INTRODUCTION — The management of hen's egg allergy does not differ from that of other food allergies [1]. It requires instructions on avoidance and education about treatment of reactions in the event of accidental exposure. It also includes monitoring for the resolution of the allergy. (See "Management of food allergy: Avoidance" and "Anaphylaxis: Emergency treatment" and "Food allergy in children: Prevalence, natural history, and monitoring for resolution".)

This topic reviews various aspects of management of egg allergy, including instructions about avoidance of egg protein, education in the proper management of accidental exposures, and monitoring for resolution of the allergy. Issues with egg-containing vaccines and lipid emulsions are also covered in this topic, although options for administration of the influenza vaccine in patients with egg allergy are discussed separately. The epidemiology, pathogenesis, clinical features, and diagnosis of egg allergy are also discussed separately. (See "Egg allergy: Clinical features and diagnosis" and "Influenza vaccination in individuals with egg allergy".)

The management of food allergy in the specific settings of schools and camps is discussed in detail separately. (See "Food allergy in schools and camps" and "Food allergy in college and university students: Overview and management".)

General discussions of food allergy are presented separately in appropriate topic reviews.

AVOIDANCE — The most straightforward approach in managing any food allergy is complete avoidance of the culprit food. Eliminating hen's egg (both egg white and egg yolk) from the diet can be difficult and can pose nutritional as well as quality-of-life concerns since egg is a ubiquitous food in many cultures and diets. Egg is an ingredient in baked goods, breaded foods, cream fillings, custards, candies, canned soups, casseroles, frostings, ice creams, lollipops, marshmallows, marzipan, pastas, salad dressings, and meat-based dishes such as meatballs or meatloaf (Food Allergy Research and Education [FARE]). Accidental exposures are common. In one prospective series of 500 infants aged 3 to 15 months with suspected or confirmed egg and/or milk allergy, 72 percent had an allergic reaction, most commonly to milk, egg, or peanut, during a three-year period, with an annualized reaction rate of 0.81 per year [2]. Twenty-one percent of these were triggered by egg, giving an annualized rate of reaction to egg of 0.17 per year. Eighty-seven percent of all reactions were due to accidental exposures. (See "Management of food allergy: Nutritional issues" and "Food allergy: Impact on health-related quality of life" and "Management of food allergy: Avoidance" and "Food allergy in children: Prevalence, natural history, and monitoring for resolution", section on 'Role of avoidance'.)

Counseling about avoidance should include discussions about the following issues:

●Cross-contact and hidden ingredients – Patients must be counseled about the potential for accidental exposure to food allergens via cross-contact (ie, inadvertent exposure to the allergenic food by contamination of "safe" foods with small amounts of the culprit food). This can happen anywhere food is served, including restaurants and bakeries. In addition, egg whites and shells are used as clarifying agents and can be found in soup stocks, consommés, wine, alcohol-based beverages, and coffee drinks. Egg white is also used as a wash to make bread products shiny. (See "Management of food allergy: Avoidance", section on 'Skills for daily living'.)

●Food labels – Patients must read all food labels (FARE). Legislation has been enacted in the United States and many other countries mandating that the ingredient labels on food packages clearly identify the presence of hen's egg when it is an intended ingredient [3]. (See "Management of food allergy: Avoidance", section on 'Food labeling'.)

●Advisory labeling – Some products in the United States and other countries may have advisory labeling, such as "may contain egg." This type of labeling is generally not currently regulated. The risk of allergic reactions to these products is not known, and the frequency and amount of egg contamination in these products has not been studied. (See "Management of food allergy: Avoidance", section on 'Advisory labeling'.)

●Cross-reactivity – Serologic cross-reactivity with other bird eggs (turkey, duck, goose, seagull, and quail) has been reported [4], and there are case reports suggesting clinical cross-reactivity [5]. A minority of patients with allergy to egg are reactive to chicken meat as well. Chicken serum albumin (Gal d 5) is responsible for this cross-reactivity [6]. Given the low rates of clinical reactivity reported, patients with hen's egg allergy are not routinely advised to avoid other bird eggs or chicken meat. (See "Food allergens: Overview of clinical features and cross-reactivity".)

●Egg substitutes – Counseling should include a discussion about egg alternatives and substitutes (table 1 and table 2). Commercial products marketed as "egg substitutes" may have egg ingredients. (See "Management of food allergy: Nutritional issues", section on 'Egg allergy'.)

