A food allergy results when the immune system mistakenly targets a harmless food protein – an allergen – as a threat and attacks it. Unlike other types of food disorders, such as intolerances, food allergies are “IgE mediated.” This means that your immune system produces abnormally large amounts of an antibody called immunoglobulin E — IgE for short. IgE antibodies fight the “enemy” food allergens by releasing histamine and other chemicals, which trigger the symptoms of an allergic reaction.
Although nearly any food is capable of causing an allergic reaction, only eight foods account for 90 percent of all food-allergic reactions in the United States. These foods are: Peanut, Tree nuts, Milk, Egg, Wheat, Soy, Fish, Shell fish.
An allergic reaction to food can affect the skin, the gastrointestinal tract, the respiratory tract, and, in the most serious cases, the cardiovascular system. Reactions can range from mild to severe, including the potentially life-threatening condition known as anaphylaxis. In the U.S., food allergy symptoms send someone to the emergency room every three minutes.
Symptoms typically appear within minutes to several hours after eating the food to which you are allergic.
Mild symptoms may include one or more of the following:
- Hives (reddish, swollen, itchy areas on the skin)
- Eczema (a persistent dry, itchy rash)
- Redness of the skin or around the eyes
- Itchy mouth or ear canal
- Nausea or vomiting
- Stomach pain
- Nasal congestion or a runny nose
- Slight, dry cough
- Odd taste in mouth
- Uterine contractions
Severe symptoms may include one or more of the following:
- Obstructive swelling of the lips, tongue, and/or throat
- Trouble swallowing
- Shortness of breath or wheezing
- Turning blue
- Drop in blood pressure (feeling faint, confused, weak, passing out)
- Loss of consciousness
- Chest pain
- A weak or “thread” pulse
- Sense of “impending doom”
Anaphylaxis is a severe allergic reaction that occurs very rapidly. During anaphylaxis, allergic symptoms can affect several areas of the body and may threaten breathing and blood circulation. Food allergy is the most common cause of anaphylaxis. People who have both asthma and a food allergy are at greater risk for anaphylaxis.
Epinephrine is a medication that can reverse the severe symptoms of anaphylaxis. It is given as a “shot” and is available as a self-injector, also known as an epinephrine auto-injector, that can be carried and used if needed. Epinephrine is a highly effective medication, but it must be administered promptly during anaphylaxis to be most effective. Delays can result in death in as little as 30 minutes. Even if epinephrine is administered promptly and symptoms seem to subside completely, the individual who was treated with epinephrine should always be taken to the emergency room for further evaluation and treatment.
Proper diagnosis of a suspected food allergy should always be evaluated and treated by a board-certified allergist. The first step to diagnose a food allergy is a thorough medical history with questions to determine if food allergy may be causing your symptoms and to identify the culprit food(s) followed by a physical exam.
Next, the allergist may conduct tests to help identify a food allergy. While these tests alone do not always provide clear-cut answers, the allergist will combine your test results with the information given in your medical history to provide a diagnosis. These tests may include:
- Skin prick test (which is the most accurate and preferred method of evaluating allergies)
- Blood allergy testing
- Oral food challenge (this should only be performed by a board certified allergist who is specially trained)
- Atopy patch testing
- Trial elimination diet
The most important treatment for food allergies is a proper diagnosis and strict avoidance of the food allergen to prevent an allergic reaction. Currently, there is no cure for food allergies.
Mild to moderate symptoms (e.g., itching, sneezing, hives and rashes) are often treated with antihistamines and oral or topical steroids.
For patients at risk of experiencing a severe reaction (anaphylaxis), epinephrine is prescribed. Epinephrine is the only medication that can reverse the symptoms of anaphylaxis. It is available in an auto-injector (Auvi-Q™, EpiPen® or Adrenaclick®). If prescribed, use epinephrine at the first sign of an allergic reaction and go to the emergency room for further treatment, even if symptoms appear to resolve after epinephrine is administered. It is important to be trained on how to properly use the auto- injector and to carry it with you wherever you go.