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Tree Nut Allergy: Overview, Diagnosis, and Treatment

About Tree Nut Allergy

Allergies to tree nuts are severe, common, and long-lasting.1-3 Nine nuts account for the majority of tree nut allergies: walnut, almond, pistachio, cashew, pecan, hazelnut, macadamia, brazil nut, and pine nut.4

Tree nut (TN) allergy appears to be higher in children and varies by region but affects 0.05 percent to 7.3 percent of the population.4 TN allergy typically develops by the age of two years, and the number of tree nuts that a patient is sensitized to can increase with age.4 In the case of nut-induced anaphylaxis, as with other foods, symptoms usually present within minutes of ingestion.5 Biphasic reactions, in which return of anaphylactic symptoms occurs following an asymptomatic period of an hour or more after the initial reaction, without further exposure to antigen, can occur in 3 percent to 20 percent of severe food reactions.5

Reactions frequently occur on the first-known ingestion of the food and are typically lifelong, although there are small percentages of patients who do outgrow them.6 TN allergy has a lower likelihood of resolution (9 percent) compared with other food allergies.3,4,7

In comparison with other foods, allergic reactions to tree nuts seem to be particularly severe, with multisystemic or respiratory symptoms in up to 81 percent of the cases, and tree nut allergies account for 18 percent to 40 percent of cases of anaphylaxis.4,6-8 Peanut and TN allergies account for 70 percent to 90 percent of reported food-related anaphylactic fatalities.1,4,6 TN allergies account for a relatively high proportion of fatal food-induced anaphylaxis.9

18% to 40%

Tree nut allergies account for 18 percent to 40 percent of cases
of anaphylaxis.4,6-8

The most common clinical manifestations of allergic reactions to food include:1

Skin reactions: acute urticaria (hives), angioedema (swelling), and erythema (redness of the skin).

Respiratory tract symptoms: laryngeal edema, rhinorrhea, and bronchospasm.

Gastrointestinal-related signs and symptoms: nausea, vomiting, abdominal pain, and diarrhea. 

These reactions are acute in onset, with symptoms occurring within minutes or up to a few hours after ingestion.8 Skin reactions are the most common clinical manifestations of allergic reactions to food.1 Severity of coexisting atopic diseases—such as allergic rhinitis, asthma, or eczema—is associated with more severe reactions.4

As allergy to tree nut is usually lifelong and accounts for many food-induced severe and fatal allergic reactions, the diagnosis of tree nut allergy carries considerable significance.2

Tree nut allergy: Refining differential diagnosis through testing

The diagnosis of TN allergy is the same as other food allergies; it is based upon a thorough medical history, testing via skin-prick or specific IgE blood testing, and if needed, an oral food challenge (OFC).4,5,10 These key diagnostic tools are essential for arriving at an accurate diagnosis.10

Making an accurate diagnosis is particularly important both to avoid unnecessary dietary restrictions and to prevent life-threatening reactions.10 

Who should be tested?

Allergies to TN have become an important health concern as availability to nuts has increased.4 And identifying individuals with TN allergy is important, as these patients are at risk for severe reactions.1-3 Patients are typically told that they should avoid TN as accidental ingestions by allergic individuals are common and carry injectable epinephrine for the rest of their lives.2 As allergy to TN is usually lifelong and accounts for many food-induced severe and fatal allergic reactions, the diagnosis of TN allergy carries considerable significance.2

Click to View Algorithm10

The evaluation for a patient with a possible food allergy begins with a thorough history and physical exam. If the clinical history suggests an IgE-mediated food allergy, skin-prick or specific IgE blood tests are needed to help confirm the diagnosis.

What is component testing?

What is component testing?

When a patient asks, “Do I have a tree nut allergy?,” it’s tempting to get a “yes” or “no” answer and leave it at that. But what if there was a way to uncover even more information about an allergic sensitization, such as the specific protein that’s triggering your patient’s reaction?

