Macadamia Nut
Allergy Facts, Symptoms, and Treatment

Allergies to tree nuts such as macadamia nuts are common and often severe. These types of allergies typically develop by the age of 2, and the number of tree nuts to which a person is allergic may increase with age.1 Roughly 30 percent of people with a tree nut allergy are allergic to more than one nut. And while peanuts are actually legumes, approximately 20 to 30 percent of those with a peanut allergy are also allergic to one or more types of tree nuts.2 In fact, together, peanuts and tree nuts account for 70 to 90 percent of reported food-related anaphylactic fatalities. Prevalence for tree nut allergy varies by age, region, and the definitions used for diagnosis, but it appears to affect 0.05 to 7.3 percent of the population. And unfortunately, compared to other food allergies, the chances of outgrowing these allergies are lower and restricted to an estimated 10 percent of sensitized individuals.1

The following nine varieties account for the majority of tree nut allergies: walnuts, almonds, pistachios, cashews, pecans, hazelnuts, macadamias, Brazil nuts, and pine nuts.1 Derived from a type of evergreen tree, macadamia nuts (as they're commonly called) are actually a type of seed that's often roasted, salted, and used in confections and chocolates. Containing 73 percent fat, macadamias are also a good source of calcium, phosphorus, iron, and vitamin B.3 In terms of prevalence, less than 5 percent of people in the United States who are sensitized to tree nuts are allergic to macadamia nuts.1

Where are macadamia nuts found?

While macadamias are often roasted and salted and are commonly used in confections and chocolates, they can also be found in additional sources such as nut mixes, baked goods, ice creams, and cereals.3,5

The following items may contain tree nuts and seeds:7 baked goods, baking mixes, barbeque and pesto sauces, cereals, chocolates, pralines, crackers, dressings, gravies, flavored coffees, frozen desserts, muesli, nougats, almond chicken, pad thai, chili and trout amandines and giandujas (i.e., chocolate blended with hazel nuts), marzipans (i.e., almond paste), almond milks, nut milks, tree nut oils, spreads (e.g., cheese spreads and chocolate nut spreads such as Nutella, which contains hazelnuts), vegetarian dishes, Indian curries, Asian dishes, pastas, liqueurs (e.g., amaretto and Frangelico), natural flavorings and extracts (e.g., pure almond extract), salads, trail mixes, and snack foods.

Also note that the words "natural flavors" and "botanicals" may indicate the presence of nuts or nut flavorings.4 Asian restaurants can be especially problematic because they often use nuts and seeds in their cuisine, and since pans may be used for multiple meal preparations, there's an inherent risk for cross-contamination.8

Nonfood items that may contain tree nuts include:7 bean bags, bird seeds, cosmetics, hair care products, sunscreens, massage oils, and pet foods.

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Are there other allergens I could be sensitized to?*

Some people with a macadamia nut allergy may also experience symptoms when eating other seemingly unrelated foods. This is called cross-reactivity and occurs when your body's immune system identifies the proteins, or components, in different substances as being structurally similar or biologically related, thus triggering a response.7 The most common cross-reactivity with macadamia nut is coconut but also peanut and other tree nuts to a lesser extent.13

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

How do I manage my allergy?

Since accidental ingestion of tree nuts and cross-contamination between nut species are common, eliminating all tree nuts from your diet simplifies allergy management. But to better determine whether you should avoid all tree nuts or only those to which you're allergic, consult your healthcare provider.1 He or she also may recommend a plan that includes the following.10-12,14

  • Read ingredient labels and "may contain" advisory panels on food and nonfood products carefully, and avoid all foods and products containing any form of the allergen. Note that these lists and panels may not appear on the same side of a product's packaging and that manufacturers frequently change ingredients. If you're unable to obtain a list of ingredients, it's safest to avoid that item.
  • Avoid cross-contamination when cooking by using two sets of cooking and eating utensils, with one exclusively for the allergic individual. Wash all dishes and utensils in hot soapy water between uses.
  • Craft an action plan with a list of steps for you and others to take should you accidentally ingest the allergen. Print out a copy of the plan and carry it with you.
  • Talk with restaurant chefs about your allergy and order food that's simply prepared and void of any form of the allergen. Avoid desserts, as they often contain or have come into contact with food allergens.
  • Plan ahead for traveling to ensure your food allergy will be managed and any emergency medication is always available.
  • Wear a medical ID bracelet identifying the allergen to which you're allergic.
  • Carry any recommended or emergency medication with you at all times.
  • Teach children with food allergies which foods to avoid. Work with caregivers and school staff to eliminate or reduce exposure to the allergen and to ensure they understand when and how to use medication to treat symptoms.

Your healthcare provider may direct you to take one of the following medications:

  • Epinephrine auto-injector when there are signs of an acute severe event, aka anaphylaxis (see below). Ensure your family members know how to administer it in case of an emergency.
  • Antihistamines as a supplement may be useful in relieving mild symptoms (e.g., itch); however, they do not halt the progression of an allergic reaction.
  • Bronchodilator (albuterol) as a supplemental therapy for respiratory symptoms, especially in those with a history of bronchospasm or asthma.

