What is causing my allergies this time of year

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

Seasonal Allergies.

How do I explain it to my children?

March 25, 2015|Written by M. Rodrigo Brao

Achoo! Achoo! Your son has been sneezing every morning and while you hand him yet another Kleenex, you´re probably asking yourself whether he has allergies? Each year, when spring blossoms, allergies do too and children are no exception when it comes below to developing them. Juan Casado, Head of Paediatrics at the Niño Jesus Hospital in Madrid, assures parents that children do not show signs of allergies until they are at least four or five years ancient. But how do we know for sure?

And how can we explain it to our children so they understand?

“Mommy, what´s incorrect with me?” 4 symptoms to seasonal allergies

The first way to detect if your kids own allergies is simply to observe them. Remember, young children don´t know how to express their feelings fairly yet, except for an occasional  “I´m not feeling well.” That´s why it’s significant to establish a excellent healthy communication and while you attempt to get them to be specific in their answers, be on the lookout for the following symptoms:

Sneezing: Allergies cause sneezing, but they are more frequent and stronger than a regular freezing.

If your kid sneezes, you can enquire him whether he´s sneezed love that at school or at the park every day.

Runny Nose: When kids get a freezing, their runny nose differs from the helpful they get when they develop seasonal allergies. So, next time you assist your kid wipe his nose, make certain to glance at the Kleenex to see if the mucus is transparent and watery.

Red Nose and Cough: If you catch your daughter scratching her nose and hear a dry cough, she probably has a seasonal allergy. If and when she complains, make certain to stay positive. “A extremely ugly creature has climbed into your nose but if you´re a courageous little girl, you´ll win him over”.

Tearing: When a person who is allergic to pollen for example, breathes these particles, the body answers with teary eyes.

If your kid shows signs of teary eyes and he isn´t unhappy or mad, there is a large chance he´s allergic.

If your children own the above symptoms, the best thing to do is make an appointment with the doctor, for further testing.

A simple and magical explanation

If you know your kid is allergic, he or she must know what´s going on in order to avoid the causes (exposure to pollen, for example).

What is causing my allergies this time of year

It might not be simple to explain why he or she is diverse from the relax of their friends but a little patience and simple simple words they can understand will do the trick. Every you own to do is turn your kid into the hero of his own story.

Pollen, the bad guy: The words allergy and allergic are hard words for a kid to remember. The best way to get them to understand is by telling them a tale. “When spring arrives, a villain appears from in between the plants and causes some people to sneeze. The villain changes his appearance and turns into yellow dust. His name? Pollen.

Histamine, the warrior: Histamine plays a major role in numerous allergic reactions.

You can tell your son that a warrior called Histamine lives inside his body and he is there to protect him when he is blind to Pollen. Histamine detects the villain easily and expels him form his body by causing him to sneeze, cough, get teary eyed or a runny nose. And as soon as he does, he must tell mommy or daddy so he can swallow the magic potion (allergy medicine).

Good plants, bad plants: There are numerous allergies caused by pollen.

So once you get the results, read what trees, plants, flowers or bushes, your kid is allergic to. Later, you can make a collage of the excellent plants and the bad so your son or daughter learns to identify each group.

Would you care to read more? At WebMD, they created a list of 15 tips on how to assist your children prevent seasonal allergies.

Has this article helped you to explain what seasonal allergies are to your children?

Photo Credits: Juhan Sonin

Photo Credits: Quinn Norton

CATEGORIES:PLAYING TOGETHER|TAGS:activities, Allergic, Allergy, children, development, Fairytales, family, famosa, learning, positive, responsibility, seasonal allergies, spring, tips, together, toys

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Severe allergic reaction (anaphylaxis)

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

Seasonal Allergies. How do I explain it to my children?

March 25, 2015|Written by M. Rodrigo Brao

Achoo! Achoo! Your son has been sneezing every morning and while you hand him yet another Kleenex, you´re probably asking yourself whether he has allergies? Each year, when spring blossoms, allergies do too and children are no exception when it comes below to developing them. Juan Casado, Head of Paediatrics at the Niño Jesus Hospital in Madrid, assures parents that children do not show signs of allergies until they are at least four or five years ancient.

But how do we know for sure? And how can we explain it to our children so they understand?

“Mommy, what´s incorrect with me?” 4 symptoms to seasonal allergies

The first way to detect if your kids own allergies is simply to observe them. Remember, young children don´t know how to express their feelings fairly yet, except for an occasional  “I´m not feeling well.” That´s why it’s significant to establish a excellent healthy communication and while you attempt to get them to be specific in their answers, be on the lookout for the following symptoms:

Sneezing: Allergies cause sneezing, but they are more frequent and stronger than a regular freezing.

If your kid sneezes, you can enquire him whether he´s sneezed love that at school or at the park every day.

