A Guide to the Most Common Food Allergens

Overview of Top Food Allergens. Getty Images

About 90% of all food allergies are related to eight foods: milk, soy, egg, wheat, peanut, tree nut, fish, and shellfish. Each of these common allergens present their own set of challenges, and some individuals may have an allergy to more than one food allergen, something called multiple food allergies.

Food allergies in children tend to occur early in life, and children may outgrow their food allergy over time.

Food allergies in adults may develop at any time, and tend to crop up later in life. Some people will have a food allergy that is life long, from childhood and through their adulthood.

Here are the nuts and bolts on the most common food allergies:


Milk allergy is the most common food allergy among American children and about 2.5% of children under age three have a milk allergy. Milk allergy is typically diagnosed in the first year of life. Most children will outgrow milk allergy by the time they are 5 years old (and some up to 8 years); some won’t outgrow it until adolescence. People with a milk allergy are allergic to the milk proteins contained in milk (casein and whey) and must avoid all foods made with milk. Lactose intolerance (the inability to properly digest the carbohydrate in milk, called lactose) is not a milk allergy.

Milk in food: Milk must be identified on food products in plain language, such as “contains milk” according to the Food Allergy Labeling and Consumer Protection Act (FALCPA) law.

It’s prudent to know the code words for milk so you can spot them on an ingredients label. Some surprising sources of milk include non-dairy creamer, deli meats, hotdogs, canned tuna, and skin and hair care products.


Egg allergy is the second most common food allergy among children with about 1.5% of all children allergic to eggs, and typically diagnosed before age two.

Eggs are not a major allergen for adults. Up to 80% of children will outgrow their egg allergy by age 5 (or up to age 10) and the remainder will outgrow it by adolescence. An individual can be allergic to the egg white, the egg yolk, or both. The recommendation is to avoid the whole egg if an egg allergy is present.

Egg in food: Egg must be labeled on food labels in plain language, such as “contains egg,” according to FALCPA. Always read the ingredients label for evidence of egg in a food product. Be aware of hidden egg ingredients such as liquid egg substitutes and pasta. Egg may be present in immunizations such as the flu vaccine and the MMR vaccine. It may also be present in certain medications, like anesthesia medications.


About 0.4% of children are allergic to soy; soy is not a major allergen for adults. Many children with a soy allergy will outgrow it by age 3, and most will outgrow it by age 10. Reactions to soy tend to be mild, however, although rare, severe reactions can occur.

Children who are allergic to soy may also be allergic to milk. Individuals with a soy allergy must avoid all foods and non-food products containing and/or made with soy.

Soy in food: Soy must be labeled on food packages in plain language, for example, “contains soy,” according to FALCPA. Many foods contain soy so be sure to read the ingredients label.


About 0.4% of children in the U.S. are allergic to wheat. Wheat allergy is rare in adults. Approximately 20% of children who are allergic to wheat will be allergic to other grains, so check with your allergist if foods containing barley, rye or oats are okay to eat. Many kids will outgrow a wheat allergy by the age of 3 years. Celiac disease requires avoidance of gluten, which is found in wheat, rye, barley and contaminated oat products; many individuals with celiac disease follow a wheat-free diet but must also avoid other sources of gluten.

Wheat in food: Wheat is the predominant grain in the American diet so it can be tricky to avoid. It is found in a variety of foods including breads, cereals, and crackers, as well as in unlikely foods like beer, soy sauce, deli meats, ice cream and imitation crabmeat. Wheat can also be found in non-food items such as Play-Doh and glue. Individuals with wheat allergy can substitute alternative grains and cover their nutritional needs.


Approximately 1.6% of children and 0.6% of adults are allergic to peanut. There is evidence that the rate of peanut allergy is increasing and studies are ongoing in search of a cure for peanut allergy. Peanut allergy is considered a life-threatening allergy because rates of anaphylaxis are higher than that of milk, egg or wheat allergy. Only about 20% of children will outgrow their peanut allergy.

Peanuts grow underground (not in trees like tree nuts) and are part of the legume family, which also is home to soybeans, peas, lentils and beans. Having a peanut allergy does not mean you have a greater risk for allergy to beans and other legumes. It is estimated that 25-40% of people with a peanut allergy also have a tree nut allergy. If you are allergic to peanut, you may also be allergic to lupine.

Peanut in Food:

Peanuts in food products must be labeled according to FALCPA, in plain language on the package. Peanut butter is used in unlikely products like chili as a thickener, and in pet food. Peanut oil can be found in skin care products.

Tree Nuts

Approximately 1.1% of children and 0.5% of adults have a tree nut allergy. About 9% of children with a tree nut allergy will outgrow it. Tree nuts include a broad range of nuts, such as walnuts, pecans, pistachios, hazelnuts, almonds and more—essentially every nut that isn’t a peanut. Due to the risk of cross-contact, individuals with tree nut allergy may also avoid peanuts. The risk of anaphylactic reaction to tree nuts is higher than that to milk, egg or wheat. It is possible to be allergic to one nut and not to others; or to be allergic to two types of tree nuts and not others. The recommendation is to avoid all tree nuts if you are allergic to one or any tree nut.

Tree Nuts in Food: Tree nuts must be labeled on the ingredients label or food package in plain language, according to FALCPA. There are many names for tree nuts, from the specific nut to the Latin name in cosmetic products, so be aware of the code words for tree nuts. Tree nuts can be found in cereals, crackers, cookies, candy, chocolates and some cold cuts.


About 0.1% of children have a fish allergy while 0.4% of adults live with it. Fish allergy tends to develop in adulthood and can be a severe, life-long allergy. Salmon, tuna and halibut are the most common fish allergies. It is possible to be allergic to one type of fish species and not others, however many individuals with a fish allergy will be advised to avoid all fish. Aged fish (or fish that isn’t fresh) can produce a natural histamine which can trigger a reaction similar to a food allergic reaction. This is called scromboid poisoning and includes swelling of the mouth or throat, difficulty breathing, or nausea or vomiting after eating fish.

Fish in Food:  According to FALCPA, the specific type of fish included in a food product must be disclosed in plain language on the package. Fish has been found in surprising foods like Caesar salad dressing, artificial seafood, Worcestershire sauce and barbeque sauce, so make sure to read the food and ingredients label. Restaurants may fry fish and other foods like French fries in the same vat of oil, which contaminates the oil with fish and makes it unsafe to eat for those with a fish allergy. Be aware of certain products like kosher gelatin, which is made from fish bones.


Shellfish allergy occurs in adults more often than children, with about 60% experiencing their first reaction as an adult. Fish and shellfish come from two different fish families, so an allergy to one type doesn’t necessarily mean you will be allergic to both. There are two types of shellfish: crustacea (shrimp, crab and lobster) and mollusks (clams, oysters, mussels and scallops). Allergic reactions to crustacean shellfish are more common and tend to be severe; most individuals who are allergic to shellfish are advised to avoid both kinds of shellfish.

Shellfish in Food: The specific shellfish must be labeled as an ingredient on packaged food when it is included, according to FALCPA. Mollusks are not considered a major allergen and may not be fully disclosed on a product label. Avoid seafood restaurants as there is a high risk for cross-contamination, even if you don’t order a shellfish option. Fish sauce is often used in Asian restaurants as a flavoring; avoid eating in such restaurants or at a minimum, use extreme caution. Shellfish proteins may become airborne during steaming so use prudence around kitchens where shellfish is being cooked.

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