peanut allergy

Peanut allergy

Peanut allergy is one of the most common causes of severe allergy attacks. Peanut allergy symptoms can be life-threatening (anaphylaxis). For some people with peanut allergy, even tiny amounts of peanuts can cause a serious reaction. Peanut allergy is the leading cause of death related to food-induced anaphylaxis in the United States 1) and although overall mortality is low, the fear of life-threatening anaphylactic reactions contributes significantly to the medical and psychosocial burden of disease. In the majority of patients, peanut allergy begins early in life and persists as a lifelong problem.

Peanut allergy has been increasing in children. In 1999, peanut allergy was estimated to affect 0.4% of children and 0.7% of adults in the United States 2) and by 2010, peanut allergy prevalence had increased to approximately 2% among children in a national survey 3). Even if you or your child has had only a mild allergic reaction to peanuts, it’s important to talk to your doctor. There is still a risk of a more serious future reaction.

Recently published studies 4), 5), 6) have shown that the introduction of peanut to infants with severe eczema and/or egg allergy before 12 months can reduce the risk of these infants developing peanut allergy by around 80%.

In February 2015, the New England Journal of Medicine published the results of the Learning Early About Peanut [LEAP] trial 7). This trial was based on a prior observation 8) that the prevalence of peanut allergy was 10-fold higher among Jewish children in the United Kingdom compared with Israeli children of similar ancestry. In Israel, peanut-containing foods are usually introduced in the diet when infants are approximately 7 months of age and consumed in substantial amounts, whereas in the United Kingdom children do not typically consume any peanut-containing foods during their first year of life. The Learning Early About Peanut [LEAP] trial randomized 640 children between 4 and 11 months of age with severe eczema, egg allergy, or both to consume or avoid peanut-containing foods until 60 months of age, at which time a peanut oral food challenge was conducted to determine the prevalence of peanut allergy. Learning Early About Peanut [LEAP] trial participants were stratified at study entry into 2 separate study cohorts on the basis of pre-existing sensitization to peanut, as determined by means of skin prick testing: one cohort consisted of infants with no measureable skin test wheal to peanut (negative skin test response) and the other consisted of those with measurable wheal responses (1–4 mm in diameter). Infants with a 5 mm wheal diameter or greater were not randomized because the majority of infants at this level of sensitization were presumed to be allergic to peanut. Among the 530 participants in the intention-to-treat population with negative baseline skin test response to peanut, the prevalence of peanut allergy at 60 months of age was 13.7% in the peanut avoidance group and 1.9% in the peanut consumption group (an 86.1% relative reduction in the prevalence of peanut allergy). Among the 98 participants with a measurable peanut skin test response at entry, the prevalence of peanut allergy was 35.3% in the avoidance group and 10.6% in the consumption group (a 70% relative reduction in the prevalence of peanut allergy).

The results of the Learning Early About Peanut [LEAP] 9) study provided new evidence to support early, rather than delayed, peanut introduction during the period complementary foods are first given to infants. Specifically, the LEAP study demonstrated a successful 11 to 25% absolute reduction in the risk of developing peanut allergy in high-risk infants (and a relative risk reduction of up to 80%) if peanut was introduced between 4 and 11 months. It is important to note that children with lesser risk factors for peanut allergy were excluded from the LEAP study, so there is no prospective, randomized data that speaks to the benefit or risk of early peanut introduction in the general to low-risk populations.

In the LEAP study, only 1.9% of infants at high risk of peanut allergy who were introduced to peanuts early in life developed a peanut allergy by age 5. In the group that avoided peanuts, 13.7% of the children had developed an allergy.

The LEAP trial was the first randomized trial to study early allergen introduction as a preventive strategy. Because of the size of the observed effect and the large number of study participants, its outcome received wide publicity in both the medical community and the press. This raised the need to operationalize the LEAP findings by developing clinical recommendations focusing on peanut allergy prevention. To achieve this goal and its wide implementation, the National Institute of Allergy and Infectious Diseases invited the members of the 2010 Guidelines Coordinating Committee and other stakeholder organizations to develop an addendum on peanut allergy prevention to the 2010 “Guidelines for the diagnosis and management of food allergy in the United States.” Twenty-six stakeholder organizations participated in this 2015–2016 Coordinating Committee.

Table 1. Summary of Addendum Guidelines for the diagnosis and management of food allergy in the United States 1, 2, and 3

Addendum guidelineInfant criteriaRecommendationsEarliest age of peanut introduction
1Severe eczema, egg allergy, or bothStrongly consider evaluation by sIgE measurement and/or SPT and, if necessary, an OFC. Based on test results, introduce peanut-containing foods.4–6 months
2Mild-to-moderate eczemaIntroduce peanut-containing foodsAround 6 months
3No eczema or any food allergyIntroduce peanut-containing foodsAge appropriate and in accordance with family preferences and cultural practices
[Source 10)]

The Expert Panel came to consensus on the following 3 definitions used throughout the addendum guidelines.

