What Is a Food Allergy?
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 a food intolerance a true food allergy is “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. The symptoms may be mild (rashes, hives, itching, swelling) or severe (trouble breathing, wheezing, loss of consciousness). A food allergy can be fatal.
Food allergy is a serious and potentially life-threatening condition affecting 32 million Americans. Food allergies affect an estimated 8% of children in the United States, that’s 1 in 13 children, or about 2 students per classroom. Food allergy has increased among U.S. children over the past 20 years, with the greatest increase in Black children. Family history appears to play a role in whether someone develops a food allergy. If a child’s parents have a food allergy, their children are at an increased risk. Also, if you have other kinds of allergic reactions, like eczema or allergic rhinitis, you have a greater risk of food allergy.
Food allergy symptoms are most common in infants and children, but they can appear at any age. You can even develop an allergy to foods you have eaten for years with no problems. Studies over the past several years have suggested that adult-onset food allergies are more prevalent than previously thought.
Although nearly any food can cause an allergic reaction, eight foods account for 90 percent of all food-allergic reactions in the United States. These foods are: peanuts, tree nuts, milk, eggs, wheat, soy, fish, and shellfish. Sesame was recently added as the ninth most common type of food allergy.
The foods most associated with food allergy in infants and children are: milk, eggs, peanuts, tree nuts, soy and wheat.
The most common food allergens in adults are: peanuts, tree nuts, fish, shellfish, fruit and vegetable pollen (oral allergy syndrome).
Milk, egg, wheat, and soy allergies are often outgrown. Most people do not outgrow peanut, tree nut, fish, and shellfish allergies.
Symptoms of food allergies can vary from person to person and from reaction to reaction. Reactions can also differ by episode, making diagnosis and management of food allergies difficult. Symptoms can range from mild to severe and usually appear within minutes of eating the food, though they can sometimes occur hours later.
Each of the symptoms can occur alone or in combination with other symptoms. In a severe reaction, symptoms may appear, in combination, from different areas of the body.
Symptoms of a mild allergic reaction may include:
- Itchy or runny nose, sneezing
- Itchy or tingling sensation in the mouth
- A few hives, mild itching of skin
- Mild nausea or discomfort
More severe symptoms include:
- Hives over large area of the body
- Shortness of breath, wheezing, repetitive cough
- Swelling of tongue or lips
- Hoarse, tightness in throat, trouble breathing or swallowing
- Pale/blueish appearance, faint, dizzy
- Stomach discomfort such as abdominal cramps, diarrhea, vomiting
- Feeling of impending doom
The most severe allergic reaction is anaphylaxis — a life-threatening whole-body allergic reaction that can impair your breathing, cause a dramatic drop in your blood pressure, and affect your heart rate. Anaphylaxis can come on within minutes of exposure to the trigger food and can be fatal if not treated promptly with an injection of epinephrine (adrenaline). Food allergy is the most common cause of anaphylaxis, although several other allergens — insect stings, medications, or latex—are other potential triggers.
Oral Food Allergy Syndrome
Many patients with pollen allergy specifically to trees and weeds experience mouth and throat itching when eating some fresh fruits and vegetables. For example, a patient who is allergic to tree pollen may experience mouth itching when eating apples. Patients with ragweed allergy may experience mouth itching from eating melons and bananas. The list of tree/weed and fruit/vegetable cross reactivity is long. It is important to tell your allergist if you experience any of these symptoms.
Studies show that nearly half of presumed food allergies are not true allergies. That is why an accurate diagnosis is essential. Our board-certified allergists have special training and experience and utilize the following in making a food allergy diagnosis:
- Your history of symptoms
- Physical exam
- Allergy testing
Often the food causing the reaction may not be obvious. At Atlanta Allergy & Asthma, we may use more than one type of test to diagnose food allergy. Allergy skin prick testing, blood tests, and when appropriate, oral food challenges are utilized to confirm a diagnosis. Additionally, we are now able to conduct component testing for peanut allergic patients to determine the risk of having a severe reaction.
Allergy skin testing is the most accurate and preferred method of evaluating allergies. These tests are safe, minimally invasive, and easily interpreted. There are times when an oral food challenge is performed to confirm a specific food allergy diagnosis. This should be done in a medical facility by staff who is specially trained in this procedure. It is very important that a patient suspecting a food allergy be treated by an expert in the field, like the board-certified allergists at Atlanta Allergy & Asthma.
