Itchy mouth after pistachio gelato, or hives after a slice of baklava? Pistachio has gone from snack bowl to spreads, chocolate bars and pastries, and it travels with its close relative, cashew. Our test checks your blood for IgE antibodies to three single pistachio proteins, as part of 300 allergens and allergen components, so you can see whether you are sensitised to pistachio and to cashew.
The pistachio proteins that matter for allergy are storage proteins. Lab tests call them Pis v 1 (a 2S albumin), Pis v 2 (a legumin) and Pis v 3 (a vicilin). They stay stable when heated, so roasted pistachios and pistachio pastries carry them just like raw nuts.
Each of these has a close twin in cashew: Pis v 1 matches cashew's Ana o 3, Pis v 2 matches Ana o 2, and Pis v 3 matches Ana o 1. That is why the two nuts are so often linked in lab results and in the reactions people report.
People describe itching in the mouth and throat, swollen lips, hives, stomach pain or vomiting, usually within minutes to two hours of eating pistachio. Some report wheezing or feeling faint.
Swelling of the lips, tongue or throat, trouble breathing or feeling faint after eating is an emergency. Call 112 (EU) or your local emergency number. Do not wait for a test.
Pistachio and cashew belong to the same plant family. Studies of tree nut allergy find that most people who react to cashew also react to pistachio. In some studies, IgE to the cashew protein Ana o 3 was a strong pointer to reactions to pistachio as well.
A positive result shows sensitisation, not that you will react. If you have never reacted to pistachio, do not cut it out on a result alone. If you have, take the result to a doctor or allergist, who may suggest further tests.
The lab measures IgE to three single pistachio proteins (molecular components). There is no whole pistachio extract on the panel. Your lab report gives each a measured value and class, from Negative to Very high, on the same report as the three cashew proteins, so you can see the pattern for both nuts at once.
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One finger-prick sample checks IgE to 300 allergens and allergen components, from birch and peanut to cat and house dust mite. Post it to the lab, and about 5 days after it arrives you get a value for every one. Our plain-English guide shows you how to read them. €399 in total, €1.33 per allergen.
The two are closely linked. They share very similar proteins, and many people who react to one also react to the other. The test checks both in the same sample, so a doctor can see whether your antibodies recognise one nut or both.
Not usually. The main pistachio allergens are heat-stable storage proteins. Roasting, baking or grinding into a cream does not remove them.
Yes. Look out for mortadella, nougat, pistachio cream fillings, baklava, ice cream and some pesto. In the EU, pistachio must be named on the label of packaged food. Loose foods and restaurant dishes are harder, so ask.
It shows sensitisation: your blood has IgE to pistachio proteins. Whether that means a clinical allergy depends on your history. A doctor puts the two together and may suggest further tests or a supervised food challenge.
