Nut allergy is a type of foo allergy. It is a hypersensitivity to dietary substances from tree nuts causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people. Nut allergy is slightly different than peanut allergy inasmuch as the type of nuts that cause the allergic reactions are not the same. Peanuts are considered legumes whereas tree nuts are considered dry fruits. The symptoms of peanut allergy and nut allergy are the same, but a person with peanut allergies may not necessarily also be allergic to tree nuts, and vice versa.