Food Allergies From A to Z: Learn to Manage Them Better

Tips and Terms to Help You Better Cope

Learning to live with food allergies just got easier. This article offers a simple-to-understand A to Z guide to help you navigate the pitfalls and challenges of living with food allergies, whichever type you have.

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Anaphylaxis is a potentially life-threatening allergic reaction that requires immediate medical attention. It can occur within minutes to hours of eating an allergy-causing substance, known as an allergen.

The reaction involves the whole body and is caused by the release of a chemical called histamine that causes airways to tighten and tissues and blood vessels to swell. If left untreated, anaphylaxis can lead to severe respiratory distress, unconsciousness, or even death.

Anyone with a history of anaphylaxis should carry an epinephrine auto-injector (called an EpiPen) in the event of an anaphylactic emergency.

Blood Tests

There are different blood tests, called immunoassays, that can help diagnose the specific type of food allergy that you have. These include:

Both tests detect immune proteins, called antibodies, produced by the immune system in response to a specific allergen.


Many people with food allergies can react to tiny amounts of a food allergen, often severely. For these individuals, it is critical to avoid cross-contamination in which a small amount of a food allergen accidentally gets into another food.

Cross-contamination can occur at home when a utensil or surface is not cleaned after it comes into contact with a food allergen. It can also occur at restaurants or food manufacturing plants that produce more than one food product.

Dairy Allergies

A dairy allergy, also known as milk allergy, is one of the most common food allergens (and the most common among infants and toddlers). While many children outgrow a dairy allergy by age three or four, some do not. Symptoms can range from mild to severe, including rare cases of anaphylaxis.

If you have a dairy allergy, it is important to find non-dairy substitutes that can help you meet your daily calcium needs (ranging from 200 milligrams for infants, 1,300 milligrams for teens, and up to 1,200 milligrams for adults).

Elimination Diet

To pinpoint the cause of a food allergy, your healthcare provider may recommend you try an elimination diet.

An elimination diet involves removing a specific food (or group of foods) from your diet for a set period of time, then reintroducing the foods one by one to see which ones are causing a reaction.

Food Allergies

A food allergy is the body’s abnormal response to food. The body’s immune system is normally responsible for protecting you from infections and diseases but can sometimes respond inappropriately to food allergens that it regards as foreign.

About 32 million people in the United States have at least one food allergy, including 26 million adults and 5.6 million children. The most common food allergies include:

  • Milk
  • Eggs
  • Peanuts
  • Tree nuts
  • Fish
  • Shellfish
  • Wheat
  • Soy

Gastrointestinal Symptoms

Many food allergies can result in gastrointestinal symptoms, including nausea, vomiting, abdominal pain, and diarrhea. This is due in part to white blood cells, called mast cells, that populate the gastrointestinal tract and other tissues of the body.

When a food allergy occurs, the body releases antibodies that cause mast cells to break open and release histamine. It is the release of histamine, and the resulting swelling of digestive tissues that causes the gastrointestinal symptoms of food allergies.


For many people with food allergies, the one sign of an allergic reaction may be hives. Hives, also known as urticaria, occur when the rapid dilation of blood vessels beneath the skin causes underlying tissues to swell and form raised, itchy welts.

Hives are one type of skin reaction that can occur with a food allergy. Rashes and angioedema (a more generalized, non-itchy swelling of tissue) are two others.

Immunoglobulin E

Immunoglobulin E (IgE) is the antibody responsible for allergies. When released in response to an allergen, IgE triggers the degranulation (breaking open) of mast cells and another type of white blood cell known as a basophil.

The breaking open of these cells releases histamine into the system and other inflammatory chemicals (such as leukotrienes and interleukin) that cause allergy symptoms.


When faced with foods with no label, questionable ingredients, or may have been subject to cross-contamination, it is important to make an informed judgment. When in doubt, just say no.

It is certainly not worth the risk if there is any chance of exposure to a food allergen. It is always best to play it safe when offered foods you are unfamiliar with, particularly if you have a history of severe allergies. 

Kitchen Safety

For those living with severe food allergies, it is critical to ensure safe preparation, cooking, and storage practices within your kitchen. This may require color-coded plates, sterile environments to avoid cross-contamination, and easy-to-read food labels.

If your child has food allergies, it is often best to ban all known or suspected foods from the house. Alternatively, you can maintain separate cabinets or drawers to avoid confusion when grabbing snacks or cooking ingredients.

Label Food Products

Once diagnosed with a food allergy, it is important for you to learn how to read food labels and how to identify food allergens by their different names (such as farina and bulgar which are both forms of wheat).

The Food Allergen Labeling and Consumer Protection Act of 2004 mandates that foods that contain the major food allergens—milk, eggs, fish, crustacean shellfish, peanuts, tree nuts, wheat, and soy—must state so clearly on their product labels.

Even so, allergens can sometimes be hidden in foods and other products. Becoming "fluent" in food allergens is crucial if you have prone to severe allergic reactions.

Manage Your Lifestyle

The key to living with food allergies is having a plan of action when at school, home, and work or when traveling or dining out. It is best to think ahead and have your protocol in place so that you can prevent allergies from occurring.

For example, before your child heads off to school, ensure the teacher is aware of their needs, including what foods are "safe" and "unsafe" and what to do in an emergency.

If dining out socially, call ahead to discuss your dietary concerns with the restaurant of your host. By planning, you can manage your food allergies without undermining your or your family's quality of life.

