Hen's egg allergy

What is egg allergy?

Egg allergy is caused by an allergic reaction to egg protein. This protein is found mostly in the egg white but also in the yolk. It is common and usually mild in children under five years and usually first noticed in infancy when egg is introduced into the diet for the first time. It is rare for egg allergy to develop in adulthood (where it is often severe).

What are the symptoms?

Most reactions in children are mild. Commonly, infants refuse the egg-containing food, develop redness and sometimes swelling and hives around the mouth soon after skin contact and then vomit after eating. Stomach-ache or diarrhoea may also occur. Rarely, some children also develop a more severe reaction with cough, an asthma-type wheeze or even anaphylaxis. Further reactions do not, as a rule, become increasingly severe unless a greater amount or a less well-cooked form of egg is eaten; accidental reactions are almost always milder than the original. Accidental skin contact usually only causes a rash but no generalized or dangerous symptoms; severe reactions rarely occur unless egg is eaten.

Egg allergy may also be responsible for worsening of eczema, but this is more difficult to diagnose given the slower time to onset of symptoms and is usually only seen in very young children.

Will the allergy resolve?

Egg allergy will resolve by itself in most children, usually by school-age. Generally, as they grow out of it, children tolerate well-cooked egg (for example cakes) first, followed by lightly cooked egg in pancake, before finally being able to eat lightly cooked whole egg. Children who have had more severe reactions (such as with wheezing) may take longer to grow-out of their allergy and in some cases egg allergy will persist.

How is egg allergy diagnosed?

The diagnosis of egg allergy is based on the history of previous reactions and can be confirmed by skin tests or blood tests.

What is the treatment?

Initially you may need to avoid all sources of egg in your child’s diet. Egg can be found in a wide range of foods, including cakes, pastries, desserts, meat products, salad dressings, glazes, pasta, battered and bread crumbed foods, ice cream, mayonnaise, chocolates and sweets. It may also be referred to by unusual terms especially on imported foods for example egg lecithin or albumen (egg white). The proteins in eggs from other birds are very similar to those in hens' eggs and should be avoided too.

Depending on your child’s history of reactions, you may be advised to introduce egg as a baked ingredient in foods such as cake. A significant number of children with egg allergy can tolerate baked egg in their diet. If your child has a history of more severe reactions (e.g. wheezing) the allergy team may advise you to bring your child in for a hospital food challenge to baked egg at an appropriate time.

You should also obtain antihistamine syrup (available without prescription) and keep this available at mealtimes. Children who are considered to be at high risk of a severe allergic reaction, should be provided with an adrenaline injector by their doctor (this is unusual). A treatment plan will be provided and you should keep a copy with your child's medication and also give copies to others, such as nursery/school teachers and grandparents. You should also provide emergency medication for your child's school or nursery, which your doctor can prescribe.

Can my child have their routine immunisations?

All children with egg allergy should receive their normal childhood immunisations, including the MMR vaccination as a routine procedure performed by their family doctor/nurse. MMR does not contain egg. Studies on large numbers of egg-allergic children show that there is no increased risk of severe allergic reactions to the vaccine.

As with other vaccines, MMR should be postponed if children are unwell. Adrenaline should be readily available at the clinical site in all cases because anaphylaxis, although rare, can occur due to allergy to the vaccine itself or any other component.

If previous vaccination (MMR or other) resulted in a severe allergic reaction (any breathing problems or collapse), then the child should be seen by an allergy specialist before further immunizations are given.

What about other immunizations?

Influenza vaccine is prepared on hen's egg and may contain small amounts of egg protein.

Inactivated influenza vaccines that are egg-free or have a low ovalbumin content are available and may be administered safely in individuals with egg allergy by your GP/nurse. LAIV (Fluenz Tetra®) is also safe for use in egg-allergic children.

People who can eat at least some form of egg can have the vaccine even if they have had an allergy to egg in the past and even if their allergy tests for egg are still positive.

Yellow fever vaccine contains measurable amounts of egg protein and people with egg allergy who need it should be seen by an allergy specialist.

Can I continue to breastfeed my baby?

If you are breastfeeding, any food proteins, such as egg, will also be present in your breast milk. If your baby is well, with no allergic symptoms, then it is fine for you to eat egg as normal. Do not remove egg from your own diet as this will make no difference to your baby’s symptoms and may compromise your own diet. If you have concerns that your baby has symptoms whilst breastfeeding, please discuss with your doctor or dietitian.

Does egg allergy mean my child is at risk of other allergies?

Most children with egg allergy will already have a history of eczema. Egg allergy also increases the risk of developing asthma later in childhood, but not in all children. Allergies to other foods are more common in egg-allergic children.

I have another child/infant to whom I have not given egg. When should it be introduced into their diet?

The Department of Health recommends that egg should be introduced into the weaning diet from around six months. There is no evidence to suggest that delaying the introduction of egg beyond six months will reduce the chance of your child developing egg allergy. Exclusion of egg beyond 12 months of age may increase their risk of developing egg allergy.