What is an allergy?
Why are eggs a common cause of food allergy?
When am I most likely to get an egg allergy?
How do I know if it’s eggs that I’m allergic to?
Will I be allergic to eggs forever?
Can my egg allergy be cured?
Can anyone develop an allergy to eggs?
Will I be able to eat egg-containing foods, like pasta?

What is an allergy?

When we are given a flu jab or a measles vaccination, the object is to give us immunity to a particular infection.  Our immune system responds to the vaccine as it does to other harmful substances, in this case by producing chemical antidotes known as antibodies.  If we try to define allergy, the simplest explanation is that it is “immunity gone wrong”.  Instead of providing protection against harmful invaders, it can trigger excessive reactions - not to harmful germs but to food proteins or to innocuous substances such as grass pollen, dust mites or household pets. 

Why are eggs a common cause of food allergy?

The frequency of all food intolerance, but especially egg allergy, is at a peak in the first year of life, suggesting that the baby who has the ability to digest mother’s milk may not always be mature enough to accept other foods.  The age at which the food is introduced into the diet can, in fact, have a major effect.  Since eggs are among the foods that tend to be introduced early in a baby’s life, that can be one of the problems. 

There are other reasons.  Some foods are more liable than others to provoke allergic reactions because of the kind of proteins they contain.  The size of the protein molecule can be important, and some proteins are more digestible, absorbable, and stable than others. Eggs, for example, contain proteins that, in the raw state, are of the right size and stability to cause allergies, but in most cases cannot withstand the effect of heat.  This explains why people with a mild allergy to eggs can tolerate some cooked foods, such as cakes or pasta, even when they contain relatively large quantities of egg.

When am I most likely to get an egg allergy?

Egg allergy is most common in infants under the age of twelve months and then becomes progressively less of a problem. Few children are allergic to egg after the age of six, though in some cases this allergy can persist to adult life. Those with other allergies or with a family history of allergy seem to be particularly vulnerable.

It is a curious finding that more than half of the infants who develop egg allergy begin to have symptoms within minutes of being given an egg for the first time. While it is possible that some have received small amounts of egg in a manufactured baby food, it is also possible that some have actually been sensitized before birth or via breast milk.  The most immediate reactions usually involve a rash around the mouth and face.  More general skin reactions and wheezing, sneezing and vomiting may also follow, and a longer lasting eczematous skin reaction can also be troublesome.  In some children, there may also be intolerance to other foods such as cow’s milk or fish.

How do I know if it’s eggs that I’m allergic to?

In infants and small children the development of an egg allergy can be dramatic. The most common way in which this allergy presents itself is with a red rash around the mouth within seconds of eating an egg, followed in a few minutes by swelling around the mouth, on the face, and also inside the mouth.  A few babies develop vomiting, though loose stools are relatively uncommon.  Later, further areas of skin swelling or eczema can occur, together with features such as wheezing, sneezing, or running of the eyes.  If there has been local skin swelling on contact with egg (especially raw egg) this can be very strongly suggestive. Children who have this problem will often refuse egg when it is offered to them.

Although egg allergy can also develop in adult life this is nearly always a condition that develops in infancy or early childhood. The symptoms in an egg allergic reaction in an adult can be similar to those seen in childhood but particularly include skin swellings or eczema and asthma, which can develop more gradually. If there is a strong suggestion of a reaction to food but the cause is not clear, a negative skin or blood test in an NHS Allergy Clinic may help to exclude egg as a cause of symptoms.  Challenge tests with egg or with other foods may sometimes be advised.

Will I be allergic to eggs forever?

Although there are some food allergies that tend to be life-long – such as allergy to peanuts – egg allergy is not one of them.  By the age of six of seven, most egg-allergic children can eat eggs again with impunity, and a new development of egg allergy after this age is uncommon.  There are, however, some precautions that need to be taken. 

The help of a dietitian will be needed if all egg-containing foods are to be avoided.  In severe cases it will also be important to have advice about treatment that might be needed in an emergency. In milder cases advice will be needed after a symptom-free period, so that the careful reintroduction of eggs can be considered.  In any case, a record should be kept of any occasions when an egg-containing food is eaten by mistake and of any symptoms that may follow, so that a judgment can be made as to whether the symptoms are diminishing.

Can my egg allergy be cured?

Attempts at desensitising people with food allergy have as yet been unsuccessful.  The mainstays of treatment are therefore based on restricted diets and on drugs to suppress the more severe symptoms.  For those who have very severe reactions it may be necessary to keep egg out of the house and to provide training for adrenaline to be given if necessary.

Fortunately, egg allergy usually diminishes and disappears after a period of time, especially in children. In mild cases and if egg is successfully avoided there may be improvement within months, and by the age of six or seven the large majority of children need no restriction in their egg consumption.

Can anyone develop an allergy to eggs?

Among allergic people as a whole, hay fever, asthma, reactions in the mouth or stomach and skin reactions are by far the most common manifestations, but reactions of this kind are not very commonly due to food.  When suspected egg or other food reactions are put to the test, most adults who believe themselves to be food-allergic turn out to be mistaken.  In children it is sometimes the other way round and the diagnosis is easily missed - especially in reactions to cow’s milk, but less so when eggs are the culprits.

Will I be able to eat egg-containing foods, like pasta?

Heat can alter egg proteins, and small quantities of egg in a cooked food may cause no reaction in a mildly allergic individual.  It is important, if you can, to keep a record of any food-related reactions and their possible causes. Severely allergic people will, however, need to take particular care, especially over foods that may have a ‘hidden’ egg content.  While the use of eggs in custard, mayonnaise, soufflés and cakes are well known; their use in bread, in the glazes added to buns or pies, and in sweets such as ‘dolly mixture’ may not be so obvious.   The advice of a dietitian is therefore important.