Food allergy is also distinct from adverse reactions that do not involve an immune response. These adverse reactions may result from a metabolic disorder (such as lactose or alcohol intolerance), a pharmacologic reaction (such as sensitivity to caffeine), a structural abnormality (such as hiatal hernia), or another, undefined response [2,18,19]. Headache, heartburn, vomiting, irritability or nervousness, and gas or bloating are symptoms related to food intolerance, whereas the hallmark symptoms of food allergy are rash or hives, itchy skin, cramping stomach pain, diarrhea, and in severe cases, shortness of breath, wheezing, and chest pain [2,18].

The percentage of children who achieve desensitization or resolution of food allergy varies according to the allergen and increases with age (Table 4) [2,8,34]. Most children who have allergy to milk, egg, soy, or wheat lose the sensitivity over time, with the time varying according to food. In contrast, allergy to peanut, tree nuts, and shellfish usually persists into adulthood [2]. Allergy to peanut or tree nuts is lost in about 20% of children after the age of 5 years [8]. The level of allergen-specific IgE is often an indicator of persistence; high initial levels of allergen-specific IgE have been associated with lower rates of resolution, and decreases in IgE levels over time often indicate the onset of tolerance [2,8].

Several strategies have been proposed as measures to prevent the development of food allergy, including maternal dietary restrictions, the use of soy-based formula, exclusive breastfeeding, and delayed or early introduction of solid foods and of allergenic foods. Maternal dietary restrictions and/or use of soy formula have not been shown to be effective in preventing food allergy and are not recommended in current guidelines [40,42].

Food allergy manifests itself primarily through the skin, gastrointestinal tract, and respiratory system, and symptoms are categorized as acute or delayed (Table 5) [2]. Cutaneous symptoms are typically the most common.

Oral allergy syndrome, also known as pollen-associated food allergy syndrome, is most common among individuals with pollen allergy. This syndrome is primarily a localized IgE-mediated reaction, with mild symptoms that include itching, irritation, or swelling occurring around the mouth after eating raw fresh fruits and vegetables, and other symptoms, such as rash, hives, watering of the eyes, nasal congestion, or tingling of the lips or tongue, may also develop. Symptoms usually resolve within a few minutes after ingestion and rarely progress to a systemic reaction. Often, no allergic reaction occurs after ingestion of fruits and vegetables that have been cooked, as heating destroys the foods' proteins. Due to cross-reactivity, allergic reactions can be more common when levels of ragweed pollen are high [2,25].

Like food allergy, asthma is an atopic disease, and, as noted previously, there is a strong association between the two conditions. Food-induced wheezing and bronchospasms occur in up to 50% of children during acute allergic reactions to food. In addition, asthma has been identified as a risk factor for anaphylaxis and is associated with poorer outcomes in children with food allergy. One study found that children with an allergy to cow's milk had a 10 times greater chance of severe reaction if they also had asthma. It has been recommended that any child with asthma be evaluated for food allergy, especially when acute episodes are unexplained or when asthmatic symptoms are accompanied by other manifestations of food allergy. Similarly, children with food allergy, especially those who have allergy to more than one food or who have severe allergy, should be evaluated for asthma [55].

In obtaining a detailed history, several questions are crucial, and healthcare professionals should ask the following [2,27]:

The skin prick test is performed with a lancet containing a 1 mm point. A drop of the selected allergen is introduced into the skin, usually on the volar or inner aspect of the forearm. A pen is commonly used to mark a grid on the arm, and the allergens are instilled at intervals of at least 2 cm. The reaction is usually obvious after 10 to 15 minutes. In general, a wheal with a diameter of 3 mm or more is considered positive, and the larger the wheal, the more likely an allergy is present. However, the size of the wheal does not predict the severity of a reaction, and there are no standards for interpreting the results of skin prick tests [2,22,27].

Negative findings on a skin prick test are of the most value, as the test has an excellent negative predictive value (95% or more), especially when testing for allergy to egg, milk, wheat, peanut, tree nuts, fish, and shellfish. Negative skin prick test results rarely occur in an individual who has an IgE-mediated reaction to one of these foods; nevertheless, if the history is strong, a food allergy should not be ruled out on the basis of negative results on a skin prick test alone. The combination of a positive test result and an inconclusive history should prompt an oral food challenge [2,22,27].

Some issues to consider with skin prick testing include [2,27]:

The rising prevalence of food allergy and the associated public concern has heightened awareness of the problem in restaurants, schools, day care settings, camps, airplanes, and other community-based institutions. Still, vigilance and precaution are required. In a study of food-induced allergic reactions among infants (3 to 15 months of age), half of the reactions were caused by food given to them by someone other than a parent [37]. Precaution is needed with older children and teenagers, as well, whose behaviors are often guided by a need to be accepted by peers. Practitioners should emphasize the importance of asking about ingredients when eating at a restaurant or away from home and of accurate interpretation of food labels. Issues with eating at restaurants include cross contamination (the most common cause of allergic reactions related to meals in a restaurant), knowledge gaps among restaurant staff, and nondisclosure of an allergy to restaurant staff [67].