  1. Severe eczema is defined as persistent or frequently recurring eczema with typical morphology and distribution assessed as severe by a health care provider and requiring frequent need for prescription-strength topical corticosteroids, calcineurin inhibitors, or other anti-inflammatory agents despite appropriate use of emollients.
  2. Egg allergy is defined as a history of an allergic reaction to egg and a skin prick test wheal diameter of 3 mm or greater with egg white extract, or a positive oral egg food challenge result.
  3. A specialist is defined as a health care provider with the training and experience to (1) perform and interpret skin prick tests and oral food challenges and (2) know and manage their risks. Such persons must have appropriate medications and equipment on site.

Addendum guideline 1

The Expert Panel recommends that infants with severe eczema, egg allergy, or both have introduction of age-appropriate peanut-containing food as early as 4 to 6 months of age (not before 4 months) to reduce the risk of peanut allergy. Other solid foods should be introduced before peanut-containing foods to show that the infant is developmentally ready. The Expert Panel recommends that evaluation with peanut-specific IgE (peanut sIgE) measurement, skin prick tests, or both be strongly considered before introduction of peanut to determine if peanut should be introduced and, if so, the preferred method of introduction. To minimize a delay in peanut introduction for children who may test negative, testing for peanut sIgE may be the preferred initial approach in certain health care settings, such as family medicine, pediatrics, or dermatology practices, in which skin prick testing is not routine. Alternatively, referral for assessment by a specialist may be an option if desired by the health care provider and when available in a timely manner.

Figure 1 provides recommended approaches for evaluation of children with severe eczema, egg allergy, or both before peanut introduction.

Figure 1. Recommended approaches for evaluation of children with severe eczema and/or egg allergy before peanut introduction

Recommended approaches for evaluation of children for peanut allergy

Note: *To minimize a delay in peanut introduction for children who may test negative, testing for peanut-specific Ige may be the preferred initial approach in certain health care settings. Food allergen panel testing or the addition of sIgE testing for foods other than peanut is not recommended due to poor positive predictive value

[Source 11)]

Peters et al 12) have published the first prospective, population-based study on the natural history of peanut allergy. The HealthNuts study 13) recruited 5,276 twelve-month-old infants and skin prick tested them to common food allergens including peanut. Any infant who was sensitized to peanut was invited to have an oral food challenge, the gold standard test for the diagnosis of peanut allergy. Peanut allergy was confirmed in 156 infants. At the age of four these children were invited to undergo repeat oral food challenge to test for whether they had outgrown their peanut allergy. Overall, the study found that 22% of children outgrew their peanut allergy by four years of age. Skin prick testing and blood tests for peanut-specific IgE (sIgE) are commonly used to monitor the course of peanut allergy, although thresholds for these tests which predict whether peanut allergy has persisted or resolved are unknown. This study reported that at age four, children with skin prick testing ≥ 8mm and peanut-specific IgE (sIgE) ≥ 2.1kU/L had a 95% probability of remaining allergic to peanut, while children with skin prick testing ≤ 2mm had a 90% probability of having developed tolerance 14).

A novel finding was that skin prick testing and peanut-specific IgE (sIgE) measured at 12 months of age was also able to predict which infants would still be allergic to peanut at the age of four. Infants with skin prick testing ≥ 13mm or peanut-specific IgE (sIgE) ≥ 5.0kU/L at age 12 months had a 95% probability of having persistent peanut allergy at age 4 years. Despite considering multiple other prognostic factors, (including tree nut and house dust mite sensitization, coexisting food allergies, eczema, and asthma) no other clinical predictors of the development of tolerance could be identified.

These thresholds are the first to be generated from a population-based study in which all participants underwent oral food challenge at both diagnosis and follow-up and are a valuable tool for the management of peanut allergy. They will be useful in reducing the need for unnecessary oral food challenge in children with a high risk of persistent peanut allergy.

A peanut sIgE level of less than 0.35 kUA/L has strong negative predictive value for the diagnosis of peanut allergy 15). Therefore, peanut sIgE testing may help in certain health care settings (eg, family medicine, pediatric, or dermatology practices, where skin prick testing is not routine) to reduce unnecessary referrals of children with severe eczema, egg allergy, or both and to minimize a delay in peanut introduction for children who may have negative test results. However, the EP emphasizes that a peanut sIgE level of 0.35 kUA/L or greater lacks adequate positive predictive value for the diagnosis of peanut allergy, and an infant with a value of 0.35 kUA/L or greater should be referred to a specialist.