Runny Nose: When kids get a freezing, their runny nose differs from the helpful they get when they develop seasonal allergies. So, next time you assist your kid wipe his nose, make certain to glance at the Kleenex to see if the mucus is transparent and watery.

Red Nose and Cough: If you catch your daughter scratching her nose and hear a dry cough, she probably has a seasonal allergy.

If and when she complains, make certain to stay positive. “A extremely ugly creature has climbed into your nose but if you´re a courageous little girl, you´ll win him over”.

Tearing: When a person who is allergic to pollen for example, breathes these particles, the body answers with teary eyes. If your kid shows signs of teary eyes and he isn´t unhappy or mad, there is a large chance he´s allergic.

If your children own the above symptoms, the best thing to do is make an appointment with the doctor, for further testing.

A simple and magical explanation

If you know your kid is allergic, he or she must know what´s going on in order to avoid the causes (exposure to pollen, for example).

It might not be simple to explain why he or she is diverse from the relax of their friends but a little patience and simple simple words they can understand will do the trick. Every you own to do is turn your kid into the hero of his own story.

Pollen, the bad guy: The words allergy and allergic are hard words for a kid to remember. The best way to get them to understand is by telling them a tale. “When spring arrives, a villain appears from in between the plants and causes some people to sneeze.

The villain changes his appearance and turns into yellow dust. His name? Pollen.

Histamine, the warrior: Histamine plays a major role in numerous allergic reactions. You can tell your son that a warrior called Histamine lives inside his body and he is there to protect him when he is blind to Pollen. Histamine detects the villain easily and expels him form his body by causing him to sneeze, cough, get teary eyed or a runny nose. And as soon as he does, he must tell mommy or daddy so he can swallow the magic potion (allergy medicine).

Good plants, bad plants: There are numerous allergies caused by pollen.

So once you get the results, read what trees, plants, flowers or bushes, your kid is allergic to. Later, you can make a collage of the excellent plants and the bad so your son or daughter learns to identify each group.

Would you care to read more? At WebMD, they created a list of 15 tips on how to assist your children prevent seasonal allergies.

Has this article helped you to explain what seasonal allergies are to your children?

Photo Credits: Juhan Sonin

Photo Credits: Quinn Norton

CATEGORIES:PLAYING TOGETHER|TAGS:activities, Allergic, Allergy, children, development, Fairytales, family, famosa, learning, positive, responsibility, seasonal allergies, spring, tips, together, toys

RELATED POSTS

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COMMENTS (0)

Observational studies

Several observational studies own suggested that early introduction of potentially allergenic foods may be associated with a decreased risk of developing food allergy.

A questionnaire-based survey conducted in 2008 found that the prevalence of peanut allergy was ten-fold higher among Jewish children in the United Kingdom (UK) compared with Jewish children in Israel [12]. This difference in prevalence was attributed to earlier and more frequent peanut exposure in the first year of life in Israel compared with the UK. A population-based, cross-sectional study (HealthNuts) that included over 2500 infants found a lower risk of egg allergy among those that were introduced to egg at 4–6 month of age compared to those introduced at 10–12 months of age or later [13].

What is causing my allergies this time of year

Another observational study examining the feeding history of over 13,000 infants found the incidence of IgE-mediated cow’s milk allergy to be significantly lower in infants who were introduced to cow’s milk formula within the first 14 days of life and given it regularly thereafter, compared to those who were introduced to the formula after 3 months of age [14]. Similarly, a case–control study that included approximately 200 children showed that early introduction of cow’s milk formula was associated with a lower incidence of IgE-mediated cow’s milk allergy [15].

Data from a Finnish birth cohort that included 994 children found that delaying the introduction of multiple foods, including oats (> 5 months) and wheat (> 6 months), was significantly associated with an increased risk of allergic sensitization to food and inhalant allergens [16]. Another birth cohort study conducted in the United States (US) showed that introducing solid food or cow’s milk (complementary food) at less than 4 months of age was associated with a reduced risk of peanut allergy by age 2–3 years in children with a parental history of asthma or allergy [17].

A study that included approximately 1600 children observed that delaying initial exposure to cereal grains until 6 months of age may increase the risk of developing IgE-mediated wheat allergy [18]. More recently, data from over 2100 children included in the Canadian Healthy Baby Longitudinal Development (CHILD) birth cohort study showed that delaying the introduction of cow’s milk products, egg, and peanut beyond the first year of life significantly increased the odds of sensitization to these foods [19].

Prospective clinical trials

In recent years, randomized controlled trials own provided further support for the association between early food introduction and the prevention of food allergy.

The most compelling evidence to date comes from the LEAP study, which randomized 640 high-risk infants (defined as those with severe eczema and/or egg allergy) in the UK to either early (age 4–11 months) or delayed (avoidance until age 5 years) peanut introduction. The trial showed that the early and regular (3 times per week) consumption of peanut in these high-risk infants reduced the development of peanut allergy by 86% by 5 years of age [4]. The Persistence of Oral Tolerance to Peanut extension of the LEAP study (LEAP-On) investigated whether participants who had consumed peanut in the primary trial would remain protected from peanut allergy after cessation of peanut consumption for 12 months [20].

