Everything You Need to Know About Common Food Allergies

About 32 million people — including 6% of children — experience food allergies in the United States, according to the Centers for Disease Control and Prevention. There is currently no cure for food allergy. Current treatment requires strict avoidance of the food(s) the patient is allergic to.

Despite the high prevalence of these allergies, the U.S. isn’t exactly allergy-proof. From trying mystery sauces at restaurants to cross contamination in a school cafeteria or a first kiss after a dinner date — the risk of exposure to allergens is everywhere.

Even small — or trace — exposures to the food people are allergic to can lead not only to symptoms like itching and skin rash, or hives, but swelling of the face and throat, as well as difficulty breathing. In the most severe instances, an allergic reaction can be fatal.

Given the seriousness of food allergies, it’s important to heed any of a broad range of possible symptoms after food is consumed, and seek medical attention for adults or kids to ensure proper diagnosis and allergy management. Here’s what to know about common food allergens — and how to stay safe if allergic to them.

The Most Common Food Allergens

The Food and Drug Administration designates nine foods as the most common food allergens:

— Milk.

— Eggs.

— Fish.

— Crustacean shellfish.

— Tree nuts.

— Peanuts.

— Wheat.

— Soybeans.

— Sesame.


Typically, protein

is the cause of a food allergy. For milk, that’s cow’s milk protein — casein and whey. Cow’s milk is the most common allergy in infancy and childhood. Foods to avoid: milk and all milk products (yogurt, cheese, cottage cheese, sour cream), butter, milk powder, custard and chocolate. Pay particular attention to processed grains that may contain a milk derivative, such as casein and whey. Note that a milk allergy differs from lactose intolerance, which is a problem digesting the sugar (lactose) in milk.


Both egg whites and egg yolks contain the protein that can cause allergies, but an allergy to egg whites is most common. However, since it’s impossible to separate the white and the yolk without any cross-contamination, you must avoid eggs as a whole. Foods to avoid: eggs, of course, but also albumin, mayonnaise and meringue. Ice cream and many baked goods also contain eggs, as well as other foods where eggs are often a hidden ingredient, such as salad dressings and meatballs.


Fish — or specifically finned fish such as tuna, halibut or salmon — is another common food allergen. Even cooking fish, such as sautéing on your stove — which can aerosolize the protein — can impact someone with a fish allergy. Fish is a common ingredient in Worcestershire sauce, Caesar salad and many Asian dishes that use fish-based stock.

Crustacean shellfish

Shellfish allergy is the most common food allergy in adults. Shellfish in all forms (shrimp, crab lobster, mussels, scallops, etc.) should be avoided, as well as any foods containing these products. Often, people with shellfish allergies can’t even be in the same vicinity as the shellfish or they’ll react.

Tree nuts

Tree nuts include almonds, cashews, walnuts, Brazil nuts, hazelnuts, chestnuts, macadamia nuts, pecans and pistachios — as well as any nut butters or other foods containing these nuts, such as pralines and other candies. Along with peanuts and shellfish, tree nut allergies are among the food allergies most frequently linked with anaphylaxis — the rapidly occurring allergic reaction that can kill. Besides avoidance of the allergen, it’s recommended people carry epinephrine — which can reverse life-threatening effects like a dangerous drop in blood pressure during anaphylaxis — or other allergy medications to manage an unexpected allergic reaction.


Peanuts are the most severe allergy for children. This legume can cause an anaphylactic reaction from even a small amount of exposure; therefore, children need to be very careful not to consume any product that even has a trace amount of peanuts or peanut butter. Peanuts can be used in many food items, so it’s important to read the ingredients list for all foods if your child has a peanut allergy.


Wheat allergy is different from celiac disease. Wheat is found in many foods, such as cereals, pastas, crackers and ice cream. Other foods to avoid: flour, couscous, faro, bread crumbs, bulgur, seitan, semolina and food starch.