Thus, peanut sIgE testing can place an infant into one of 2 categories (see Figure 1):

  • sIgE Category A: If the peanut sIgE level is less than 0.35 kUA/L (ImmunoCAP), the Expert Panel recommends that peanut should be introduced in the diet soon thereafter, with a cumulative first dose of approximately 2 g of peanut protein given in this feeding. This can be given as a feeding at home, considering the low likelihood of a severe allergic reaction. If the caregiver or health care provider has concerns, a supervised feeding can be offered at the health care provider’s office.
  • sIgE Category B: If the peanut sIgE level is 0.35 kUA/L or greater (ImmunoCAP), the Expert Panel recommends that the child be referred to a specialist for further consultation and possible skin prick testing.

The Expert Panel does not recommend food allergen panel testing or the addition of sIgE testing for foods other than peanut because of their poor positive predictive value, which could lead to misinterpretation, overdiagnosis of food allergy, and unnecessary dietary restrictions 16).

Skin Prick Tests with peanut extract can place an infant in one of 3 categories (see Figure 1 above):

  • Skin Prick Test Category A: If a Skin Prick Test to peanut extract produces a wheal diameter of 2 mm or less above saline control, the Expert Panel recommends that peanut be introduced in the diet soon after testing, with a cumulative first dose of approximately 2 g of peanut protein given in this feeding. This can be given at home, considering the low likelihood of a severe allergic reaction. If the caregiver or health care provider has concerns, a supervised feeding can be offered at the health care provider’s office.
  • Skin Prick Test Category B: If a Skin Prick Test to peanut extract produces a wheal diameter of 3 to 7 mm greater than that elicited by the saline control, the Expert Panel suggests that a supervised peanut feeding or a graded oral food challenge be undertaken at a specialist’s office or a specialized facility. Infants in this category can be sensitized without being allergic to peanut and might benefit from early peanut consumption. If the supervised peanut feeding or graded oral food challenge yields no reaction, the Expert Panel recommends that peanut should be added to the child’s diet. If the supervised peanut feeding or the graded oral food challenge results in an allergic reaction, the Expert Panel recommends that the child should strictly avoid dietary peanut and the family should be counseled regarding food allergy management.
  • Skin Prick Test Category C: If a Skin Prick Test produces a wheal diameter 8 mm or greater than that elicited by the saline control, the likelihood of peanut allergy is high. Children in this category should continue to be evaluated and managed by a specialist 17).

How much dietary peanut protein to introduce

If the decision is made to introduce dietary peanut based on the recommendations of addendum guideline 1, the total amount of peanut protein to be regularly consumed per week should be approximately 6 to 7 g over 3 or more feedings. In the LEAP trial, at evaluations conducted at 12 and 30 months of age, 75% of children in the peanut consumption group reported eating at least this amount of peanut, based on analysis of a 3-day food diary recorded just before the evaluation.

Additional comments

  • Breast-feeding recommendations: The Expert Panel recognizes that early introduction of peanut may seem to depart from recommendations for exclusive breast-feeding through 6 months of age 18). However, it should be noted that data from the nutrition analysis of the LEAP cohort 19) indicate that introduction of peanut did not affect the duration or frequency of breast-feeding and did not influence growth or nutrition.
  • Age of peanut introduction: For children with severe eczema, egg allergy, or both, the Expert Panel recommends that introduction of solid foods begins at 4 to 6 months of age, starting with solid food other than peanut, so that the child can demonstrate the ability to consume solid food without evidence of nonspecific signs and symptoms that could be confused with IgE-mediated food allergy. However, it is important to note that infants in the LEAP trial were enrolled between 4 and 11 months of age and benefitted from peanut consumption regardless of age at entry. Therefore, if the 4- to 6-month time window is missed for any reason, including developmental delay, infants may still benefit from early peanut introduction. On the other hand, older age at screening is associated with larger wheal diameters induced by peanut Skin Prick Test and hence a higher likelihood of established peanut allergy 20).
    A practical consideration for applying this guideline at 4 to 6 months of age is that infants visit their health care provider for well-child evaluations and infant immunizations at this time. This provides a fortuitous opportunity for eczema evaluation, caregiver reporting of egg allergy, and, if needed, referral to a specialist for peanut allergy evaluation before dietary introduction of peanut.
  • Considerations for family members with established peanut allergy: The Expert Panel recognizes that many infants eligible for early peanut introduction under this guideline will have older siblings or caregivers with established peanut allergy. The Expert Panel recommends that in this situation caregivers discuss with their health care providers the overall benefit (reduced risk of peanut allergy in the infant) versus risk (potential for further sensitization and accidental exposure of the family member to peanut) of adding peanut to the infant’s diet.
  • Children identified as allergic to peanut: For children who have been identified as allergic to peanut, the Expert Panel recommends strict peanut avoidance. This may include those children in Skin Prick Test Category B who fail the supervised peanut feeding or the oral food challenge, or those children in Skin Prick Test Category C who, on further evaluation by a specialist, are confirmed as being allergic to peanut. These children should be under long-term management by a specialist.

