{
 "topic": "Peanut Allergy",
 "slug": "peanut-allergy",
 "category_id": 14965,
 "summary": "Peanut allergy prevention and management: LEAP-trial-based early introduction guidelines by eczema/egg-allergy risk tier, skin-prick/IgE risk stratification, and anaphylaxis treatment.",
 "written_by": "claude-sonnet",
 "references": [
  {
   "title": "Pediatric Clinical Practice Guidelines & Policies, 18th Edition",
   "author": "American Academy of Pediatrics",
   "pages": [
    1335
   ]
  },
  {
   "title": "Pediatric Board Study Guide",
   "author": null,
   "pages": [
    386
   ]
  },
  {
   "title": "Pediatric Nutrition (Ronald E. Kleinman, Frank R. Greer)",
   "author": null,
   "pages": [
    188,
    1009
   ]
  },
  {
   "title": "Pediatric Nutrition Handbook",
   "author": "Kleinman, Ronald E.",
   "pages": [
    834
   ]
  },
  {
   "title": "Update in Pediatrics",
   "author": null,
   "pages": [
    82
   ]
  },
  {
   "title": "Kliegman R. Nelson Textbook of Pediatrics 2-Volume Set 22ed 2024",
   "author": null,
   "pages": [
    1463
   ]
  },
  {
   "title": "Illustrated Textbook of Paediatrics (Tom Lissauer, Will Carroll)",
   "author": "Lissauer, Tom,Carroll, Will",
   "pages": [
    301
   ]
  },
  {
   "title": "Pediatric Clinical Practice Guidelines and Policies",
   "author": "American Academy of Pediatrics (AAP);",
   "pages": [
    1365
   ]
  }
 ],
 "short": [
  {
   "title": "In short",
   "content": "- Peanut allergy affects 1-3% of children in many westernized countries, with prevalence roughly tripling over the past 10-15 years in some countries (e.g., the US); it affects about 1 in 50 primary-school-aged children in the US, Canada, UK, and Australia, translating to nearly 100,000 new cases annually in the US and UK combined.\n- Only about 20% (a minority) of peanut-allergic children \"outgrow\" their allergy, and this occurs almost exclusively within the first 5 years of life, rarely later.\n- Food allergy is the leading single cause of anaphylaxis treated in US, European, and Australian emergency departments, accounting for about 30,000 ED visits and 100-125 deaths per year in the US; peanut allergy is the leading cause of fatal and near-fatal food allergic reactions in the US.\n- The landmark LEAP trial showed that early, regular peanut introduction (at least 6 g of peanut protein over 3+ meals/week) in high-risk infants (egg allergy and/or severe atopic dermatitis) reduced peanut allergy risk: only 3% of high-risk infants who regularly consumed peanut developed allergy by age 5, versus 17% of those who avoided it.\n- Risk stratification for infants guides introduction timing: severe eczema and/or egg allergy = strongly consider allergist evaluation (specific IgE, skin prick test, oral food challenge if needed) before introducing peanut, earliest at 4-6 months; mild-to-moderate eczema = introduce peanut-containing foods around 6 months; no eczema or food allergy = introduce peanut when age-appropriate per family preference (generally after 6 months).\n- Peanut skin prick test interpretation: 0-2 mm wheal = low risk, introduce at home or supervised in-office feeding; 3-7 mm = moderate-to-severe risk, refer to specialist or supervised office feeding; 8 mm or more = infant very likely allergic, continue management with a specialist. Peanut-specific IgE: under 0.35 kUA/L = low risk; 0.35 or greater = refer to allergist.\n- The oral food challenge remains the gold standard for diagnosis.\n- There is insufficient evidence to support delayed introduction of peanut to prevent allergy, even in infants at high risk based on family history alone; a purposeful delay in introducing allergens is unproven/not recommended, as is maternal allergen avoidance during pregnancy or lactation.\n- Anaphylaxis (rash, swelling, wheezing after exposure) requires epinephrine, antihistamines, and systemic corticosteroids, with observation for late-onset (biphasic) reactions; management includes strict avoidance, food label reading, an epinephrine auto-injector at all times, a medical alert bracelet, and allergist referral.\n"
