Peanut allergy

What it is

In a food allergy, the immune system overreacts to a food or a substance in a food.³ With peanut, that food is not actually a nut. Peanuts grow underground and belong to a different plant family, the legumes.¹ ACAAI puts it plainly: peanuts are legumes, not nuts.²

Peanut allergy is the most common food allergy in children under 18 and the third most common in adults.¹ It affects up to 2% of children, and many carry it into adulthood.¹ It is usually lifelong: only about 20 percent of children with a peanut allergy outgrow it over time.¹

Because peanuts are legumes, people often ask about beans and peas. FARE says a peanut allergy does not mean a greater chance of allergy to other legumes, although an allergy to lupine, a legume used in vegan cooking, can occur in people with peanut allergy.¹ Tree nuts are a separate matter: between 25% and 40% of people allergic to peanuts also react to at least one tree nut.²

Symptoms it causes

Peanuts can cause a severe, potentially life-threatening allergic reaction, and even very small amounts of peanut can cause a serious one.¹ Peanut and tree nut allergies are among the most common causes of anaphylaxis in the United States.² Anaphylaxis is a life-threatening reaction that affects the whole body and can impair breathing.³

FDA lists the general signs of a food allergy as hives, flushed skin or a rash, a tingling or itchy mouth, swelling of the face, tongue or lips, vomiting or diarrhea, stomach cramps, coughing or wheezing, dizziness, swelling of the throat, trouble breathing and loss of consciousness. They may appear within a few minutes to a few hours after eating.⁶

Casual skin contact with peanut is less likely to cause a severe reaction, but it can become a problem if the skin then touches the eyes, nose or mouth.¹ An allergist can test for a peanut allergy.⁴

Reading food labels

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

A packaged food that contains peanut must name it in one of two ways: in parentheses after an ingredient, or in a “Contains” statement next to or right after the ingredient list.⁵ Not every product that contains an allergen has a “Contains” statement, so FDA points readers to the whole ingredient list.⁷

Phrases such as “may contain peanuts” or “produced in a facility that also uses peanuts” 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’s own example is a cracker made on the same equipment as cookies that contain peanuts, whose label might say “may contain peanuts.” FDA calls the “may contain” statement voluntary, and not all manufacturers use it.⁷

Peanut oil follows its own rule. FALCPA’s definition of a major food allergen leaves out highly refined oils made from those foods.⁸ FDA guidance says the source of an oil, highly refined or not, generally must still appear in its name in the ingredient list, as in “soybean oil,” and the source of an oil that is not highly refined must be declared as an allergen.⁹ FARE notes that cold-pressed, expelled or extruded peanut oils are not highly refined and may contain small amounts of peanut protein.¹

Peanut also hides under other names. FARE’s list includes arachis oil (another name for peanut oil), beer nuts, ground nuts, monkey nuts, mandelonas (peanuts soaked in almond flavoring), artificial nuts, peanut flour and peanut protein hydrolysate.¹