The eight major food allergens are milk, eggs, peanuts, tree nuts, fish, crustacean shellfish, wheat, and soybeans. These were established by the Food Allergen Labeling and Consumer Protection Act (FALCPA) in 2004, and they account for the vast majority of serious allergic reactions to food in the United States. Food allergies affect roughly 8 percent of children and nearly 11 percent of adults in the U.S.
As of January 1, 2023, sesame was added as the ninth major allergen under the FASTER Act, so you’ll increasingly see it called out on food labels too. But the original eight remain the core list that drives allergen labeling on every packaged food and dietary supplement sold in the country.
Milk
Milk allergy is one of the most common food allergies in young children. It involves an immune reaction to proteins in cow’s milk, not the same thing as lactose intolerance (which is a digestive issue, not an immune one). The tricky part is that milk proteins show up under dozens of names on ingredient labels: casein, caseinates, whey, lactalbumin, lactoglobulin, and hydrolysates are all milk-derived.
Beyond the obvious sources like cheese, butter, yogurt, cream, and ice cream, milk proteins hide in processed meats (hot dogs, sausages, deli meats), margarine, caramel flavoring, chocolate, nougat, and even some high-protein flours. Both natural and artificial flavorings can contain milk derivatives, so the “Contains: Milk” statement on packaging is essential to check.
Eggs
Egg allergy is most common in children, and many kids outgrow it by adolescence. The proteins that trigger reactions are found in both the white and the yolk, though egg white proteins tend to be the bigger culprits. Eggs appear in baked goods, pasta, mayonnaise, meringue, and many sauces. On labels, look for terms like albumin, globulin, lysozyme, and ovomucin, all of which are egg-derived.
Peanuts
Peanuts are legumes, not true nuts, which is why they get their own category separate from tree nuts. Peanut allergy tends to be lifelong and is one of the most common triggers of severe allergic reactions. Peanut proteins can be found in many Asian and African cuisines, baked goods, candy, and sauces. Even small amounts of cross-contact during manufacturing can be enough to trigger a reaction in highly sensitive individuals.
There’s also an interesting overlap between peanuts and seasonal allergies. People with birch pollen allergy sometimes react to peanuts because certain proteins in peanuts are structurally similar to birch pollen proteins. This is called oral allergy syndrome, and it typically causes mild itching or tingling in the mouth rather than a full systemic reaction.
Tree Nuts
Tree nuts are a broad category that includes almonds, walnuts, pecans, cashews, pistachios, Brazil nuts, macadamia nuts, and hazelnuts, among others. The FDA recently updated its official tree nut list, removing coconut, chestnuts, hickory nuts, shea nuts, and several others that no longer meet the threshold of scientific evidence for inclusion as major allergens.
Being allergic to one tree nut doesn’t automatically mean you’re allergic to all of them, but many people do react to multiple species. Your allergist can test for specific nuts to help you figure out which ones to avoid. Notably, tree nut allergens are labeled differently from peanuts on packaging because they are considered separate categories. A “Contains” statement for tree nuts must specify which nut is present (for example, “Contains: Almonds”).
Fish
Fish allergy covers finned fish like salmon, tuna, cod, tilapia, and halibut. It’s more common in adults than children and is usually lifelong. Fish proteins can become airborne during cooking, which means some people react just from being near fish being prepared. On food labels, the specific type of fish must be named.
Crustacean Shellfish
This category includes shrimp, crab, lobster, and crawfish. One important distinction: the law only requires labeling for crustacean shellfish, not mollusks (clams, mussels, oysters, scallops, squid). Mollusks are a separate biological group, and while some people are allergic to both, cross-reactivity between crustaceans and mollusks is less common than cross-reactivity within each group. If you’re allergic to shrimp, you have a meaningful chance of reacting to other crustaceans, but a lower chance of reacting to clams or scallops. Still, your allergist may recommend caution with all shellfish depending on your history.
Wheat
Wheat allergy is an immune reaction to proteins found in wheat. It’s not the same as celiac disease. Wheat allergy involves antibodies that respond to wheat proteins and can cause immediate symptoms like hives, swelling, or difficulty breathing. Celiac disease is an autoimmune condition specifically triggered by gluten that damages the small intestine over time. The two conditions require different diagnostic approaches and different levels of dietary restriction.
Wheat shows up in bread, pasta, cereal, and baked goods, but also in less obvious products like soy sauce, processed meats, and some ice creams. People with wheat allergy can often tolerate other grains like rice, oats, and barley (unless they have separate sensitivities to those).
Soybeans
Soy allergy is most common in infants and young children, and many outgrow it. Soy is one of the most pervasive ingredients in processed food. It appears as soy lecithin, soy protein isolate, textured vegetable protein, and soybean oil (though highly refined soybean oil is exempt from allergen labeling because the refining process removes most of the protein). Soy turns up in everything from bread and canned soups to infant formula and protein bars.
How Allergen Labeling Works
Under federal law, any packaged food containing one of the major allergens must declare it in one of two ways: either by using the common name of the allergen in the ingredient list (for example, listing “milk” instead of just “casein”) or by including a separate “Contains” statement near the ingredient list. For tree nuts, fish, and crustacean shellfish, the specific species must be named.
What the law does not regulate are advisory statements like “may contain traces of” or “processed in a facility that also processes.” These are entirely voluntary, and there’s no standard for what level of risk they represent. Some companies use them liberally as a legal precaution, while others skip them entirely. For people with severe allergies, this gap in regulation can make advisory labels unreliable. When in doubt, contacting the manufacturer directly is the most dependable way to assess cross-contact risk.
Oral Allergy Syndrome and Cross-Reactivity
Some food allergies are connected to pollen allergies through proteins that share a similar structure. This is called oral allergy syndrome. If you have birch pollen allergy, for instance, you may notice tingling or itching in your mouth when eating raw apples, pears, cherries, hazelnuts, carrots, or celery. The major apple allergen is about 63 percent structurally identical to the major birch pollen allergen, which is why the immune system can confuse the two.
Different pollen allergies link to different foods. Ragweed allergy is associated with reactions to watermelon, cantaloupe, and bananas. Grass pollen allergy can trigger reactions to melon, oranges, and tomatoes. Cooking usually breaks down the proteins responsible, so many people with oral allergy syndrome can eat the cooked version of a food that bothers them raw. These reactions are typically mild, but they can occasionally be more significant, particularly with nuts like hazelnuts and almonds.