Soybeans are a member of the legume family, but that doesn’t mean you’re automatically allergic to other legumes. Foods to avoid: soybeans, soy milk, tofu, edamame, miso, soy protein and soy sauce. Pay particular attention to granola bars, energy drinks, baked goods and foods that may have added soy.


In January 2023, sesame became a new addition to the list of top allergens. The edible seeds are found in hummus, tahini, sushi, hamburger buns, bagels, energy bars, sesame oil and certain spice blends.

[See: Health Issues That Are Sometimes Mistaken for Gluten Sensitivity.]

Avoidng Common Food Allergens

For people with food allergies, avoiding allergic reactions isn’t easy. Things like cross contamination, wrongly or vaguely labeled food items, aerosolized contact and indirect contact with others consuming the allergen nearby increase levels of risk every day.

The FDA requires food distributors to visibly label products that contain, or “may contain” the nine most common allergens. However, that “may contain” label doesn’t offer much guiding information.

“When labels say things like ‘may contain’ or ‘traces of’ or ‘processed in a facility with,’ nobody knows what that actually means,” says allergist and immunologist Dr. Farah Khan, who is with the Nationwide Children’s Hospital in Columbus, Ohio.

These labels could imply dangerous scenarios like allergens being processed on the same machinery as the food you are trying to buy, or not-so-worrisome situations like being processed in two different rooms, hallways apart from each other. But, she adds, there’s no way to know unless you try to call the company.

“Sometimes it just feels impossible to get down to what a food actually contains,” Khan says. “In those cases, we really are encouraging patients to have a conversation with your allergist about ‘what does this mean?'”

For some people, allergists may suggest they avoid foods with this labeling, while others may get the “OK” to try them out. The decision is very individual, Khan says.

And yet, regardless of how careful they are with their own eating habits, a person with an allergy can come in contact with allergens in social situations — or dating life — too.

“If somebody just ate a meal with peanuts and you go to kiss them after dinner, they probably still have a little bit of that peanut protein on their lips or inside of their mouth that can be transferred to you by direct contact with your lips or mouth,” says Khan.

To stay in the clear, you may want to wait about an hour after dinner before that kiss. A study showed that most peanut allergen clears saliva within an hour of consuming the food. However, risk can vary from person to person.

People with peanut allergies are less likely to be impacted by airborne or aerosolized exposure, which people who are allergic to things like shellfish may be more vulnerable to, says Jeanne Lomas, the director of allergy & immunology at WellNow Allergy, an affiliate of urgent care provider WellNow Urgent Care, which specializes in allergy testing and immunotherapy. That’s because shellfish is often prepared by boiling the fish, which makes the allergen easier to breathe in, she adds.

“An allergic patient may breathe in the steam and exhibit allergic symptoms,” says Lomas. “This would differ from an open jar of peanut butter sitting on a counter, which would be very unlikely to cause symptoms unless the allergic person ingested or came into contact with the item.”

[SEE: Top Pharmacist-Recommended Stomach and GI Products.]

What Happens If You Come Into Contact With a Food Allergen?

If you don’t have a food allergy, ingesting one of the nine top food allergens won’t do anything to you — except, maybe, fill you up. If you are allergic, however, your body will experience an immune response that ranges from mild to severe.

People experience allergic reactions if they have specific antibodies called IgE to certain foods. Upon contact with the allergen, these antibodies react — fast. Allergic reactions often occur between 10 to 15 minutes after eating.

“When that person ingests the food, it sets off a cascade of immunologic actions triggering allergy cells to release certain substances, which cause symptoms like swelling, itching,” says Lomas. “In food allergies, the symptoms can vary in severity, but any ingestion of the food should cause at least some symptoms.”

Food allergy symptoms

The first symptom of an acute food allergic reaction is often “an overall unwell feeling,” Lomas says. This can include:

— Itching of the mouth.

— Itching of the skin.

