What Is Tree Nut Allergy?

  • Pranjal Ajit Yeole Bachelor's of Biological Sciences, Biology/Biological Sciences, General, University of Warwick, UK


Tree nut allergy is an allergic condition caused by the proteins inside various tree nuts. Those proteins are detected as foreign substances by our body, and as a response, IgE antibody is manufactured. The high levels of IgE results in allergic reactions. Tree nut allergy can be life-threatening and requires acute awareness as well as timely management via epinephrine injections to save lives. Despite the financial, emotional, and quality of life burdens, anticipatory education, prevention, and planning can help you to lead a fulfilling life.


Tree nut allergy is highly prevalent, and it includes being allergic to nuts originating from trees. An individual can either be allergic to all the tree nuts or some of them.1 The reaction of the body to tree nuts might pose a significant risk, which can lead to lethal cases.1, 2 Therefore, accurate diagnosis and exceptional care to avoid certain foods, including tree nuts, is required.

What are tree nuts?

Tree nuts can be described as fruits which are arid, sealed, intact, and contain a single seed.1 The free nut allergy includes the following seeds:

  • Almonds
  • Brazil nuts
  • Cashew nuts
  • Hazelnuts
  • Chestnuts
  • Macadamia nuts
  • Pecan nuts
  • Pistachios
  • Walnuts

Hazelnut allergy is the most common tree nut allergy across the EU.3

What are the causes of tree nut allergy?

Tree nuts contain proteins that vary from one species of tree nut to another. Those proteins are recognized by our immune system as foreign substances.3, 4 The foreign protein substances detected by our immune system result in the production of fighter molecules called antigens. The body generates molecules known as antibodies to battle with those antigens.4 

Tree nuts yield into the production of Immunoglobulin E (IgE) antibody.3, 4 They are called allergens because they cause allergic reactions in our bodies.5 Some studies have confirmed the occurrence of co-allergy in individuals with a type of tree nut to other tree nuts.

What are the symptoms of tree nut allergy?

The symptoms of tree nut allergy can range from mild to severe level.6 

The symptoms can be categorized as the following: 

  • Gastrointestinal Tract: abdominal pain, vomiting
  • The skin: urticaria, angioedema
  • The respiratory tract: rhino-conjunctivitis, wheezing in severe cases 
  • The cardiovascular system: loss of consciousness, low blood pressure

The level of reactions changes due to the type of allergens you are exposed to. Also, anaphylactic shock has serious outcomes, such as a drop in blood pressure and devastating errors in the cardiovascular system, making it life-threatening. It requires urgent measures.6

Diagnosis of tree nut allergy

All types of food allergies have similar diagnostic methods along with case-specific patient stories. 

Serum-specific IgE and skin prick testing (SPT) are the most common methods applied for tree nut allergy testing.5 For the SPT test, the allergen-inclusive food extract is dropped onto the skin and by using a needle a puncture method is applied to the skin. 

However, component-resolved diagnostics (CRDs) and molecular allergen analysis tests can give more definite results as they identify the specific proteins in an allergen causing the allergic reactions. This can be further explained by the other methods, including the blood serum levels of IgE antibodies. It can provide confirmation of a particular food allergy but not the types of proteins inside that allergen.5 

Management of tree nut allergy

We can subdivide the management into two basic sub-categories:

  1. Dietary Management

This is simply inclusive of the awareness of signs, having background information about the food laws, detailed planning of the trips such as pre-determining the safe places to eat and being very well informed about the food and dairy products containing the tree nuts. 

Also, is it very important to carry out discussions regarding the safety and well-being of the pre-school, elementary, and college students who are at high risk of being exposed to nuts.   They require strict monitoring as well as educational knowledge about their condition.

  1. Medical Management

The medical management of tree nut allergy is very similar to the management of other food allergies. It can be further divided into two categories: 1) Acute management and 2) long-term management

Epinephrine autoinjectors (EAIs) are the first line of treatment for nut-related cases as there’s a serious risk of anaphylaxis, which can be fatal. Therefore, people with nut allergies should always have ease of access to EAIs.5 However, the dose of epinephrine is extremely vital to be regulated according to age and weight since overdose is a serious concern. 

Long-term management consists of the determination of every single type of allergy and regulation of the environment as well as acquiring the necessary information and education to be fully prepared in the long run.

Treatment of tree nut allergy

The allergic reactions are either treated with antihistamines or epinephrine. There is a new concept called food immunotherapy. Food immunotherapy is applied to people with tree nut allergy, especially to children. The main concept is based on disbursing the doses of the allergen food slowly and steadily to a child, aiding the body to get accustomed to those allergens.5 The most popular method is ingesting the food, but there are other options, such as putting it under the tongue or via an injection.

The main aim of food immunotherapy is the prevention of sudden and unexpected exposure to nut tree allergies being severe or even fatal. The management method of epinephrine is also a treatment method applied in emergencies. 

Living with a tree nut allergy

Emotionally, it can be sapping to live with the tree nut allergy. A person can be concerned about the chance of contamination with the tree nut and the consequences. However, being fully aware of the risks, having a strong background in food labelling, informing surrounding people, and always carrying an epinephrine injector for sudden scenarios are sufficient to live a normal life without any emotionally draining concerns.

Generally, the physiological effect of food allergy in every form is high.7 People with allergies have been confirmed to have depression, anxiety, post-traumatic stress, being judged or made fun of by others, and a lessened quality of life.