This extension study found that the benefits of early peanut introduction persisted after 12 months of cessation of peanut consumption, supporting the concept that early peanut tolerance is not a transient phenomenon.

In the Enquiring About Tolerance (EAT) trial, 1303 exclusively breastfed infants from the general population were randomized to either early (age 3 months) or standard (age 6 months) introduction of six allergenic foods (peanut, cooked egg, cow’s milk, sesame, whitefish, and wheat) [21].

The EAT investigators hypothesized that early introduction of these allergenic foods would reduce the prevalence of food allergy by age 3 years. The intention-to-treat analysis revealed a 20% reduction in the prevalence of food allergy in the early introduction group that was not statistically significant, likely because of the high rate of non-adherence to the dietary protocol. However, in an adjusted per protocol analysis, significant reductions were seen in the rates of peanut and egg allergy in the early introduction group.

Other prospective trials own investigated the effects of early egg introduction.

In the Prevention of Egg Allergy with Tiny Quantity Intake (PETIT) trial, 147 Japanese infants with eczema were randomly assigned to daily consumption of heated egg powder or placebo along with aggressive treatment of eczema [22]. The study found that randomization to heated egg powder at age 6 months significantly reduced the risk of egg allergy by 78% compared with avoidance until age 12 months. The trial was stopped early due to benefit. The Solids Timing for Allergy Research (STAR) randomized 86 high-risk infants with moderate-to-severe eczema to get pasteurized raw whole-egg powder or rice powder (placebo) at 4 months of age [23].

At 8 months, both groups were introduced to whole cooked egg under medical supervision. At 1-year, there was a non-significant trend toward a lower rate of egg allergy in the group who received pasteurized raw egg powder at age 4 months vs. whole cooked egg at age 8 months. However, the trial was terminated early due to the high rate of allergic reactions in the egg-sensitized children randomized to early introduction at age 4 months. The Starting Time of Egg Protein (STEP) study, which included 820 infants without eczema but with a family history of atopy, found that early introduction of pasteurized raw egg powder at age 4–6 months was associated with a non-significant trend toward a reduced risk of egg allergy compared to introduction at age 10 months [24].

A per-protocol analysis found that significantly fewer children in the early introduction group had IgE-mediated egg allergy at 12 months of age.

In the Beating Egg Allergy Trial (BEAT), 319 infants who were SPT-negative to egg but who had a family history of atopy were randomized to get either pasteurized whole-egg powder or placebo at 4 months of age [25]. Subjects were treated until 8 months of age, at which time egg was introduced into the diet.

At 1 year, egg sensitization was significantly lower in the treatment group compared with the placebo group. However, there was only a non-significant trend toward a reduced risk of developing egg allergy in the early introduction group. Findings from the Hen’s Egg Allergy Prevention (HEAP) study also call into question the safety of early pasteurized raw egg introduction [26]. This trial, which included 406 infants from the general population, found no evidence that early introduction of pasteurized raw egg powder at age 4–6 months prevented either egg allergy or egg sensitization.

Furthermore, among the children with baseline egg sensitization who were excluded from randomization but then challenged with egg separately (n = 23), two-thirds experienced an anaphylactic reaction upon this initial introduction.

Although the results of egg allergy studies own been conflicting or inconclusive, a recent meta-analysis of randomized controlled trials investigating the timing of allergenic food introduction and the risk of developing food allergy found “moderate certainty” evidence (based on 5 trials, including 1915 children) that introducing egg between 4 and 6 months of age reduced the risk of egg allergy (relative risk [RR], 0.56; p = 0.009) [27], showing much better efficacy with using cooked as opposed to raw egg.

This meta-analysis also found “moderate certainty” evidence (based on 2 trials [LEAP and EAT], 1550 patients) that peanut introduction between age 4–11 months reduced the risk of peanut allergy (RR, 0.29; p = 0.009).

Immune system response to a substance that most people tolerate well

For the medical journal of this title, see Allergy (journal).

Allergy
Hives are a common allergic symptom
Specialty Immunology
Symptoms Red eyes, itchy rash, runny nose, shortness of breath, swelling, sneezing[1]
Types Hay fever, food allergies, atopic dermatitis, allergic asthma, anaphylaxis[2]
Causes Genetic and environmental factors[3]
Diagnostic method Based on symptoms, skin prick test, blood test[4]
Differential diagnosis Food intolerances, food poisoning[5]
Prevention Early exposure to potential allergens[6]
Treatment Avoiding known allergens, medications, allergen immunotherapy[7]
Medication Steroids, antihistamines, epinephrine, mast cell stabilizers, antileukotrienes[7][8][9][10]
Frequency Common[11]

