A nut allergy is an immune system reaction that occurs when the body mistakenly identifies proteins in nuts as harmful. This can lead to symptoms ranging from mild reactions, such as hives or stomach upset, to severe anaphylaxis, which can be life-threatening. Common nuts that trigger allergies include peanuts, walnuts, almonds, and cashews. People with a nut allergy must avoid all forms of nuts and products containing them. It's important to read food labels carefully, as nuts can be hidden in many processed foods. In some cases, individuals may also need to carry an epinephrine auto-injector for emergency treatment.