Tree nut allergy

What it is

Tree nuts range from the familiar almond, cashew and walnut to the less familiar pine nut and lichee nut.¹ The six tree nut allergies most often reported by children and adults are to walnut, almond, hazelnut, pecan, cashew and pistachio.²

An allergy to tree nuts is one of the most common food allergies.¹ It affects over 2% of children, and many carry it into adulthood.² It usually lasts a lifetime: fewer than 10 percent of people with a tree nut allergy outgrow it.¹

Peanuts are legumes, not nuts, but the two allergies often overlap. Between 25% and 40% of people allergic to peanuts also react to at least one tree nut.¹ Tree nuts also overlap with each other. About 50% of children allergic to one tree nut are allergic to another, and about two-thirds of people who react to cashew or walnut also react to pistachio or pecan, respectively.²

Symptoms it causes

Symptoms can include stomach pain, cramps, nausea and vomiting, diarrhea, difficulty swallowing, itching of the mouth, throat, eyes or skin, a stuffy or runny nose, and shortness of breath.¹ Reactions can be mild or very severe.² FDA notes that a mild reaction does not always mean the allergy is mild.⁶

Allergies to tree nuts and peanuts are among the most common causes of anaphylaxis in the United States.¹ Anaphylaxis is a life-threatening reaction that affects the whole body and can impair breathing.³ An allergist can test for food allergies.⁴

Reading food labels

Tree nuts are a major food allergen under US law. The Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) named eight major food allergens, tree nuts among them, and the FASTER Act made sesame the ninth, effective January 1, 2023.⁵

A packaged food must name the allergen in parentheses after an ingredient, or in a “Contains” statement next to or right after the ingredient list.⁵ For tree nuts, the law requires the name of the specific type of nut.⁸ FDA guidance says the general term “tree nuts” is not enough: the label must say, for example, almonds, pecans or walnuts, and the singular form, such as “almond,” is acceptable.⁹

Under FDA’s current guidance, only 12 tree nuts are major food allergens: almond, black walnut, Brazil nut, California walnut, cashew, filbert or hazelnut, heartnut (Japanese walnut), macadamia nut (bush nut), pecan, pine nut (pinon nut), pistachio, and English or Persian walnut.⁹

Coconut is no longer on that list. Neither are beech nut, butternut, chestnut, chinquapin, cola or kola nut, ginkgo nut, hickory nut, lichee nut, palm nut, pili nut and shea nut.¹⁰ FDA says these nuts should not be included in a “Contains” statement, even when they are used as ingredients, but they must still be listed by name in the ingredient list, unless an exemption applies.¹⁰ FDA expects a transition period, so some products with a long shelf life may still list coconut in a “Contains” statement for a few years.¹⁰

Phrases such as “may contain walnuts” or “produced in a facility that also uses walnuts” are advisory statements. FDA says they are not required by law. Manufacturers can use them for cross-contact that cannot be avoided, but only if they follow good manufacturing processes and have taken every precaution to avoid it, and the statements must be truthful and not misleading.⁵ FDA calls the “may contain” statement voluntary, and not all manufacturers use it.⁷

Tree nuts can also turn up outside the snack aisle. Tree nut oils, which may contain nut protein, are found in some lotions, hair care products and soaps, and some alcoholic drinks may contain nuts or nut flavoring.¹ FARE’s list of ingredient names that point to tree nuts includes gianduja, marzipan or almond paste, nut butters, nut milks, nut oils, pesto and praline.²