What to do when baby has food allergy

An allergic reaction can consist of 1 or more of the following:

  1. a cough
  2. wheezing and shortness of breath
  3. runny or blocked nose
  4. itchy skin or rash
  5. swollen lips and throat
  6. itchy throat and tongue
  7. diarrhoea or vomiting
  8. sore, red and itchy eyes

In a few cases, foods can cause a severe allergic reaction (anaphylaxis) that can be life-threatening.

Get medical advice if you ponder your kid is having an allergic reaction to a specific food.

Don’t be tempted to experiment by cutting out a major food, such as milk, because this could lead to your kid not getting the nutrients they need. Talk to your health visitor or GP, who may refer you to a registered dietitian.


Introducing foods that could trigger allergy

When you start introducing solid foods to your baby from around 6 months ancient, introduce the foods that can trigger allergic reactions one at a time and in extremely little amounts so that you can spot any reaction.

These foods are:

  1. eggs (eggs without a red lion stamp should not be eaten raw or lightly cooked)
  2. foods that contain gluten, including wheat, barley and rye
  3. shellfish (don’t serve raw or lightly cooked)
  4. seeds (serve them crushed or ground)
  5. soya
  6. nuts and peanuts (serve them crushed or ground)
  7. cows’ milk
  8. fish

See more about foods to avoid giving babies and young children.

These foods can be introduced from around 6 months as part of your baby’s diet, just love any other foods.

Once introduced and if tolerated, these foods should become part of your baby’s usual diet to minimise the risk of allergy.

Evidence has shown that delaying the introduction of peanut and hen’s eggs beyond 6 to 12 months may increase the risk of developing an allergy to these foods.

Lots of children outgrow their allergies to milk or eggs, but a peanut allergy is generally lifelong.

If your kid has a food allergy, read food labels carefully.

Avoid foods if you are not certain whether they contain the food your kid is allergic to.


Signs and symptoms

Food allergies generally own a quick onset (from seconds to one hour) and may include:[13]

  1. Swelling (angioedema) of lips, tongue, eyelids, or the whole face[13]
  2. Itching of mouth, lips, tongue, throat, eyes, skin, or other areas[13]
  3. Nausea[13]
  4. Hoarse voice[13]
  5. Fainting[13]
  6. Lightheadedness[13]
  7. Wheezing and/or shortness of breath[13]
  8. Diarrhea, abdominal pain, and/or stomach cramps[13]
  9. Difficulty swallowing[13]
  10. Hives[13]
  11. Rash
  12. Runny or congested nose[13]
  13. Vomiting[13]

In some cases, however, onset of symptoms may be delayed for hours.[13]

Symptoms can vary.

The quantity of food needed to trigger a reaction also varies.[14]

Serious harm regarding allergies can start when the respiratory tract or blood circulation is affected. The previous can be indicated through wheezing and cyanosis. Poor blood circulation leads to a feeble pulse, pale skin and fainting.[15]

A severe case of an allergic reaction, caused by symptoms affecting the respiratory tract and blood circulation, is called anaphylaxis. When symptoms are related to a drop in blood pressure, the person is said to be in anaphylactic shock.

What to do when baby has food allergy

Anaphylaxis occurs when IgE antibodies are involved, and areas of the body that are not in direct contact with the food become affected and show symptoms.[16] Those with asthma or an allergy to peanuts, tree nuts, or seafood are at greater risk for anaphylaxis.[17]


Food additives and children

Food contains additives for numerous reasons, such as to preserve it, to help make it safe to eat for longer, and to give colour or texture.

All food additives go through strict safety testing before they can be used.

Food labelling must clearly show additives in the list of ingredients, including their name or «E» number and their function, such as «colour» or «preservative».

A few people own adverse reactions to some food additives, love sulphites, but reactions to ordinary foods, such as milk or soya, are much more common.

Read more about food colours and hyperactivity.

Further information

Sheet final reviewed: 24 July 2018
Next review due: 24 July 2021

Food allergy
Hives on the back are a common allergy symptom.
Specialty Emergency medicine
Symptoms Itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, low blood pressure[1]
Usual onset Minutes to several hours of exposure[1]
Duration Long term, some may resolve[2]
Causes Immune response to food[1]
Risk factors Family history, vitamin D deficiency, obesity, high levels of cleanliness[1][2]
Diagnostic method Based on a medical history, elimination diet, skin prick test, oral food challenge[1][2]
Differential diagnosis Food intolerance, celiac disease, food poisoning[1]
Prevention Early exposure to potential allergens[2][3]
Treatment Avoiding the food in question, having a plan if exposure occurs, medical alert jewelry[1][2]
Medication Adrenaline (epinephrine)[1]
Frequency ~6% (developed world)[1][2]