Testing with allergen components helps you assess your patient’s risk of reaction severity, from mild and localized to severe, including the risk of anaphylaxis, or potentially no clinical reaction at all.4

So instead of just answering the question of “Do I have a tree nut allergy?,” you can know exactly which protein triggers their reaction, and the risk of reaction severity and cross-reaction associated with that protein. Specific IgE blood testing for tree nut components can also help determine whether an oral food challenge (OFC) test is recommended. An OFC test can be used to confirm a food allergy or to see if a patient has outgrown a food allergy.

By detecting sensitization with tree nut component testing, you can create a personalized management plan for your patient.


It’s not just knowledge you’ll be giving them, but peace of mind, too.

Tree nut allergy and quality of life

Food allergy, including TN allergy, can have a dramatic effect on quality of life.11 Many studies have detailed the negative effect of food allergy on quality of life, as well as the financial and emotional toll a food allergy takes.12 Issues identified include feeling different because of the diet, worrying about foods, physical and emotional distress, increased responsibility, effect on social activities (social restrictions, school, travel, and dining out), anxiety, stress, bullying, and having to consistently exercise greater caution.12 Particularly in TN allergy, reactions outside the home tend to be more severe and are more likely to be treated with epinephrine.5

Strict avoidance of TN remains the mainstay of treatment for nut-allergic individuals.5 It is important for healthcare providers to educate patients on reading and interpreting food labels, as TN avoidance can be difficult.13 A high level of patient education is needed to maintain safety when it comes to allergen avoidance.12 Patients with food allergies are forced to correctly read and interpret food labels.14 

In general, efforts of patients allergic to nuts to control avoidance at home can be successful, though there are certain circumstances and situations, including restaurants, childcare, school, and travel, that remain high risk for cross-contamination and accidental exposure.5,14

Accidental TN reactions are frequently attributed to desserts (e.g., cakes and ice creams) containing nuts, often in hidden forms, such as in sauces or ingredients in food.15 Asian restaurants and dessert shops (e.g., bakeries and ice cream shops) were common sources of foods that triggered reactions.15

Patients allergic to TN frequently exhibit sensitization to other TN.4,5 Specific TN display a significant amount of cross-reactivity, for example, cashew-pistachio and walnut-pecan, are particularly strong.3-6 Clinical cross-reactivity to multiple nuts has been reported in up to one-third of patients evaluated for TN allergy.5 And, despite the fact that TN and peanuts are not botanically related, co-sensitization between peanut and TN is common.4,5 Although clinical cross-reactivity between nuts may be difficult to establish, the possibility of exhibiting symptoms to multiple nuts plays an important role in the management of patients allergic to nut, especially in children.5

Testing Confidence

Testing Increases Diagnostic Confidence

Adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis to 90 percent.i,ii Conventionally, a diagnosis of allergic or autoimmune disease relies on the case history and a physical examination. However, adding diagnostic testing to aid in a differential diagnosis has been shown to increase confidence in diagnosis.i,ii Diagnostic testing can also help to improve the patient’s quality of life and productivity, reduce costs associated with absenteeism, and optimize use of medication, in addition to decreasing unscheduled healthcare visits.iii,iv 

i. Duran-Tauleria E, Vignati G, Guedan MJ, et al. The utility of specific immunoglobulin E measurements in primary care. Allergy. 2004;59 (Suppl78):35-41.
ii. NiggemannB, Nilsson M, Friedrichs F. Paediatric allergy diagnosis in primary care is improved by in vitro allergen specific IgE testing. Pediatr Allergy Immunol. 2008;19:325-331
iii. Welsh N, et al. The Benefits of Specific Immunoglobulin E Testing in the Primary Care Setting. J Am Pharm Assoc. 2006;46:627.
iv. Szeinbach SL, Williams B, Muntendam P, et al. Identification of allergic disease among users of antihistamines. J Manag Care Pharm. 2004; 10 (3): 234-238