Addendum guideline 2

The Expert Panel suggests that infants with mild-to-moderate eczema should have introduction of age-appropriate peanut-containing food around 6 months of age, in accordance with family preferences and cultural practices, to reduce the risk of peanut allergy. Other solid foods should be introduced before peanut-containing foods to show that the infant is developmentally ready. The Expert Panel recommends that infants in this category may have dietary peanut introduced at home without an in-office evaluation. However, the Expert Panel recognizes that some caregivers and health care providers may desire an in-office supervised feeding, evaluation, or both.

Additional support for early introduction of peanut in infants who do not have severe eczema comes from the Enquiring About Tolerance study 21), which enrolled infants from the general population at 3 months of age and sequentially introduced 6 allergenic foods beginning at the time of enrollment. These children were not intentionally selected based on increased risk of food allergy or atopy. Although the intention-to-treat group did not show benefit, most likely because of relatively poor compliance with feeding recommendations, the children in the per-protocol group who had peanut introduced early in infancy showed a significant reduction in peanut sensitization and peanut allergy at age 3 years. This study also provides support for guideline 3 below.

Addendum guideline 3

The Expert Panel suggests that infants without eczema or any food allergy have age-appropriate peanut-containing foods freely introduced in the diet together with other solid foods and in accordance with family preferences and cultural practices.

There is no evidence exists for restricting allergenic foods in infants without known risks for food allergy. The probability for development of peanut allergy in such children is very low. However, approximately 14% of all children with peanut allergy at age 12 to 18 months in the HealthNuts Study lacked known risk factors for food allergy 22). Consequently, because such children constitute a significant majority of any birth cohort, they contribute substantially to the overall societal burden of peanut allergy. The Expert Panel finds no evidence to suggest that mechanisms of oral tolerance induction would differ in these infants from the immunologic mechanisms that are protective in infants at higher risk of peanut allergy. Thus, the early introduction of dietary peanut in children without risk factors for peanut allergy is generally anticipated to be safe and to contribute modestly to an overall reduction in the prevalence of peanut allergy. Furthermore, in countries such as Israel, where peanut products are a popular component of the diet and where they are introduced early in life, the prevalence of peanut allergy is low 23).

Instructions for Home Feeding of peanut protein for infants at low risk of an allergic reaction to peanut

These instructions for home feeding of peanut protein are provided by your doctor. You should discuss any questions that you have with your doctor before starting. These instructions are meant for feeding infants who have severe eczema or egg allergy and were allergy tested (blood test, skin test, or both) with results that your doctor considers safe for you to introduce peanut protein at home (low risk of allergy).

General instructions

  1. Feed your infant only when he or she is healthy; do not do the feeding if he or she has a cold, vomiting, diarrhea, or other illness.
  2. Give the first peanut feeding at home and not at a day care facility or restaurant.
  3. Make sure at least 1 adult will be able to focus all of his or her attention on the infant, without distractions from other children or household activities.
  4. Make sure that you will be able to spend at least 2 h with your infant after the feeding to watch for any signs of an allergic reaction.

Feeding your infant

  1. Prepare a full portion of one of the peanut-containing foods from the recipe options below.
  2. Offer your infant a small part of the peanut serving on the tip of a spoon.
  3. Wait 10 min.
  4. If there is no allergic reaction after this small taste, then slowly give the remainder of the peanut-containing food at the infant’s usual eating speed.

What are symptoms of an allergic reaction? What should I look for?

  • Mild symptoms can include:

    • a new rash
      or
    • a few hives around the mouth or face
  • More severe symptoms can include any of the following alone or in combination:

    • lip swelling
    • vomiting
    • widespread hives (welts) over the body
    • face or tongue swelling
    • any difficulty breathing
    • wheeze
    • repetitive coughing
    • change in skin color (pale, blue)
    • sudden tiredness/lethargy/seeming limp

If you have any concerns about your infant’s response to peanut, seek immediate medical attention/call your local emergency number.

Four recipe options, each containing approximately 2 g of peanut protein

Note: Teaspoons and tablespoons are US measures (5 and 15 mL for a level teaspoon or tablespoon, respectively).