The most commonly used self-injectable epinephrine in the United States is EpiPen, although other brands are available, including Adrenaclick, Auvi-Q, Twinject, Adrenalin, and Symjepi. The EpiPen disposable drug-delivery system comes in two doses: 0.3 mg in 0.3 mL (EpiPen) and 0.15 mg in 0.3 mL (EpiPen Jr) autoinjectors, designed to be given intramuscularly. The manufacturer's labeling recommends one initial 0.15-mg dose for children weighing 15 to <30 kg or one 0.3-mg initial dose for children and adults who weigh ≥30 kg (the standard for all epinephrine-containing autoinjectors) [68]. Another brand available in the United States, Auvi-Q, is a 0.1-mg autoinjector approved for use in children who weigh 7.5 to <15 kg [68].

The Federal Food, Drug and Cosmetic Act (FD&C Act) was enacted in 1938 to protect the public health by ensuring safety of food, drugs, medical devices, and cosmetics that are manufactured and sold in the United States. The Act authorizes the FDA to oversee these products, including approval of new drugs and devices, inspecting of manufacturing facilities, and enforcing labeling requirements [81]. The FD&C Act is amended as evidence supports, with The Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) being the first change, which went into effect January 1, 2006, and requires that labels clearly indicate ingredients and specifically note the presence any of the eight major food allergens. The FD&C was again amended in 2021, when the Food Allergy Safety, Treatment, Education, and Research Act (FASTER Act) was passed. The FASTER Act added sesame as the ninth major food allergen recognized in the United States and began food allergen labeling and manufacturing requirements (established by FALCPA) as of January 1, 2023 [82]. In January 2025, the FDA published the Food Allergen Labeling Requirements of the Federal Food, Drug, and Cosmetic Act (Edition 5), to include the following changes to existing food labeling to be implemented by January 1, 2028 [79,113]:

The FDA enforces the provisions of these laws in most packaged food products containing the nine major food allergens, including dietary supplements, but does not include meat, poultry, and egg products (which are regulated by the U.S. Department of Agriculture); alcoholic beverages subject to Alcohol and Tobacco Tax and Trade Bureau labeling regulations; raw agricultural commodities; highly refined oils; drugs; cosmetics; and most foods sold at retail or food service establishments that are not pre-packaged with a label [82].

Product labels are required to identify the presence of food allergens in the ingredient list or immediately after next the ingredient list in a "contains" statement (e.g., "Contains Wheat, Milk, and Soy"). Allergen source ingredients must be listed in English and may either be listed in the ingredient statement, for example, "wheat flour" instead of "flour," or in parentheses following the source ingredient, as in "whey (milk)" or "natural flavor (peanut)" [82]. Patient education on how to read food labels for those with food allergy is available on the AAAAI website at https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/food-labels [79,85].

Another barrier to identifying food allergens is using precautionary allergen labels as marketing language. Phrases that are used to indicate possible cross-contact with allergens include variations of the following [82,85]:

These phrases (among others) are not regulated by the FDA and do not accurately indicate different levels of risk. The distinction between varying precautionary phrases is unclear, and this type of marketing has been shown to lead to poor understanding of allergen labeling and varying degrees of risk perception among food allergic and non-allergic consumers alike [82,84].

The interpretation of food labels is a complex process, involving general food knowledge, literacy, and other factors. When reading labels, people with food allergy and caregivers draw on factors in addition to precautionary labels, such as trust of a particular brand or manufacturer, previous experience with a product, and images and product names (not intended to denote risk) [82,85]. The NIAID expert panel suggests that healthcare professionals provide education and training to patients with food allergies and their caregivers about how to best interpret ingredient lists on food labels and how to recognize incomplete labeling of ingredients. The panel also suggests that individuals with food allergy avoid products with precautionary labeling [2].

Another barrier to identifying food allergens is using precautionary allergen labels as marketing language. Phrases that are used to indicate possible cross-contact with allergens include variations of the following [82,85]:

These phrases (among others) are not regulated by the FDA and do not accurately indicate different levels of risk. The distinction between varying precautionary phrases is unclear, and this type of marketing has been shown to lead to poor understanding of allergen labeling and varying degrees of risk perception among food allergic and non-allergic consumers alike [82,84].

The interpretation of food labels is a complex process, involving general food knowledge, literacy, and other factors. When reading labels, people with food allergy and caregivers draw on factors in addition to precautionary labels, such as trust of a particular brand or manufacturer, previous experience with a product, and images and product names (not intended to denote risk) [82,85]. The NIAID expert panel suggests that healthcare professionals provide education and training to patients with food allergies and their caregivers about how to best interpret ingredient lists on food labels and how to recognize incomplete labeling of ingredients. The panel also suggests that individuals with food allergy avoid products with precautionary labeling [2].