A food allergy is an abnormal immune response to food.[1] The symptoms of the allergic reaction may range from mild to severe.[1] They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure.[1] This typically occurs within minutes to several hours of exposure.[1] When the symptoms are severe, it is known as anaphylaxis.[1] A food intolerance and food poisoning are separate conditions, not due to an immune response.[1][4]

Common foods involved include cow’s milk, peanuts, eggs, shellfish, fish, tree nuts, soy, wheat, rice, and fruit.[1][2][5] The common allergies vary depending on the country.[1] Risk factors include a family history of allergies, vitamin D deficiency, obesity, and high levels of cleanliness.[1][2] Allergies happen when immunoglobulin E (IgE), part of the body’s immune system, binds to food molecules.[1] A protein in the food is generally the problem.[2] This triggers the release of inflammatory chemicals such as histamine.[1] Diagnosis is generally based on a medical history, elimination diet, skin prick test, blood tests for food-specific IgE antibodies, or oral food challenge.[1][2]

Early exposure to potential allergens may be protective.[2][3] Management primarily involves avoiding the food in question and having a plan if exposure occurs.[2] This plan may include giving adrenaline (epinephrine) and wearing medical alert jewelry.[1] The benefits of allergen immunotherapy for food allergies is unclear, thus is not recommended as of 2015[update].[6] Some types of food allergies among children resolve with age, including that to milk, eggs, and soy; while others such as to nuts and shellfish typically do not.[2]

In the developed world, about 4% to 8% of people own at least one food allergy.[1][2] They are more common in children than adults and appear to be increasing in frequency.[2] Male children appear to be more commonly affected than females.[2] Some allergies more commonly develop early in life, while others typically develop in later life.[1] In developed countries, a large proportion of people believe they own food allergies when they actually do not own them.[7][8][9] The declaration of the presence of trace amounts of allergens in foods is mandatory only in Brazil.[10][11][12]


Pathophysiology

Conditions caused by food allergies are classified into three groups according to the mechanism of the allergic response:[36]

  • IgE-mediated (classic) – the most common type, occurs shortly after eating and may involve anaphylaxis.
  • Non-IgE mediated – characterized by an immune response not involving immunoglobulin E; may happen some hours after eating, complicating diagnosis
  • IgE and/or non-IgE-mediated – a hybrid of the above two types

Allergic reactions are hyperactive responses of the immune system to generally innocuous substances.

When immune cells encounter the allergenic protein, IgE antibodies are produced; this is similar to the immune system’s reaction to foreign pathogens.

What to do when baby has food allergy

The IgE antibodies identify the allergenic proteins as harmful and initiate the allergic reaction. The harmful proteins are those that do not break below due to the strong bonds of the protein. IgE antibodies bind to a receptor on the surface of the protein, creating a tag, just as a virus or parasite becomes tagged. Why some proteins do not denature and subsequently trigger allergic reactions and hypersensitivity while others do is not entirely clear.[37]

Hypersensitivities are categorized according to the parts of the immune system that are attacked and the quantity of time it takes for the response to happen. The four types of hypersensitivity reaction are: type 1, immediate IgE-mediated; type 2, cytotoxic; type 3, immune complex-mediated; and type 4, delayed cell-mediated.[38] The pathophysiology of allergic responses can be divided into two phases.

The first is an acute response that occurs immediately after exposure to an allergen. This phase can either subside or progress into a «late-phase reaction» which can substantially prolong the symptoms of a response, and result in tissue damage.

Many food allergies are caused by hypersensitivities to specific proteins in diverse foods. Proteins own unique properties that permit them to become allergens, such as stabilizing forces in their tertiary and quaternary structures which prevent degradation during digestion. Numerous theoretically allergenic proteins cannot survive the destructive environment of the digestive tract, thus do not trigger hypersensitive reactions.[39]

Acute response

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

What to do when baby has food allergy

These TH2 cells interact with other lymphocytes called B cells, whose role is the 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.[40]

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.

What to do when baby has food allergy

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, the allergen, and the mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to specific body systems.[40]

Late-phase response

After the chemical mediators of the acute response subside, late-phase responses can often happen 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.[41] Cytokines from mast cells may also frolic a role in the persistence of long-term effects.[42]

Allergic reactions are hyperactive responses of the immune system to generally innocuous substances. When immune cells encounter the allergenic protein, IgE antibodies are produced; this is similar to the immune system’s reaction to foreign pathogens.

