Understanding Egg Allergy
Egg allergy is one of the most common food allergies, particularly in infants and young children. While many children outgrow it before starting school, for some, the allergy persists into adolescence or even adulthood. An allergic reaction to egg can range from mild symptoms, such as a rash, to severe anaphylaxis, making early diagnosis and management crucial.
At The London Allergy Clinic, we specialise in diagnosing and managing egg allergies. With over 40 years of experience, our expert clinicians offer a range of tests and treatments tailored to each patient’s needs.

What Causes an Egg Allergy?
An egg allergy occurs when the immune system mistakenly identifies proteins found in eggs as harmful. This triggers an immune response, leading to allergic symptoms. The primary proteins responsible for egg allergy are found in the egg whites although some individuals react to both the yolk and whites.
Symptoms of an Egg Allergy
Symptoms of an egg allergy appear quickly (within 1 hour) after exposure and can vary in severity.
Common reactions include:
Skin reactions: Hives, redness, or swelling, particularly around the mouth
Gastrointestinal symptoms: Nausea, vomiting, diarrhoea, or stomach cramps
Respiratory issues: Sneezing, coughing, wheezing, or difficulty breathing
Anaphylaxis: A severe, life-threatening reaction requiring immediate medical attention
The severity of the symptoms may be impacted by how well the egg is cooked and how much egg is eaten.
Around 80% of patients with an egg allergy can tolerate egg if it is well-cooked, for example baked into a cake. The reason being that the proteins within the egg which trigger the allergy are denatured by heat. See below for a list of foods containing well-cooked egg.
Who is at Risk?
Certain factors increase the likelihood of developing an egg allergy:
Eczema: Babies with eczema are more prone to food allergies, including egg allergy.
Family history: A family history of allergies, asthma, or eczema raises the risk.
Other food allergies: Those allergic to cow’s milk or other foods may be more susceptible.
Can You Outgrow an Egg Allergy?
The good news is that around 70-80% of children outgrow their egg allergy by the age of five. However, some continue to have reactions into later childhood or adulthood. In some cases, individuals may tolerate baked or well-cooked egg but react to raw or lightly cooked egg.
Foods That Contain Egg
It is essential for individuals with an egg allergy to carefully read ingredient labels, as egg is present in many foods, including (but not limited to):
Undercooked/raw egg: Mayonnaise, salad cream, uncooked cake batter, luxury ice creams, mousse, trifle, soufflé and nougat-containing chocolate bars such as Milky Way or Mars.
Loosely cooked egg: Scrambled eggs, omelettes, fried eggs, hollandaise sauce, quiches & homemade pancakes.
Well-cooked egg: Cakes, dried egg pasta, sausages containing egg, egg-glaze on pastry, shop-bought pancakes.
Egg-free alternatives, including vegan options, are increasingly available in supermarkets and health food stores.
Nestlé helpfully publish an 'Egg Avoidance' list which states all of their products which are safe for consumption for egg allergy sufferers:
Food labels with the following ingredients may indicate the presence of egg:
Albumin
Lysozyme (an enzyme derived from egg)
Letcithin (E322) is, in rare cases, made from egg. More commonly it is made from soya which is safe for egg allergies.
Emulsisfier or binder may suggest egg has been used
Diagnosing an Egg Allergy
The London Allergy Clinic offers comprehensive testing to confirm an egg allergy, including:
Skin Prick Testing: A fast and effective test where small amounts of egg protein are applied to the skin to check for a reaction. Learn more
Specific IgE Blood Tests: Measures the level of IgE antibodies to egg proteins in the blood. Learn more
Managing an Egg Allergy
Management depends on the severity of the allergy and whether baked egg is tolerated. Our allergy specialists provide personalised guidance, including:
Strict avoidance: For severe reactions, complete egg elimination is required.
Dietary advice: Substitutes and alternatives for cooking and baking.
Emergency plans: Education on recognising anaphylaxis and using adrenaline auto-injectors.
FAQs
Can a baby develop an egg allergy from breastfeeding?
Small amounts of egg protein may pass through breast milk. If an infant shows signs of allergy, a mother may trial eliminating egg from her diet.
Can people with egg allergies tolerate baked egg?
Around 80% of individuals with an egg allergy can tolerate baked egg. A specialist should determine if this is safe.
What is the most severe reaction to an egg allergy?
Anaphylaxis is the most severe reaction, requiring immediate medical attention.
Where can I get tested for an egg allergy?
The London Allergy Clinic offers Skin Prick Testing and Specific IgE Blood Tests at our London clinics. Book an appointment today.
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