Oral immunotherapy is now recognized as an alternative treatment to food avoidance in some patients with IgE-mediated food allergy. Several types of immunotherapy have been evaluated, including subcutaneous, epicutaneous, heated food, sublingual, and oral immunotherapy. Subcutaneous immunotherapy is no longer used because of severe systemic reactions, and although epicutaneous immunotherapy uses the lowest maintenance dose of the immunotherapies and also has an improved safety profile, it is less efficacious [73,92,96].

Immunotherapy with heated food proteins has been evaluated in children with generally transient allergies, such as to egg or milk. Heating egg and milk proteins at high temperature denatures allergenic proteins, making them less allergenic. Approximately 70% to 75% of children with egg or milk allergy have tolerated baked egg or milk, and introducing baked egg into the diet of children with egg allergy has accelerated the development of tolerance to regular egg, compared with strict avoidance of the food. In a 2021 study, researchers found that after 18 months of boiled egg white immunotherapy, 88% of children were regularly consuming egg and 72% were desensitized to the target dose [94]. A study published in 2024 found that, among children with milk allergy, immunotherapy using baked milk showed desensitization after 12 and 24 months of treatment, with the longer duration of treatment (24 months) increasing efficacy [93]. This treatment approach may not be effective for children with severe food allergy or for those with a high milk-specific IgE.

In 2020, the FDA approved the first oral immunotherapy peanut allergen powder (Palforzia) for the mitigation of allergic reaction, including anaphylaxis, with accidental exposure to peanuts in individuals 1 to 17 years of age with a confirmed peanut diagnosis. The powder is packaged in pull-apart capsules, allowing the allergen to be added to a small amount of semisolid food and consumed. Efficacy studies showed 67.2% of recipients tolerated a 600-mg dose, compared with 4.0% of placebo participants [97,112]. Peanut allergen powder is to be used in conjunction with a peanut-avoidant diet and epinephrine should be available during use [112].

Questions have arisen about the safety of some vaccinations for individuals with food allergy, specifically the measles-mumps-rubella (MMR) vaccine and certain types of influenza vaccine, both of which are cultured in egg embryos. Studies have demonstrated that the MMR vaccine is safe for children with egg allergy, and the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the NIAID-sponsored guidelines all support MMR vaccination for children with egg allergy, even children who have a history of severe reactions [2].

The 2010 NIAID-sponsored guidelines note that there is insufficient evidence to recommend administering either trivalent inactivated or live-attenuated influenza vaccines to children with egg allergy who have a history of hives, angioedema, allergic asthma, or systemic anaphylaxis to egg proteins [2]. However, since that time, the results of several studies have shown that the influenza vaccine is safe for most people with a history of egg allergy, without the need to divide and administer the vaccine by a two-step approach or for skin testing with vaccine [102,103]. Based on these findings, the ACIP recommends that mild (hives only) or more severe symptoms (angioedema, respiratory distress, lightheadedness, recurrent emesis, administration of epinephrine or another emergency medical intervention) after exposure to egg are no longer contradictions for any influenza vaccine in adults or children. These individuals should receive any licensed, recommended, age-appropriate influenza vaccine [103,104]. The vaccine should be administered by a healthcare provider who is familiar with identifying and managing the potential manifestations of egg allergy if any symptoms are previously known. A previous severe allergic reaction to influenza vaccine, regardless of the component suspected of causing the reaction, is a contraindication to future receipt of the vaccine [103]. The AAP and a joint AAAAI and ACAAI task force support these recommendations, noting that the risks of not vaccinating outweigh the risks of vaccinating [102].

Early recognition of the clinical signs and symptoms of anaphylaxis is necessary to ensure immediate, appropriate treatment. In most cases, these signs and symptoms will occur within one hour after the accidental ingestion (ranging from within less than one minute to a few hours) and will vary in terms of presence, sequence, and severity. In 1% to 20% of anaphylaxis cases, there will be a biphasic response, with recurrence of symptoms 8 to 12 hours later, after the individual had seemed to recover [100]. The interval between the initial reaction and the recurrence has ranged from 1 to 72 hours. A biphasic reaction occurs in approximately 6% to 11% of children; such reactions typically occur within 8 hours after the first reaction but may occur as long as 72 hours later [12,108] .

As with less severe food-induced allergic reactions, cutaneous manifestations are the most common, followed by respiratory and gastrointestinal symptoms [12,110]. In one study of more than 600 children, cutaneous manifestations were documented in 87% to 98% of children; respiratory manifestations, in 59% to 81%; and gastrointestinal manifestations, in 50% to 59% [110]. The cardiovascular system is less frequently involved and is more often involved in adolescents [110]. Still, cutaneous manifestations may be absent in about 10% to 20% of cases of anaphylaxis, which may contribute to under-recognition [2].