Allergies, also known as allergic diseases, are a number of conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment.[12] These diseases include hay fever, food allergies, atopic dermatitis, allergic asthma, and anaphylaxis.[2] Symptoms may include red eyes, an itchy rash, sneezing, a runny nose, shortness of breath, or swelling.[1]Food intolerances and food poisoning are separate conditions.[4][5]

Common allergens include pollen and certain foods.[12] Metals and other substances may also cause problems.[12] Food, insect stings, and medications are common causes of severe reactions.[3] Their development is due to both genetic and environmental factors.[3] The underlying mechanism involves immunoglobulin E antibodies (IgE), part of the body’s immune system, binding to an allergen and then to a receptor on mast cells or basophils where it triggers the release of inflammatory chemicals such as histamine.[13] Diagnosis is typically based on a person’s medical history.[4] Further testing of the skin or blood may be useful in certain cases.[4] Positive tests, however, may not mean there is a significant allergy to the substance in question.[14]

Early exposure to potential allergens may be protective.[6] Treatments for allergies include avoiding known allergens and the use of medications such as steroids and antihistamines.[7] In severe reactions injectable adrenaline (epinephrine) is recommended.[8]Allergen immunotherapy, which gradually exposes people to larger and larger amounts of allergen, is useful for some types of allergies such as hay fever and reactions to insect bites.[7] Its use in food allergies is unclear.[7]

Allergies are common.[11] In the developed world, about 20% of people are affected by allergic rhinitis,[15] about 6% of people own at least one food allergy,[4][6] and about 20% own atopic dermatitis at some point in time.[16] Depending on the country about 1–18% of people own asthma.[17][18] Anaphylaxis occurs in between 0.05–2% of people.[19] Rates of numerous allergic diseases appear to be increasing.[8][20] The expression «allergy» was first used by Clemens von Pirquet in 1906.[3]


Cause

Risk factors for allergy can be placed in two general categories, namely host and environmental factors.[31] Host factors include heredity, sex, race, and age, with heredity being by far the most significant.

However, there own been recent increases in the incidence of allergic disorders that cannot be explained by genetic factors alone. Four major environmental candidates are alterations in exposure to infectious diseases during early childhood, environmental pollution, allergen levels, and dietary changes.[32]

Hygiene hypothesis

Main article: Hygiene hypothesis

Allergic diseases are caused by inappropriate immunological responses to harmless antigens driven by a TH2-mediated immune response.

Numerous bacteria and viruses elicit a TH1-mediated immune response, which down-regulates TH2 responses. The first proposed mechanism of action of the hygiene hypothesis was that insufficient stimulation of the TH1 arm of the immune system leads to an overactive TH2 arm, which in turn leads to allergic disease.[56] In other words, individuals living in too sterile an environment are not exposed to enough pathogens to hold the immune system busy. Since our bodies evolved to deal with a certain level of such pathogens, when they are not exposed to this level, the immune system will attack harmless antigens and thus normally benign microbial objects—like pollen—will trigger an immune response.[57]

The hygiene hypothesis was developed to explain the observation that hay fever and eczema, both allergic diseases, were less common in children from larger families, which were, it is presumed, exposed to more infectious agents through their siblings, than in children from families with only one kid.

What is causing my allergies this time of year

The hygiene hypothesis has been extensively investigated by immunologists and epidemiologists and has become an significant theoretical framework for the study of allergic disorders. It is used to explain the increase in allergic diseases that own been seen since industrialization, and the higher incidence of allergic diseases in more developed countries. The hygiene hypothesis has now expanded to include exposure to symbiotic bacteria and parasites as significant modulators of immune system development, along with infectious agents.

Epidemiological data support the hygiene hypothesis. Studies own shown that various immunological and autoimmune diseases are much less common in the developing world than the industrialized world and that immigrants to the industrialized world from the developing world increasingly develop immunological disorders in relation to the length of time since arrival in the industrialized world.[58] Longitudinal studies in the third world protest an increase in immunological disorders as a country grows more affluent and, it is presumed, cleaner.[59] The use of antibiotics in the first year of life has been linked to asthma and other allergic diseases.[60] The use of antibacterial cleaning products has also been associated with higher incidence of asthma, as has birth by Caesarean section rather than vaginal birth.[61][62]

Foods

Main article: Food allergy

A wide variety of foods can cause allergic reactions, but 90% of allergic responses to foods are caused by cow’s milk, soy, eggs, wheat, peanuts, tree nuts, fish, and shellfish.[33] Other food allergies, affecting less than 1 person per 10,000 population, may be considered «rare».[34] The use of hydrolysed milk baby formula versus standard milk baby formula does not appear to change the risk.[35]

The most common food allergy in the US population is a sensitivity to crustacea.[34] Although peanut allergies are notorious for their severity, peanut allergies are not the most common food allergy in adults or children.

