What is one of the major food allergens?

One of the major food allergens is peanuts. Peanuts are a type of legume that is related to beans, lentils, and soybeans. They are a common ingredient in many foods, such as peanut butter, candy, and cookies. Peanuts can cause a severe allergic reaction in some people, even if they only come into contact with a small amount. Symptoms of a peanut allergy can include hives, swelling, difficulty breathing, and anaphylaxis.