If you're with someone who's having an allergic reaction and shows signs of shock, act fast. Look for pale, cool, and clammy skin; a weak, rapid pulse; trouble breathing; confusion; and loss of consciousness. Do the following immediately:

  • Call local emergency services.
  • Ensure the affected individual is lying down with legs elevated.
  • Administer epinephrine immediately for any obvious signs of anaphylaxis.
  • Check the affected individual's pulse and breathing and administer CPR or other first-aid measures if necessary.

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Macadamia Nut Allergen Facts, Symptoms, and Treatment

Common Symptoms

Tree nut allergy symptoms typically occur within minutes of ingestion and can range from hives to anaphylaxis, a potentially life-threatening reaction that impairs breathing and can send the body into shock.2,4 In fact, tree nut allergy accounts for 18 to 40 percent of anaphylaxis cases. This severity is particularly problematic because many people can't recognize tree nuts. In one study, for example, only half of participants with a tree nut allergy correctly identified all forms of the nut to which they were allergic.1

Tree nut allergy symptoms can include:4

  • Abdominal pain, cramps, nausea, and vomiting
  • Diarrhea
  • Difficulty swallowing
  • Itching of the mouth, throat, eyes, skin, or other areas
  • Nasal congestion, runny nose
  • Shortness of breath
  • Anaphylaxis, a potentially life-threating condition

In at least one case, anaphylaxis after contact with macadamia nuts has been reported as has occupational dermatitis from macadamia shells in a nut-processing plant.5

How do I know if I'm allergic?*

Together with your symptom history, skin-prick testing or specific IgE blood testing can help determine if you are allergic to a particular allergen. If you are diagnosed with an allergy, your healthcare provider will work with you to create a management plan.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

Is there a risk for a severe event?

Symptoms of macadamia nut allergy are diverse and can vary from Oral Allergy Syndrome (OAS) to severe life-threatening anaphylaxis.5

  1. Weinberger T, Sicherer S. Current perspectives on tree nut allergy: a review. J Asthma Allergy. 2018 Mar 26;11:41-51. doi: 10.2147/JAA.S141636. PMID: 29618933; PMCID: PMC5875412. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5875412/pdf/jaa-11-041.pdf.
  2. McWilliam V, Koplin J, Lodge C, Tang M, Dharmage S, Allen K. The Prevalence of Tree Nut Allergy: A Systematic Review. Curr Allergy Asthma Rep. 2015 Sep;15(9):54. doi: 10.1007/s11882-015-0555-8. PMID: 26233427.
  3. Encyclopedia Britannica [Internet]. Chicago: Encyclopedia Britannica Inc.; 2020 Nov 22. Available from https://www.britannica.com/print/article/353606.
  4. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014. Available from: https://acaai.org/allergies/types/food-allergies/types-food-allergy/tree-nut-allergy.
  5. Knop, K & Hagendorens, Margo & Bridts, Chris & Stevens, Wim & Ebo, Didier. (2010). Macadamia nut allergy: 2 Case reports and a review of the literature. Acta clinica Belgica. 65. 129-32. 10.1179/acb.2010.026.  Available from:  https://www.researchgate.net/publication/44619646_Macadamia_nut_allergy_2_Case_reports_and_a_review_of_the_literature
  6. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014. Available from: https://acaai.org/allergies/types/food-allergies/types-food-allergy/oral-allergy-syndrome.
  7. EAACI, et al. Molecular allergology user's guide. Pediatric Allergy Immunol. 2016 May;27 Suppl 23:1-250. do: 10.1111/pai.12563. PMID: 27288833. (245-254 p.) Available from: http://www.eaaci.org/documents/Molecular_Allergology-web.pdf.
  8. Lomas JM, Järvinen KM. Managing nut-induced anaphylaxis: challenges and solutions. J Asthma Allergy. 2015 Oct 29;8:115-23. doi: 10.2147/JAA.S89121. PMID: 26604803; PMCID: PMC4631427. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4631427/pdf/jaa-8-115.pdf.
  9. Roberts, G., Xatzipsalti, M., Borrego, L., Custovic, A., Halken, S., Hellings, P., Papadopoulos, N., Rotiroti, G., Scadding, G., Timmermans, F., Valovirta, E. Paediatric rhinitis: Position paper of the European Academy of Allergy and Clinical Immunology. Allergy. 2013 Sep;68(9):1102-16.
  10. American College of Allergy, Asthma & Immunology [Internet]. Arlington Heights, IL: American College of Allergy, Asthma & Immunology; 2014. Available from: https://acaai.org/allergies/types-allergies/food-allergy/food-allergy-avoidance.
  11. Harvard Health Publishing [Internet]. Boston, MA: Harvard Medical School; 2020. Available from: https://www.health.harvard.edu/healthbeat/6-tips-for-managing-food-allergies.
  12. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Sep 14. Available from: https://www.mayoclinic.org/diseases-conditions/anaphylaxis/symptoms-causes/syc-20351468.
  13. Polk B., Dinakarpandian D., Nanda M., Barnes, C., Dinakar C. Association of tree nut and coconut sensitizations.Ann Allergy Asthma Immunol 2016 Oct;117(4):412-416.
  14. Wright BL, Walkner M, Vickery BP, Gupta RS. Clinical Management of Food Allergy. Pediatr Clin North Am. 2015 Dec;62(6):1409-24. doi: 10.1016/j.pcl.2015.07.012. Epub 2015 Sep 7. PMID: 26456440; PMCID: PMC4960977.
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