— Upset stomach or nausea.

In infants and toddlers, parents may be able to sense something is wrong if the child appears less active or unusually clingy, Lomas says.

The most severe type of reaction to a food allergen is anaphylaxis. This can manifest in symptoms like:

— Trouble breathing.


— Swelling.

— Throat tightness.

— Throat hoarseness.

Nausea or vomiting.

Abdominal pain.


— Dizziness or fainting.

— Low blood pressure.

— Rapid heartbeat.

Cardiac arrest.

“Anaphylaxis essentially means you have at least two organ systems involved in the allergic reaction,” says Khan. “Sometimes it’s ‘I had itching’ — skin involvement — ‘and my stomach started to hurt and I was getting queasy and I vomited’ — GI involvement.”

The different combos people experience, as well as the intensity of their reactions vary from person to person.

Treatment and Prevention of Food Allergies

If a person is experiencing anaphylaxis, they will need to be treated with an epinephrine auto-injector, or an EpiPen. If one is not available, call 911 for emergency help.

How to use an EpiPen

Like its name (epinephrine auto-injector) suggests, an EpiPen needs to be injected into a person’s body in order to work correctly.

When using the product, place the orange tip on the middle of the upper leg, or outer thigh, of the person who is having the allergic reaction. The pen should be angled perpendicular to the thigh. Push until you hear a “click,” and hold in place for 3 full seconds.

Epi-pens are available by prescription from your allergist.

Prevention of peanut allergies

Palforzia (a peanut allergen powder) is an oral immunotherapy product approved in patients 4 to 17 years of age to reduce the severity of allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanut; its benefits are restricted to peanut allergy.

Those who take Palforzia must continue to avoid peanuts in their diets.

Xolair for the reduction of allergic reactions

Recently, the FDA recently approvedXolair (omalizumab) for the reduction of allergic reactions, including anaphylaxis, that may occur with accidental exposure to one or more foods in adult and pediatric patients aged 1 year and older with IgE-mediated food allergy. Xolair is an injectable prescription medicine taken every two to four weeks. People taking Xolair for food allergies should still continue to avoid all foods they are allergic to.

How Common Food Allergies Develop

People cannot develop an allergy to a food allergen if they’ve never come in contact with it before, so a person who has a milk allergy, per se, may not experience a reaction the first time they eat yogurt. Unless, that is, they’ve come in contact with the allergen through other routes, like breakage in the skin barrier.

This can occur due to conditions like eczema, which opens bodily pathways to numerous substances, including food allergens.

“That’s one way that their immune system is seeing the allergenic proteins without even having consumed it,” Khan explains.

Gene mutations in the filaggrin gene, or FLG, can also cause skin barrier disruptions which predispose a person to food allergies or other allergic diseases like asthma, increasing their risk of unintentional exposure.

Early exposure

Unless they’ve already been diagnosed with a food allergy, allergists recommend incorporating — not excluding –common allergens in your child’s diet.

While that advice may sound counterintuitive, it’s based on findings from Learning Early About Peanuts Trial, a food allergy safety study that was conducted in 2015. LEAP compared the allergy profile of children who avoided peanuts until age four to babies who ate peanuts during that time frame and found that the children who ate peanuts were less likely to develop a peanut allergy by more than 80%.

Before the trial, allergists had typically told patients and parents to hold off on incorporating common allergens into children’s diets.

“The take-home message here is, we want to keep them eating the allergenic foods early and often!” Lomas says, with emphasis on the “often.”

“One mistake many parents make is trying a new food for a few days in a row, then never exposing the child again until weeks or even months later,” adds Lomas. “In a high-risk child, this can actually promote development of food allergy.”

For children who are not developmentally ready to consume hard foods, like nuts, Lomas recommends mixing nut butter into things like oatmeal or puree, assuming they are able to tolerate the latter.

