a plane. Neither one of them had eaten peanuts and, in one case, the passengers within three rows of this person had offered to voluntarily abstain from eating any nuts. I suspect that either the smell permeated the cabin or some old peanut "dust" was present on the plane's tray table, which then may have rubbed off onto the allergic individual.
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Why is peanut allergy becoming so much more prevalent? The answer is simply that we are eating them more. Peanuts are healthy - if you aren't allergic to them - , and as we adopt healthier lifestyles, we are incorporating them more often in one form or another into our diet.
One question frequently asked of me is whether or not people can outgrow their food allergies. The answer is both yes and no. While I see this frequently with eggs and less commonly with dairy, nut allergies are rarely outgrown.
Food Allergy Reactions
Reactions that may indicate a food allergy are itchy mouth, "fullness" in the throat, shortness of breath, an intense red, itchy rash all over the body, difficulty breathing, and vomiting. In a worst case scenario, as I mentioned above, a food allergy reaction can result in death. Although severe reactions do occur, milder food reactions are more common. Common mild allergic food reactions would be red, itchy skin with hives or eczema (also called atopic dermatitis), and another type of itchy skin rash which can be caused by eggs and many other foods. Some of my patients with mild food allergies have also complained of fatigue or increased nasal irritation.
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Diagnosis
When I see someone who has symptoms of a food allergy, I pay close attention to the time which elapsed between the consumption of the suspected food and their reaction. Food allergy reactions usually occur within minutes and sometimes within seconds. So when a person says to me that they ate a certain food yesterday, some skin itching today is probably not due to a food allergy.
Sometimes a diagnosis can be made via trial and error, by eliminating a suspected food. If the skin clears up, the food is reintroduced to see if the skin flares once more. If you are attempting such an elimination diet, stay off the offending foods for at least two weeks and add back each food one at a time every three days.
The best diagnoses, for food allergies, however, are skin testing and RAST (blood) testing. In skin testing, the offending food is lightly scratched into the skin by a disposable plastic "scratcher." If you are allergic, the area gets red and itchy. Its advantages are that the test results are ready within twenty minutes, and that it is cheaper than RAST tests. RAST testing (which measures the presence of certain allergy-inducing antibodies in your bloodstream) is helpful in your family physician's office, where there is no specific allergy specialist who does skin testing. RAST testing is also useful as a confirmation of results from skin testing; in individuals who have a rash on their back which would complicate a skin test; and when only a couple of foods are suspected.
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Managing Food Allergies
I always equip my patients with a treatment protocol, in other words a game plan, to follow in case of accidental ingestion, which initially includes an over-the-counter antihistamine, such as diphenhydramine (Benadryl), as well as an epinephrine injection kit, such as an Epi-Pen. I also instruct them to go to a hospital emergency room in case of an attack. In some more severe cases, cases, my treatment protocol includes other medications (like cimetidine or a steroid like prednisone). I also recommend that, if they have a classic food allergy, they should wear a Medical Alert bracelet.
Since some of my patients tell me that allergic foods taste "funny," I sometimes instruct them to leave a suspicious food in their mouth a few seconds before swallowing. The body's natural desire to eliminate the problematic food by vomiting can be lifesaving.
Prevention
Food allergies are most easily developed when we are young. At this stage our intestines are not fully developed and allow large, complex proteins such as peanut protein to cross into the body. Our young bodies recognize such proteins as foreign and form antibodies against them. This may be why there is a great deal of cow's milk allergy in the US, and soy allergy in Japan, where those milks are fed to infants.
To prevent peanut allergy, I feel that babies ideally should not get peanut protein at all during the first two or three years of life. I also advise that pregnant women avoid peanuts, especially if there is a family history of food allergies or strong allergic reactions in general. They should also avoid peanut proteins when breast feeding. It may also be helpful to delay the introduction of some other foods (like other nuts, shellfish, cow's milk, wheat, and soy) into an infant's diet for the first six months of life, but this is a controversial issue.
