When you’re allergic to peanuts or tree nuts, even a small amount can cause a severe allergic reaction. Peanuts aren’t true nuts (they’re a legume, just like beans and lentils), but their protein structure is similar to tree nuts and they’re one of the most common food allergens. And because the protein structure is similar, folks allergic to peanuts are often allergic to tree nuts, such as almonds, walnuts, pecans, hazelnuts, macadamia nuts, filberts, pine nuts, pistachios, cashews and Brazil nuts.
Allergic reactions occur when the nut protein alerts the body’s immune system to protect itself; it does so by releasing chemicals like histamine. These chemicals cause symptoms that vary from person to person, but typically include wheezing and coughing, problems breathing, anaphylaxis, throat tightness, stomach cramps, vomiting, diarrhea, itchy, watery and/or swollen eyes, hives and a drop in blood pressure. One person can actually react to the same food differently at different times.