Food Allergies

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Allergic reactions to foods usually occur while eating or within minutes to a few hours of eating the offending food. Signs and symptoms of food allergy can involve the nose, lips, mouth, throat, skin, lungs, and digestive system either individually or in combination. Although the symptoms below are common in allergic reactions, Food Allergies are not the only cause of these symptoms. For example, a reaction might occur as a result of eating spoiled food. Because allergic reactions to foods can be life threatening, it is important to see a doctor if you suspect that you have a food allergy.

Skin symptoms include itching, swelling, flushing, and hives.

Gastrointestinal (digestive) symptoms include tingling and burning of the lips, mouth, and throat; and nausea, vomiting, abdominal pain, and diarrhea.

Respiratory symptoms include nasal congestion, runny nose, sneezing, throat swelling, wheezing, and/or difficulty breathing.

Anaphylactic reactions to food are rare but life threatening. If a person is thought to be having an allergic reaction and has trouble breathing or has a reaction that is rapidly worsening, seek emergency medical assistance immediately. If the person has a self-injectable epinephrine device on hand, epinephrine should be given, and then 911 should be called right away.


Allergic reactions to food can vary from mildly annoying to life threatening. A small number of highly allergic individuals are susceptible to a life-threatening allergic reaction known as anaphylaxis. Symptoms usually appear rapidly—within seconds or minutes—of exposure to an allergen, although in a few cases, reactions have been delayed by several hours.

Skin contact with an offending food usually results in local itching, redness, and swelling, and rarely causes anaphylaxis. Typically, anaphylaxis occurs after eating the food. For those with exquisite sensitivity, ingesting even minute amounts of the food, such as traces left on utensils or cooking equipment, can cause a reaction. Foods most commonly associated with anaphylaxis are peanuts, seafood, tree nuts and, in younger children particularly, eggs and cow's milk.

In anaphylaxis, specialized cells of the immune system release massive amounts of chemicals—particularly histamine. Multiple parts of the body can be affected:

  • The skin is commonly involved. Flushing, itching, hives, swelling, or a generalized sensation of warmth may develop.
  • A loss of fluid from blood vessels can lead to a drop in blood pressure, causing the individual to feel lightheaded or even lose consciousness.
  • Anaphylaxis can cause swelling of tissue that results in obstruction of the nose, mouth, and throat. Individuals may first notice hoarseness or a lump in the throat. If the swelling of the airway is severe, the individual can have difficulty breathing.
  • Muscles surrounding the airways in the lungs can constrict and mucous glands in the lungs can release large amounts of mucus, causing chest tightness, shortness of breath, and wheezing.
  • The gastrointestinal tract is often involved in the reaction when an allergen is ingested. The person may experience nausea, vomiting, abdominal cramping, and diarrhea.
  • Women may experience pelvic cramps because of contractions of the uterus.

If you suspect that an anaphylactic reaction is occurring, administer epinephrine by injection into the muscle of the outer thigh if available and immediately seek medical help. Treatment must begin before blood pressure and breathing problems become life threatening, and early intervention can be lifesaving.

Last reviewed on 11/6/09

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