Food allergy is both over, and under, diagnosed. The most important aspect of treatment for food allergy is an accurate diagnosis. Although there is no cure, there have been significant advancements in the research and therapies for food allergy, specifically peanut allergy.
In early 2020, the U.S. Food and Drug Administration approved the first drug for treatment of peanut allergy for children. The therapy is indicated for patients 4–17 with a confirmed diagnosis of peanut allergy. This prescription medication, derived from peanuts, can minimize the risk of severe allergic reaction, including anaphylaxis, in the event of an accidental peanut exposure. For more information, see our PALFORZIA FAQ (or download our FALFORZIA FAQ printable version).
All patients with a confirmed diagnosis of food allergy must practice strict avoidance of the allergy-causing food. This is the ONLY way to prevent a reaction. Every patient should read labels on packaged foods and ask friends and family what ingredients they have used when preparing meals. Do not eat foods from a buffet if you cannot identify all ingredients and do not be shy in restaurants. Always make the servers and chef aware of your specific allergies.
It is critical that patients with food allergy carry injectable epinephrine and that they are taught in the allergist's office how to use it correctly. Of the reported cases of fatal anaphylaxis to peanut, delay in the use of injectable epinephrine was the number one cause for the fatal outcome.
Epinephrine (adrenaline) is the first-line treatment for anaphylaxis, Anaphylaxis can occur within seconds or minutes of exposure to the allergen, can progress quickly and can be fatal. Food allergy patients must be prepared for accidental ingestion by ALWAYS carrying self-injectable epinephrine.
Administer epinephrine immediately if you experience severe symptoms such as shortness of breath, trouble breathing or swallowing, throat tightness, repetitive coughing, weak pulse, hives, or a combination of symptoms from different body areas, such as hives, rashes or swelling on the skin coupled with vomiting, diarrhea, or abdominal pain.
There are several forms of auto-injectable epinephrine: EpiPen, EpiPen Jr. AUVI-Q, SYMJEPI, and several generics of Adrenaclick, EpiPen and EpiPen Jr. No matter your choice, make sure you and those close to you are trained and comfortable with how to use your device.
Injectable Epinephrine Options and Training Videos
- Epinephrine Options and Training by Food Allergy Research & Education
- What Are Your Options for Injectable Epinephrine Devices? by Kids with Food Allergies: A Division of the Asthma & Allergy Foundation of America
If epinephrine is used, proceed to the nearest emergency room or urgent care center for observation. The benefits of epinephrine may only last 15–20 minutes, which means the reaction can reappear. Always have two doses available, as the severe reaction can recur in about 20 percent of individuals. There is no way to predict who will need a second dose of epinephrine, so this recommendation applies to everyone diagnosed with a food allergy. If you are uncertain whether a reaction warrants epinephrine, use it immediately; the benefits of epinephrine far outweigh the risk of a dose that may not have been necessary.
Can Food Allergies Be Prevented?
In the case of peanut allergy, the National Institute for Allergy and Infectious Disease (NIAID) issued new guidelines in 2017 in order to define high, moderate and low-risk infants for developing peanut allergy. Research now tells us that early introduction of peanut can help prevent the development of peanut allergy. The guidelines also address how to proceed with introduction based on risk. More information on when and how to introduce peanut-containing foods to infants.
Food Allergies Over Time
Food allergy is among the diseases considered to be part of the Atopic March. This refers to the progression of allergic diseases in a person’s life: eczema, food allergy, allergic rhinitis and asthma. Although not everyone will follow this progression, or experience every condition, each diagnosis can be an indication that other allergic diseases will follow. Children with food allergy, especially to eggs, have a 50–90 percent chance of developing nasal allergies and asthma as they get older. Of milk allergic children, 50 percent will have an allergy to other foods and 40 percent of children with peanut allergy will develop allergy to other nuts. One-third of children with severe atopic dermatitis (eczema) will have a food allergy trigger.
An accurate diagnosis by a board-certified allergist is the first step in living with food allergy, however we urge patients to connect with others that are experiencing the challenges that come when any member of the family is diagnosed with a food allergy. There are excellent websites and local family support groups that help families that are seeking information and advice. We have listed several below.
Food Allergy Research and Education (FARE) is an excellent source for information about food allergies.