Peanut Allergy and Tree Nut Allergy – The Facts

The peanut is a legume, related botanically to foods such as peas, beans and lentils. Tree nuts are in a different botanical category and include almonds, hazelnuts, walnuts, cashew nuts, pecans, Brazil nuts, pistachios and macadamia nuts. As the botanical category is different, many people only react to peanut and not tree nuts, and vice versa.

A key message for people with peanut or tree nut allergy is take your allergy seriously. You should visit your GP and ask to be referred to an NHS allergy clinic for a proper assessment and high-quality advice.

How common are peanut allergy and tree nut allergy?

Nut allergies are common and affect approximately 1 in 50 children and around 1 in 200 adults in the UK.

If you suspect or know you have a peanut or tree nut allergy you need to go to your GP and seek a referral to an NHS allergy clinic for a thorough assessment. This will include tests to confirm which types of nut are responsible for causing your symptoms. Your GP can locate an allergy clinic by visiting the website of the British Society for Allergy and Clinical Immunology (BSACI)

A referral is important even if your symptoms were mild because it is possible that a future allergic reaction could be more severe. According to experts you are at high risk if:

• You have had a severe reaction in the past, such as swelling in the throat, breathing difficulties (even mild) or faintness
• You have asthma as well as an allergy, particularly if that asthma requires regular use of preventer inhalers
• You have had an allergic reaction to a tiny amount of peanut or tree nut

A recent review of fatal food anaphylaxis data in the UK found that peanut and tree nut allergy are the most common known food triggers, however, the proportion of deaths due to peanut and tree nut allergy from 1998 to 2018 has decreased in the UK.

The age of the person with the allergy could be a risk factor. One study found fatal reactions to food are more likely to occur between the ages of 17-27. As young people begin to manage their allergies for themselves, they may be less cautious with regard to risk, reluctant to ask direct questions in restaurants and subject to peer pressure.

Once you have a confirmed peanut or tree nut allergy diagnosis, it is important to exclude your allergen from your diet. Read food labels carefully and question staff in restaurants, takeaways and other catering establishments. You can find more information on shopping and preparing food here.

Some people with peanut allergy may be allergic to tree nuts, and some people allergic to one tree nut may be allergic to others. Research suggests a significant number of people with cashew nut allergy are also allergic to pistachios. There is a similar link between walnut and pecan nuts. There is also the possibility of certain nuts coming into contact with others during food production. Eating nuts from the shells helps reduce the risk of cross-contamination from other nuts.

If you have an allergy to peanut or to one type of tree nut, it is important to have allergy testing for other nuts so your allergy specialist can advise on including them in your diet. Research suggests it is important to include nuts you are not allergic to in your diet, as this helps to maintain tolerance and avoid developing an allergy to those nuts in the future. Introduction of other nuts must only be done as advised by your allergy specialist, after allergy testing.

Legumes: Peanuts are actually legumes. A small number of people with peanut allergy may react to other legumes (such as soya, peas, chickpeas, fenugreek, beans and lentils). One research study found 5% of children with a legume allergy reacted to more than one legume.

Lupin: Lupin is a legume. Studies have shown that some people with peanut allergy react to lupin.

Sesame seeds: A US study found children with a history of reactions to both peanuts and tree nuts were more likely to have allergic reactions to sesame. A recent European study also found a link between peanut, tree nut and sesame seed allergy.

Other foods: People with nut allergy frequently ask if they should avoid certain foods with “nut” in the name – even those that are botanically different to tree nuts. These include pine nuts, coconut, nutmeg and chestnut.  If you are allergic to nuts and have never had a reaction to any of these foods, it is likely that they are safe for you to eat.

Your allergy specialist will be able to give you specific advice regarding which foods you should avoid.

Some people with peanut allergy report that they experience symptoms when peanut snacks are handed out to passengers with their drinks during air travel. The most likely cause of these reactions is skin contact. If you touch a fold-down tray or another surface that has previously been touched by a passenger eating peanuts, and then touch your eyes or mouth, you could have a reaction. To minimise the risk, carry “wet wipes” to clean surfaces as soon as you get on the plane.

A recent review paper says: “Studies have shown that peanut does not easily become airborne, and this is not a likely route of exposure. Peanut dust on unwashed surfaces that becomes inadvertently ingested, or false presumption that a food is safe that actually contains peanuts are the 2 most likely sources of potential peanut exposure in flight.”

However, you must be guided by your doctor or allergy specialist, and your allergy history. If you know you are at the high end of the risk scale (for example, you have reacted by inhaling peanut allergen in the past) then it would be sensible to contact the airline well in advance to request that peanuts are not distributed on your flight.

There have been major advances in the development of treatments for peanut allergy including oral immunotherapy, epicutaneous immunotherapy (skin patches) and peanut allergy vaccine. Click here to read our Allergen Immunotherapy factsheet for further information and keep an eye on the Latest News section of our website for any development updates.