The following information is intended to help people with allergy to walnuts to manage the condition successfully. The information is intended as general guidance. If you know or believe you are allergic to walnuts, it is important to visit your GP and seek a referral to an allergy clinic.
General information
Allergy to walnuts can be one of two types.
The first type is considered to be a primary food allergy, where a person becomes allergic to walnuts through direct contact with them, or contact with products derived from walnuts such as walnut oil. This type of allergy has the potential to cause a severe, life-threatening allergic reaction (anaphylaxis), which includes breathing difficulty.
The second type of walnut allergy can be considered a secondary food allergy. A person with this type of allergy is initially allergic to pollen, and then starts reacting to walnut. This happens because of a process called cross-reactivity — where a protein found in pollen has similarities with a protein found in walnuts and therefore some people react to walnut. These reactions are usually mild and include itching or swelling in the mouth. This is known as pollen food syndrome (previously oral allergy syndrome). People affected may also have mild reactions to hazelnuts, almonds, certain kinds of pipped fruit (such as apples) stoned fruits (such as peaches, cherries) and raw vegetables (such as carrots and celery). Only a minority of all those people with walnut allergy have secondary walnut allergy.
It is important that you know which of the two types of walnut allergy you are affected by. Discuss this with your allergist.
Avoiding other nuts
People who are allergic to walnuts are commonly allergic to pecan nuts as well and may be advised to avoid both. It is possible you could also be allergic to other nuts including Brazils or cashews. So is it best to avoid all nuts if you are allergic to one or two of them?
Some allergy experts would indeed advise that total avoidance is best in order to play safe. But others disagree. One study states: “In peanut or tree nut allergic children, introduction of specific nuts to which the child is not allergic may improve quality of life and should be considered in patients with multiple foods allergies, vegan or ethnic-specific diets, in whom nuts are an important source of protein.”
Our advice is that it depends what tests you have had. If you have been tested for specific nuts, your doctor or allergist will be able to advise whether it is possible to include certain nuts in your diet. If you do eat specific nuts, it is usually advisable to do so at home so you can better control any risk of cross-contamination. Eating nuts from the shells avoids the risk of cross-contamination from other nuts.
If you have not been tested for specific nuts, then we believe in playing safe — avoiding all nuts — until you are able to be tested.
Where used
Walnuts can be eaten raw and are used in cakes, bread, biscuits, muesli, confectionery and ice cream. Walnut butter can be found in supermarkets and whole food shops. Walnuts are used in some brands of Worcester sauce.
Nuts are a common feature of Oriental cooking.
Oils
Walnut oil is normally used for its flavour and so should be assumed to be unrefined and therefore unsuitable for people with walnut allergy. It is used as a salad oil or drizzled on to grilled food.
Medicines, soaps, cosmetics and personal care products sometimes contain nut oils. It is difficult to determine the level of risk posed by these products, so we advise playing safe and avoiding them. Labels may show ingredients in Latin (the Latin name for walnut is Juglans regia. Variations include Juglans nigra).
Links
Allergy to peanuts and tree nuts Factsheet
Reviewers
This article has been reviewed by Dr Gary Stiefel, Consultant in Paediatric Allergy, University Hospitals of Leicester NHS Trust.
Dr Stiefel has no relevant disclosures.
All the information we produce is evidence based or follows expert opinion and is checked by our expert Clinical and research reviewers. If you wish to know the sources we used in producing any of our information products, please let us know, and we will gladly supply details.
Publication date: September 2018
Review date: September 2021
