Tree nut allergy

Group of nuts that includes hazelnut, almond, brazil nut, cashew, pecan, pistachio, walnut and macadamia. Definition of nut is actually a bit complicated, to do with whether the shell comes off spontaneously or not, but I stick to those defined by food labelling law.

Does not include peanut (a legume), coconut, pine nut, chestnut or tiger nut. You can be allergic to these as well, of course.

You can be allergic to just one, a couple or the whole lot. Risk of allergy to peanut is higher than if you weren’t allergic to anything.

Hazelnut and cashew allergies are common. Almond rare.

Hazelnut allergy goes along with fruit allergy and oral allergy syndrome.

Cashew allergy goes with pistachio allergy (OR for being allergic to both 575). Cashew allergy is particularly associated with anaphylaxis, even more so than peanut (but less common as allergy and allergen so less well known).

Pecan allergy goes with walnut allergy (OR 150).

Hazelnut goes with macadamia (OR 56.2).

Cross reactivity table
Correlation coefficients – Brough, JACI 2020

Diagnosis and management as per Gary Stiefel BSACI guideline.

[Helen Brough, JACI 2020]