  • Option 1: Bamba (Osem, Israel), 21 pieces (approximately 2 g of peanut protein)

    Note: Bamba is named because it was the product used in the LEAP trial and therefore has proven efficacy and safety. Other peanut puff products with similar peanut protein content can be substituted.

    1. For infants less than 7 months of age, soften the Bamba with 4 to 6 teaspoons of water.
    2. For older infants who can manage dissolvable textures, unmodified Bamba can be fed. If dissolvable textures are not yet part of the infant’s diet, softened Bamba should be provided.
  • Option 2: Thinned smooth peanut butter, 2 teaspoons (9–10 g of peanut butter; approximately 2 g of peanut protein)

    1. Measure 2 teaspoons of peanut butter and slowly add 2 to 3 teaspoons of hot water.
    2. Stir until peanut butter is dissolved, thinned, and well blended.
    3. Let cool.
    4. Increase water amount if necessary (or add previously tolerated infant cereal) to achieve consistency comfortable for the infant.
  • Option 3: Smooth peanut butter puree, 2 teaspoons (9–10 g of peanut butter; approximately 2 g of peanut protein)

    1. Measure 2 teaspoons of peanut butter.
    2. Add 2 to 3 tablespoons of pureed tolerated fruit or vegetables to peanut butter. You can increase or reduce volume of puree to achieve desired consistency.
  • Option 4: Peanut flour and peanut butter powder, 2 teaspoons (4 g of peanut flour or 4 g of peanut butter powder; approximately 2 g of peanut protein)

    Note: Peanut flour and peanut butter powder are 2 distinct products that can be interchanged because they have a very similar peanut protein content.

    1. Measure 2 teaspoons of peanut flour or peanut butter powder.
    2. Add approximately 2 tablespoons (6–7 teaspoons) of pureed tolerated fruit or vegetables to flour or powder. You can increase or reduce volume of puree to achieve desired consistency.

For health care providers: In-office supervised feeding protocol using 2 g of peanut protein

General instructions

  1. These recommendations are reserved for an infant defined in guideline 1 as one with severe eczema, egg allergy, or both and with negative or minimally reactive (1 to 2 mm) Skin Prick Test responses and/or peanut sIgE levels of less than 0.35 kUA/L. They also may apply to the infant with a 3 to 7 mm Skin Prick Test response if the specialist health care provider decides to conduct a supervised feeding in the office (as opposed to a graded oral graded food challenge in a specialized facility [see Figure 1 above].
    These recommendations can also be followed for infants with mild-to-moderate eczema, as defined in guideline 2, when caregivers and health care providers may desire an in-office supervised feeding.
  2. Proceed only if the infant shows no evidence of any concomitant illness, such as an upper respiratory tract infection.

    1. Start with a small portion of the initial peanut serving, such as the tip of a teaspoon of peanut butter puree/softened Bamba.
    2. Wait 10 min; if there is no sign of reaction after this small portion is given, continue gradually feeding the remaining serving of peanut-containing food (see options below) at the infant’s typical feeding pace.
    3. Observe the infant for 30 min after 2 g of peanut protein ingestion for signs/symptoms of an allergic reaction.

Four recipe options, each containing approximately 2 g of peanut protein

Note: Teaspoons and tablespoons are US measures (5 and 15 mL for a level teaspoon or tablespoon, respectively).

  • Option 1: Bamba (Osem, Israel), 21 pieces (approximately 2 g of peanut protein)

    Note: Bamba is named because it was the product used in the LEAP trial and therefore has known peanut protein content and proven efficacy and safety. Other peanut puffs products with similar peanut protein content can be substituted for Bamba.

    1. For infants less than 7 months of age, soften the Bamba with 4 to 6 teaspoons of water.
    2. For older infants who can manage dissolvable textures, unmodified Bamba can be fed. If dissolvable textures are not yet part of the infant’s diet, softened Bamba should be provided.
  • Option 2: Thinned smooth peanut butter, 2 teaspoons (9–10 g of peanut butter; approximately 2 g of peanut protein)

    1. Measure 2 teaspoons of peanut butter and slowly add 2 to 3 teaspoons hot water.
    2. Stir until peanut butter is dissolved and thinned and well blended.
    3. Let cool.
    4. Increase water amount if necessary (or add previously tolerated infant cereal) to achieve consistency comfortable for the infant.
  • Option 3: Smooth peanut butter puree, 2 teaspoons (9–10 g of peanut butter; approximately 2 g of peanut protein)

    1. Measure 2 teaspoons of peanut butter.
    2. Add 2 to 3 tablespoons of previously tolerated pureed fruit or vegetables to peanut butter. You can increase or reduce volume of puree to achieve desired consistency.
  • Option 4: Peanut flour and peanut butter powder, 2 teaspoons (4 g of peanut flour or 4 g of peanut butter powder; approximately 2 g of peanut protein)

    Note: Peanut flour and peanut butter powder are 2 distinct products that can be interchanged because they have, on average, a similar peanut protein content.

