Here we concentrate on immediate-onset food allergy, where symptoms usually appear within seconds or minutes of contact with the food.
Most children with a food allergy outgrow their allergy during childhood. This is particularly true for allergy to cow’s milk, wheat and hen’s eggs. For a few children, allergies to any of these foods can persist.
Some food allergies are less likely to be outgrown, particularly for allergies to peanuts, tree nuts (such as walnuts, cashews and Brazil nuts), fish and shellfish. With day-to-day management, risks can be greatly reduced. Find more information on all these allergies below.
A recent study from the Isle of Wight followed up children with peanut allergy for over 10 years and found that, during this time, 10% outgrew their allergy. It is thought that by adulthood, around 20% would have outgrown their allergy.
A systematic review of all the published studies from 2020 found that between 9-14% of children with tree nut allergy outgrew this allergy. This included some children who had had severe reactions.
The age by which the children outgrew both peanut and tree nut allergies varied significantly, so it is important for your child to have regular reviews with their allergy specialist.
Studies have shown that many children with egg allergy outgrow it, but there are differences in the age at which they outgrow it, depending on where the research was published. This is probably related to the type and severity of allergies in the children enrolled.
The Europrevall study, the largest multi-national study on food allergy, followed children with egg allergies up until they were two years of age and found that half outgrew their allergy within one year of diagnosis. A recent study (2020) found that half of children outgrew their allergy by five years of age. A 2007 American study concluded that 4% of the children outgrew their egg allergy by age four, 12% by age six, 37% cent by age ten, and 68% by age 16.
The prognosis for outgrowing a milk allergy is very positive, but research does suggest that the age this happens at varies. In the last 10 years, there has been a shift towards tolerating milk at a later age.
In the CoFAR and Europrevall studies, 53% of children outgrew their allergy by two years of age, and 57% outgrew their allergy at one year. However, as with the egg allergy, some studies have shown a slower rate of achieving tolerance, with one reporting that 19% outgrew their cow’s milk allergy at age 4, 42% at age 8, 64% at age 12, and 79% at age 16.
True wheat allergy happens when the body’s immune system reacts to one or more of the proteins found in wheat. Only a limited number of studies have looked at when wheat allergy is outgrown. A study from 2017 found that 45% of children outgrew their wheat allergy by five years of age.
Sesame allergy tends to appear early in life and, according to at least one study, persists in 80% of the children with it. Those who outgrow it are likely to outgrow it by the age of around six.
As children can outgrow their allergy, it is important to have regular follow-up appointments with your allergy specialist. If you believe your child may have outgrown their food allergy and have no appointment planned, seek medical advice. Your GP can refer you to an allergy clinic where your child may be given an oral challenge to check whether they have outgrown their allergy. Such challenge testing involves the child eating small amounts of the food, gradually building up the quantity until it can be shown that they are not allergic. This must be strictly controlled at an allergy clinic and should not be tried at home.
If the test is negative, this means your child is no longer allergic. There is a very strong chance that the allergy will not come back, although this does happen in a very small number of cases. If your child has been carrying adrenaline, the question of whether they should play safe and still carry adrenaline must be discussed with the doctor overseeing the challenge. Some doctors advise that injectors should continue to be carried for a further limited period.
Finally, if your child has outgrown their food allergy, you may wonder if they should eat the food or avoid it. There is strong evidence that you should include the food regularly in your child’s diet to ensure the tolerance to the food is maintained, and this view is widely supported by the medical community. If your child does not like the food, it is advisable to discuss this with your child’s dietitian to find foods your child likes that contain the allergen.
This article has been peer reviewed by Dr. Rosan Meyer, Paediatric Research Dietitian, Imperial College, London.
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