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Food Allergies

Food allergies are a growing, serious public health problem that affect both children and adults. Globally, as many as 550 million people may suffer from food allergies,1 with many patients sensitive to between one to three foods.2

Making food allergies difficult to identify is the fact that they often present with a wide variety of symptoms that can coincide with non-allergic food reactions.1 Gastrointestinal (GI) symptoms triggered by specific food intolerances like lactose intolerance, celiac disease, or Irritable Bowel Syndrome (IBS) are often interpreted as food allergies.2

Diagnosis, followed by counselling and advice based on test results, can help to reduce the incidence of adverse reactions and the unnecessary exclusion of foods that should be eaten as part of a normal, healthy diet.1,3

The Role of Patient History

Diagnosing food allergy starts with a physical examination and, of critical importance, a food allergy-focused patient history.2,3 Food allergy is frequently self-diagnosed, and self-reported, far more than its actual prevalence, so it is important to closely observe the history of a patient's symptoms, in conjunction with clinical evaluation and diagnostic testing, to confirm or rule out the presence of food allergies.1

Goals of a patient history also include the identification of the types or specific foods that may be responsible for the allergy. Although more than 170 foods have been identified as triggers of food allergy, eight allergen groups account for 90% of food allergies.2,4

Milk, egg, and peanut contribute to the highest number of allergic reactions in children—while peanuts, tree nuts, and seafood are the top contributing allergens in adults and teens.2,4

The information you gather in this history can then be used to guide testing decisions and interpretation of results. This systematic approach can help determine whether the patient-reported history of food allergies and data from laboratory or skin testing are sufficient for diagnosis. If they are not, an oral food challenge (OFC) may be considered to assist in the correct identification of the offending allergens.



Assess the Need for Testing

Assess the Need for Testing

Guided by the allergy-focused patient history, work through the most appropriate next steps, including considerations for specific IgE tests, skin prick tests (SPT), or both—as diagnostic tools. Diagnostic certainty in ruling in or ruling out allergy has been shown to increase when test results are added to clinical history.3

Types of Food Allergy

A detailed patient history will hopefully begin to uncover the type of food allergy your patient has.1,3 A patient’s symptom presentation can help you begin to get an idea of whether the reaction they are reporting is immune mediated or non-immune mediated.3 The latter involves general intolerances to specific types of foods or ingredients. The former involves certain cells or antibodies.5


Adverse Food Reaction5,6

Adverse Food Reaction Immune Mediated
Adverse Food Reaction Non-Immune Mediated


If you suspect a patient’s reaction is immune mediated, testing can help articulate the specific antibodies involved so that a personalized treatment plan can be put in place.

Pollen Food Allergy Syndrome

Pollen food allergy syndrome (PFAS), also known as oral allergy syndrome, is an allergic reaction that typically occurs after a patient who is sensitive to pollen eats certain foods.6 PFAS is possibly the most common food allergy in adults, with up to 60% of patients allergic to pollen being affected.7

Symptoms of PFAS happen when the food the person is allergic to touches the oral mucosa, lips, tongue, or throat.7 These symptoms of PFAS appear within minutes of eating a raw form of the food but can last for hours.7 In the majority of cases, the responsible allergens are rapidly denatured by cooking and digestion, though certain patients can still present with systemic reactions.7

On average, patients with PFAS will have 4 foods that will lead to PFAS symptoms. Foods that trigger symptoms in up to 60% of patients sensitized to pollen include raw fruits, vegetables, nuts, or grains.7 The following types of pollen may trigger reactions to various associated fruits and vegetables, including:7

Birch allergy


Almond, Apple, Apricot, Carrot, Celery, Cherry, Chestnut, Chicory, Date palm, Fennel, Fig, Grape, Hazelnut, Jackfruit, Kiwi, Melon, Orange, Nectarine, Parsley, Parsnip, Peach, Peanut, Pistachio, Pear, Plum, Potato, Prune, Spinach, Walnut, Watermelon


Grass allergy

Grass Pollen

Apple, Carrot, Celery, Chamomile, Chestnut, Currant, Date palm, Eggplant, Fig, Grape, Kiwi, Melon, Orange, Nectarine, Peach, Pistachio, Tomato, Watermelon


Mugwort allergy

Mugwort Pollen

Apple, Aniseed, Apple, Avocado, Caraway seed, Carrot, Celery, Chamomile, Coriander, Fennel, Mango, Mustard, Parsley, Peach, Peppers, Sunflower, Watermelon


Ragweed allergy

Ragweed Pollen

Apple, Banana, Cantaloupe, Carrot, Celery, Chamomile, Coriander, Cucumber, Dandelion, Fennel, Honeydew, Kiwi, Melon, Peach, Peppers, Watermelon, Zucchini