Severe or life-threatening reactions may be triggered by other allergens, and are more common when combined with asthma.[33]

Rates of allergies differ between adults and children. Peanut allergies can sometimes be outgrown by children. Egg allergies affect one to two percent of children but are outgrown by about two-thirds of children by the age of 5.[36] The sensitivity is generally to proteins in the white, rather than the yolk.[37]

Milk-protein allergies are most common in children.[38] Approximately 60% of milk-protein reactions are immunoglobulin E-mediated, with the remaining generally attributable to inflammation of the colon.[39] Some people are unable to tolerate milk from goats or sheep as well as from cows, and numerous are also unable to tolerate dairy products such as cheese.

What is causing my allergies this time of year

Roughly 10% of children with a milk allergy will own a reaction to beef. Beef contains little amounts of proteins that are present in greater abundance in cow’s milk.[40]Lactose intolerance, a common reaction to milk, is not a form of allergy at every, but rather due to the absence of an enzyme in the digestive tract.

Those with tree nut allergies may be allergic to one or to numerous tree nuts, including pecans, pistachios, pine nuts, and walnuts.[37] Also seeds, including sesame seeds and poppy seeds, contain oils in which protein is present, which may elicit an allergic reaction.[37]

Allergens can be transferred from one food to another through genetic engineering; however genetic modification can also remove allergens.

Little research has been done on the natural variation of allergen concentrations in unmodified crops.[41][42]

Stress

Chronic stress can aggravate allergic conditions. This has been attributed to a T helper 2 (TH2)-predominant response driven by suppression of interleukin 12 by both the autonomic nervous system and the hypothalamic–pituitary–adrenal axis. Stress management in highly susceptible individuals may improve symptoms.[63]

Medications

Main article: Drug allergy

See also: Adverse drug reaction and Drug eruption

About 10% of people report that they are allergic to penicillin; however, 90% turn out not to be.[45] Serious allergies only happen in about 0.03%.[45]

Genetics

Allergic diseases are strongly familial: identical twins are likely to own the same allergic diseases about 70% of the time; the same allergy occurs about 40% of the time in non-identical twins.[50] Allergic parents are more likely to own allergic children,[51] and those children’s allergies are likely to be more severe than those in children of non-allergic parents.

Some allergies, however, are not consistent along genealogies; parents who are allergic to peanuts may own children who are allergic to ragweed. It seems that the likelihood of developing allergies is inherited and related to an irregularity in the immune system, but the specific allergen is not.[51]

The risk of allergic sensitization and the development of allergies varies with age, with young children most at risk.[52] Several studies own shown that IgE levels are highest in childhood and drop rapidly between the ages of 10 and 30 years.[52] The peak prevalence of hay fever is highest in children and young adults and the incidence of asthma is highest in children under 10.[53]

Overall, boys own a higher risk of developing allergies than girls,[51] although for some diseases, namely asthma in young adults, females are more likely to be affected.[54] These differences between the sexes tend to decrease in adulthood.[51]

Ethnicity may frolic a role in some allergies; however, racial factors own been hard to separate from environmental influences and changes due to migration.[51] It has been suggested that diverse genetic loci are responsible for asthma, to be specific, in people of European, Hispanic, Asian, and African origins.[55]

Toxins interacting with proteins

Another non-food protein reaction, urushiol-induced contact dermatitis, originates after contact with poison ivy, eastern poison oak, western poison oak, or poison sumac.

Urushiol, which is not itself a protein, acts as a hapten and chemically reacts with, binds to, and changes the shape of integral membrane proteins on exposed skin cells. The immune system does not recognize the affected cells as normal parts of the body, causing a T-cell-mediated immune response.[46] Of these poisonous plants, sumac is the most virulent.[47] The resulting dermatological response to the reaction between urushiol and membrane proteins includes redness, swelling, papules, vesicles, blisters, and streaking.[48]

Estimates vary on the percentage of the population that will own an immune system response.

Approximately 25 percent of the population will own a strong allergic response to urushiol. In general, approximately 80 percent to 90 percent of adults will develop a rash if they are exposed to .0050 milligrams (7.7×10−5 gr) of purified urushiol, but some people are so sensitive that it takes only a molecular trace on the skin to initiate an allergic reaction.[49]

Insect stings

Main article: Insect sting allergy

Typically, insects which generate allergic responses are either stinging insects (wasps, bees, hornets and ants) or biting insects (mosquitoes, ticks). Stinging insects inject venom into their victims, whilst biting insects normally introduce anti-coagulants.

Latex

Latex can trigger an IgE-mediated cutaneous, respiratory, and systemic reaction. The prevalence of latex allergy in the general population is believed to be less than one percent. In a hospital study, 1 in 800 surgical patients (0.125 percent) reported latex sensitivity, although the sensitivity among healthcare workers is higher, between seven and ten percent. Researchers attribute this higher level to the exposure of healthcare workers to areas with significant airborne latex allergens, such as operating rooms, intensive-care units, and dental suites.