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In the future, it is likely that there will be an oral or injected vaccine for peanuts, which will teach the body to become less allergic.
Is it Food Allergy or Just Sensitivity?
Certain foods are often erroneously blamed for being allergic foods. Rather than being allergic they have naturally occurring histamines within the foods themselves. Examples of foods with natural histamines are
• Wine
• Chocolate
• Strawberries
• Tomatoes
If you are sensitive to one or more of these foods, you might get an itchy rash or a headache after eating them. But if you were tested, your doctor would probably not find any allergic skin or blood results. The exception is wine, some of which is made with preservatives called sulfites and can cause rare but severe allergic reactions. (That's why on wine bottles you see warnings about whether or not the wine contains sulfites.)
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Some of my patients tell me that they are allergic to milk. However, it frequently turns out that their stomach pain, gas, and bloating are caused by an inability to properly digest milk sugar (lactose) due to an enzyme deficiency. The lactose ends up fermenting in the person's intestine, causing discomfort. Eating yogurt or cheeses, drinking lactose-free milk, or taking lactase tablets or acidophilus resolves most of the problem.
Many people believe that milk is mucus producing. I am not convinced that this is true. Others believe that they are allergic to wheat and sugar. Again, this is often undetermined. However, many of these people are indeed sensitive to these foods and do feel better off them. I know parents who believe their children get fewer ear infections and are less irritable off certain foods. I have also encountered a large number of people who believe that they have a yeast allergy and frequently get yeast infections. These people seem to do well on yeast-free diets and off simple sugars (like those found in candies and chocolates).
Always remember that real food allergies can be dangerous, and that potential food allergies should be diagnosed and treated by a physician knowledgeable in this field of medicine. However, I hope after reading this article that you will be better able to determine whether or not you or someone you know might have a food allergy, and be more aware of the difference between a food allergy and a food sensitivity.
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Pet Allergies
by Morris Nejat, MD
Introduction
When it comes to pet allergies, man's best friends may often be his worst enemies. Numerous times a day, I come across patients who end up being allergic to a favorite animal or are concerned that they may be allergic to their pet. Before you make the family dog the scapegoat for a family member's allergy symptoms, you must be sure not to wrongfully accuse an innocent pet.
Diagnosis of Animal Allergy
If you suffer from allergic symptoms, you can only know for certain you have an allergy by undergoing a specific test. In my practice, I start by asking you questions about your symptoms, history of allergy, exposure, family history, etc., to get a good picture of your situation and to see what I can do to help you. To help determine whether an allergy is involved, I usually perform a skin-prick test or intracutaneous test. These tests involve either a gentle prick through a drop of allergen extract on the surface of your arm or the injection of a small amount of allergen extract into the skin. This may result in some swelling and reddening of the skin, suggesting that you have an allergy. On the other hand, if skin testing is negative, the animals in question may not be the culprit and the investigation into other sources of allergy must continue. Too often I have seen a family get rid of a loved family pet without adequate confirmation, only to find out down the road that they were wrong and it wasn't Fluffy or Rover that was making little Johnny wheeze, but rather, his teddy bear.
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Treatment of Animal Allergy
Now that you have been diagnosed with an animal allergy, it is important to understand what aspect of the animal you are allergic to. Below is a list of common animal allergies and what is best to do about each individual animal allergy:
Cat Allergy: Patients allergic to cats are allergic to the cat's saliva. However, typical allergic symptoms are not as a result of coming in direct contact with the cat's saliva. Instead, when the cat grooms itself by licking its fur and skin, it deposits its saliva on the fur. The saliva dries, leaving behind the protein antigen that is the source of allergy to cats. These allergens (cat saliva antigens) are very lightweight and are easily aerosolized. Once airborne, the antigen can spread to clothes, furniture, carpeting, or any other household item.