    1. Measure 2 teaspoons of peanut flour or peanut butter powder.
    2. Add approximately 2 tablespoons (6–7 teaspoons) of pureed tolerated fruit or vegetables to flour or powder. You can increase or reduce the volume of puree to achieve desired consistency.

Suggested procedure for introduction of peanut before 12 months (not before 4 months) when the infant is developmentally ready for solid food – under medical supervision (e.g. in doctor rooms) or at home 24)

  • Children in the high risk group should be brought to a specialist for peanut-specific IgE (sIgE) or skin prick testing to decide the safest way to introduce peanuts. If the child does not show signs of peanut allergy at the time of testing, the healthcare professional will create a plan with the child’s caretakers to introduce foods containing peanuts at home or undertake a supervised feeding in the healthcare provider’s office. The guidelines recommend starting the introduction process as early as 4 to 6 months.
  • Children in the second highest risk group, with mild to moderate eczema, should be introduced to peanuts around 6 months to reduce the risk of peanut allergy.
  • Children in the lowest risk group, with no signs of eczema or food allergy, can be introduced to peanuts when age-appropriate and according to family and cultural preferences.
  • Rub a small amount of smooth peanut butter/paste on the inside of the infant’s lip (not on their skin).
  • If there is no allergic reaction after a few minutes, feed the infant ¼ teaspoon of smooth peanut butter/paste (as a spread or mixed into other food that the infant is already eating or mixed with a few drops of warm water) and observe for 30 minutes.
  • If there is no allergic reaction, give ½ teaspoon of smooth peanut butter/paste and observe for a further 30 minutes.
  • If there is no allergic reaction, parents should continue to include peanut in their infant’s diet in gradually increasing amounts at least weekly, as it is important to continue to feed peanut to the infant as a part of a varied diet.
  • If there is an allergic reaction at any step, stop feeding peanut to the infant and seek medical advice (if at home).
  • An allergic reaction should be treated by following the Anaphylaxis Emergency Action Plan (watch the YouTube video and see Figure 1)
    • Mild or moderate allergic reactions (swelling of the lips, eyes or face, urticaria or vomiting) can be treated using non-sedating antihistamines such as cetirizine, loratadine or desloratidine. To avoid confusion with the symptoms of anaphylaxis, sedating antihistamines should not be used to treat allergic reactions.
    • If there are symptoms of anaphylaxis (difficult/noisy breathing, pale and floppy, swollen tongue) treat with adrenaline and call an ambulance immediately.
    • If an infant has an allergic reaction they may be referred to a clinical immunology/allergy specialist for further investigations

Further Information

  • Some infants will develop peanut allergy despite following National Institute of Allergy and Infectious Diseases guidelines.
  • Whilst severe allergic reactions have been reported, to date there have been no case reports of fatality to peanut ingestion in infants under 12 months of age.
  • Some infants can have an allergic reaction on the first (or subsequent) oral feeding of peanut, as they may already be sensitized to peanut prior to any known oral exposure before 12 months of age.
  • Never smear or rub food on infant skin, especially if they have eczema, as this will not help to identify possible food allergies. This could also sensitize the infant, who may then develop an allergy to that food.
  • Screening programs for infants with severe eczema and/or egg allergy prior to introduction of peanut have been proposed in the US National Institute of Allergy and Infectious Diseases Guidelines 25). There are concerns that allergy tests are not suitable for screening and referrals may delay peanut introduction to high risk infants 26).

Peanut allergy signs and symptoms

An allergic response to peanuts usually occurs within minutes after exposure. Peanut allergy signs and symptoms can include:

  • Runny nose
  • Skin reactions, such as hives, redness or swelling
  • Itching or tingling in or around the mouth and throat
  • Digestive problems, such as diarrhea, stomach cramps, nausea or vomiting
  • Tightening of the throat
  • Shortness of breath or wheezing

Anaphylaxis: A life-threatening reaction

Peanut allergy is the most common cause of food-induced anaphylaxis, a medical emergency that requires treatment with an epinephrine (adrenaline) injector (EpiPen, Auvi-Q, Twinject) and a trip to the emergency room.

Anaphylaxis signs and symptoms can include:

  • trouble breathing or noisy breathing
  • difficulty talking more than a few words and/or hoarse voice
  • wheeze
  • cough
  • swelling and tightness of the throat
  • collapse
  • light-headedness or dizziness
  • diarrhea
  • tingling in the hands, feet, lips or scalp
  • swelling of tongue
  • pale and floppy (in young children)

A severe allergic reaction (anaphylaxis) is a medical emergency. Call your local emergency immediately. Lay the person down. If they have an adrenaline injector and you are able to administer it, do so.

