Food allergy

Last reviewed: 29 May 2022
Last updated: 19 Oct 2021



History and exam

Key diagnostic factors

  • presence of risk factors
  • milk, egg, nut, fish, shellfish, wheat, or soya ingestion
  • reproducible symptoms
  • flushing, urticaria, or angio-oedema of the skin
  • sneezing, rhinorrhoea, or nasal congestion
  • dyspnoea, tachypnoea, wheezing, coughing, or cyanosis
  • hoarseness, stridor, or sense of choking
  • nausea and vomiting
  • abdominal cramping or bloating
  • diarrhoea
  • conjunctival injection or lacrimation
  • periorbital oedema
  • abrupt onset of symptoms
  • reaction caused by small amount of food
  • presence of other allergic disease
  • laryngeal oedema
More key diagnostic factors

Other diagnostic factors

  • tachycardia or bradycardia
  • reaction exacerbated by exercise or exertion
  • alcohol or medication ingestion before reaction
  • cardiac arrhythmia
  • hypotension
Other diagnostic factors

Risk factors

  • family history of food allergy
  • atopic dermatitis
  • newborn
  • perinatal peanut oil exposure
More risk factors

Diagnostic investigations

1st investigations to order

  • in vitro IgE specific immunoassay
  • skin prick testing
More 1st investigations to order

Investigations to consider

  • food challenges
  • component-resolved diagnostics
More investigations to consider

Emerging tests

  • atopy patch testing

Treatment algorithm


anaphylactic reaction

cutaneous symptoms




following stabilisation



A. Wesley Burks, MD
A. Wesley Burks

Curnen Distinguished Professor and Chair

Department of Pediatrics

University of North Carolina

Chapel Hill



AWB receives grant support to his institution from the National Institutes of Health, Food Allergy Research & Education, and Allergen Research Corporation; royalties from UpToDate; consulting honorariums from Aravax, Astella Pharma Global Development, DBV Technologies and N-Fold, LLC, as well as Aimmune Therapeutics, Consortia TX, Inc., Intrommune Therapeutics, and Prota Therapeutics for his service on their respective Scientific Advisory Boards. AWB has consulted for the following companies (which are all now expired): Biomerica, Inc., Evelo Biosciences/Epiva, Genentech, Insys Therapeutics, PPD Development, Sanofi US Services, Valeant Pharmaceuticals North America, LLC, LEK Consulting, LLC, Hycor Biomedical. AWB has received payments for speaking at the Gordon Research Conferences, the Pediatric Allergy and Asthma Meeting, and the American College of Allergy Asthma and Immunology. AWB is a minority stockholder of both Allertein and Mastcell Pharmaceuticals stock. These interests do not directly relate to the article but are being shared for full disclosure. AWB is an author of references cited in this topic.

J. Andrew Bird, MD

Associate Professor

Department of Pediatrics

Division of Allergy and Immunology

University of Texas Southwestern Medical Center




JAB has received personal fees from Food Allergy Research and Education, personal fees and non-financial support from American College of Allergy, Asthma and Immunology, grants from Nestle Health Sciences, personal fees from Nutricia North America, personal fees from Pharm-Olam International LTD, personal fees and other from Pfizer Pharmaceuticals, grants, personal fees and non-financial support from Aimmune Therapeutics, personal fees from Prota Therapeutics, personal fees from Allergy Therapeutics, Ltd, grants from NIH-NIAID, grants from Genentech, personal fees from AllerGenis, personal fees from Abbott Nutrition International, grants and personal fees from DBV Technologies, personal fees from Vincido Medical Education, personal fees from WebMD and grants from Astellas.

Peer reviewers

Justin Skripak, MD

Assistant Professor of Pediatric Allergy and Immunology

Mount Sinai School of Medicine

New York



JS declares that he has no competing interests.

Hugh A. Sampson, MD

Professor of Pediatrics

Mount Sinai School of Medicine

New York



HAS holds a 4% interest in a biotech company, Allertein Pharmaceuticals LLC, which is developing an engineered recombinant protein vaccine for peanut allergy, and 45% interest in a virtual company, Herbal Springs LLC, that holds a patent application on an herbal product for treating asthma and another for treating food allergy. HAS is an author of a number of references cited in this topic.

Adam Fox, MA(Hons) Cantab., MSc, MBBS, DCH, FRCPCH, FHEA, Dip. Allergy

Consultant and Honorary Senior Lecturer in Paediatric Allergy

Evelina Children's Hospital

Guy's & St Thomas' Hospitals NHS Foundation Trust




AF declares that he has no competing interests.

  • Food allergy images
  • Differentials

    • Atopic dermatitis
    • Urticaria
    • Auriculotemporal syndrome
    More Differentials
  • Guidelines

    • A consensus approach to the primary prevention of food allergy through nutrition: guidance from the American Academy of Allergy, Asthma, and Immunology; American College of Allergy, Asthma, and Immunology; and the Canadian Society for Allergy and Clinical Immunology
    • Peanut allergy diagnosis: A 2020 practice parameter update, systematic review, and GRADE analysis
    More Guidelines
  • Patient leaflets

    Food allergy: what is it?

    Food allergy: what treatments are available?

    More Patient leaflets
  • padlock-lockedLog in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer