The Top 8 Food Allergens: Prevalence, Risks, and Treatment

An estimated 32 million Americans live with food allergies, including roughly 5.6 million children under 18. For these individuals and their families, something as ordinary as a school lunch or a restaurant meal can carry the risk of a life-threatening reaction. Food allergy prevalence has climbed steadily over the past three decades, rising by 50% among children between 1997 and 2011, and continuing to climb since.

In 2004, Congress passed the Food Allergen Labeling and Consumer Protection Act (FALCPA), which identified eight foods responsible for approximately 90% of all serious allergic reactions in the United States. These became known as the "Big 8": peanuts, tree nuts, milk, eggs, fish, crustacean shellfish, wheat, and soybeans. In 2023, the FASTER Act added sesame as a ninth major allergen, but at EatFreely, our oral immunotherapy (OIT) program focuses on the original eight, which remain the most prevalent and most frequently treated allergens in clinical practice.

This guide walks through each of the Big 8 individually, covering how common they are, where they hide in packaged foods, and how OIT is changing the treatment landscape for each one.

1. Peanuts

Prevalence

Peanut allergy affects approximately 2.5% of U.S. children, making it one of the most common childhood food allergies. According to FARE, peanut is the leading cause of fatal and near-fatal food-induced anaphylaxis in the United States. Unlike many childhood food allergies, peanut allergy tends to persist: only about 20% of affected children will outgrow it naturally.

Common Symptoms

Reactions to peanuts range widely in severity. Mild symptoms include hives, tingling in the mouth, and stomach cramps. Moderate reactions may involve facial swelling, tightening of the throat, and vomiting. In the most severe cases, peanut exposure triggers anaphylaxis, a systemic reaction involving a dangerous drop in blood pressure, airway constriction, and loss of consciousness that can be fatal without immediate treatment with epinephrine.

Hidden Sources

Peanuts appear in a surprising number of processed foods beyond the obvious candidates. They are commonly found in Asian and African cuisines, baked goods, candy, ice cream, cereal, and granola bars. Less obvious sources include chili, egg rolls, marzipan (sometimes made with peanuts rather than almonds), salad dressings, and sauces like satay and mole. Peanut flour is used as a thickener in some soups. Cross-contamination is also a significant concern, particularly in bakeries, ice cream shops, and restaurants that cook with peanut oil.

OIT for Peanut Allergy

Peanut allergy is the most studied allergen for oral immunotherapy, and the clinical evidence is robust. The FDA-approved Palforzia was the first OIT product for any food allergen, specifically targeting peanuts. Beyond pharmaceutical OIT, physician-supervised programs using food-grade peanut protein have demonstrated desensitization rates of 60–80% in clinical trials. At EatFreely, peanut OIT is our most commonly administered treatment, and outcomes consistently show that patients can build meaningful protection against accidental exposure.

2. Tree Nuts

Prevalence

Tree nut allergy affects approximately 1.2% of children and 1% of adults in the United States. The category includes almonds, cashews, walnuts, pecans, pistachios, hazelnuts, macadamia nuts, Brazil nuts, and pine nuts. A significant clinical challenge with tree nuts is cross-reactivity: a person allergic to one tree nut has a 25–40% chance of reacting to at least one other tree nut. For this reason, many allergists recommend avoiding all tree nuts once an allergy to any single type is confirmed, though testing can sometimes identify safe exceptions.

Common Symptoms

Tree nut reactions typically mirror peanut allergy in type and severity. Symptoms include oral itching and tingling, hives, abdominal pain, vomiting, facial and throat swelling, difficulty breathing, and anaphylaxis. Tree nut allergy is the second leading cause of fatal anaphylaxis from food after peanuts.

Hidden Sources

Tree nuts appear in baked goods, cereals, crackers, flavored coffees, and confections. Almond flour has become increasingly popular in gluten-free and low-carb baking, appearing in products where consumers may not expect it. Walnut oil is used in some salad dressings and sauces. Pesto traditionally contains pine nuts. Praline, nougat, and gianduja all contain tree nuts. Natural and artificial flavorings can also be derived from tree nuts, making label reading essential.

OIT for Tree Nut Allergy

Tree nut OIT follows the same graduated-dose protocol as peanut OIT. An important advantage of multi-allergen OIT clinics like EatFreely is the ability to treat multiple tree nut allergies simultaneously alongside peanut allergy. Since cross-reactivity is so common, addressing all confirmed tree nut allergies in a single treatment course is both practical and more protective than treating one nut in isolation.

3. Milk

Prevalence

Cow's milk allergy is the most common food allergy in young children, affecting approximately 2.5% of children under age 3. The good news is that most children outgrow it: studies show that roughly 80% of milk-allergic children develop tolerance by age 16. However, those whose allergy persists into adolescence or adulthood tend to have more severe reactions and are less likely to outgrow it naturally.

Common Symptoms

Milk allergy symptoms can appear within minutes of ingestion or be delayed by several hours. Immediate reactions include hives, wheezing, vomiting, and anaphylaxis. Delayed symptoms may involve diarrhea, abdominal cramps, colic in infants, and eczema flares. It is important to distinguish milk allergy, an immune-mediated condition, from lactose intolerance, which is a digestive issue caused by insufficient production of the enzyme lactase and does not involve the immune system.

Hidden Sources

Milk proteins are among the most pervasive hidden allergens in packaged foods. Casein and whey, the two primary milk proteins, appear in non-dairy creamers, deli meat, canned tuna, some breads, processed snacks, and protein supplements. Ingredients labeled as casein, caseinate, lactalbumin, lactoferrin, or whey all indicate the presence of milk protein. Many medications and supplements also use lactose as a filler. Even "dairy-free" products may be manufactured on shared equipment with milk-containing foods.

OIT for Milk Allergy

Milk OIT has shown strong results in clinical studies, with desensitization rates comparable to those seen in peanut OIT. Treatment typically involves daily ingestion of gradually increasing amounts of milk protein, beginning with microgram quantities and building up to the equivalent of a full serving. Because milk is so difficult to avoid completely in the standard American diet, OIT is particularly impactful for milk-allergic patients. Even partial desensitization, raising the reaction threshold to tolerate a small accidental exposure, substantially reduces the day-to-day burden.

4. Eggs

Prevalence

Egg allergy is the second most common food allergy in children, affecting approximately 1.3% of children in the United States. Like milk allergy, most children outgrow egg allergy, with about 70% developing tolerance by age 16. However, children who react to both cooked and raw egg, or who have high levels of egg-specific IgE, are less likely to outgrow it.

Common Symptoms

Egg allergy reactions range from mild skin symptoms like hives and eczema to gastrointestinal symptoms like vomiting and stomach pain. More severe reactions include throat tightening, difficulty breathing, and anaphylaxis. Interestingly, many egg-allergic children can tolerate extensively heated (baked) egg in products like muffins and cakes, because the high temperatures alter the protein structure. An allergist can determine through testing and supervised challenges whether baked egg is safe for an individual patient.

Hidden Sources

Eggs appear in a wide range of processed foods. Beyond the obvious uses in baked goods, pasta, and mayonnaise, egg proteins show up in marshmallows, pretzels, some imitation crab products, foam toppings on coffee drinks, and the glossy shine on baked pastries (egg wash). Lysozyme, an egg-derived enzyme, is used in some cheeses and wines. Albumin, globulin, livetin, and ovalbumin on ingredient labels all indicate the presence of egg. Some vaccines, including certain influenza vaccines, are produced using egg-based manufacturing processes, though the amount of egg protein in modern flu shots is generally considered too low to cause reactions in most egg-allergic individuals.

OIT for Egg Allergy

Egg OIT has been studied extensively and produces strong desensitization outcomes. A typical protocol begins with microgram quantities of egg protein powder and gradually builds to a maintenance dose equivalent to roughly one egg. Because egg allergy is so common in young children, early OIT intervention can spare families years of strict avoidance. Multi-allergen clinics are particularly valuable here, since many egg-allergic children also have co-existing peanut or milk allergies that can be treated simultaneously.

5. Fish

Prevalence

Fish allergy affects approximately 1% of the U.S. population. Unlike peanut, milk, and egg allergies, fish allergy more commonly develops in adulthood and is typically lifelong. The most commonly implicated species include salmon, tuna, halibut, and cod, though any fish can trigger a reaction. Cross-reactivity between different fish species is common, occurring in roughly 50% of fish-allergic individuals, though it is not universal. Some patients are allergic to only one or two species while tolerating others safely.

Common Symptoms

Fish allergy reactions include hives, nasal congestion, headaches, gastrointestinal symptoms like nausea and diarrhea, and in severe cases, anaphylaxis. Fish is notable for also causing reactions through inhalation of cooking vapors, particularly when fish is fried, boiled, or steamed. This means that simply being in a kitchen or restaurant where fish is being prepared can trigger symptoms in highly sensitive individuals, even without ingesting the food.

Hidden Sources

Fish proteins turn up in unexpected places. Worcestershire sauce contains anchovies. Caesar salad dressing traditionally includes anchovy paste. Some barbecue sauces, Asian fish sauces (nam pla, nuoc mam), and imitation crab products contain fish. Gelatin derived from fish is used in some candies, marshmallows, and pharmaceutical capsules. Omega-3 supplements are often fish-derived. Caponata, a Sicilian eggplant dish, sometimes includes anchovies. Cross-contamination is a particular risk at seafood counters and restaurants that serve both fish and non-fish dishes from the same kitchen.

OIT for Fish Allergy

Fish OIT is less widely studied than peanut or milk OIT, but early clinical data supports its feasibility. The graduated dosing protocol is adapted to use specific fish proteins. Because fish allergy is often adult-onset and lifelong, OIT can be particularly meaningful for adults who developed the allergy later in life and face decades of avoidance ahead. Treatment is typically targeted to the specific fish species confirmed as allergens through testing.

6. Crustacean Shellfish

Prevalence

Crustacean shellfish allergy is the most common food allergy in adults, affecting approximately 2.9% of U.S. adults. It encompasses shrimp, crab, lobster, and crawfish. Like fish allergy, shellfish allergy is most often adult-onset and tends to be lifelong. Importantly, shellfish allergy is distinct from fish allergy: a person allergic to shrimp is not necessarily allergic to salmon, and vice versa. However, cross-reactivity within the crustacean group is high, so a person allergic to shrimp will often also react to crab and lobster.

Common Symptoms

Shellfish reactions are often severe. Symptoms include hives, facial swelling, difficulty breathing, abdominal pain, vomiting, dizziness, and anaphylaxis. Shellfish allergy carries one of the highest rates of anaphylaxis among all food allergies. Like fish, shellfish can also trigger reactions through inhalation of steam or cooking vapors, particularly in environments where large quantities are being prepared, such as seafood boils or restaurant kitchens.

Hidden Sources

Shellfish is a common ingredient in Asian cuisines, including many Thai, Chinese, Vietnamese, and Japanese dishes. Shrimp paste and fish sauce (which sometimes contains shrimp) are used widely as flavor bases. Glucosamine supplements are frequently derived from shellfish. Some surimi (imitation crab) products contain shellfish extract. Bouillabaisse, paella, jambalaya, and gumbo are dishes where shellfish may be present but not obvious from the name alone. Cross-contamination is a major concern at seafood restaurants and markets where crustaceans are processed alongside other foods.

OIT for Shellfish Allergy

Shellfish OIT is an emerging area of treatment. The protocol uses measured quantities of shellfish protein in a graduated dosing schedule. Because shellfish allergy is the most prevalent adult food allergy and carries a high risk of anaphylaxis, desensitization through OIT offers meaningful protection. Treatment is especially valuable for patients who cannot reliably avoid cross-contamination in their daily lives, whether due to workplace exposure, cultural cuisine, or dining out.

7. Wheat

Prevalence

Wheat allergy affects approximately 0.4% of U.S. children and is less common in adults. Most children with wheat allergy outgrow it by age 12. It is essential to distinguish wheat allergy from celiac disease, which is an autoimmune disorder triggered by gluten, and from non-celiac gluten sensitivity. Wheat allergy involves an IgE-mediated immune response to specific wheat proteins, while celiac disease involves a different immune pathway altogether. A person can have wheat allergy without having celiac disease, and vice versa.

Common Symptoms

Wheat allergy symptoms include hives, nasal congestion, abdominal cramps, nausea, vomiting, and in severe cases, anaphylaxis. A specific form of wheat allergy called wheat-dependent exercise-induced anaphylaxis (WDEIA) triggers reactions only when vigorous exercise occurs within a few hours of consuming wheat. This condition is more common in adolescents and adults and can be difficult to diagnose because reactions only happen when two separate triggers, wheat and exercise, coincide.