Nut Allergies

Another common and serious food allergy is a nut allergy. There are two distinct kinds of allergies to nuts: peanuts and tree nuts.

Peanuts grow underground and are part of the legume family, while tree nuts such as almonds, walnuts, cashews, and pecans grow above the ground.

Roughly 2.5% of children in the United States have a peanut allergy. Around 1% of all adults and children in the U.S. have a peanut allergy, a tree nut allergy, or both.

Oral Allergy Syndrome

Oral allergy syndrome (OAS) is not a true allergy. Instead, it is caused by cross-reacting allergens in pollen and certain raw fruits or vegetables.

With OAS, your immune system will mistake allergenic proteins in certain fruits or vegetables with those in certain pollens, triggering a relatively mild and short-acting reaction. Symptoms are generally limited to mild tingling, burning, and swelling of the lips, mouth, or throat.

If you have an allergy to birch pollen, for example, you may develop OAS when you eat apples, apricots, celery, nectarines, and almonds. If you are allergic to ragweed, bananas and cantaloupes may trigger OAS.

Prepare for Emergencies

Being prepared for a severe allergic reaction can be life-saving. This includes recognizing the signs and symptoms of anaphylaxis and knowing how to administer epinephrine if an anaphylactic reaction occurs. It may also mean teaching family members how to administer the injection if you experience anaphylaxis and cannot do so yourself.

Other tips include keeping an amply supply of EpiPens on hand (more than one dose may be needed), discarding any expired EpiPen, and wearing an emergency medical bracelet.

Respiratory Symptoms

Food allergies can cause respiratory symptoms ranging from mild to life-threatening. They are caused when histamine and other inflammatory chemicals trigger the dilation (widening) of blood vessels and the swelling of tissues in the respiratory tract (including the nostrils, nasal cavities, throat, and windpipe).

Respiratory symptoms can vary by their severity and may include:

Shellfish Allergy

Shellfish allergy is one of the eight major food allergies and includes mollusks like clams, scallops, and oysters and crustaceans like shrimp, crabs, and lobsters. Shellfish allergies are more common in adults than children and can often be severe.

People who are allergic to one crustacean tend to be allergic to all crustaceans. The same may be true with mollusks. However, some people may be allergic to only crustaceans or only mollusks, while some may be allergic to both.

Test, Skin Prick

A skin prick test (SPT) is a simple procedure in which a tiny amount of an allergen is placed under the skin to see if you have a reaction. It is a direct method of testing that can help your healthcare provider pinpoint the exact food allergens causing your symptoms. If there is a reaction, the skin will begin to swell at the insertion site within 15 to 30 minutes.

Skin prick tests have a relatively high rate of false-positive results, meaning that the test will suggest you are allergic to a substance even when you're not. Even so, the test can be very useful when combined with other forms of allergy testing.

Versus: Allergy vs. Intolerance

A true food allergy involves immunoglobulin E (IgE) and causes an immune system reaction that affects numerous organs in the body. Food intolerance and food sensitivity are not the same things.

Food intolerance takes place in the digestive tract and occurs when your body is unable to properly break down food. This could be due to a lack of digestive enzymes or reactions to naturally occurring substances in food, like lactose.

Food sensitivity is also associated with an abnormal immune response but one that doesn't involve IgE. The symptoms are similar to those of food intolerance but tend to be less severe.

Wheat Allergies

A wheat allergy is one of the major food allergies and is often confused with gluten intolerance or celiac disease. While people with a wheat allergy and celiac disease both can’t eat wheat, the underlying causes are completely different.

A wheat allergy is caused by an inappropriate IgE response to one of four proteins specific to wheat (namely wheat gluten, albumin, globulin, or gliadin). It can cause both gastrointestinal and respiratory symptoms as well as rash or hives.

With celiac disease, the gluten found in wheat and other cereal grains triggers an autoimmune response in which immunoglobulin A (IgA) "autoantibodies" damage the lining of the small intestines. Symptoms include diarrhea, bloating, nausea, stomach pain, and gas.


Food allergies are typically treated with the avoidance of food triggers. If needed, over-the-counter or prescription antihistamines can help relieve allergy symptoms.

One of the newer approaches under investigation involves using Xolair (omalizumab), a biological drug that may help children overcome severe milk allergies. Xolair is delivered by subcutaneous (under the skin) injections and is commonly used to treat allergic asthma and chronic hives.

Investigators are also exploring the benefits of Xolair in children with other types of food allergies. Other biologic drugs and immunotherapies are also being studied in the hope they may one day help cure certain food allergies.


Zyrtec (cetirizine) is one of several over-the-counter (OTC) antihistamines that can help relieve mild food allergy symptoms. Other OTC options include Allegra (fexofenadine), Claritin (loratadine), and Chlor-Trimeton (chlorpheniramine).

For severe symptoms, your healthcare provider may prescribe stronger antihistamines like Xyzal (levocetirizine) or Clarinex (desloratadine).

A Word from Verywell

Food allergies don't have to be scary if you take the steps to educate yourself and prepare for every contingency. It starts with understanding your specific food allergies, including how to identify and avoid known or suspected food allergens.

If your child is the one with a food allergy, they should be taught not to share foods and what to do if they experience an allergic reaction. Even young children can understand this.

If you are not sure what is causing an allergy, ask your healthcare provider for a referral to an allergist who specializes in the diagnosis and treatment of allergies.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Marlo Mittler, MS, RD
Marlo Mittler, MS, RD, is a registered dietitian specializing in pediatric, adolescent, and family nutrition. She is the owner of NutritionByMarlo.