Peanut allergy
Tingly mouth after satay, or a rash after a cereal bar you can't explain? Peanut is one of the most common food allergens in Europe, and it hides in more products than you would guess. Our test checks your blood for IgE antibodies to eight single peanut proteins, as part of 300 allergens and allergen components, so you can see whether your blood shows IgE to peanut and to which proteins.
- Group
- Food
- Also known as
- groundnut, arachis, Arachis hypogaea, monkey nut
Where you meet it
- Peanut butter, satay sauce and many South-East Asian and West African dishes
- Cereal bars, granola, chocolate bars and biscuits
- Bakery products made on shared lines ("may contain" labels)
- Groundnut oil and arachis oil, mainly cold-pressed versions
- Vegetarian and vegan products that use peanut flour or protein
What peanut is, for your immune system
Botanically, peanut is a legume, closer to peas and soy than to walnuts or hazelnuts. The proteins that matter for allergy are mostly storage proteins in the seed. Lab tests give them short names: Ara h 1, Ara h 2, Ara h 3 and Ara h 6 are storage proteins that survive roasting and digestion well. Ara h 8 is a different kind of protein that looks a lot like the main birch pollen protein.
That difference is useful. A result pattern that leans on the storage proteins is something specialists look at closely. A pattern that leans on Ara h 8 is often linked to birch pollen sensitisation and tends to be associated with milder, mouth-only symptoms. Only a doctor can put that into context for you.
What people commonly report
Reactions people describe after eating peanut range from itching in the mouth and throat to hives, swollen lips, stomach cramps, vomiting, wheezing or a drop in blood pressure. They usually start quickly, often within minutes to two hours.
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.
Sensitisation is not the same as allergy
Plenty of people have IgE antibodies to peanut and eat it without any problem. This is especially common in people with birch pollen or grass pollen sensitisation, where the antibodies recognise similar proteins rather than peanut itself.
So a positive peanut result shows sensitisation. It does not tell you that you will react, and it does not tell you how strongly. If you have never reacted to peanut, do not cut it out on the strength of a result alone. If you have reacted, take the result to a doctor or allergist, who may suggest further tests or a supervised food challenge.
How our test checks peanut
Your finger-prick sample goes to the lab, which measures IgE to eight single peanut proteins (molecular components). There is no whole peanut extract on the panel. Your lab report gives each a measured value and class, from Negative to Very high. Treat the classes as what the result pattern shows, to discuss with your doctor, not as a diet plan.
- Storage proteins: Ara h 1, Ara h 2, Ara h 3 and Ara h 6
- Ara h 8: a PR-10 protein similar to birch's Bet v 1
- Ara h 9: a lipid transfer protein (LTP)
- Ara h 15 and Ara h 18: an oleosin and a cyclophilin
- Checked in the same sample as hazelnut, soy, birch pollen and the rest of the panel
- Does not measure: IgG, food intolerance or how severe a reaction would be
Known cross-reactions
- Birch pollen
- Ara h 8 resembles the main birch protein (Bet v 1). People sensitised to birch can show peanut IgE without reacting to peanut, or with mouth-only itching.
- Soy and other legumes
- Peanut and soy are related legumes. Shared antibodies show up often in lab results, but reacting to both is much less common.
- Tree nuts
- Peanut is not a nut, but sensitisation to peanut and to tree nuts such as hazelnut often appears in the same person.
300 allergens. One test.
A finger-prick sample at home, sent by post. A detailed lab report typically 5 days after the lab receives your sample, and our plain-English guide to reading it. €300, €1 per allergen.
Questions
Can a blood test tell me if I am allergic to peanut?
It tells you whether you have IgE antibodies to peanut, which is sensitisation. Whether that means a clinical allergy depends on your history of reactions. A doctor puts the two together and, if needed, may suggest further tests or a supervised food challenge.
My result shows peanut, but I eat peanut butter without problems. What now?
That is common, often because of birch or grass pollen sensitisation. Do not change your diet on a result alone. Show the result to a doctor, who can look at which peanut proteins your antibodies recognise.
Is peanut oil a problem?
Highly refined peanut oil contains very little protein. Cold-pressed or gourmet peanut oil can contain more. If you have reacted to peanut before, ask your doctor or allergist what applies to you.
Can I test my child for peanut?
After a child's first reaction, start with a paediatrician or paediatric allergist. They can decide which tests make sense and how to read them for a child.