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Management and care of patients with tree nut allergy

The two pillars of TN allergy management are strict avoidance and prompt treatment of symptoms upon accidental exposure.4 Strict dietary avoidance of TN is the key to management but can be difficult to achieve as TN are hidden in foods, plus many people cannot recognize TNs.4,5,16 Important components of food avoidance are reading food labels and recognizing the allergen.4

TN are among the most commonly implicated foods in cases of anaphylaxis occurring in both children and adults.4,5 Patients, their families, and caregivers should be instructed how to recognize the early symptoms of an allergic reaction and how to treat an anaphylactic reaction promptly.Epinephrine is the first-line treatment for anaphylaxis, and patients with potential anaphylaxis to TNs should have ready access to an epinephrine auto-injector.4

A consideration unique to the management of TN allergy is the decision to avoid all TN or only the TN to which a patient is allergic; avoiding all nuts simplifies the management and it may also decrease the risk of reactions due to cross-contamination or misidentification, which is common.4 In general, the full avoidance of all nuts is recommended, except if the patient is regularly consuming a particular nut without any adverse effects.8 This recommendation, which can be viewed as excessively restrictive, is justified because of the possibility of cross-contamination between different nuts used as ingredients in processed foods, a possible ingredient substitution, and the difficulty of identifying individual nuts in processed foods.8 However, it is possible that patients can become sensitized to additional TNs during avoidance.4

Practice parameters have been developed to help guide the management and treatment of patients with food allergies, including TN.

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  2. Fleischer DM, Conover-Walker MK, Matsui EC, Wood RA.The natural history of tree nut allergy. J Allergy Clin Immunol. 2005 Nov;116(5):1087-93.
  3. Abrams EM, Sicherer SH. Diagnosis and management of food allergy. CMAJ. 2016;188(15):1087–1093.
  4. Weinberger T, Sicherer S. Current perspectives on tree nut allergy: a review. J Asthma Allergy. 2018; 11: 41–51.
  5. Lomas JM, Järvinen KM. Managing nut-induced anaphylaxis: challenges and solutions. J Asthma Allergy. 2015; 8: 115–123.
  6. Maloney J, et al. The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy. J Allergy Clin Immunol. 2008;122:145-51.
  7. Sicherer SH, Burks AW, Sampson HA. Clinical features of acute allergic reactions to peanut and tree nuts in children. Pediatrics. 1998;102(1):e6 

  8. Crespo JF, James JM. Fernandez C, Rodriguez J. Food allergy: Nuts and tree nuts. British J Nutrition. 2006;96;2;S95-102.
  9. Yang L, Clements S, Joks R. A retrospective study of peanut and tree nut allergy: Sensitization and correlations with clinical manifestations. Allergy Rhinol. 2015; 6:e39–e43.
  10. Kattan JD, Sicherer SH. Optimizing the Diagnosis of Food allergy. Immunol Allergy Clin North Am. 2015; 35(1): 61–76.
  11. Antolín‐Amérigo et al. Quality of life in patients with food allergy. Clin Mol Allergy. 2016;14:4.
  12. Sicherer SH, Sampson HA. Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. J Allergy Clin Immunol. 2018 Jan;141(1):41-58.
  13. Brough HA, et al. Dietary management of peanut and tree nut allergy: what exactly should patients avoid? Clin Exp Allergy. 2015 May;45(5):859-871.
  14. Davis PA et al. Tree Nut and Peanut Consumption in Relation to Chronic and Metabolic Diseases Including Allergy. J Nutr. 2008 Sep;138(9):1757S-1762S.
  15. Furlong TJ, DeSimone J, Sicherer SH.Peanut and tree nut allergic reactions in restaurants and other food establishments. J Allergy Clin Immunol. 2001 Nov;108(5):867-70.
  16. Ewan PW. Clinical study of peanut and nut allergy in 62 consecutive patients: new features and associations. BMJ 1996;312(7038):1074-8.