- FOOD ALLERGY (FA) is an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food.
- The symptoms of this disease can range from mild to severe and, in rare cases, can lead to anaphylaxis.
- The most common food allergens are eggs, milk, peanuts, tree nuts, soy, wheat, crustacean shellfish, and fish.
- Nonallergic food reactions, such as food intolerance, are frequently confused with FAs.
- Food allergy is managed by allergen avoidance or treatment of symptoms.
- FOOD-INDUCED ANAPHYLAXIS is a serious, IgE-mediated allergic reaction that is rapid in onset and may cause death.
- GASTROINTESTINAL (GI) FOOD ALLERGIES
Note: Significant overlap may exist among these conditions.
- Immediate GI hypersensitivity refers to an IgE-mediated FA in which upper GI symptoms may occur within minutes and lower GI symptoms may occur either immediately or with a delay of up to several hours. This is commonly seen as a manifestation of anaphylaxis. Among the GI conditions, acute immediate vomiting is the most common reaction and the one best documented as immunologic and IgE mediated.
- Eosinophilic esophagitis (EoE) involves localized eosinophilic inflammation of the esophagus. In children, EoE presents with feeding disorders, vomiting, reflux symptoms, and abdominal pain. In adolescents and adults, EoE most often presents with dysphagia and esophageal food impactions. In some patients, avoidance of specific foods will result in normalization of histopathology.
- Eosinophilic gastroenteritis (EG) describes a constellation of symptoms that vary depending on the portion of the GI tract involved and a pathologic infiltration of the GI tract by eosinophils, which may be localized or widespread. EoE is a common manifestation of EG.
- Food protein-induced allergic proctocolitis (AP) typically presents in infants who seem generally healthy but have visible specks or streaks of blood mixed with mucus in the stool. The lack of systemic symptoms, vomiting, diarrhea, and growth failure helps differentiate this disorder from other GI FA disorders that present with similar stool patterns.
- Food protein-induced enterocolitis syndrome (FPIES) usually occurs in young infants and manifests as chronic emesis, diarrhea, and failure to thrive. Upon re-exposure to the offending food after a period of elimination, a subacute syndrome can present with repetitive emesis and dehydration. Milk and soy protein are the most common causes.
- Oral allergy syndrome (OAS), also referred to as pollen-associated FA syndrome, is a form of localized IgE-mediated allergy, usually to raw fruits or vegetables, with symptoms confined to the lips, mouth, and throat. OAS most commonly affects patients who are allergic to pollens. Symptoms include itching of the lips, tongue, roof of the mouth, and throat, with or without swelling, and/or tingling of the lips, tongue, roof of the mouth, and throat.
- CUTANEOUS REACTIONS to foods are some of the most common presentations of FA.
- Acute urticaria is a common manifestation of FA. Lesions develop rapidly after ingesting the problem food and appear as polymorphic, round, or irregularly shaped pruritic wheals, ranging in size from a few millimeters to several centimeters.
- Angioedema most often occurs in combination with urticaria. It is characterized by nonpitting, nonpruritic, well-defined edematous swelling that involves subcutaneous tissues (for example, face, hands, buttocks, and genitals), abdominal organs, or the upper airway. When the upper airway is involved, laryngeal angioedema is a medical emergency requiring prompt assessment.
- Atopic dermatitis (AD), also known as atopic eczema, is linked to a complex interaction between skin barrier dysfunction and environmental factors such as irritants, microbes, and allergens. The role of FA in the pathogenesis and severity of this condition remains controversial. In some sensitized patients, particularly infants and young children, food allergens can induce urticarial lesions, itching, and eczematous flares, all of which may aggravate AD.
- Allergic contact dermatitis (ACD) is a form of eczema caused by cell-mediated allergic reactions to chemical haptens that are additives to foods or occur naturally in foods such as mango. Clinical features include marked pruritus, erythema, papules, vesicles, and edema.
- Contact urticaria is due to direct contact between the skin and the offending food and can be of two types: 1) IgE mediated or 2) non-IgE mediated, non-immunologic — eg, caused by direct histamine release. In IgE-mediated contact urticaria there is localized or generalized urticaria and at times systemic reactions. In non-IgE-mediated contact urticaria, systemic symptoms are rarely seen.