These latex-rich environments may sensitize healthcare workers who regularly inhale allergenic proteins.[43]

The most prevalent response to latex is an allergic contact dermatitis, a delayed hypersensitive reaction appearing as dry, crusted lesions. This reaction generally lasts 48–96 hours. Sweating or rubbing the area under the glove aggravates the lesions, possibly leading to ulcerations.[43]Anaphylactic reactions happen most often in sensitive patients who own been exposed to a surgeon’s latex gloves during abdominal surgery, but other mucosal exposures, such as dental procedures, can also produce systemic reactions.[43]

Latex and banana sensitivity may cross-react.

Furthermore, those with latex allergy may also own sensitivities to avocado, kiwifruit, and chestnut.[44] These people often own perioral itching and local urticaria. Only occasionally own these food-induced allergies induced systemic responses. Researchers suspect that the cross-reactivity of latex with banana, avocado, kiwifruit, and chestnut occurs because latex proteins are structurally homologous with some other plant proteins.[43]

Other environmental factors

There are differences between countries in the number of individuals within a population having allergies. Allergic diseases are more common in industrialized countries than in countries that are more traditional or agricultural, and there is a higher rate of allergic disease in urban populations versus rural populations, although these differences are becoming less defined.[64] Historically, the trees planted in urban areas were predominantly male to prevent litter from seeds and fruits, but the high ratio of male trees causes high pollen counts.[65]

Alterations in exposure to microorganisms is another plausible explanation, at present, for the increase in atopic allergy.[32] Endotoxin exposure reduces release of inflammatory cytokines such as TNF-α, IFNγ, interleukin-10, and interleukin-12 from white blood cells (leukocytes) that circulate in the blood.[66] Certain microbe-sensing proteins, known as Toll-like receptors, found on the surface of cells in the body are also thought to be involved in these processes.[67]

Gutworms and similar parasites are present in untreated drinking water in developing countries, and were present in the water of developed countries until the routine chlorination and purification of drinking water supplies.[68] Recent research has shown that some common parasites, such as intestinal worms (e.g., hookworms), secrete chemicals into the gut wall (and, hence, the bloodstream) that suppress the immune system and prevent the body from attacking the parasite.[69] This gives rise to a new slant on the hygiene hypothesis theory—that co-evolution of humans and parasites has led to an immune system that functions correctly only in the presence of the parasites.

Without them, the immune system becomes unbalanced and oversensitive.[70] In specific, research suggests that allergies may coincide with the delayed establishment of gut flora in infants.[71] However, the research to support this theory is conflicting, with some studies performed in China and Ethiopia showing an increase in allergy in people infected with intestinal worms.[64] Clinical trials own been initiated to test the effectiveness of certain worms in treating some allergies.[72] It may be that the term ‘parasite’ could turn out to be inappropriate, and in fact a hitherto unsuspected symbiosis is at work.[72] For more information on this topic, see Helminthic therapy.


Prevention

Further information: Allergy prevention in children

Giving peanut products early may decrease the risk allergies while only breastfeeding during at least the first few months of life may decrease the risk of dermatitis.[92][93] There is no excellent evidence that a mother’s diet during pregnancy or breastfeeding affects the risk.[92] Nor is there evidence that delayed introduction of certain foods is useful.[92] Early exposure to potential allergens may actually be protective.[6]

Fish oil supplementation during pregnancy is associated with a lower risk.[93] Probiotic supplements during pregnancy or infancy may assist to prevent atopic dermatitis.[94][95]


Main allergy symptoms

Common symptoms of an allergic reaction include:

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


Pathophysiology

Late-phase response

After the chemical mediators of the acute response subside, late-phase responses can often happen. This is due to the migration of other leukocytes such as neutrophils, lymphocytes, eosinophils and macrophages to the initial site.

The reaction is generally seen 2–24 hours after the original reaction.[73] Cytokines from mast cells may frolic a role in the persistence of long-term effects.

What is causing my allergies this time of year

Late-phase responses seen in asthma are slightly diverse from those seen in other allergic responses, although they are still caused by release of mediators from eosinophils and are still dependent on activity of TH2 cells.[74]

Acute response

In the early stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional antigen-presenting cell causes a response in a type of immune cell called a TH2 lymphocyte; a subset of T cells that produce a cytokine called interleukin-4 (IL-4).

These TH2 cells interact with other lymphocytes called B cells, whose role is production of antibodies. Coupled with signals provided by IL-4, this interaction stimulates the B cell to start production of a large quantity of a specific type of antibody known as IgE. Secreted IgE circulates in the blood and binds to an IgE-specific receptor (a helpful of Fc receptor called FcεRI) on the surface of other kinds of immune cells called mast cells and basophils, which are both involved in the acute inflammatory response. The IgE-coated cells, at this stage, are sensitized to the allergen.[32]

If later exposure to the same allergen occurs, the allergen can bind to the IgE molecules held on the surface of the mast cells or basophils.

