Pistachio basics
Pistachio Allergy: Who Has to Tell You It's In There
Pistachio is a declarable allergen almost everywhere, but the lists do not match. We put six of them side by side: the US names twelve tree nuts, the EU eight, and Japan has never made pistachio mandatory at all.
Quick answer
A pistachio allergy is an immune reaction to the proteins in the pistachio seed, and it is grouped with the tree nut allergies. It matters more than most because of cashew: pistachio and cashew sit in the same botanical family and share three closely related storage proteins, so people who react to one very often react to the other. Most food-labeling systems require pistachio to be declared by name. The United States lists it among twelve tree nuts, the EU and UK among eight, Canada and Australia and New Zealand among nine. Japan is the exception, where pistachio has never been on the mandatory list. Symptoms range from an itchy mouth to anaphylaxis, and diagnosis belongs with a doctor rather than a home test.
A pistachio allergy is an immune reaction to the proteins in the seed of Pistacia vera, and it belongs to the group of tree nut allergies. The thing worth knowing first is not about pistachio on its own. It is about cashew. The two nuts are close botanical relatives that build nearly the same storage proteins, and an immune system that has learned to attack one will usually recognize the other.
Most countries make a food label say when pistachio is in the package. Not all of them do, and the lists they work from are different lengths. We compiled six of those lists below.
This page explains what is known and what the law says. It is not medical advice, and a suspected nut allergy is a conversation with a doctor.
What does a pistachio reaction look like?
The American College of Allergy, Asthma and Immunology lists the symptoms of a tree nut reaction as itching of the mouth, throat, eyes, skin or any other area; nasal congestion or a runny nose; abdominal pain, cramps, nausea and vomiting; diarrhea; difficulty swallowing; shortness of breath; and, at the severe end, anaphylaxis.
The NHS lists the signs that mean emergency help: the lips, mouth, throat or tongue suddenly swelling; breathing very fast or struggling to breathe; a tight throat or trouble swallowing; skin, tongue or lips turning blue, gray or pale; sudden confusion, drowsiness or dizziness; or someone fainting and not waking. In the US that is a 911 call. In the UK it is 999.
How common is it? The 2026 Diagnostics review puts pistachio allergy in the general population at roughly 1 to 2 percent, drawing on the SchoolNuts study, which found 1.6 percent among Australian adolescents, and an emergency department series in which pistachio was implicated in about 2 percent of food-induced allergic reactions. FARE reports that over 2 percent of the US pediatric population has a tree nut allergy of some kind.
Those numbers move a great deal depending on who is being counted. The same review cites Maloney and colleagues, who found that among peanut-allergic patients, 76 percent were sensitized to pistachio while clinical allergy was confirmed in only 8 percent. That gap between a positive test and an actual reaction runs through this whole subject.
Why cashew and pistachio travel together
Pistachio and cashew are both in the Anacardiaceae, the family that also holds mango, poison ivy and sumac. In FDA's own list of major allergen tree nuts they are the only two members of that family, and they are the pair with the strongest cross-reactivity in the literature.
The reason is visible in the protein registry. The WHO/IUIS Allergen Nomenclature Sub-Committee has five registered pistachio allergens. Three have a cashew counterpart doing the same job:
| Pistachio allergen | What it is | Cashew counterpart |
|---|---|---|
| Pis v 1 | 2S albumin, 7 kDa | Ana o 3 (2S albumin) |
| Pis v 2 | 11S globulin subunit, 32 kDa | Ana o 2 (legumin-like) |
| Pis v 3 | vicilin, 55 kDa | Ana o 1 (vicilin-like) |
| Pis v 4 | manganese superoxide dismutase, 25.7 kDa | none registered |
| Pis v 5 | 11S globulin subunit, acidic, 36 kDa | Ana o 2 (legumin-like) |
The 2026 Diagnostics review puts the sequence and structural homology of those paired allergens at roughly 70 to 80 percent. At that similarity an antibody raised against the cashew protein binds the pistachio one. The full dataset carries the molecular weights and the two cashew allergens, Ana o 4 and Ana o 5, that have no pistachio counterpart.