- RESPIRATORY MANIFESTATIONS occur frequently during systemic allergic reactions and are an important indicator of severe anaphylaxis. FA is an uncommon cause of isolated respiratory symptoms, namely rhinitis and asthma.
Diagnosis and Assessments
Table 1. Symptoms of Food-Induced Allergic Reactions
|Target Organ||Immediate Symptoms||Delayed Symptoms|
Dry staccato cough
Accessory muscle use
Cough, dyspnea and wheezing
Angioedema of the lips, tongue, or palate
Colicky abdominal pain
Irritability and food refusal with weight loss (young children)
Loss of consciousness
Sense of ‘‘impending doom’’
- The general population of children need not be tested for FA to highly allergenic foods prior to their introduction into the diet. (B-III)
Note: The general population of children does not have pre-existing severe allergic disease and also does not have a family history of FA.
- The health care professional considering a diagnosis of food-induced anaphylaxis should understand: (A-III)
- The signs and symptoms characteristic of anaphylaxis
- The timing of symptoms in association with food ingestion/exposure
- Comorbid conditions, such as asthma, that may affect treatment and outcome
- The limited utility of laboratory parameters in the acute care setting
- FA should be considered: (A-II)
- In individuals presenting with anaphylaxis or any combination of symptoms listed in Table 1 that occur within minutes to hours of ingesting food, especially in young children and/or if symptoms have followed the ingestion of a specific food on more than one occasion
- In infants, young children and selected older children diagnosed with certain disorders, such as moderate to severe AD, EoE, enterocolitis, enteropathy, and AP
- In adults diagnosed with EoE
- Use the medical history and physical examination to aid in the diagnosis of FA. (A-III)
- Medical history: The expert panel (EP) recommends using a detailed medical history to help focus the evaluation of an FA. Although the medical history often provides evidence for the type of food-induced allergic reaction and the potential causative food(s) involved, history alone cannot be considered diagnostic of FA.
- Physical examination: The EP recommends performing a focused physical examination of the patient, which may provide signs consistent with an allergic reaction or disorder often associated with FA. However, by itself, the physical examination cannot be considered diagnostic of FA.
- Parent and patient reports of FA must be confirmed, because multiple studies demonstrate that 50% to 90% of presumed FAs are not allergies. (A-I)
- To assist in the identification of foods that may be provoking IgE-mediated food-induced allergic reactions, perform:
- A skin puncture test (SPT) (A-II)
- Allergen-specific IgE (sIgE) tests (A-II)
- But NOT intradermal testing (A-III)
- And NOT the routine use of measuring total serum IgE (A-III)
Note: These tests alone are not diagnostic of FA.
- Do NOT use atopy patch test (APT) for the routine evaluation of noncontact FA. (B-III)
- Eliminating one or a few specific foods from the diet may be useful in the diagnosis of FA, especially in identifying foods responsible for some non-IgE-mediated food-induced allergic disorders, such as FPIES, AP, and Heiner syndrome, and some mixed IgE- and non-IgE-mediated food-induced allergic disorders, such as EoE. (B-III)
- Use oral food challenges for diagnosing FA. (A-I)
Note: The double-blind, placebo-controlled food challenge is the gold standard. However, a single-blind or an open-food challenge may be considered diagnostic under certain circumstances: if either of these challenges elicits no symptoms (ie, the challenge is negative), then FA can be ruled out; but when either challenge elicits objective symptoms (ie, the challenge is positive) and those objective symptoms correlate with medical history and are supported by laboratory tests, then a diagnosis of FA is supported.
- Do NOT use any of the following nonstandardized tests for the routine evaluation of IgE-mediated FA: (A-III)
- Basophil histamine release/activation
- Lymphocyte stimulation
- Facial thermography
- Gastric juice analysis
- Endoscopic allergen provocation
- Hair analysis
- Applied kinesiology
- Provocation neutralization
- Allergen-specific IgG4
- Cytotoxicity assays
- Electrodermal test (Vega)
- Mediator release assay (Lifestyle Eating and Performance [LEAP] diet)
- SPTs, sIgE tests, and APTs may be considered to help identify foods that are associated with EoE, but these tests alone are not sufficient to make the diagnosis of FA. (B-III)
Note: The role of these tests in the diagnosis of other eosinophilic GI diseases has not been established.
