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 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.
Cashew allergy goes with pistachio allergy. 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.