What to do when baby has food allergy

The IgE antibodies identify the allergenic proteins as harmful and initiate the allergic reaction. The harmful proteins are those that do not break below due to the strong bonds of the protein. IgE antibodies bind to a receptor on the surface of the protein, creating a tag, just as a virus or parasite becomes tagged. Why some proteins do not denature and subsequently trigger allergic reactions and hypersensitivity while others do is not entirely clear.[37]

Hypersensitivities are categorized according to the parts of the immune system that are attacked and the quantity of time it takes for the response to happen.

The four types of hypersensitivity reaction are: type 1, immediate IgE-mediated; type 2, cytotoxic; type 3, immune complex-mediated; and type 4, delayed cell-mediated.[38] The pathophysiology of allergic responses can be divided into two phases. The first is an acute response that occurs immediately after exposure to an allergen.

What to do when baby has food allergy

This phase can either subside or progress into a «late-phase reaction» which can substantially prolong the symptoms of a response, and result in tissue damage.

Many food allergies are caused by hypersensitivities to specific proteins in diverse foods. Proteins own unique properties that permit them to become allergens, such as stabilizing forces in their tertiary and quaternary structures which prevent degradation during digestion.

Numerous theoretically allergenic proteins cannot survive the destructive environment of the digestive tract, thus do not trigger hypersensitive reactions.[39]

Acute response

In the early stages of allergy, a type I hypersensitivity reaction against an allergen, encountered for the first time, causes a response in a type of immune cell called a TH2 lymphocyte, which belongs to 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 the 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.[40]

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, the allergen, and the mode of introduction, the symptoms can be system-wide (classical anaphylaxis), or localized to specific body systems.[40]

Late-phase response

After the chemical mediators of the acute response subside, late-phase responses can often happen 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.[41] Cytokines from mast cells may also frolic a role in the persistence of long-term effects.[42]


Cause

Although sensitivity levels vary by country, the most common food allergies are allergies to milk, eggs, peanuts, tree nuts, seafood, shellfish, soy, and wheat.[18] These are often referred to as «the large eight».[19] Allergies to seeds — especially sesame — seem to be increasing in numerous countries.[20] An example an allergy more common to a specific region is that to rice in East Asia where it forms a large part of the diet.[21]

One of the most common food allergies is a sensitivity to peanuts, a member of the bean family.

Peanut allergies may be severe, but children with peanut allergies sometimes outgrow them.[22] Tree nuts, including almonds, brazil nuts, cashews, coconuts, hazelnuts, macadamia nuts, pecans, pistachios, pine nuts, and walnuts, are also common allergens. Sufferers may be sensitive to one specific tree nut or to numerous diverse ones.[23] Also, seeds, including sesame seeds and poppy seeds, contain oils where protein is present, which may elicit an allergic reaction.[23]

Egg allergies affect about one in 50 children but are frequently outgrown by children when they reach age five.[24] Typically, the sensitivity is to proteins in the white, rather than the yolk.[23]

Milk from cows, goats, or sheep is another common food allergen, and numerous sufferers are also unable to tolerate dairy products such as cheese.

A little portion of children with a milk allergy, roughly 10%, own a reaction to beef.

What to do when baby has food allergy

Beef contains a little quantity of protein that is also present in cow’s milk.[25]

Seafood is one of the most common sources of food allergens; people may be allergic to proteins found in fish, crustaceans, or shellfish.[26]

Other foods containing allergenic proteins include soy, wheat, fruits, vegetables, maize, spices, synthetic and natural colors,[citation needed] and chemical additives.

Balsam of Peru, which is in various foods, is in the «top five» allergens most commonly causing patch test reactions in people referred to dermatology clinics.[27][28][29]

Sensitization

Sensitization can happen through the gastrointestinal tract, respiratory tract and possibly the skin.[30] Damage to the skin in conditions such as eczema has been proposed as a risk factor for sensitization.[31] An Institute of Medicine report says that food proteins contained in vaccines, such as gelatin, milk, or egg can cause sensitization (development of allergy) in vaccine recipients, to those food items.[32]

Atopy

Food allergies develop more easily in people with the atopic syndrome, a extremely common combination of diseases: allergic rhinitis and conjunctivitis, eczema, and asthma.[33] The syndrome has a strong inherited component; a family history of allergic diseases can be indicative of the atopic syndrome.[medical citation needed]

Cross-reactivity

Some children who are allergic to cow’s milk protein also show a cross-sensitivity to soy-based products.[34] Some baby formulas own their milk and soy proteins hydrolyzed, so when taken by infants, their immune systems do not recognize the allergen and they can safely consume the product.

Hypoallergenic baby formulas can be based on proteins partially predigested to a less antigenic form. Other formulas, based on free amino acids, are the least antigenic and provide finish nutritional support in severe forms of milk allergy.

People with latex allergy often also develop allergies to bananas, kiwifruit, avocados, and some other foods.[35]


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