Pistachio Nut
Allergy Facts, Symptoms, and Treatment

Allergies to tree nuts such as pistachios 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 .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 small trees believed to be indigenous to Iran, pistachios are actually a type of seed. High in protein, fat, dietary fiber, and vitamin B6, pistachios are eaten fresh or roasted and are commonly incorporated into items such as baklava, halvah, ice cream, and a variety of other desserts.3

Pistachios and cashews share similar allergenic proteins, so those who react to pistachios may also react to cashews and vice versa.4 However, pistachio allergy is somewhat less common. Of those with tree nut allergies in the United States, for example, only an estimated 7 percent are allergic to pistachios.1 That said, in areas where pistachios are cultivated, the prevalence of pistachio allergy is twice as high as areas where cultivation isn't carried out.5

Where are pistachio nuts found?

Pistachio nuts are eaten fresh or roasted and are commonly incorporated into items such as baklava, halvah, ice cream, and a variety of other desserts. In addition, pistachios have also been used to add yellowish green coloring to confections.3

The following items may contain tree nuts and seeds:4 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.6 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:4 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 pistachio 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. The most common cross-reactivities with pistachios are plant foods, e.g., tree nuts, fruits, soybeans, vegetables, and legumes.4

Pistachios and cashews share similar allergenic proteins, so those who react to pistachios may also react to cashews and vice versa.4

If you experience an itchy mouth or ears, scratchy throat, hives on the mouth, or swelling of the lips, mouth, tongue, or throat after eating pistachios or other related fresh fruits, raw vegetables, or tree nuts, you may suffer from Pollen Food Allergy Syndrome (PFAS) also called Oral Allergy Syndrome (OAS). This condition is caused by your immune system's reaction to similar proteins, or components, found in foods and pollens.7 It is quite common, as one study suggests that up to 25 percent of children with allergic rhinitis (aka hay fever) also suffer from PFAS.9 Common pollen allergies that could cause OAS when eating pistachios include tree (e.g., birch), grass, and weed.4

*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.10-13

  • 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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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.2,6 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:6

  • Adominal 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-threatening event

Allergic reactions from tree nuts can also come from cross-reactivity to birch pollen in the form of Oral Allergy Syndrome (OAS), aka Pollen Food Syndrome (PFS) and Pollen Food Allerg Syndrome (PFAS).2,7

Symptoms of OAS can include:7

  • Itchy mouth and hives on the mouth
  • Scratchy throat
  • Swelling of the lips, mouth, tongue, and throat
  • Itchy ears


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?

Pistachio nuts consist of different types of proteins that all have different characteristics and different levels of risk for causing symptoms. Some people may tolerate pistachio if it is extensively heated (cooked/roasted), as high temperatures break down the causative proteins. For another patient, pistachio should be avoided completely since the protein is stable to heat and it could potentially cause a severe event, also called anaphylaxis. Your specific risk profile depends on which proteins in the pistachio you are allergic to.4

  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.; 2017 Aug 16. Available from: https://www.britannica.com/print/article/461822.
  4. 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.
  5. Noorbakhsh, Reihaneh & Mortazavi, Seyed & Sankian, Mojtaba & Shahidi, Fakhri & Tehrani, Mohsen & Azad, Farahzad & Behmanesh, Fatemeh & Varasteh, Reza. (2011). Pistachio Allergy-Prevalence and In vitro Cross-Reactivity with Other Nuts. Allergology international : official journal of the Japanese Society of Allergology. 60. 425-32. 10.2332/allergolint.10-OA-0222. Available from: https://www.researchgate.net/publication/51147606_Pistachio_Allergy-Prevalence_and_In_vitro_Cross-Reactivity_with_Other_Nuts.
  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/tree-nut-allergy.
  7. 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.
  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. 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.