Once cat allergy is confirmed, the best way to decrease allergy symptoms is to remove the cat from the home. If you decide to keep the cat, however, you should at least try to keep the cat out of the bedroom or at least off of the bed.
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However, relatively high concentrations of cat antigen can remain, even months after the cat is removed. Thereby, it is important to clean or replace the carpeting, furniture, and all other material that may harbor the cat saliva antigen. If you can wash the cat weekly, doing so may also help reduce the cat allergen load in the house. Many of the products available to treat home furnishings have been shown to have little effect on the presence of cat allergen levels in the home. There are less dramatic means to improve or eliminate cat allergy symptoms other than getting rid of your pet; these means include the use of medications and allergy immunization.
Dog Allergy: Patients allergic to dogs are allergic to the dog's saliva. As with cats, dogs groom themselves by licking their fur and skin, depositing dog saliva antigens that also become airborne when dry, and spread to clothes, furniture, carpeting, etc. Allergy to dogs is not as problematic as allergy to cats, primarily because:
• Dogs are usually kept outside.
• Dogs are kept outside of bedrooms.
• Dogs are washed regularly.
Once dog allergy is confirmed, the best way to decrease allergy symptoms is to remove the dog from the home. As with cat allergy, you can also use medications and allergy immunization.
Horse Allergy: Patients often overlook and mistake allergy to horses, for allergy to pollens or molds. These patients are usually allergic to horse hair and dander. Treatment for this allergy would include medications, horse avoidance and/or allergy immunization to decrease the sensitivity to horse allergen.
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Rodent Allergy: Patients become allergic to rodents due to exposure to these animals in their daily work. The most common people at risk are veterinarians, laboratory technicians, and people who live in close quarters with rodents (such as pet owners and those who live in rodent-infested homes). Some examples of common rodents that humans come in contact with include mice, rats, and guinea pigs.
The rodent's urine has a high concentration of protein, which is the primary allergen to humans. The urine is often sprayed rather than deposited, thereby increasing human exposure. After the urine dries, the urinary proteins become airborne and are inhaled, leading to allergic symptoms.
Rabbit Allergy: Patients become allergic to rabbits due to exposure to these animals in their daily work. The most common people at risk are veterinarians, laboratory technicians, and pet owners. The rabbit's saliva and fur are the common allergen.
Cockroach Allergy: Roaches, especially the German Cockroach, are a very common pest in crowded cities worldwide. Recent studies have shown exposure to roach droppings as a major risk factor for the development of allergies and asthma in the inner-city. Avoidance consists of roach baits and traps, extermination, and cleanliness. This includes not leaving food out in open containers, washing dishes after each meal, and keeping cupboards free of food debris. Unfortunately, one can't encourage cleanliness in their neighbors! Patients who are not responsive can be treated with medications and allergy immunization.
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Dust Mite Allergy: Dust mites are approximately 0.3 millimeters in length, too small to be seen with the naked eye. They are eight-legged and sightless, and live on skin scales and other debris. Mites excrete partially digested food and digestive enzymes as a fecal particle, which release allergens very rapidly. Most patients allergic to dust mites are actually allergic to the dust mite feces. The mite fecal pellets are similar to pollen grains in three major ways:
• The fecal particles size
• The quantity of allergen carried
• The rate of proteins release
By being so similar to pollen grains, they are just the right size to cause allergies. Dust mites become a part of our environment and lifestyle because of their natural adaptations. Since they are entirely dependent on ambient humidity for hydration, and they are unable to search for environmental water-supplies, they tend to live in places that "store" water. This may include carpets, sofas, mattresses and clothing. As humidity falls, mites withdraw from the surface and migrate to where there is more humidity; e.g., deeper in the mattress. Even in very dry conditions, it may take months for mites to die and for their allergen levels to fall.
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Avoiding and protecting yourself and your family from dust mite allergies can be summarized as one important rule-keep dust mites away from coming in contact with you! Washing your bedding at least once a week will reduce the number of dust mites you may come in contact with.