Figure 1. Anaphylaxis Emergency Action Plan

Anaphylaxis-Emergency-Action-PlanWhat causes peanut allergy

According to the leading experts in allergy, an allergic reaction begins in the immune system. Your immune system protects you from invading organisms that can cause illness. If you have an allergy, your immune system mistakes an otherwise harmless substance (e.g. peanut) as an invader. This substance is called an allergen. The immune system overreacts to the allergen by producing Immunoglobulin E (IgE) antibodies. These antibodies travel to cells that release histamine and other chemicals, causing an allergic reaction.

An allergic reaction typically triggers symptoms in the nose, lungs, throat, sinuses, ears, lining of the stomach or on the skin. For some people, allergies can also trigger symptoms of asthma. In the most serious cases, a life-threatening reaction called anaphylaxis can occur.

Peanut allergy occurs when your immune system mistakenly identifies peanut proteins as something harmful. Direct or indirect contact with peanuts causes your immune system to release symptom-causing chemicals into your bloodstream.

Exposure to peanuts can occur in various ways:

  • Direct contact. The most common cause of peanut allergy is eating peanuts or peanut-containing foods. Sometimes direct skin contact with peanuts can trigger an allergic reaction.
  • Cross-contact. This is the unintended introduction of peanuts into a product. It’s generally the result of a food being exposed to peanuts during processing or handling.
  • Inhalation. An allergic reaction may occur if you inhale dust or aerosols containing peanuts, from a source such as peanut flour or peanut oil cooking spray.

Risk factors for peanut allergy

It isn’t clear why some people develop allergies while others don’t. However, people with certain risk factors have a greater chance of developing peanut allergy.

Peanut allergy risk factors include:

  • Age. Food allergies are most common in children, especially toddlers and infants. As you grow older, your digestive system matures, and your body is less likely to react to food that triggers allergies.
  • Past allergy to peanuts. Some children with peanut allergy outgrow it. However, even if you seem to have outgrown peanut allergy, it may recur.
  • Other allergies. If you’re already allergic to one food, you may be at increased risk of becoming allergic to another. Likewise, having another type of allergy, such as hay fever, increases your risk of having a food allergy.
  • Family members with allergies. You’re at increased risk of peanut allergy if other allergies, especially other types of food allergies, are common in your family.
  • Atopic dermatitis. Some people with the skin condition atopic dermatitis (eczema) also have a food allergy.

While some people think food allergies are linked to childhood hyperactivity and to arthritis, there’s no evidence to support this.

Complications of peanut allergy

Complications of peanut allergy can include anaphylaxis. Children and adults who have a severe peanut allergy are especially at risk of having this life-threatening reaction.

Diagnosis of peanut allergy

The discussion you and your doctor have about your symptoms and medical history starts the process of diagnosis. A physical exam usually follows this discussion. The next steps typically include some of the following:

  • Food diary. Your doctor may ask you to keep a food diary of your eating habits, symptoms and medications.
  • Elimination diet. If it isn’t clear that peanuts are causing your symptoms, or if your doctor thinks you may have a reaction to more than one type of food, he or she may recommend an elimination diet. You may be asked to eliminate peanuts or other suspect foods for a week or two, and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. If you’ve had a severe reaction to foods, this method can’t safely be used.
  • Skin test. A small amount of food is placed on your skin, which is then pricked with a needle. If you’re allergic to a particular substance, you develop a raised bump or reaction.
  • Blood test. A blood test can measure your immune system’s response to particular foods by checking the amount of allergy-type antibodies in your bloodstream, known as immunoglobulin E (IgE) antibodies.

Information from all these sources may help determine if you have a peanut allergy or if your symptoms are likely due to something else, such as food intolerance.

Peanut allergy treatment

There’s no definitive treatment for peanut allergy, but researchers continue to study desensitization. Oral immunotherapy (desensitization) involves giving children with peanut allergies, or those at risk for peanut allergies, increasing doses of food containing peanuts over time. However, the long-term safety of oral immunotherapy for peanut allergy is still uncertain, and this treatment is not yet FDA approved.

New research suggests that desensitizing at-risk children to peanuts between ages 4 and 11 months may be effective at preventing peanut allergy. Check with your doctor because there are significant risks of anaphylaxis if early introduction of peanuts is performed incorrectly.

In the meantime, as with any food allergy, treatment involves taking steps to avoid the foods that cause your reaction and knowing how to spot and respond to a severe reaction.

Being prepared for a reaction

The only way to prevent a reaction is to avoid peanuts and peanut products altogether. But peanuts are common, and despite your best efforts, you’re likely to come into contact with peanuts at some point.

