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Food allergy

Definition
Food allergy is an adverse food-stimulated immune response initiated on exposure to a given food.
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Pathophysiology
Food allergy is mostly caused by IgE-mediated antibodies (type 1 or early; 48%) and IgE-independent immune response including type IV (18%), type III (10%), and type II (6%) to specific foods (milk, eggs, wheat, fish, soy, peanuts, fish, shellfish, cherries, peaches, plums, apricots, nuts, and seeds) influenced by genetic and environmental (improved hygiene, lifestyle, diet and nutrition) factors.
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Epidemiology
The prevalence of IgE-mediated food allergy in the US is estimated at 10,000 in 100,000 adults.
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Disease course
Clinical manifestations of an immediate reaction include anaphylactic shock, urticaria, and angioedema. Late reaction food reaction symptoms include fatigue, irritability, depression, hyperactivity, insomnia, headache, poor concentration, paleness, itching limbs, involuntary bedwetting, asthma, colds, indigestion, colic, diarrhea, bloating, and skin lesions. The disease impairs QoL necessitating lifelong prevention of the specific food.
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Prognosis and risk of recurrence
The mortality risk associated with fatal anaphylaxis is < 1%.
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Key sources
The following summarized guidelines for the evaluation and management of food allergy are prepared by our editorial team based on guidelines from the European Academy of Allergy and Clinical Immunology (EAACI 2023; 2021; 2018; 2014), the American Academy of Family Physicians (AAFP 2023), the American Academy of Allergy, Asthma & Immunology (AAAAI 2023; 2020), the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN 2023), the Global Allergy and Asthma European Network (GA²LEN 2022), the Latin American Society for Pediatric Gastroenterology, Hepatology and Nutrition (LASPGHAN 2022), the American Academy of Allergy, Asthma & Immunology (AAAAI/CSACI/ACAAI 2021), the National Institute of Allergy and Infectious Diseases (NIAID 2017), the British Society for Allergy and Clinical Immunology (BSACI 2017), and the American Academy of Allergy, Asthma & Immunology (AAAAI/ACAAI 2014).
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Guidelines

1.Diagnostic investigations

Medical history: as per EAACI 2023 guidelines, elicit a detailed allergy-focused clinical history as the first step of the diagnostic evaluation in patients with suspected IgE-mediated food allergy.
B
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  • Specific allergy testing

  • Serum IgE (general indications)

  • Serum IgE (severe eczema)

  • Serum IgE (alpha-gal syndrome)

  • Component-resolved diagnostic tests

  • Oral food challenge

  • Other tests

2.Medical management

Antihistamines
Consider administering antihistamines in adult and pediatric patients with acute non-life-threatening symptoms from food allergy.
C
Do not use antihistamines
D
or mast cell stabilizers as prophylactic therapy.
D

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  • Epinephrine autoinjectors

  • Corticosteroid autoinjectors

  • Specific immunotherapy (indications, children)

  • Specific immunotherapy (indications, adults)

  • Specific immunotherapy (monitoring)

  • Biological therapies

3.Nonpharmacologic interventions

Elimination diets: as per GA²LEN 2022 guidelines, consider advising avoidance of the offending food in patients with documented food allergy unless individual circumstances and risks allow for some consumption, as advised by their healthcare professional. Consider advising to continue the intake of the offending food in most breastfeeding mothers having infants with a food allergy; consider advising avoidance in rare cases.
C

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  • Probiotics

4.Specific circumstances

Patients with coexisting asthma: as per GA²LEN 2022 guidelines, optimize asthma control in patients with food allergies to reduce morbidity and mortality due to asthma.
B

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  • Patients with cow's milk allergy (evaluation)

  • Patients with cow's milk allergy (hydrolyzed formulas)

  • Patients with cow's milk allergy (immunotherapy)

  • Patients with peanut allergy

  • Patients with egg allergy

5.Patient education

General counseling: as per AAAAI 2023 guidelines, educate patients on avoidance of potential exposure to their allergens.
B
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6.Preventative measures

Early introduction of foods
As per AAFP 2023 guidelines:
Introduce peanuts, cow's milk, wheat, and cooked eggs early at 4-6 months of age to reduce the risk of developing food allergies.
A
Introduce peanuts and cooked eggs early at 4-6 months of age to reduce the risk of developing food allergies in high-risk infants.
B

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  • Hydrolyzed formulas

  • Measures with no evidence for benefit

7.Follow-up and surveillance

Indications for specialist referral: refer patients with eosinophilic esophagitis to an allergist/immunologist for diagnostic evaluation.
B

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  • Assessment of treatment response

  • Serial clinical assessment

8.Quality improvement

School policies: ensure that all staff within the school and early years setting receive appropriate training in managing an allergic reaction.
B
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  • Restaurant policies