●Unexpected and nonfood sources – Medications and vaccines may have ingredients derived from egg. Patients should ensure that the clinicians and pharmacists caring for them are aware of their egg allergy, especially before receiving any new medication or vaccine. Labeling of nonfood items is not strictly regulated in the United States and most other countries. The yellow fever vaccine may induce reactions in egg-allergic individuals. Protocols are available for the safe administration of this vaccine in egg-allergic individuals. In contrast, the measles, mumps, and rubella (MMR) vaccine and influenza vaccine are well tolerated by egg-allergic individuals and should be administered in the routine manner. (See "Management of food allergy: Avoidance", section on 'Food allergens in nonfood items' and "Allergic reactions to vaccines", section on 'Egg' and "Immunizations for travel", section on 'Yellow fever vaccine' and "Influenza vaccination in individuals with egg allergy".)

The following scenarios illustrate some of the issues involved and our approach to avoidance. Individual clinicians may decide to adopt different strategies depending upon their level of expertise and the resources available (eg, ability to perform oral food challenges [OFCs]). Our approach to reintroducing various forms of hen's egg is discussed below. (See 'Monitoring for resolution and reintroduction' below.)

●If a patient with an allergy to egg in any or all forms or of any severity wishes to avoid all egg, we do not discourage this approach.

●We allow persons to continue to eat egg in more extensively heated or processed forms than what triggered their reaction(s) if they have eaten egg in these forms regularly and in the recent past (similar to passing an OFC). In most cases, this involves patients who reacted to lightly cooked egg (eg, scrambled egg, French toast) but have a history of tolerating extensively heated egg (eg, muffins, waffles). We generally suggest that these patients avoid more intermediate forms of cooked egg, such as meatballs/meatloaf, breaded foods, casseroles, custard, and mayonnaise.

One caveat to this approach that should be discussed with patients is that it is possible that a patient may have a reaction due to ingestion of a larger amount of egg or more lightly cooked egg than usual (eg, normally tolerates egg in muffins but has a reaction when blueberries are used in the muffins and the batter does not cook completely around the blueberries).

●We advise patients who have reacted to intermediately cooked or extensively heated egg to avoid all forms of egg.

MANAGEMENT OF REACTIONS

Acute immunoglobulin E (IgE)-mediated reactions — Patients with IgE-mediated egg allergy are at risk for severe reactions (table 3 and table 4), and the severity of symptoms can vary from reaction to reaction [7,8]. Thus, we prescribe epinephrine autoinjectors for all patients with a history of anaphylactic reactions to egg and typically do so for patients with milder IgE-mediated reactions to egg as well. In addition, the patient should have a written anaphylaxis emergency action plan (Anaphylaxis Emergency Action Plan - English) (Anaphylaxis Emergency Action Plan - Spanish). These measures are discussed in detail separately. (See "Anaphylaxis: Emergency treatment" and "Prescribing epinephrine for anaphylaxis self-treatment".)

As with other forms of food allergy, the severity of symptoms in a given individual with egg allergy may vary considerably between reactions. In addition, the severity of an initial reaction does not predict the severity of subsequent reactions. As examples:

●In a small study investigating whether children with egg allergy of varying severity could tolerate extensively heated forms of egg, 18 percent of children who reacted to extensively heated egg and 23 percent who reacted to lightly cooked egg required treatment with epinephrine [7].

●In another series of 167 children that examined dietary advice and adherence in patients with egg allergy, the initial episode was a local reaction in 29 percent, a mild-to-moderate systemic reaction in 31 percent, and a severe systemic reaction in 18 percent [8]. Twenty percent of the children in this study had a subsequent reaction to egg that was more severe than the initial event.

●Children whose only apparent clinical manifestation of food allergy is atopic dermatitis are at risk of an acute systemic reaction upon reintroduction of that food after an elimination diet [9].

●Children with egg allergy are more likely to develop asthma, and concomitant asthma places patients at higher risk for severe allergic reactions to foods [10].

Delayed gastrointestinal reactions — The management of children with non-IgE-mediated egg allergy, including eosinophilic esophagitis and food-protein induced enterocolitis syndrome, is presented in specific topic reviews. (See "Treatment of eosinophilic esophagitis" and "Dietary management of eosinophilic esophagitis" and "Food protein-induced enterocolitis syndrome (FPIES)".)

MONITORING FOR RESOLUTION AND REINTRODUCTION — Children with egg allergy should be monitored for resolution of the allergy since most will outgrow the allergy in childhood. Monitoring for resolution includes assessing history of any accidental exposures and reactions, serial testing for sensitization (in vitro and/or skin prick testing [SPT]), and food challenges. The general steps taken to determine if an allergy has resolved are covered in detail separately. The approach for hen's egg allergy is outlined here. (See "Egg allergy: Clinical features and diagnosis", section on 'Natural course' and "Food allergy in children: Prevalence, natural history, and monitoring for resolution", section on 'Monitoring for resolution' and "Food allergy in children: Prevalence, natural history, and monitoring for resolution", section on 'Natural history of specific allergies'.)

Factors that improve the odds of passing a challenge include:

●Lower egg-specific IgE levels [11,12].