Two numbers describe what this means in a clinic, and they are very far apart. In the IDEAL study of cashew-sensitized children, 98 percent were also sensitized to pistachio, but pistachio sensitization was clinically relevant in only 34 percent of them. Roughly one child in five allergic to one of the two nuts tolerates the other. That is why the study's authors recommend a supervised food challenge instead of avoiding both on a test result. FARE, describing the same relationship from the other end, says about two-thirds of patients reactive to cashew will react to pistachio.
Pis v 1 is the component that tends to matter most. The review describes it as among the most frequently recognized, resistant to heat and to digestion, and associated with systemic reactions. Pis v 4 is rarely reported and its clinical relevance is unclear.
Heat does not solve this. The review states that most pistachio allergens are largely heat-stable and that common food processing has limited impact on allergenicity. A roasted pistachio is not a safer pistachio.
Does the label have to say pistachio?
Usually. The lists are not the same length, though, and one major economy leaves it out.
| Jurisdiction | Instrument | Tree nuts named | Pistachio |
|---|---|---|---|
| United States | FDA allergen guidance, Table 1 | 12 | Named, Pistacia vera L. |
| European Union | Reg (EU) No 1169/2011, Annex II item 8 | 8 | Named, Pistacia vera |
| United Kingdom | Annex II as retained in UK law | 8 | Named, Pistacia vera |
| Canada | Food and Drug Regulations, B.01.010.1 | 9 | Named |
| Australia and New Zealand | Food Standards Code, Standard 1.2.3 | 9 | Named |
| Japan | Food Labeling Standards | 1 mandatory, 3 recommended | Not on either list |
The full dataset has a row for every nut in every jurisdiction, with the wording each instrument uses and a source link.
Three things fall out of putting them next to each other.
Pine nut is a major allergen in the US, Canada, Australia and New Zealand, and missing from the EU and UK lists. Annex II does not mention it at all. The gap is not about pistachio, but it shows how far from settled these lists are.
Only the US and the EU pin the nut to a species. Both give scientific names. Canada, Australia, New Zealand and Japan name nuts in plain words only. That matters most for walnut, where the US separates black walnut, California walnut and heartnut from English walnut and the EU names only Juglans regia.
Japan has never made pistachio mandatory. As of February 2025 the Consumer Affairs Agency required labeling for eight specific ingredients and recommended it for 21 more, and pistachio was on neither. On 21 January 2025 the agency announced it intends to raise cashew to the mandatory list and add pistachio to the recommended one, by the end of a fiscal year that ran to March 2026. Even after that change, a recommendation is not a requirement. Japan imported about 1,850 metric tons of pistachios in 2024, 87 percent of them from the US.
What changed in the US in January 2025
FDA's fifth-edition allergen guidance shortened the tree nut list, and the reasoning is worth reading. The guidance says plainly that "there is no universally accepted botanical definition of the term 'tree nut'", and that the evidence on allergenicity "varies greatly, in quantity and quality" across the foods the term might cover. So FDA kept the nuts it says have "a robust body of scientific evidence" behind them and dropped the rest.
Twelve nuts came off: coconut, beech nut, butternut, chestnut, chinquapin, cola or kola nut, ginkgo nut, hickory nut, palm nut, pili nut, shea nut and lichee nut.
The instruction that follows is the surprising part. Nuts no longer on the list "should not be included in the 'Contains' statement" even when they are used as ingredients, because that statement is reserved for major food allergens. They still have to appear in the ingredient list by name. So a US label that warns "Contains coconut" is now doing something FDA has asked manufacturers to stop doing.
Pistachio was never in doubt. It stayed, as Pistacia vera L., and US law requires the specific nut to be declared rather than the phrase "tree nuts" on its own.
Where pistachio turns up without being obvious
Reading the ingredient list is the whole job, and a few categories make it harder.
