A food allergy is when your body’s immune system has an inappropriate response to a specific food or substance in a food. When your immune system mistakes a food for a harmful substance, it creates immunoglobulin E (IgE) antibodies to fight it. The next time you eat even the tiniest bit of that food, the IgE antibodies sense it and cause your immune system to release chemicals to fight it off. These chemicals cause the symptoms of an allergic reaction.

According to the U.S. Food and Drug Administration (FDA), eight kinds of food cause 90 percent of food allergies. Luckily, the Food Allergen Labeling and Consumer Protection Act of 2004, which took effect January 1, 2006, requires food manufacturers to disclose in plain language whether packaged products contain any of these eight types of food (or proteins that came from these foods):

  • milk
  • eggs
  • peanuts
  • wheat
  • soy
  • fish
  • shellfish
  • tree nuts

This labeling requirement doesn’t apply to meat, poultry, and egg products. The United States Department of Agriculture’s (USDA) Food Safety and Inspection Service regulates these foods.

Certain factors put you at greater risk for having a food allergy.


According to the Mayo Clinic, food allergies are most common in toddlers and infants. Allergies to milk, soy, wheat, and eggs may decrease in impact over time. Allergies to nuts and shellfish are more likely to last a lifetime.

Family history

If asthma, eczema, hives, or hay fever is common among your family members, you’re more likely to have a food allergy.

Other allergies

If you're already allergic to one food or already have another type of allergy, you have a greater risk of developing a food allergy.

Asthma and eczema

Asthma, eczema, and food allergies often coexist. Asthma can also make food allergy symptoms more severe.

History of food allergies

Although a childhood food allergy may disappear as you age, there’s still a chance the allergy may return later in life.


Milk allergies are much more common in children than adults. They’re especially common in very young children. According to Food Allergy Research & Education (FARE), milk allergy is the most common childhood food allergy, affecting 2.5 percent of children under the age of three.

Two types of protein in milk can cause an allergic reaction: casein and whey, with whey being the culprit in the majority of cases.


As with milk, egg allergies are much more common in children than adults. According to the American College of Asthma, Allergy, & Immunology, at least 2 percent of children have this allergy. A number of proteins in both the yolks and whites of eggs can cause allergies. However, according to the Mayo Clinic, allergies to egg whites are more common than allergies to egg yolks. It’s important to note that those with severe egg allergies should talk to their doctor before receiving a flu shot, as egg protein is used to create the vaccine.


Peanut allergies are more common in children than in adults.

Peanuts are the cause of the most severe food allergy attacks. It’s essential to get your child checked for a peanut allergy even after the mildest of reactions to peanuts or peanut butter. Even if your child has only had minor reactions, there’s a serious risk for severe attacks in the future.

Many food products that don’t contain peanuts are processed in factories with peanuts, and may have some peanut proteins in them. Read food labels carefully if you or your child has a peanut allergy.


Four classes of wheat proteins can cause allergic reactions: albumin, globulin, gliadin, and gluten. Wheat proteins, especially gluten, are present in many types of food, including:

  • bread
  • cakes and muffins
  • pasta
  • crackers
  • beer
  • ketchup
  • soy sauce
  • ice cream
  • food starch
  • natural flavorings

Some people have an exercise-related allergy to wheat. These individuals have severe symptoms that only appear if they exercise within a few hours after eating wheat. Unfortunately, these people often experience anaphylaxis if their symptoms are triggered.

Celiac disease is sometimes incorrectly called a gluten allergy. It’s really an autoimmune, digestive disorder. An individual can have both a wheat allergy and celiac disease, however.

Baker’s asthma occurs when a person has difficulty breathing after inhaling wheat or other types of flours. However, these individuals can often eat cooked wheat products without a problem.


Soy allergies are also more common in children than adults. Most children will react less intensely to soy by the time they are three years old. Most of the time, allergic reactions to soy are mild.

Soy is an ingredient in many products. Sometimes it might not be obvious that soy is present. It’s important to read all food labels if you have a soy allergy. When reading labels, look for the following words: soy, soya, soybeans, glycine max, and edamame.


Although a person with a fish allergy may be allergic to only one species of fish, it’s generally recommended that they avoid all fish to be on the safe side. Unlike many other food allergies, fish allergies tend to last a person’s whole life. This is one of the most common food allergies in adults.

Fish is often found in food products where it may not be expected, so always read food labels if you have a fish allergy.


All sorts of shellfish can cause allergic reactions. Some common examples are crustaceans (crabs, lobster, shrimp, prawns) and mollusks (clams, mussels, oysters, squid, and octopus). Some people are only allergic to one kind of shellfish. Others must avoid all types. Shellfish allergies are more common among adults than children.

According to the American College of Asthma, Allergy, & Immunology, along with peanuts and tree nuts, shellfish allergies are more likely to cause anaphylaxis symptoms.

Tree nuts

Tree nuts that may cause an allergic reaction include almonds, pecans, cashews, pistachios, and walnuts. As with shellfish, some people are allergic to only one type of nut, while others have reactions to all.