A tree nut allergy is an abnormal immune response to one or more tree nuts. When a person with an allergy is exposed to certain tree nuts, their immune system launches an “attack” against the proteins in the tree nut and can even create antibodies (specifically immunoglobulin E or IgE) that target the nut proteins. This response provokes the rapid development of allergic symptoms, which can affect a variety of body systems and may be mild, moderate, or severe and life-threatening.
There are many different kinds of tree nuts, including almonds, Brazil nuts, cashews, hazelnuts, pecans, pistachios, pine nuts and walnuts. An allergy to one tree nut does not guarantee an allergy to another, but it is common for people to react to more than one tree nut. Tree nut allergies tend to develop during childhood and are usually lifelong.[1]