Egg allergy: what to avoid, where it can be hidden and how to replace it

What happens in the body with an egg allergy?

With an egg allergy, the immune system mistakes some egg proteins for a threat and reacts to them. Almost all of them are found in the egg white. The best-known ones are ovalbumin, ovomucoid and lysozyme.

It is one of the most common food allergies in childhood, alongside milk allergy. It usually appears during the first two years of life, often on first exposure to egg. A reaction typically occurs quickly, within minutes or a few hours. Hives, swelling of the lips or eyelids, vomiting, coughing or wheezing are the most common symptoms. See “Allergies when introducing foods to babies”.

With an allergy, even a small amount can trigger a reaction. If you’re unsure whether you have an allergy or an intolerance, we explain the difference in our guide to food allergies and intolerances: what they are and how they differ.

Can children outgrow an egg allergy?

In many cases, yes. According to European allergy guidelines, between half and six in ten children with an egg allergy outgrow it around school age [1].

You cannot guess whether egg is now tolerated. An allergist decides by carrying out an oral food challenge, giving gradually increasing amounts of egg under medical supervision with everything ready in case of a reaction [2]. It is never done at home, even if there have been no problems for months.

Until then, egg must still be avoided. Avoiding it carefully, without removing anything else, helps the child continue to grow as they should while waiting for the challenge.

Raw, cooked and baked egg: are they all the same?

Not always. Heat changes some egg proteins, which is why some people react to lightly cooked egg but tolerate it in a cake. Ovomucoid is the exception because it withstands cooking. People with antibodies to it usually also react to baked egg [3].

An allergist can investigate this with blood tests and other tests. If they consider it safe, they may recommend baked egg using a specific recipe and amount [1]. When recommended, it is eaten regularly to maintain tolerance [1].

If your allergist has not recommended it, baked egg must also be avoided. A cake that another child tolerates tells you nothing about how your child will react.

Where can egg be hidden, and how do you read the label?

By law, egg is one of the fourteen allergens that must be declared on labels [4]. It must be emphasised in the ingredients list, in bold or a different typeface [4]. Bakeries, food preparation premises, bars and canteens must also make this information available, even when the product is not packaged [4].

Sometimes it appears under a technical name. Albumin, ovalbumin, lysozyme (E-1105) and egg lecithin are all egg ingredients. Lecithin E-322 may come from other sources; if it comes from egg, the label must say so [4].

Read the label every time, even on products you buy regularly, because recipes can change without warning.

“May contain traces of egg” is a voluntary warning and does not say how much may be present. Whether you can eat the product depends on your situation; your allergist will advise you [1].

Lysozyme is also used in some medicines. If you take one, ask a pharmacist or your doctor whether it is suitable for you with your allergy.

What is lost when egg is removed, and how can it be replaced?

Egg provides high-quality protein, as well as some vitamins and iron. Removing it does not leave a gap that is difficult to fill if the rest of the meal is well planned.

Protein can come from meat, fish, pulses, dairy products and tree nuts, if there is no other allergy. In children, the risk arises when more foods than necessary are eliminated, or they are avoided for longer than necessary [1]. That is why guidelines recommend that a dietitian review the diet in more complex cases [1].

Cooking substitutes bind ingredients and add lightness, but they do not provide the protein found in egg. A cake made with banana is still a snack; the day’s protein needs to come from lunch and dinner.

Can a child with an egg allergy be vaccinated?

Yes, in the vast majority of cases. The MMR vaccine (measles, mumps and rubella) is given at the usual vaccination centre [5]. The usual precautions for any vaccine apply, including for children who have had anaphylaxis, according to the Vaccine Advisory Committee of the Spanish Association of Paediatrics [5].

The flu vaccine can be given at any level of egg allergy and without prior testing [6]. The yellow fever vaccine, which is required for some trips, contains more egg protein, so an allergist should assess it beforehand [5].

The decision belongs to the paediatrician or doctor giving the vaccine. Always tell them about the allergy before the injection.

School meals, birthdays and eating out

Schools that provide meals must offer a modified menu for pupils with an allergy, provided the family supplies a medical certificate [7]. If the kitchen cannot prepare one, the school must provide a fridge and a way to heat food brought from home [7].

The best protection is a written action plan that the school can access, and an adrenaline auto-injector if one has been prescribed [1]. Dining staff need to know where it is and how to use it.

For birthdays, it works well to bring a portion of homemade egg-free cake. That way, your child can eat the same as everyone else, and nobody has to improvise.

What mistakes do we often see in consultations?

• Avoiding chicken as well. Unless the allergist says otherwise, poultry does not need to be excluded.
• Trying “a little bit” at home to see if it is now tolerated. This challenge must be done under medical supervision.
• Buying unpackaged bread or pastries without asking. The bakery must tell you which allergens they contain.
• Removing more foods than necessary “just in case”. A child’s diet can quickly become less varied when more and more foods are removed.

The question we hear most often in consultations is when a child will be able to eat egg again. The allergist’s challenge will provide the answer. Until then, our role is to help the child eat a varied, safe diet that provides everything they need.