Cross-linking of the IgE and Fc receptors occurs when more than one IgE-receptor complicated interacts with the same allergenic molecule, and activates the sensitized cell. Activated mast cells and basophils undergo a process called degranulation, during which they release histamine and other inflammatory chemical mediators (cytokines, interleukins, leukotrienes, and prostaglandins) from their granules into the surrounding tissue causing several systemic effects, such as vasodilation, mucous secretion, nerve stimulation, and smooth muscle contraction.

This results in rhinorrhea, itchiness, dyspnea, and anaphylaxis. Depending on the individual, allergen, and mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to specific body systems; asthma is localized to the respiratory system and eczema is localized to the dermis.[32]

Allergic contact dermatitis

Although allergic contact dermatitis is termed an «allergic» reaction (which generally refers to type I hypersensitivity), its pathophysiology actually involves a reaction that more correctly corresponds to a type IV hypersensitivity reaction.[75] In type IV hypersensitivity, there is activation of certain types of T cells (CD8+) that destroy target cells on contact, as well as activated macrophages that produce hydrolyticenzymes.


Diagnosis

Effective management of allergic diseases relies on the ability to make an precise diagnosis.[76] Allergy testing can assist confirm or law out allergies.[77][78] Correct diagnosis, counseling, and avoidance advice based on valid allergy test results reduces the incidence of symptoms and need for medications, and improves quality of life.[77] To assess the presence of allergen-specific IgE antibodies, two diverse methods can be used: a skin prick test, or an allergy blood test.

Both methods are recommended, and they own similar diagnostic value.[78][79]

Skin prick tests and blood tests are equally cost-effective, and health economic evidence shows that both tests were cost-effective compared with no test.[77] Also, early and more precise diagnoses save cost due to reduced consultations, referrals to secondary care, misdiagnosis, and emergency admissions.[80]

Allergy undergoes dynamic changes over time.

Regular allergy testing of relevant allergens provides information on if and how patient management can be changed, in order to improve health and quality of life. Annual testing is often the practice for determining whether allergy to milk, egg, soy, and wheat own been outgrown, and the testing interval is extended to 2–3 years for allergy to peanut, tree nuts, fish, and crustacean shellfish.[78] Results of follow-up testing can guide decision-making regarding whether and when it is safe to introduce or re-introduce allergenic food into the diet.[81]

Other testing

Challenge testing: Challenge testing is when little amounts of a suspected allergen are introduced to the body orally, through inhalation, or via other routes.

Except for testing food and medication allergies, challenges are rarely performed. When this type of testing is chosen, it must be closely supervised by an allergist.

Elimination/challenge tests: This testing method is used most often with foods or medicines. A patient with a suspected allergen is instructed to modify his diet to totally avoid that allergen for a set time. If the patient experiences significant improvement, he may then be «challenged» by reintroducing the allergen, to see if symptoms are reproduced.

Unreliable tests: There are other types of allergy testing methods that are unreliable, including applied kinesiology (allergy testing through muscle relaxation), cytotoxicity testing, urine autoinjection, skin titration (Rinkel method), and provocative and neutralization (subcutaneous) testing or sublingual provocation.[89]

Skin prick testing

Skin testing is also known as «puncture testing» and «prick testing» due to the series of tiny punctures or pricks made into the patient’s skin. Little amounts of suspected allergens and/or their extracts (e.g., pollen, grass, mite proteins, peanut extract) are introduced to sites on the skin marked with pen or dye (the ink/dye should be carefully selected, lest it cause an allergic response itself).

A little plastic or metal device is used to puncture or prick the skin. Sometimes, the allergens are injected «intradermally» into the patient’s skin, with a needle and syringe. Common areas for testing include the inside forearm and the back.

If the patient is allergic to the substance, then a visible inflammatory reaction will generally happen within 30 minutes. This response will range from slight reddening of the skin to a full-blown hive (called «wheal and flare») in more sensitive patients similar to a mosquito bite. Interpretation of the results of the skin prick test is normally done by allergists on a scale of severity, with +/− meaning borderline reactivity, and 4+ being a large reaction.

Increasingly, allergists are measuring and recording the diameter of the wheal and flare reaction. Interpretation by well-trained allergists is often guided by relevant literature.[82] Some patients may believe they own sure their own allergic sensitivity from observation, but a skin test has been shown to be much better than patient observation to detect allergy.[83]

If a serious life-threatening anaphylactic reaction has brought a patient in for evaluation, some allergists will prefer an initial blood test prior to performing the skin prick test. Skin tests may not be an option if the patient has widespread skin disease, or has taken antihistamines in the final several days.

Blood testing

An allergy blood test is quick and simple, and can be ordered by a licensed health care provider (e.g., an allergy specialist) or general practitioner. Unlike skin-prick testing, a blood test can be performed irrespective of age, skin condition, medication, symptom, disease activity, and pregnancy. Adults and children of any age can get an allergy blood test. For babies and extremely young children, a single needle stick for allergy blood testing is often more tender than several skin pricks.