●Downward trends over time in egg-specific IgE or SPT reaction [13-15].

●Absence of an interval history of symptoms triggered by accidental exposure. Accidental exposures to foods containing egg are common [2]. Thus, the clinical history is often useful in predicting the likelihood of a successful baked egg introduction.

●Fewer failed challenges, longer interval since last failed challenge, and failure at a higher dose.

Extensively heated (baked) egg — Several studies have indicated that 66 to 88 percent of individuals with egg allergy can tolerate extensively heated or baked forms of egg [7,11,16,17]. Supervised oral food challenges (OFCs) are recommended to determine whether an individual with egg allergy can safely include extensively heated egg in their diet because of the risk of reactions and the predictive limitations of in vitro and SPT.

The potential benefits of including extensively heated egg in the diet, if tolerated, extend beyond improvements in quality of life. Data suggest that tolerance to extensively heated egg is a good prognostic factor for the development of tolerance to less heated forms of egg and that including extensively heated egg in the diet may accelerate the development of tolerance [18,19]. However, consumption of extensively heated egg may also increase the risk of a reaction due to inconsistencies in the amount of egg in baked products leading to a greater exposure or due to incomplete cooking leading to exposure to lightly cooked egg. (See 'Avoidance' above.)

While there is some variation in the predictive value of SPTs with hen's egg extract and specific IgE levels, the data indicate that there is a >80 percent chance that baked egg will be tolerated if egg white-specific IgE (EW-IgE) is <2 kUA/L, whereas a level >10 kUA/L suggests an increased likelihood of reacting to baked egg [7,11,16]. In one series, the pass rate was approximately 50 percent when the EW-IgE was ≤15 kU/L [12]. SPT is less reliable in predicting baked egg challenge outcomes [11,20]. Prick-prick testing with the challenge food was informative in one study, with 100 percent negative predictive values when mean wheal diameters were <3 mm for three different forms of extensively heated egg (cake, frittata, and boiled egg) [17]. This suggests that these patients could introduce extensively heated egg without first undergoing an OFC. However, prick-prick testing with the food is not standardized. The utility of measurement of specific IgE to egg components (ovomucoid, ovalbumin) has also not been extensively studied, and results have not consistently correlated with clinical outcomes [12]. (See "Component testing for animal-derived food allergies", section on 'Egg'.)

In those who reacted during baked-egg challenge, 12 to 44 percent had multisystem involvement requiring treatment with intramuscular epinephrine [7,11,21]. In one series of 174 OFCs to baked egg, baked milk, cooked egg, cow's milk, peanut, or tree nuts in 158 children, new symptoms were more likely to appear ≥60 minutes after stopping an OFC for baked egg or baked milk compared with other foods (29 and 21 percent versus 0 to 10 percent, respectively), with one-third of anaphylactic reactions to baked egg beginning more than an hour after the OFC was discontinued [21]. Hypoxemia and hypotension were only observed in baked-egg and baked-milk challenges. In contrast, mucocutaneous reactions were reported less commonly in baked-egg and baked-milk OFCs compared with OFCs to other foods. In all patients with delayed anaphylaxis to egg (baked or cooked), the OFC was ended due to gastrointestinal symptoms that were not treated. Extending the dosing interval, adding more dosing steps, early treatment of subjective symptoms, and/or prolonging the observation time may be warranted in patients who are at higher risk for reacting to baked-egg OFC (eg, higher IgE levels, recent reactions, history of more severe reactions or anaphylaxis). (See "Milk allergy: Management", section on 'Extensively heated (baked) cow's milk'.)

Findings from one study suggest the cooking temperature, cooking time, and final internal temperature of the food are more important than the presence of a wheat matrix. In this study, 54 children with a history of egg allergy and positive skin test to raw hen's egg were skin tested (prick-prick method) to three different forms of extensively heated egg: baked egg in a wheat matrix in the form of a cake that was baked at 180°C (356°F) for at least 30 minutes, baked egg without a wheat matrix in the form of a single egg frittata fried in olive oil for three minutes and then cooked in a 180°C oven for at least 30 minutes, and egg boiled for 10 minutes [17]. All children were then challenged to the cake, regardless of skin test results. Those who passed the cake OFC were sequential challenged to the frittata and then, if that OFC was passed, to the boiled egg. OFC pass rates were 88 percent for the cake, 74 percent for the frittata, and 56 percent for the boiled egg.

Our approach — For patients with lower egg-specific IgE levels (≤2 kU/L) [22,23] or SPT reactions less than or equal to the histamine control on follow-up testing, especially if the clinical history is reassuring, we will offer food challenge initially to lightly cooked egg rather than extensively heated (baked) egg. The chance of success with these challenges is approximately 50 percent (based upon egg-specific IgE levels). Patients who fail the direct egg challenge are eligible for a challenge to baked egg. Some families prefer to start with the baked-egg challenge as they feel the addition of baked-egg products into the child's diet is a higher priority.

