Tree nut allergies are a common type of food allergy that occurs when the immune system mistakenly identifies proteins in tree nuts as harmful. This can lead to various symptoms, including hives, swelling, difficulty breathing, and in severe cases, anaphylaxis. Common tree nuts include almonds, walnuts, cashews, hazelnuts, pecans, and pistachios. People with tree nut allergies must avoid all tree nuts and products containing them. It's important to read food labels carefully, as tree nuts can be found in many processed foods. Cross-contamination can also occur, so individuals should be cautious when eating out or consuming packaged foods.