An allergy blood test is available through most laboratories. A sample of the patient’s blood is sent to a laboratory for analysis, and the results are sent back a few days later. Multiple allergens can be detected with a single blood sample. Allergy blood tests are extremely safe, since the person is not exposed to any allergens during the testing procedure.

The test measures the concentration of specific IgE antibodies in the blood. Quantitative IgE test results increase the possibility of ranking how diverse substances may affect symptoms.

A law of thumb is that the higher the IgE antibody worth, the greater the likelihood of symptoms. Allergens found at low levels that today do not result in symptoms can not assist predict future symptom development. The quantitative allergy blood result can assist determine what a patient is allergic to, assist predict and follow the disease development, estimate the risk of a severe reaction, and explain cross-reactivity.[84][85]

A low entire IgE level is not adequate to law out sensitization to commonly inhaled allergens.[86]Statistical methods, such as ROC curves, predictive worth calculations, and likelihood ratios own been used to examine the relationship of various testing methods to each other.

These methods own shown that patients with a high entire IgE own a high probability of allergic sensitization, but further investigation with allergy tests for specific IgE antibodies for a carefully chosen of allergens is often warranted.

Laboratory methods to measure specific IgE antibodies for allergy testing include enzyme-linked immunosorbent assay (ELISA, or EIA),[87]radioallergosorbent test (RAST)[87] and fluorescent enzyme immunoassay (FEIA).[88]

Patch testing

Main article: Patch test

Patch testing is a method used to determine if a specific substance causes allergic inflammation of the skin.

It tests for delayed reactions. It is used to assist ascertain the cause of skin contact allergy, or contact dermatitis. Adhesive patches, generally treated with a number of common allergic chemicals or skin sensitizers, are applied to the back.

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The skin is then examined for possible local reactions at least twice, generally at 48 hours after application of the patch, and again two or three days later.

Differential diagnosis

Before a diagnosis of allergic disease can be confirmed, other possible causes of the presenting symptoms should be considered.[90]Vasomotor rhinitis, for example, is one of numerous illnesses that share symptoms with allergic rhinitis, underscoring the need for professional differential diagnosis.[91] Once a diagnosis of asthma, rhinitis, anaphylaxis, or other allergic disease has been made, there are several methods for discovering the causative agent of that allergy.


Signs and symptoms

Affected organ Common signs and symptoms
Nose Swelling of the nasal mucosa (allergic rhinitis) runny nose, sneezing
Sinuses Allergic sinusitis
Eyes Redness and itching of the conjunctiva (allergic conjunctivitis, watery)
Airways Sneezing, coughing, bronchoconstriction, wheezing and dyspnea, sometimes outright attacks of asthma, in severe cases the airway constricts due to swelling known as laryngeal edema
Ears Feeling of fullness, possibly pain, and impaired hearing due to the lack of eustachian tube drainage.

Skin Rashes, such as eczema and hives (urticaria)
Gastrointestinal tract Abdominal pain, bloating, vomiting, diarrhea

Many allergens such as dust or pollen are airborne particles. In these cases, symptoms arise in areas in contact with air, such as eyes, nose, and lungs. For instance, allergic rhinitis, also known as hay fever, causes irritation of the nose, sneezing, itching, and redness of the eyes.[21] Inhaled allergens can also lead to increased production of mucus in the lungs, shortness of breath, coughing, and wheezing.[22]

Aside from these ambient allergens, allergic reactions can result from foods, insect stings, and reactions to medications love aspirin and antibiotics such as penicillin.

Symptoms of food allergy include abdominal pain, bloating, vomiting, diarrhea, itchy skin, and swelling of the skin during hives. Food allergies rarely cause respiratory (asthmatic) reactions, or rhinitis.[23] Insect stings, food, antibiotics, and certain medicines may produce a systemic allergic response that is also called anaphylaxis; multiple organ systems can be affected, including the digestive system, the respiratory system, and the circulatory system.[24][25][26] Depending on the rate of severity, anaphylaxis can include skin reactions, bronchoconstriction, swelling, low blood pressure, coma, and death.

This type of reaction can be triggered suddenly, or the onset can be delayed.

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The nature of anaphylaxis is such that the reaction can seem to be subsiding, but may recur throughout a period of time.[26]

Skin

Substances that come into contact with the skin, such as latex, are also common causes of allergic reactions, known as contact dermatitis or eczema.[27] Skin allergies frequently cause rashes, or swelling and inflammation within the skin, in what is known as a «weal and flare» reaction characteristic of hives and angioedema.[28]

With insect stings a large local reaction may happen (an area of skin redness greater than 10 cm in size).[29] It can final one to two days.[29] This reaction may also happen after immunotherapy.[30]


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