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Peanut allergy is an IgE-mediated hypersensitivity reaction to peanut protein - an allergy being a hypersensitivity reaction initiated by specific immunologic mechanisms (IgE-mediated, as in peanut allergy, or non-IgE mediated, as in celiac disease), distinguished from hypersensitivity generally, which describes objectively reproducible symptoms following exposure to a stimulus at a dose usually tolerated by most people.\n"
  },
  {
   "title": "Epidemiology",
   "content": "Peanut allergy affects between 1% and 3% of children in many westernized countries. Prevalence appears to have risen sharply over the past 10-15 years, with estimates suggesting it may have tripled in some countries such as the United States. Extrapolated prevalence translates to nearly 100,000 new cases annually in the United States and United Kingdom combined, affecting roughly 1 in 50 primary-school-aged children in the US, Canada, UK, and Australia; a similar rise in incidence is now being observed in developing countries such as Ghana. Only a minority of peanut-allergic children \"outgrow\" their allergy, and this occurs almost exclusively during the first 5 years of life, rarely beyond that age.\n"
  },
  {
   "title": "Etiology",
   "content": "Peanut is one of several ingestant allergens (alongside cow's milk, other nuts, soy, egg, wheat, seeds, legumes, seafood, and fruits) that account for most pediatric allergic disease, alongside inhalant allergens (house-dust mite, pollens, pet dander, molds) and other triggers (insect stings/bites, drugs, natural rubber latex). Sensitization can also occur through environmental exposure to peanut via a disrupted skin barrier, as seen in infants with eczema, including from trace quantities of peanut in house dust. Risk factors for developing an IgE-mediated food allergy include severe eczema (highest risk), mild-to-moderate eczema, other known food allergies, and genetic predisposition including allergic disease in a first-degree relative; some infants with no identifiable risk factors still develop food allergy.\n"
  },
  {
   "title": "Prevention",
   "content": "Recommendations for peanut allergy prevention are based largely on the Learning Early About Peanut (LEAP) trial and endorsed by the AAP. In the LEAP trial, offering infants with egg allergy and/or severe atopic dermatitis at least 6 g of peanut protein over 3 or more meals per week substantially decreased the risk of peanut allergy: only 3% of high-risk infants who regularly consumed peanut developed allergy by age 5, compared with 17% of those who avoided peanut. Based on this evidence, three risk-based guidelines for peanut introduction have been established. For infants with severe eczema, egg allergy, or both, clinicians should strongly consider evaluation by serum peanut-specific IgE and/or skin prick testing, with an oral food challenge if necessary, and introduce peanut-containing foods based on the results, as early as 4-6 months of age. For infants with mild-to-moderate eczema, peanut-containing foods should be introduced around 6 months of age without necessarily requiring prior allergy testing. For infants with no eczema or known food allergy, peanut-containing foods should be introduced when age-appropriate, in accordance with family preferences and cultural practices (generally after 6 months). There is currently insufficient evidence to support delayed introduction of peanut products to prevent allergy, even in infants at high risk based solely on a strong family history (biparental, or parent and sibling) of allergy; a purposeful delay in introducing allergens to infants is considered unproven and not recommended, as is maternal allergen avoidance during pregnancy or lactation, and hydrolyzed formulas are also unproven for this purpose. A complete allergy evaluation is nonetheless suggested for any child suspected of having peanut allergy.\n"
  },
  {
   "title": "Diagnostics",