Hidden Sources

Wheat is one of the most pervasive ingredients in the Western diet. Beyond bread, pasta, and cereal, wheat proteins appear in soy sauce (most brands are brewed with wheat), modified food starch, hydrolyzed vegetable protein, some ice creams, hot dogs, processed meats, and many condiments. Wheat flour is used as a thickener in soups, gravies, and sauces. Spelt, kamut, farro, and durum are all varieties of wheat. Beer and some spirits are produced using wheat. Even non-food products like Play-Doh contain wheat, which matters for young children with wheat allergy.

OIT for Wheat Allergy

Wheat OIT follows the same graduated protocol used for other allergens, using measured wheat protein powder. Because wheat is so difficult to eliminate completely from the diet, even partial desensitization that raises the reaction threshold can be transformative. Patients undergoing wheat OIT often report a dramatic reduction in the anxiety and logistical burden of constant label reading and restaurant negotiation. For children, treatment can allow a return to eating school lunches and participating in normal social activities involving food.

8. Soybeans

Prevalence

Soy allergy affects approximately 0.4% of U.S. children. Like milk and egg allergies, most children outgrow soy allergy by age 10. However, soy allergy presents a unique practical challenge: soy derivatives are present in an estimated 60% of processed foods sold in the United States. This makes complete avoidance exceptionally difficult, even for vigilant families.

Common Symptoms

Soy allergy symptoms are generally milder than those caused by peanuts or shellfish, but severe reactions including anaphylaxis can occur. Common symptoms include hives, itching, tingling in the mouth, abdominal pain, diarrhea, and nasal congestion. Some soy-allergic individuals develop eczema flares after exposure. Soy is also a trigger for a condition called food protein-induced enterocolitis syndrome (FPIES) in infants, which causes severe vomiting and diarrhea several hours after ingestion.

Hidden Sources

Soy is perhaps the most difficult allergen to avoid in the modern food supply. Soybean oil, soy lecithin, soy protein isolate, and soy flour appear in breads, crackers, cookies, canned soups, sauces, canned tuna, infant formulas, protein bars, and countless other processed products. Soy lecithin is used as an emulsifier in chocolate, margarine, and many baked goods. Textured vegetable protein (TVP) is soy-based and is used as a meat extender in some ground meat products, chili, and frozen meals. Many Asian sauces, including soy sauce, teriyaki, hoisin, and miso, contain soy. Even some adhesives on envelopes and stamps have historically contained soy protein.

OIT for Soy Allergy

Soy OIT uses soy protein powder in a graduated dosing protocol. Given how difficult soy is to avoid in processed foods, OIT is particularly practical for soy-allergic patients. Building tolerance to even small amounts of soy can dramatically expand the range of safe foods and reduce the risk of accidental reactions from trace exposures that are nearly impossible to eliminate through avoidance alone. Soy OIT is commonly combined with treatment for other allergens in multi-allergen protocols.

Why Multi-Allergen Treatment Matters

Research from FARE's Patient Registry shows that 82% of food allergy patients have multiple food allergies, and 42% experience more than one allergic reaction per year despite their best avoidance efforts. The reality is that food allergies rarely travel alone. A child diagnosed with peanut allergy has a significant chance of also being allergic to tree nuts, milk, eggs, or other allergens on this list.

This is why multi-allergen OIT clinics exist. Treating one allergy at a time, in sequence, would take years and leave patients vulnerable to their untreated allergens throughout. Simultaneous multi-allergen OIT, treating two, three, or even all eight allergens at once, addresses the full scope of a patient's allergic disease in a single treatment course. The clinical data supports this approach, and for families managing multiple allergies, it is the most practical path forward.

Get Tested and Treated

If you or your child has been diagnosed with one or more food allergies, or if you suspect undiagnosed food allergies based on reactions you have experienced, the first step is proper testing with a board-certified allergist. Skin prick tests and specific IgE blood tests can identify which of the Big 8 allergens are causing reactions and how severe the sensitivity is. From there, your allergist can discuss whether oral immunotherapy is appropriate and create a personalized treatment plan.

At EatFreely, our team of board-certified allergists treats all 8 major food allergens through physician-supervised OIT at 8 Houston-area clinics. We treat patients from age 8 months through adulthood, and we accept insurance to make treatment accessible.