For a severe allergic reaction, you may need an emergency injection of epinephrine and to visit the emergency room. Many people with allergies carry an epinephrine autoinjector (EpiPen, Auvi-Q, Twinject). This device is a syringe and concealed needle that injects a single dose of medication when pressed against your thigh.

Know how to use your autoinjector

If your doctor has prescribed an epinephrine autoinjector:

  • Carry it with you at all times. It may be a good idea to keep an extra autoinjector in your car and in your desk at work.
  • Always replace it before its expiration date. Out-of-date epinephrine may not work properly.
  • Ask your doctor to prescribe a backup autoinjector. If you misplace one, you’ll have a spare.
  • Know how to operate it. Ask your doctor to show you. Also, make sure the people closest to you know how to use it — if someone with you can give you a shot, he or she could save your life.
  • Know when to use it. Talk to your doctor about how to recognize when you need a shot. However, if you’re not sure whether you need a shot, it’s usually better to go ahead and use the emergency epinephrine.

Home remedies

One of the keys to preventing an allergic reaction is knowing how to avoid the food that causes your symptoms. Follow these steps:

  • Never assume a food doesn’t contain peanuts. Peanuts may be in foods that you had no idea contained them. Always read labels on manufactured foods to make sure they don’t contain peanuts or peanut products. Manufactured foods are required to clearly state whether foods contain any peanuts and if they were produced in factories that also process peanuts. Even if you think you know what’s in a food, check the label. Ingredients may change.
  • Don’t ignore a label that says a food was produced in a factory that processes peanuts. Most people with a peanut allergy need to avoid all products that could contain even trace amounts of peanuts.
  • When in doubt, say “no thanks.” At restaurants and social gatherings, you’re always taking a risk that you might accidentally eat peanuts. Many people don’t understand the seriousness of an allergic food reaction, and may not realize that a tiny amount of a food can cause a severe reaction. If you are at all worried that a food may contain something you’re allergic to, don’t try it.
  • Be prepared for a reaction. Talk with your doctor about carrying emergency medications in case of severe reaction.

Avoiding foods that contain peanuts

Peanuts are common, and avoiding foods that contain them can be a challenge. The following foods often contain peanuts:

  • Ground or mixed nuts
  • Baked goods, such as cookies and pastries
  • Ice cream and frozen desserts
  • Energy bars
  • Cereals and granola
  • Grain breads
  • Marzipan, a candy made of nuts, egg whites and sugar

Less obvious foods may contain peanuts or peanut proteins, either because they were made with them or because they came in contact with them during the manufacturing process. Some examples include:

  • Nougat
  • Salad dressings
  • Chocolate candies, nut butters (such as almond butter) and sunflower seeds
  • Ethnic foods including African, Chinese, Indonesian, Mexican, Thai and Vietnamese dishes
  • Foods sold in bakeries and ice-cream shops
  • Arachis oil, another name for peanut oil
  • Pet food

Coping and support

If your child has peanut allergy, take these steps to help keep him or her safe:

  • Involve caregivers. Ask relatives, babysitters, teachers and other caregivers to help. Teach the adults who spend time with your child how to recognize signs and symptoms of an allergic reaction to peanuts. Emphasize that an allergic reaction can be life-threatening and requires immediate action. Make sure that your child also knows to ask for help right away if he or she has an allergic reaction.
  • Use a written plan. List the steps to take in case of an allergic reaction, including the order and doses of all medications to be given, as well as contact information for family members and health care providers. Provide a copy of the plan to family members, teachers and others who care for your child.
  • Discourage your child from sharing foods. It’s common for kids to share snacks and treats. However, while playing, your child may forget about food allergies or sensitivities. If your child is allergic to peanuts, encourage him or her not to eat food from others.
  • Make sure your child’s epinephrine autoinjector is always available. An injection of epinephrine (adrenaline) can immediately reduce the severity of a potentially life-threatening anaphylactic reaction, but it needs to be given right away. If your child has an emergency epinephrine injector, make sure your family members and other caregivers know about your child’s emergency medication — where it’s located, when it may be needed and how to use it.
  • Make sure your child’s school has a food allergy management plan. Guidelines are available to create policies and procedures. Staff should have access to and be trained in using an epinephrine injector.
  • Have your child wear a medical alert bracelet or necklace. This will help make sure he or she gets the right treatment if he or she isn’t able to communicate during a severe reaction. The alert will include your child’s name and the type of food allergy he or she has, and may also list brief emergency instructions.

If you have peanut allergy, do the following:

  • Always carry your epinephrine autoinjector.
  • Wear a medical alert bracelet or necklace.

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