Conclusion
The medications used to treat animal allergy are similar to those used to treat other forms of allergy such as seasonal allergies and asthma. They include antihistamines, nasal steroids, and asthma pills and sprays. You should discuss which of these medications would best suit your symptoms with your allergy or asthma specialist. Allergy immunizations work basically by gradually building immunologic tolerance to the specific antigens you are allergic to. This process usually begins with weekly injections and gradually progresses to monthly injections that can be halted after three to five years of therapy with a good chance of maintaining your immunity to a particular antigen. Although roaches and dust mites may not be your idea of pets, getting rid of these creatures may significantly improve your tolerance of the pets you love.
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Childhood Allergies: What Should Parents Know?
Bruce Pener, MD
The incidence of allergies in children has increased significantly in the last two decades. There are now more children with asthma, hay fever, and eczema than ever before. Closely following this increased prevalence of allergies is the rise in asthma, which has become the number one diagnosis for child hospital admissions. In my own practice in recent years, I have seen a steady stream of children as young as six months presenting with an allergic rash (eczema) as well as asthma and chronic nasal irritation (chronic rhinitis). Parents tell me that their children have runny noses, itchy and watery eyes, coughing and wheezing, without any evidence of viral infection. Many are convinced that their child's exposure to flowers, grass, weeds, and pets is the culprit.
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General Information on Allergies
Allergies can develop in the first few months of life, evident as nasal congestion, cough, rash, or diarrhoea following the ingestion of certain foods. Allergies affect all races and have been found in all parts of the world. Allergy is the term used to describe our immunologic sensitivity to an allergen (any substance that causes an allergic reaction). This sensitization may occur by inhaling airborne allergens or eating food that contains allergens. The consequence of allergens entering into our body involves the release of chemical messengers that bring about the well-known symptoms of allergy listed below:
• Sneezing
• Itchy or stuffy nose
• Watery nasal discharge
• Itchy eyes
• Eye tearing and redness
And less frequently:
• Cough
• Palatal (roof of the mouth) itch
• Bronchial asthma symptoms, such as wheezing.
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Genetic Factors
If your child develops allergies, the cause will have been a combination of the genes he or she inherited from you as well as their environmental exposures. As parents, if one of you has a history of allergies, then each child will have about a 40% chance of developing allergies. If both of you have allergies, the risk increases to about 80%.
Genetic factors have also been intensively researched in recent years and what has emerged is that the genetics of allergy are quite complex, involving interactions between our environment and inherited tendencies. The exact genes that account for our allergies have not been fully identified.
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Environmental Exposure
In contrast to the genetic influences, the influence of environmental exposure has been well-established. The presence of pets, such as cats and dogs, in homes clearly affects whether your susceptible child will be reactive to these allergens. It is also true, however, that children can still become sensitized to allergens that have been eliminated from the home environment. Exposure to allergens, such as animal dander, is hard to avoid in school or day care and in outdoor areas as these allergens may be on the coats and clothing of children from homes with pets.
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There are also currently many theories as to other possible causes for allergy in children (and adults):
• Exposure to particulate matter released from the burning of diesel fuel, mainly from trucks, triggers the allergic response. This theory has been proved in the laboratory, where certain cells exposed to diesel particulate matter show signs of an allergic response.
• Air pollution has been cited as a stimulus that can provoke the development of childhood asthma. Evidence for this is that high ozone and sulphur dioxide levels often coincide with peak asthma exacerbations or flare-ups.
• Tiny airborne mould spores (specifically, the species Alternaria), which cannot be seen, have recently been associated with epidemics of asthma in certain cities in children and adults.
• Dust mites and cockroaches appear to be major sensitization agents in our inner cities. Cockroaches have proven to be very difficult to eliminate; dust mites are only somewhat easier.