   "content": "The oral food challenge is the gold standard for diagnosing peanut allergy. Peanut skin prick testing is interpreted by wheal size: 0-2 mm indicates low risk of reaction, allowing introduction at home or supervised feeding in the office; 3-7 mm indicates moderate-to-severe risk, warranting referral to a specialist or supervised in-office feeding; 8 mm or greater indicates the infant is very likely allergic, and management should continue with a specialist. Peanut-specific serum IgE testing uses a similar risk framework: less than 0.35 kUA/L indicates low risk of reaction, while 0.35 kUA/L or greater warrants referral to an allergist. For high-risk infants (severe eczema and/or egg allergy) with a positive peanut skin test or peanut-specific IgE above 0.35 kUA/L, an observed peanut challenge can determine clinical reactivity before initiating at-home introduction of infant-safe peanut forms. Allergy testing before introduction is not usually needed for infants without these risk factors.\n"
  },
  {
   "title": "Clinical Features",
   "content": "Peanut allergy is the leading cause of fatal and near-fatal food allergic reactions in the United States, and food allergy overall is the leading single cause of anaphylaxis treated in emergency departments in the US, Europe, and Australia, accounting for approximately 30,000 emergency department visits and 100-125 deaths annually in the US. An anaphylactic reaction can present with rash, swelling, and wheezing following exposure to the allergen.\n"
  },
  {
   "title": "Treatment",
   "content": "Acute anaphylaxis is treated with epinephrine, antihistamines, and systemic corticosteroids, with observation afterward for late-onset (biphasic) reactions. Long-term management centers on strict avoidance: the child and family should be counseled to avoid all peanut-containing foods, read all food labels carefully, and carry an epinephrine auto-injector at all times for emergency use. A medical alert bracelet indicating the peanut allergy should be ordered and worn at all times. Referral to an allergist is appropriate for further evaluation and ongoing management following an initial diagnosis or reaction.\n"
  }
 ],
 "clinical": [
  {
   "title": "Deciding When and How to Introduce Peanut",
   "content": "Stratify every infant by eczema severity and egg-allergy status before deciding on peanut introduction timing. For an infant with severe eczema, egg allergy, or both, strongly consider referral for peanut-specific IgE and/or skin prick testing (with an oral food challenge if results are indeterminate) before introducing peanut, aiming for introduction as early as 4-6 months once safety is established; interpret a skin prick wheal of 0-2 mm as low risk (introduce at home or in a supervised office feeding), 3-7 mm as moderate-to-severe risk (refer to a specialist or arrange supervised office feeding), and 8 mm or more as very likely allergic (continue management with a specialist) - apply the same risk tiers to peanut-specific IgE using the 0.35 kUA/L cutoff. For an infant with mild-to-moderate eczema, introduce peanut-containing foods around 6 months without needing prior testing. For an infant with no eczema or known food allergy, introduce peanut-containing foods whenever age-appropriate, per family preference and cultural practice. Do not counsel families to delay peanut introduction as a preventive strategy, even with a strong family history of allergy - the evidence (LEAP trial) instead supports early, regular introduction (at least 6 g of peanut protein over 3+ meals weekly in high-risk infants) as protective, cutting allergy risk from about 17% to about 3% by age 5 in that population.\n"
  },
  {
   "title": "Managing a Reaction and Ongoing Care",
   "content": "Treat any presentation of rash, swelling, and wheezing after peanut exposure as anaphylaxis: give epinephrine promptly, along with antihistamines and systemic corticosteroids, and observe for a late-onset (biphasic) reaction before discharge. After stabilization, arrange a complete allergy evaluation and allergist referral for any child suspected of having peanut allergy - do not rely on history alone given the risk of both under- and overdiagnosis. Equip the family with a written avoidance plan, instruction on careful food-label reading, an epinephrine auto-injector to be carried at all times, and a medical alert bracelet. Counsel that most children with peanut allergy do not outgrow it, and that any resolution occurs almost exclusively within the first 5 years of life - so ongoing allergist follow-up and periodic reassessment (rather than a one-time diagnosis) is the appropriate long-term model of care.\n"
  }
 ]
}