Allergy testing
Nut allergy component testing
Blood tests that separate dangerous nut allergy from mild cross-reactivity - often changing the advice a family lives by.
Key facts
At a glance
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Why components: whole-nut tests cannot tell severe storage-protein allergy from mild pollen-related reactions; component tests can.
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Key markers: Ara h 2 (peanut), Cor a 14 (hazelnut), Jug r 1 (walnut) and Ana o 3 (cashew) flag higher-risk allergy patterns.
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Preparation: none - a standard blood sample, unaffected by antihistamines.
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Results: typically within one to two weeks privately.
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Follow-up: a consultant allergist translates the pattern into practical advice - avoidance scope, adrenaline pens, and whether a supervised challenge is worthwhile.
The full picture
What this test involves, and how to get it
Nut allergy component testing measures antibodies against individual proteins within peanuts and tree nuts, and the distinction it draws is genuinely consequential. Antibodies to seed storage proteins - Ara h 2 in peanut, Cor a 14 in hazelnut, Jug r 1 in walnut, Ana o 3 in cashew - point to stable, potentially severe allergy. Antibodies only to pollen-related proteins usually mean mild mouth itching in birch-allergic people, with cooked and processed forms often tolerated. Two patients with identical whole-peanut test results can therefore receive opposite advice once components are known.
The test needs one blood sample, works regardless of antihistamines, and returns within a week or two privately. It is most valuable when whole-nut results are ambiguous, when deciding whether all tree nuts must be avoided or only one, before considering a supervised food challenge, and in teenagers renegotiating the rules they grew up with. NHS specialist centres use component testing routinely but referral waits can be long; private allergy clinics can arrange blood work within days, with a consultant appointment to interpret the pattern - which matters, because component results are precisely the sort of nuanced data that should never be self-interpreted from a lab report.
A quiet reminder
This guide is for information, not medical advice.
Your own clinician knows your history and can tell you which parts apply to you. Next review of this page: 2027-09-27.
Frequently asked
Common questions about Nut allergy component testing.
Quick, plain-English answers to what people ask us most.
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What is Nut allergy component testing?
Nut allergy component testing is a blood test that measures a specific substance or marker in your blood, giving your doctor useful information about how a particular system in your body is functioning. It is one of many tools used alongside your symptoms and history to build a fuller clinical picture. Your doctor can explain exactly why it is relevant in your case.
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Why would a doctor order Nut allergy component testing?
This test is typically requested to investigate specific symptoms, monitor an existing condition, or check for a deficiency or imbalance that could explain how you are feeling. It may also be used as part of a broader panel of related tests rather than in isolation. The result helps guide whether further tests, treatment, or simple monitoring is appropriate.
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Do I need to prepare for this test?
Some blood tests require fasting, a specific time of day, or pausing certain medications or supplements beforehand, while others need no special preparation at all. You will usually be told what applies to your specific test when it is booked. If you are unsure, it is worth checking with the clinic or lab in advance.
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What happens during the test?
A small blood sample is taken, usually from a vein in your arm, in a process that takes only a few minutes. It is generally straightforward and similar to any other routine blood draw. You can normally return to your usual activities straight afterwards.
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Does this test hurt or carry any risks?
A standard blood draw involves brief discomfort from the needle but is otherwise low-risk. Minor bruising at the site is the most common side effect and usually settles quickly. Let the person taking your sample know if you have a needle phobia or have had problems with blood tests before, as they can help make it more comfortable.
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How long do results take?
Results are typically available within a few days, though turnaround can vary depending on the specific test and laboratory used. You will usually be told when and how to expect your results at the time of testing. More specialised tests may occasionally take longer.
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What do abnormal results mean, and what happens next?
An abnormal result can have several possible explanations, from common and benign causes to conditions that need further assessment, and is best interpreted by a doctor alongside your symptoms and history. Depending on the finding, next steps might include repeating the test, further investigation, or referral to a specialist. Try not to draw firm conclusions from a number alone before speaking to a clinician.
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Is this test available on the NHS, or is it better to go private?
This test can often be arranged privately within days, with results reviewed by a specialist, whereas routine NHS access may depend on your GP agreeing it is clinically indicated and can involve a longer wait. Cost for private testing varies by provider. Many people choose the private route for speed and convenience, particularly if they are self-funding for reassurance rather than an urgent clinical concern.
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Is this test accurate and reliable?
Blood tests like this are well established and generally reliable when carried out by an accredited laboratory. Results can occasionally be affected by factors such as timing, recent illness, medication, or hydration, which is why doctors interpret a single result in context rather than in isolation. If a result seems unexpected, repeating the test is sometimes recommended.
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How do I book this test privately, and how quickly can I be seen?
You can typically book privately with or without a GP referral, and appointments, including blood draw and results review, are often available within a few days. A doctor will explain what your result means and advise on any next steps.