This abundance of possible causes may seem daunting, but studies have nevertheless shown that certain measures like maintaining a pet-free home, breastfeeding, or soy formula feeding for at least six months or more, along with the late introduction of solid foods (greater than six months of age) can delay the onset of allergic symptoms in susceptible children.
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What Is a Parent to Do?
The goal shared by both physicians and parents alike in treating childhood asthma and allergies should be to minimize the side effects of medications while maximizing the chance of our children to lead normal daily lives. Clearly identifying allergens that your children are sensitive to through allergy skin testing or using a specific blood test (called a RAST test), can be extremely helpful to you in implementing the following avoidance and control measures.
Avoidance and Control Measures for Children with Allergies
• Removing carpet, encasing bedding with breathable covers, hot laundering of linens, and keeping windows closed at night and in the early morning hours can minimize your children's allergic burden and exposure. Also decreasing the prevalence of dust mites in the bedrooms of your children who are allergic to dust mites and are asthmatic can have a major improvement in their lung function and result in a reduced need for concomitant medications to treat their flare-ups.
• Avoidance of allergy triggers, which may include such irritants and odours as perfume, tobacco smoke, and colognes, will also help your allergic children. Unfortunately, since viruses, particularly rhinoviruses (the cause of the common cold), are the most common stimulant of childhood asthma, and there are as yet no specific practical means available to deal with inactivating this virus or decreasing its penetration in the upper respiratory tract, we are powerless to prevent virus exposure. However, vaccination with flu vaccine and appropriate new agents, as they are released and shown to be safe for children, will be very worthwhile.
• Weather changes can be extremely provocative of asthmatic symptoms as are other seasonal factors, such as presence of pollen. Unfortunately, they are difficult to avoid.
• Scheduling outdoor playtime or exercise at non-peak pollen periods, such as afternoons or early evening, can be effective.
• Having your child wear a mask when helping with gardening, vacuuming, or dusting can be very helpful.
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Medications
In addition, the recent availability of newer therapeutic agents for use in children has been extremely useful in managing rhinitis as well as asthma:
• Non-sedating antihistamines available in liquid form and rapidly dissolving tablet form can be very beneficial.
• Sodium cromolyn, which is an over the counter product, used as a nasal spray to prevent nasal allergy symptoms has also been shown to be effective.
• Inhaled nasal corticosteroids have been also shown to be quite effective in ameliorating allergic inflammation.
• A leukotriene antagonist, a new class of drugs, has been approved for the treatment of childhood asthma and is available in a chewable form. Such agents can decrease asthma symptoms and also improve the quality of life.
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In summary, allergies are partly due to genetic tendencies of a child born to parents or relatives with allergies to react to normally harmless substances in the environment (allergens). Common allergens include pollen grains, dust mites, house dust, airborne mould particles and animal dander. Long-term complications of allergy in children include sinus problems (sinusitis) and recurrent ear problems such as serious and chronic fluid in the middle ear (otitis media). Those conditions may require antibiotics as well as, in the care of ears, the placement of ear tubes for ventilation.
It is my opinion that the biggest challenge we face together as physicians and parents is the lack of participation of the allergy specialist in the care of our allergic and asthmatic children. Primary care providers, such as family physicians and pediatricians, need to be encouraged involve the allergist more frequently in the care of their patients and to trust the allergist as an equal partner in the delivery of appropriate health care. Meeting this challenge will be extremely important to both the patient and the parent.
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Facing Your Allergies
Beth Corn, MD
This year more than 50 million Americans will sniffle, wheeze, cough, or scratch their way through a bout of allergies. Some suffer from short-lived seasonal allergies, while others suffer all year long-usually in response to foods, pets, or the dust mites that take residence in all of our mattresses and pillows. An unlucky few will suffer from a combination of the two. Below, Dr. Beth Corn, of the department of Clinical Immunology at the Mount Sinai Medical Centre in New York City, talks about who gets allergies, how to know for sure when it's allergies, and the rare occasions when they can be life threatening.