She adds to remember that everyone’s situation is different — and incorporating top allergens into your child’s diet doesn’t guarantee an allergy-free future. If concerning signs or symptoms arise when introducing a new food (think: rashes, swelling, vomiting), discontinue the food until meeting with an allergist or pediatrician.

Can adults develop food allergies?

It’s unlikely, but not impossible, for adults to develop new food allergies. If they do, they are more likely to develop a new allergy to something like tree nuts or shellfish than peanuts. This may be in part due to the typical diet and the types of foods children are fed growing up, says Lomas.

“Our immune systems are constantly changing with different exposures,” Lomas adds. “A person can indeed develop food allergies at any point in their life. It is much less common though, to develop food allergies to foods you are frequently consuming as an adult compared with those you only ingest sporadically a few times per year.”

Adults and children can also develop new intolerances to foods. A common one is lactose intolerance, where a patient lacks the enzyme lactase needed to properly digest dairy products. Unlike an allergy, a food intolerance is not caused by specific antibodies to the food, and is not life-threatening.

Intolerance typically presents in abdominal symptoms like bloating, cramping, nausea, diarrhea or constipation, Lomas says. She recommends people with intolerances visit a dietician or gastroenterologist to work through a healthy meal plan that doesn’t upset their stomach.

How Do Doctors Test People for Food Allergies?

Doctors can use a skin test to assess a person for food allergies. The test involves placing a small amount of the suspected allergen on the patient’s skin, then scratching or pricking the skin to deepen contact. The provider will watch for any redness or swelling to determine whether or not the patient is experiencing a reaction to the substance. This tends to take about 15 minutes.

The test is not always 100% accurate, so is reserved for those who come in expressing concerns or symptoms and not given to all patients. Further, the severity of someone’s response to the food allergen cannot be determined through testing, Khan says. “It just tells us the likelihood of having allergic reaction symptoms (to that food).”

In some cases, practitioners may also use bloodwork testing to examine your immune system’s response to particular foods by measuring allergy-related antibodies.

“Sometimes we use the skin test and the bloodwork together to give us a picture of the likelihood that this is a true allergy, versus some other kind of reaction,” Khan says.

Food allergy challenges

If testing or discussions with your allergist imply that your child is outgrowing a food allergy, you may be asked to come into their office and partake in a “food challenge.”

During this time, your child will be fed their food allergen in a controlled environment, where the allergist can watch for symptoms. This can help an allergist determine things that testing cannot, like the severity of the reaction and how much food is capable of setting it off.

“Depending on the volume of the food that they have tolerated, we either say ‘no, you, you definitely can’t have any of it,’ or ‘this is your threshold amount you can eat,'” says Khan. “That’s on a case-by-case basis and it really depends on a conversation with the patient and the parents.”

If a patient experiences an allergic reaction during a food challenge, the allergist will administer treatment — typically starting with antihistamines — and most likely advise the patient and family to continue avoiding the allergen for the time being.

People may also want to request a food allergy challenge if they are nervous about introducing allergens to their child’s diet and want to do so under supervision.

Living Among Food Allergens

Allergic reactions can be scary, but living among common food allergens doesn’t have to be.

“Our job as allergists is to educate our patients and our parents and our families so that allergies don’t have this substantial impact on their quality of life where they’re constantly living in fear,” says Khan.

Increasing awareness about the top food allergens — especially for people who don’t have them — can help loosen the pull they have on the quality of life for people who are allergic. Reducing shame around having allergies, and normalizing advocating for oneself are also essential steps in harm reduction, Khan says.

“I don’t want them to be afraid to advocate for themselves,” Khan adds. “If you’re going out to eat, you can definitely do that. But that means communicating effectively with your waiter or the kitchen staff or the chef that you have an allergy so that they can be careful.”

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Everything You Need to Know About Common Food Allergies originally appeared on usnews.com

Update 04/15/24: This story was published at an earlier date and has been updated with new information.

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