Food Allergies in Children

Food allergies are a growing problem among infants and children. Approximately 40% of infants and young children with moderate to severe eczema suffer from food allergies,1 with eggs, cow's milk, soy, and wheat accounting for the majority of allergenic foods.1,2,8

Fortunately, the majority of children with an egg or milk allergy will outgrow it by age 5.2 In the meantime, though, children allergic to those and other foods often experience a diminished quality of life. This is often due to:9,10

  • Social isolation due to food restrictions
  • Anxiety among children and parents regarding school attendance and social events
  • Avoidance of major foods, which can lead to malnutrition and a failure to thrive11

For these reasons, early identification and avoidance of the allergenic foods is critical. Furthermore, there is a known link between food allergies and other disease: about 40%–60% of children with an allergy to eggs or milk will develop asthma and 30%–55% will develop allergic rhinitis.2

Knowing the Signs and Symptoms

Symptoms of food allergies include:15

  • Gastrointestinal symptoms
  • Mild wheezing or cough 
  • Itching or tingling mouth, lips or throat 
  • Fatigue 
  • Urticaria  
  • Failure to thrive 
  • Intense itching 
  • Facial edema 
  • Feeling very hot or very cold 
  • Rising anxiety 
  • Pale or flushed appearance 
  • Dyspnea  
  • Wheezing
  • Hoarseness 
  • Croupy/choking cough 
  • Very pale/cyanotic lips 
  • Unresponsiveness 
  • Circulatory collapse
Chronic serous otitis media

During your detailed patient history, you will likely uncover several symptoms that could be attributed to food allergies. Symptoms range from mild to severe and, in some cases, can be fatal.1 For example, patients with asthma face an increased risk for severe exacerbations if they also have food allergies.12 Severe allergic reactions, such as anaphylaxis, in children were reported to have increased up to 7-fold between 1992-2012, but have since stabilized in the last 5 years.13

Allergy Testing

Testing can help corroborate these findings, support the correct diagnosis and, ultimately a tailored management plan.

  1. Pawankar R, Holgate ST, Canonica GW, et al. World Allergy Organization (WAO) White Book on Allergy. 2013. http://www.worldallergy.org/UserFiles/file/WhiteBook2-2013-v8.pdf. Accessed November 2017.  

  2. Kurowski K, Boxer RW. Food allergies: detection and management. Am Fam Physician. 2008;77:1678-1688. 

  3. Burks AW, Tank M, Sicherer S, et al. ICON: Food allergy. J Allergy Clin Immunol. 2012;129:906-920. 

  4. FARE. Food Allergy Research.Facts and Statistics. https://www.foodallergy.org/life-food-allergies/food-allergy-101/facts-and-statistics. Accessed January 2018.

  5. Spergel JM. Nonimmunoglobulin E-Mediated Immune Reactions to Food. Allergy Asthma Clin Immunol. 2006;2(2):78-85.

  6. Sicherer SH, Teuber SS. Academy Practice Paper: Current approach to the diagnosis and management of adverse reactions to foods. J Allergy Clin Immunol. 2004;114(5):1146-50.

  7. Kashyap RR, Kashyap RS. Oral Allergy Syndrome: An Update for Stomatologists. J Allergy. 2015;2015:543928. 

  8. Sampson HA, Aceves S, Bock SA, James J, Jones S, Lang D, et al. Food allergy: a practice parameter update - 2014. J Allergy Clin Immunol. 2014;134:1016–25. e43.

  9. Flokstra-de Blok BM, et al. Health-related quality of life of food allergic patients: comparison with the general population and other diseases. Allergy. 2010;65:238-24.4

  10. Le TM, Zijlstra WT, van Opstal EY, et al. Food avoidance in children with adverse food reactions: influence of anxiety and clinical parameters. Pediatr Allergy Immunol. 2013:24(7):650-655.

  11. Mehta H, Groetch M, Wang J. Growth and Nutritional Concerns in Children with Food Allergy. Curr Opin Allergy Clin Immunol. 2013;13(3):275-279. 

  12. Wang J, Liu AH. Food allergies and asthma. Curr Opin Allergy Clin Immunol. 2011;11(3):249-254. 

  13. Cianferoni A, Muraro A. Food-Induced Anaphylaxis. Immunol Allergy Clinics N America. 2012;32(1):165-195. doi:10.1016/j.iac.2011.10.002.

  14. Turner PJ, Gowland MH, Sharma V, et al. Increase in anaphylaxis-related hospitalizations but no increase in fatalities: An analysis of United Kingdom national anaphylaxis data, 1992-2012. J Allergy Clin Immunol. 2015;135(4):956-963.e1.

  15. Żukiewicz-Sobczak WA, Wróblewska P, Adamczuk P, Kopczyński P. Causes, symptoms and prevention of food allergy. Postepy Dermatol Alergol. 2013;30(2):113-116.