What are allergies, and why do they happen?
An allergy occurs when your body sees an ordinary substance as foreign, and the immune system tries to combat the substance. Certain chemicals in the body are released in response to the substance, and these chemicals actually cause the release of other chemicals, which cause symptoms like itchy eyes, runny nose, post-nasal drip, itchy ears and in some cases, even asthma. The foreign substance could be tree pollen, grass, ragweed, cat, dust, a certain food, or any number of other ordinary substances that the body somehow identifies as foreign.
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Are there different types of allergies?
Many people have seasonal allergies, which is commonly referred to as 'hay fever'. The reason that it has this name is because about 150 years ago, the hay-harvesting season was in the spring and people thought that these symptoms were a response to the hay. But in actuality the symptoms are caused by grass and trees. There are other seasonal allergies, like the fall allergies, which are the result of ragweed and weed.
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The other type of allergy is called a chronic, or 'perennial' allergy, which means it can occur all year. Allergies to dust mites, moulds and pet allergies are all perennial allergies, because the sufferer can be exposed all year long.
Some people have both perennial and seasonal allergies. So they inch through the year with their perennial allergy, and then get hit with the seasonal allergy, and the symptoms compound each other.
Is there a tendency for allergies to run in families?
If you have one parent who has allergy, you have a 30% chance of having allergy yourself. If you have two parents, then the odds go up. And then there are some people who have allergies but there is no family history.
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Can a person have an allergy for a long time and not know it?
Sure. People can walk around with what they think are cold symptoms for five years and just assume it's a cold. Then someone might say to them, "Maybe this is an allergy." And they go and they get tested and, lo and behold, they have dust mite allergy. So it is certainly possible. If you or someone you know is having repeated symptoms, then it's time to go see a doctor. Nobody should be walking around with a cold for four weeks.
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How can people be sure they have an allergy?
If you're having the same symptoms every fall, chances are that you're not just getting a cold every fall. There's a good chance that it's due to ragweed and weed allergy. If you're waking up every morning and you feel congested and swollen, chances are it's an allergy to the dust mites that live in the bed. If every time you're exposed to a cat you start to feel a little short of breath or have itchy eyes or a runny nose, then chances are it's an allergy to the cat.
A primary-care physician can determine that someone has an allergy based on the symptoms and the scenario. But I think most primary-care physicians would refer patients to an allergist to fine-tune the treatment.
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What lifestyle changes can be made to control allergies?
The first step of treatment is to identify the cause of the allergy, and learn to avoid it. For instance, it's important to keep a very clean environment to minimize dust mites in your home. Dust mites live in everyone's mattress and pillow. But we recommend that patients who are dust-mite allergic purchase coverings for their mattress and all the pillows on their bed to lock in the dust. We also recommend that patients minimize dust-collecting objects in their bedroom. They should minimize the number of books, stuffed animals and carpets.
Are allergies dangerous?
Anaphylaxis is a very severe allergic reaction that affects a number of areas of the body. It can cause a blood pressure drop, throat closure, wheezing, or hives all over the body. When all of this happens at once, this is called anaphylaxis. If someone is having an anaphylactic reaction, they have to receive a shot of adrenaline or epinephrine. They're also given antihistamines and steroids.
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Are some people at higher risk for anaphylaxis than others?
It's kind of a tricky answer, but people who have had an anaphylactic reaction are probably at higher risk to have a subsequent anaphylactic reaction, but just because someone has allergies does not mean that they're going to have an anaphylactic reaction.
Is there anything that someone who has had that type of reaction can do to prevent future reactions? Anyone who has had an anaphylactic reaction in the past-whether it be to a bee sting or to a food-should try to avoid being exposed to bees or to the food that caused it. And this person should walk around with an anaphylaxis kit and an epinephrine pen, which is called an EpiPen, which is just adrenaline. They should also keep antihistamines and steroids with them.
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