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A walnut allergy is an allergy, known scientifically as Juglan recia, to walnuts, a type of tree nut produced by walnut trees. An allergy is an adverse reaction by the body's immune system to a certain component of some foods. Certain proteins present in walnuts and other foods are thought to cause allergic reactions which can range from mild to life threatening and in severe cases result in death. Walnuts usually must be ingested to trigger an allergic reaction in people suffering from this type of allergy but in severe cases the reaction may be triggered by merely inhaling the aroma of walnuts.
Via a mechanism that is not entirely understood, the immune system mistakes some component of a food as a harmful substance and produces and releases antibodies to attempt to negate the perceived threat. These antibodies will also trigger the release of a class of chemicals from called histamines. The presence of histamines is responsible for most of the symptoms of allergies.
When a person has a mild food allergy, such as a walnut allergy, the symptoms may be minor enough to go unnoticed or may not be attributed to an allergic reaction at all. Some people may experience no more than a slight itchiness or dryness of the throat or eyes. Common symptoms of a walnut allergy include hives, rashes, swelling of the face, throat or extremities, and, in severe cases, difficulty breathing and anaphylactic shock. People with a walnut allergy may experience one or more of the symptoms listed above. Most minor allergic reactions may be treated with over the counter antihistamine medications, but severe reactions may require emergency treatment with a drug such as epinephrine or hospitalization.
Anaphylactic shock is a life-threatening allergic reaction which may be triggered by the ingestion of even a small amount of the allergen. It causes the body to go into a state of shock with a drastic and almost immediate drop in blood pressure and can cause a complete disruption of normal respiration due to swelling of the throat and other airways. A person suffering from anaphylactic shock can die from suffocation as they lose the ability to breathe.
Allergies to tree nuts, such as walnuts, affect approximately 1.2% of all people. About 9% of children with walnut allergies outgrow them as they get older, usually by six years of age. Often, someone who suffers from an allergy to one type of tree nut may also be allergic to other types of tree nuts, particularly pecans or almonds, although this is not always the case.