Spirits and liqueurs. This is the real hole. EU and UK Annex II exempts nuts used for making alcoholic distillates. Separately, allergen labeling on US spirits is voluntary under 27 CFR 5.82, and the Alcohol and Tobacco Tax and Trade Bureau proposed making it mandatory in January 2025. When we audited pistachio liqueur we found most bottles publish no ingredients list at all, and one US producer roasts its pistachios in peanut oil.
Green desserts and fillings. Pistachio cream, pistachio paste, pistachio ice cream, baklava, kunafa and Dubai chocolate all normally contain pistachio, and the color is not a reliable guide either way. Several products we audited get their green from dye rather than from nuts.
Nut milks and creamers. Pistachio milk is a tree nut drink and is labeled as one. The reverse trap is more common: almond, cashew and pistachio drinks are often made on shared equipment, and precautionary wording about that is voluntary.
Mortadella and pesto. Mortadella with pistachio is a standard product, and pesto recipes substitute pistachio for pine nut freely.
Pistachio extract and flavoring, which cut both ways. Most of it contains no nut at all. Of 14 pistachio extracts and flavorings whose published composition we read in October 2026, pistachio is named in none of the 13 that disclose anything, so a nut-free one is usually findable and several brands label it that way deliberately. But the statements contradict each other across near-identical products: one declares "CONTAINS: TREE NUTS" where another declares "Tree Nut Free", and six of the 14 publish no allergen statement at all. Treat the bottle in front of you as the only evidence, and ask the manufacturer when it matters.
Getting a diagnosis
A reaction after eating pistachio is worth taking to a doctor rather than working out at home. Skin prick tests and blood tests for specific IgE both measure sensitization, which is not the same as allergy. Component testing can narrow it further by looking for antibodies to individual proteins such as Pis v 1 rather than to whole pistachio extract, and the 2026 review argues that storage-protein sensitization is more strongly associated with systemic reactions than a whole-extract result is. The oral food challenge, done under supervision, is the test that settles the question.
None of that is a reason to experiment. If you have reacted to a nut, the sensible next step is an allergist, not a bigger portion.
Methodology
We compiled the tree nut allergen lists of six jurisdictions from primary legal or regulatory text, read on 28 September 2026. The US list is Table 1 of FDA's fifth-edition allergen guidance, read page by page from the guidance PDF. The EU and UK entries are item 8 of Annex II to Regulation (EU) No 1169/2011, read from the retained text on legislation.gov.uk, because EUR-Lex returned a holding page rather than the document on the day we checked. The two texts are identical in this item. Canada is the Food and Drug Regulations as published on the Justice Laws Website. Australia and New Zealand is the Food Standards Australia New Zealand consumer guidance to Standard 1.2.3.
Japan is the one entry we could not take from primary law in English. It comes from a USDA Foreign Agricultural Service GAIN report dated 28 February 2025, which records the position at that date and the Consumer Affairs Agency's announced intention to change it. We could not confirm whether that change has taken effect, and a January 2026 trade report still described it in the future tense. The dataset records Japan's February 2025 position and the proposal, not a current status. The point that survives either way is that pistachio has never been on Japan's mandatory list.
The allergen component table is the WHO/IUIS Allergen Nomenclature Sub-Committee database, which is the body that assigns these names. We paired each pistachio allergen with the cashew allergen in the same protein family. Those pairings are ours; the registry does not make them. The homology figures, the clinical descriptions and the prevalence numbers come from the published literature and are attributed in the text to the paper that reports them, with the review cited where it collects a figure from an earlier study rather than producing it.
We did not test, measure or diagnose anything, and nothing here is medical advice. Allergen lists get revised. If a figure here is out of date, tell us through the about page and we will correct it and log the change below.
Citing this comparison
You are welcome to cite or reproduce the tables and the datasets (labeling lists, allergen components), including for commercial publication, with attribution to pistachiomilk.org and a link to this page (Creative Commons CC BY 4.0). A suggested citation:
Ricci, E. (2026). Pistachio Allergy: Who Has to Tell You It's In There. pistachiomilk.org. https://pistachiomilk.org/pistachio-allergy/
Version history: v1.0, published 28 September 2026. Six jurisdictions and ten registered allergens, as read on that date. Corrections and additions will be listed here.