Many people fear nut allergy more than any other food allergy, with good reason: Peanut and tree nut allergies cause the highest number of fatal and near-fatal allergic reactions, according to the National Institute of Allergy and Infectious Diseases. Peanuts actually belong to the legume family, but many people with peanut allergy also react to tree nuts, such as walnuts, hazelnuts and pistachios. Unlike many food allergies, nut allergies often last a lifetime. Symptoms of nut allergy are similar to -- but sometimes more severe than -- other food allergies.
Skin changes are the most common manifestation of allergic reaction to nuts. Skin reactions, which generally appear within a few minutes to several hours and can last up to several days, include rashes, reddening of the skin or urticaria -- the medical term for hives. Other skin reactions or mucus membrane reactions can occur, including conjunctivitis, or red, watering eyes; itching and swelling, especially around the eyes; or runny nose. In up to 81 percent of people who are allergic to nuts, the reaction will affect more than one body system, according to a report in the February 2012 issue of "Immunology and Allergy Clinics of North America."
Nut allergy symptoms are often felt along the entire gastrointestinal, or GI, tract. Gastrointestinal symptoms of an allergic reaction can occur immediately or within several hours after ingestion. Those that tend to occur quickly include swelling of the lips, tongue and palate. Itching of the mouth and throat also are noticed soon after the tissues come into contact with nuts. Abdominal pain, vomiting and diarrhea may occur either minutes or hours after eating nuts.
Respiratory symptoms are common after with contact with nuts in allergic individuals. The onset of breathing problems is rapid. Symptoms range from sneezing to wheezing and rapid breathing, feelings of tightness and pain in the chest and the sensation of not being able to get enough air. A person experiencing respiratory distress during a severe attack may notice physical symptoms such as flared nostrils; a bluish color to the skin from lack of oxygen, called cyanosis; and retraction -- a sucking in of the skin over the trachea -- between the ribs or below the breastbone.
The most serious of the allergic reactions, anaphylaxis, occurs when the circulatory system collapses, causing blood pressure to fall and blood flow to organs to decline suddenly. Anaphylaxis often develops very quickly after a severely allergic person comes into contact with nuts, usually within minutes and almost never after 2 hours. An anaphylactic reaction may be preceded by a sense of impending doom. In addition to skin, respiratory and GI reactions, the person suffering anaphylaxis will experience heart and lung problems. These may include cardiovascular system collapse with possible abrupt loss of function. The first symptom of anaphylaxis may be feeling faint or losing consciousness.
Seeking Medical Attention
Food allergies can develop even if you have eaten a food before without a reaction. Seek immediate medical attention if you develop breathing problems or symptoms of anaphylaxis after exposure to nuts. If you develop milder symptoms, such as a rash, or GI problems after eating nuts, your next reaction could still be more severe. Any symptoms of allergy that you notice should prompt a call to your doctor.