- Use the medical history and oral food challenge to establish a diagnosis of FPIES. (A-I)
Note: However, when history indicates that infants or children have experienced hypotensive episodes or multiple reactions to the same food, a diagnosis may be based on a convincing history and absence of symptoms when the causative food is eliminated from the diet.
- Use the medical history, resolution of symptoms when the causative food is eliminated from the diet, and recurrence of symptoms following an oral food challenge to diagnose AP. (A-II)
- Use the medical history, including the absence of symptoms while
the causative food is avoided, and positive patch tests to diagnose ACD. (A-II)
- Use the medical history, including the resolution of symptoms while the causative food is avoided, and positive patch tests to establish the diagnosis of systemic contact dermatitis. (B-III)
- Use the medical history, including the absence of symptoms while the causative food is avoided, positive sIgE tests or SPTs, and positive immediate epicutaneous skin tests (for example, positive immediate responses to APTs), to establish the diagnosis of food-induced IgE-mediated contact urticaria. (B-III)
- Consider children less than 5 years old with moderate to severe AD for FA evaluation for milk, egg, peanut, wheat, soy, and any other food that the parents reported to trigger atopic dermatitis, if at least one of the following conditions is met: (B-III)
- The child has persistent AD in spite of optimized management and topical therapy.
- The child has a reliable history of an immediate reaction after ingestion of a specific food.
- Use follow-up testing for individuals with FA depending on the specific food to which the individual is allergic. Whether testing is done annually or at other intervals depends on the food in question, the age of the child, and the intervening medical history. (B-II)
- Patients at risk* for developing FA do not need to limit exposure to foods that may be cross-reactive with the 8 major food allergens in the United States (milk, egg, peanut, tree nuts, soy, wheat, fish, and crustacean shellfish) or to potential nonfood allergens (for example, dust mites, pollen, or pet dander). (B-III)
- Individuals with documented or proven IgE-mediated or non-IgE-mediated FA should avoid ingesting their specific allergen or allergens. (A-III)
- Patients with FA and their caregivers should be provided with information on food allergen avoidance and emergency management that is age and culturally appropriate. (A-III)
- Individuals without documented or proven FA need not avoid potentially allergenic foods as a means of managing AD, asthma, or EoE. (A-II)
- All children with FA should have nutritional counseling and regular growth monitoring. (A-III)
- Individuals with FA and their caregivers should receive education and training on how to interpret ingredient lists on food labels and how to recognize labeling of the food allergens used as ingredients in foods. Products with precautionary labeling, such as ‘‘this product may contain trace amounts of [allergen]’’ should be avoided. (B-III)
- There are no medications currently recommended to prevent IgE-mediated or non-IgE-mediated food-induced allergic reactions from occurring in an individual with existing FA. (A-II)
- Although consensus recommendations for MMRV vaccine vary from the different organizations, children with egg allergy, even those with a history of severe reactions, should receive vaccines for measles, mumps, and rubella (MMR) and for MMR with varicella (MMRV). (A-III)
Note: The safety of this practice has been recognized by ACIP and AAP and is noted in the approved product prescribing information for these vaccines.
Pregnancy and Infancy
- Restricting maternal diet during pregnancy or lactation as a strategy for preventing the development or clinical course of FA is NOT recommended. (A-III)
- All infants should be exclusively breast-fed until 4 to 6 months of age, unless breastfeeding is contraindicated for medical reasons. (A-III)
- Using soy infant formula instead of cow’s milk infant formula is NOT recommended as a strategy for preventing the development of FA or modifying its clinical course in at-risk* infants. (A-II)
- Consider using hydrolyzed infant formulas, as opposed to cow’s milk formula, as a strategy for preventing the development of FA in at-risk* infants who are not exclusively breast-fed. (B-II)
Note: Cost and availability of extensively hydrolyzed infant formulas may be weighed as prohibitive factors.
- The introduction of solid foods should NOT be delayed beyond 4 to 6 months of age. Potentially allergenic foods may be introduced at this time as well. (B-III)