Moreover, living with tree nut allergy can be highly costly. It can reach up to $1.7 billion to manage special diets, $857 million to prevent unforeseen contact with food allergens, and $650 million can be spent to relocate safer schools for the allergens.

Cross-contamination and labelling

There are case reports where individuals with common tree nut allergies such as almonds have cross-reactivity with non-allergenic seeds such as mahaleb.8 On the other hand, peanuts are not tree nuts, however, there are individuals with a tree nut allergy who have cross-allergy with peanuts and they show severe effects. Within those circumstances, cross-contamination is a concern for allergic people.

In another study, it was indicated that ice cream shops and bakeries/doughnut shops are the most prevalent places for cross-contamination of food with allergens.9 The main reason proposed was miscommunication between the manager and the workers or the customers and workers. Consequently, people have trust issues with those places, and they prefer not to consume their products.

Tree nut allergy & children

Coping with tree nut allergies as parents of small children can be very harsh. The children are unaware of the tree nut allergens, labellings, and the risks. Unfortunately, we do not live in a well-educated society and do not have high standards of food allergy precautions. Therefore, going to birthday parties, attending social events, watching films at the cinema, and getting a safe education at school all become a high fear of concern. However, even though education is mandatory, all the other activities are also required for the healthy development of a child.

Children also reported being exposed to bullying, such as throwing allergic food onto them or intentionally contaminating the lunch/breakfast at the school with their friends.7

In summary, children with food allergies, including tree nut allergy, require vigilant care. This situation gives parents high levels of stress and anxiety.7

Ongoing research and future outlook

Until recently, the research on tree nut allergy was based on being co-allergic to other foods or multiple tree nuts and understanding the molecular mechanism behind those connections. However, there was no research on treatment alternatives. The only treatment methods are antihistamines and epinephrine, which are also applied to all types of allergies.

Currently, there is ongoing research on the safety and effectiveness of immunotherapy on adults and children with tree nut allergy. In line with this is a recently published study based on preschool-aged children.10 They have delivered immunotherapy methods for the tree nut allergy and proposed that the allergic situation of the body to tree nuts has been overcome with some tolerable side effects.


In summary, tree nut allergy is a highly frequent but seriously life-threatening allergic condition,  as a consequence of various proteins found in different types of tree nuts. It is highly life-saving to have a proper diagnosis and show exceptional care about the condition to live a safe and healthy life.

Accurate diagnosis involves skin prick testing (SPT) and serum-specific IgE analysis. Management ranges from dietary, precautions, and education to medical approaches. The crucial point here is the use of epinephrine injection at the right time and as quickly as possible to prevent anaphylactic reactions, which may have deadly results. Unfortunately, there is no further promising research in the treatment sector; however, understanding and addressing the challenges, as well as taking proactive education and avoidance, can provide a safe and improved quality of life.


  1. Kuźmiński A, Przybyszewski M, Przybyszewska J, Ukleja-Sokołowska N, Pałgan K, Bartuzi Z. Tree nut allergy. Advances in Dermatology and Allergology. 2021;38(4):358–63. 
  2. Brough HA, Gourgey R, Radulovic S, Caubet JC, Lack G, Anagnostou A. Latest Developments in the Management of Nut Allergies. Current Treatment Options in Allergy. 2021 Jun;8(2):97–110. 
  3. Tree nut allergens. Molecular Immunology [Internet]. 2018 Aug 1;100:71–81. Available from: https://www.sciencedirect.com/science/article/pii/S0161589018300907#:~:text=Hazelnut%2C%20walnut%2C%20pecan%2C%20and 
  4. Godwin L, Crane JS. Biochemistry, Immunoglobulin E (IgE) [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541058/ 
  5. Weinberger T, Sicherer S. Current perspectives on tree nut allergy: a review. Journal of Asthma and Allergy. 2018 Mar;Volume 11:41–51. 
  6. Fuhrmann V, Huang HJ, Akarsu A, Shilovskiy I, Elisyutina O, Khaitov M, et al. From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack. Frontiers in Immunology. 2021 Sep 23;12. 
  7. Feng C, Kim JH. Beyond Avoidance: the Psychosocial Impact of Food Allergies. Clinical Reviews in Allergy & Immunology. 2018 Sep 1;57(1):74–82. 
  8. Benoit L, Masiri J, Janagama H, Gendel SM, Samadpour M. Case Report: Allergic Reactivity to Mahaleb (Prunus mahaleb) Spice in a Subject With Almond and Other Tree Nut Allergies. Allergy & Rhinology. 2020 Jan;11:215265672095908. 
  9. Furlong TJ, DeSimonea J, Sicherer SH. Peanut and tree nut allergic reactions in restaurants and other food establishments. Journal of Allergy and Clinical Immunology [Internet]. 2001 Nov;108(5):867–70. Available from: https://www.sciencedirect.com/science/article/pii/S0091674901338915 
  10. Epstein‐Rigbi N, Levy MB, Nachshon L, Koren Y, Katz Y, Goldberg MR, et al. Efficacy and safety of food allergy oral immunotherapy in adults. Allergy. 2022 Oct 3; 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Selun Ilseven

Masters of Cancer Research and Precision Oncology- MSc, University of Glasgow, Scotland.

Selun, with a robust foundation in genetics, cancer research, and precision oncology, she combines her extensive scientific knowledge with years of expertise in science writing, communication, and managing scientific societies.

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