Cow’s milk is the most common food allergy in young children, while peanuts and shellfish top the list in adults. Overall, about 1 in 20 children and roughly 1 in 10 adults in the United States have a confirmed food allergy, and nearly half of adults with food allergies developed at least one of them after age 18.
The U.S. recognizes nine major food allergens: milk, eggs, peanuts, tree nuts, wheat, soy, fish, shellfish, and sesame. At the time the original labeling law passed in 2004, these foods accounted for 90% of all food allergies and serious allergic reactions in the country.
The Nine Major Allergens
Milk and eggs are the most common triggers in infants and toddlers. Both are introduced early in a child’s diet, and the immune system can misidentify their proteins as threats. Peanut allergy is close behind and tends to get the most attention because it is more likely to cause severe reactions and less likely to be outgrown.
Tree nuts (almonds, cashews, walnuts, and others), fish, and shellfish round out the allergens that most often persist into adulthood or appear for the first time in adults. Wheat and soy allergies are relatively common in childhood but are frequently outgrown. Sesame was officially added as the ninth major allergen under the FASTER Act, and as of January 1, 2023, packaged foods containing sesame must declare it on the label.
Children vs. Adults
About 5.3% of U.S. children have a diagnosed food allergy, and the rate actually climbs with age: 3.9% of children under 5, 5.0% of those 6 to 11, and 6.9% of teenagers 12 to 17. Boys are slightly more likely to be affected than girls (5.9% vs. 4.7%).
In adults, a large nationally representative study found that about 10.8% had convincing, symptom-confirmed food allergies. That translates to roughly 26 million American adults. Of those, 38% had experienced a reaction severe enough to send them to an emergency department. Perhaps most surprising: 48% reported that at least one of their allergies developed after age 18. Shellfish and peanut allergies are the most common culprits in this adult-onset group.
Which Allergies Kids Outgrow
Not all childhood food allergies are permanent, but the odds vary dramatically depending on the food. Egg allergy has the best outlook: about 89% of children with egg allergy naturally outgrow it by age 6. Milk allergy follows a similar pattern, with most children tolerating milk by school age.
Peanut allergy is a different story. Roughly 29% of children with peanut allergy resolve it by age 6, but the overall prevalence stays steady because new cases keep appearing. Children who had severe eczema early in life, larger reactions on skin-prick testing, or allergies to multiple foods are less likely to outgrow either egg or peanut allergy.
Tree nut, fish, and shellfish allergies tend to be the most persistent. If these are diagnosed in childhood, they typically remain through adulthood.
How Food Allergies Are Diagnosed
The gold standard is an oral food challenge: you eat tiny, gradually increasing amounts of the suspected food under medical supervision. This is the most accurate test, but it’s time-consuming, requires specially trained staff, and carries the risk of triggering a reaction, so it’s not used as a first step.
In practice, most people start with a skin-prick test or a blood test. A skin-prick test involves placing a drop of allergen extract on the skin and lightly pricking the surface. A raised red bump appearing within about 15 minutes suggests sensitivity. A blood test measures levels of food-specific IgE antibodies, the immune molecules involved in allergic reactions. Both tests can produce false positives, meaning they may flag an allergy that doesn’t actually cause symptoms when you eat the food. That’s why test results are always interpreted alongside your history of reactions.
Allergens Vary Around the World
What counts as a “major allergen” depends on where you live, because different diets expose populations to different proteins. The European Union regulates 14 allergens, adding mustard, celery, lupin, sulfites, and molluscan shellfish (like mussels and oysters) to the list. These additions reflect how commonly those foods appear in European cooking.
In East Asia, the picture shifts even further. Japan requires labeling for buckwheat, which can cause severe anaphylaxis and is widely consumed in soba noodles. South Korea mandates labeling for buckwheat, tomato, peach, pork, chicken, and beef. These aren’t foods most Americans think of as allergens, but in populations that eat them frequently and from a young age, they are meaningful triggers.
Australia and New Zealand add molluscan shellfish to their mandatory list. Taiwan requires buckwheat labeling and recommends it for a long list of seafood and seeds, including octopus, abalone, and sunflower seeds. If you travel internationally or buy imported foods, the allergen labels may cover a different set of ingredients than you’re used to seeing at home.
Food Allergy vs. Food Intolerance
One important distinction: a true food allergy involves the immune system and can cause hives, swelling, difficulty breathing, or anaphylaxis. A food intolerance, like lactose intolerance, involves the digestive system and causes discomfort (bloating, cramping, diarrhea) but is not life-threatening. In the large adult study mentioned above, an additional 8.2% of participants reported food reactions that were consistent with intolerance rather than true allergy. Confusing the two is common, and it’s one reason self-reported allergy rates tend to be higher than confirmed rates.