The approach for determining when to try to introduce baked egg is similar to that for baked milk with regard to testing and food challenges (see "Milk allergy: Management", section on 'Monitoring for resolution and reintroduction'). There are no absolute cutoffs that preclude challenge to baked egg. The only caveat is that successful challenges are less commonly seen with high EW-IgE levels compared with milk. Thus, we usually offer baked-egg challenges with EW-IgE levels of ≤10 kU/L (and/or SPT ≤11 mm wheal) and uncommonly offer them with levels >20 kU/L (and/or SPT wheal >15 mm [7]), although other experts may use different cutoff values. In some cases, families may wish to pursue baked-egg challenge with EW-IgE levels >10 kU/L. However, caution is needed because severe reactions can occur from this type of OFC. Other patients (or their parents) may prefer to continue avoidance of all egg until it is felt that they are ready for straight egg challenge. Some have suggested that egg component testing helps predict challenge outcomes, but this was not supported in several studies [12,24-26]. (See "Milk allergy: Management", section on 'Our approach' and "Component testing for animal-derived food allergies", section on 'Egg'.)

The approach to the patient after a baked-egg challenge is highly individualized. Most often patients are advised to return for reevaluation and possible advancement to lightly cooked egg (eg, scrambled egg or French toast) using food challenge testing approximately every six months. Some allergy specialists allow select patients to gradually advance their diet at home, from baked egg to less heated egg (eg meatballs/meatloaf, breaded foods dipped in egg and baked) to lightly cooked egg. For patients who fail the challenge with just a mild reaction after ingesting a large dose of baked egg, an option is to have them include a smaller amount of baked egg in their diet and slowly increase the amount over time.

MANAGEMENT OF YOUNGER SIBLINGS — Parents often inquire about what measures to take to prevent egg allergy (eg, maternal avoidance during pregnancy and lactation) and when to introduce egg in a younger sibling of a child with egg allergy. In these cases, avoidance of egg is not recommended for nursing mothers, nor is delayed introduction of egg beyond six months of age, unless the infant is showing signs of allergic disease. These issues are discussed in greater detail separately. (See "Pathogenesis of food allergy", section on 'Genetics' and "The impact of breastfeeding on the development of allergic disease" and "Primary prevention of allergic disease: Maternal diet in pregnancy and lactation" and "Introducing highly allergenic foods to infants and children", section on 'Introduction in a high-risk population'.)

FUTURE TREATMENTS — There are no treatments that can cure or provide long-term remission from food allergy. However, several treatment strategies are under investigation. These approaches are either allergen specific or aimed at modulating the overall allergic response. (See "Investigational therapies for food allergy: Immunotherapy and nonspecific therapies" and "Oral immunotherapy for food allergy".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Seasonal influenza vaccination".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Beyond the Basics topics (see "Patient education: Food allergy symptoms and diagnosis (Beyond the Basics)" and "Patient education: Food allergen avoidance (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Management of hen's egg allergy includes instructions about avoidance of egg-containing products, education in the proper management of accidental exposures, and monitoring for resolution of the allergy (Anaphylaxis Emergency Action Plan - English) (Anaphylaxis Emergency Action Plan - Spanish) (Food Allergy Research and Education [FARE]) (table 1 and table 2). (See 'Introduction' above.)

●The most straightforward approach in managing any food allergy is complete avoidance of the culprit food. However, eliminating hen's egg (both egg white and egg yolk) from the diet can be difficult and can pose nutritional as well as quality-of-life concerns since egg is a ubiquitous food in many cultures and diets. Counseling should include a discussion about egg alternatives and substitutes (table 1 and table 2). In addition, evaluation of the allergy followed by an oral food challenge (OFC) to extensively heated egg is an option since a majority of those with egg allergy will tolerate egg in extensively heated (baked) products, such as a muffin. (See 'Avoidance' above and "Management of food allergy: Nutritional issues" and 'Extensively heated (baked) egg' above.)

●Patients with immunoglobulin E (IgE)-mediated egg allergy are at risk for severe reactions, and the severity of symptoms can vary from reaction to reaction. Thus, we prescribe epinephrine autoinjectors for all patients with a history of anaphylactic reactions to egg and typically do so for patients with milder IgE-mediated reactions to egg as well. (See 'Acute immunoglobulin E (IgE)-mediated reactions' above.)

●Children with egg allergy should be monitored for resolution of the allergy since most will outgrow the allergy in childhood. Monitoring for resolution includes assessing history of any accidental exposures and reactions, serial testing for sensitization (in vitro and/or skin prick testing [SPT]), and food challenges. (See 'Monitoring for resolution and reintroduction' above.)