20 questions & answers about food allergy
Does food allergy cause eczema? No! Eczema is a genetic skin problem caused by a defect in the skin barrier. It is not an allergy. Is there an association between food allergy and eczema? Yes! Find out more below from the answers to 20 common questions about food allergy (download to print here):
1: What is food allergy?
Food Allergy can be divided into two types; immediate and delayed. Symptoms of immediate food allergy usually begin very quickly after eating the food, nearly always within less than 15 minutes but very rarely up to as long as 2 hours.
Symptoms include hives (nettle sting type rash), swelling, sudden sneezing and nasal blockage, eye symptoms such as itch, redness and watering. There may also be abdominal symptoms such as pain and vomiting but these are rare without other symptoms. In some instances more severe symptoms such as breathing difficulties or collapse can develop. This is known as anaphylaxis.
Infants can also develop delayed allergy to cow’s milk, cow’s-milk-based baby formula and other forms of dairy (e.g. milk, cheese, yogurt). These symptoms can occur between 2 and 24 hours after ingestion (eating/drinking). They include a combination of tummy symptoms such as vomiting, diarrhoea, blood in the stools (poo), tummy bloating, reflux.
These infants are not at risk of anaphylaxis because the mechanisms of these types of reaction are quite different. Dairy (and other foods, but this is even more rare) can occasionally also make eczema worse, but this is not as common as is widely thought.
2: Is food allergy common in Ireland?
Yes, food allergy is increasingly common across the western world. 4% of infants in Ireland have immediate-type food allergy. Delayed reactions may be a bit more common.
3: What are the most common food allergies?
In Ireland, egg is the most common food allergy followed by milk allergy and peanut allergy. Tree nut allergy (cashew, pistachio, hazelnut etc.) sesame seed allergy and kiwi allergy are also common but probably 10 times less common than the “big 3” of egg, milk and peanut. Immediate allergy to wheat and soya are actually very unusual.
4: How do I know if my child has food allergy?
The only true way of knowing if your child has a food allergy is by feeding them that food. You can be certain that your child does not have immediate food allergy to a food if they can eat it without immediately developing nettle sting type rash and swelling.
If you think that your infant is developing sudden rashes after eating a food then it is best to discuss with your doctor before feeding it to them again.
5: What is the difference between allergy tests and intolerance tests?
Allergy tests are used to help predict whether a person will have an immediate allergic reaction to a food. There are only two forms of allergy testing that should be performed; 1. Skin prick 2. Blood test for specific IgE (this used to be known as a “RAST” test).
Intolerance tests are widely advertised as being able to help identify underlying food causes of symptoms such as abdominal pain and bloating, migraine, arthritis etc. and also eczema, however there is no scientific basis to these claims.
6: How good are allergy tests at diagnosing allergy?
Surprisingly, allergy tests are actually not very helpful. If your child has a positive allergy test to a food it does not mean that they are definitely allergic to that food. It only tells us that they are “sensitised” to that food. This means that at some time their immune system considered developing an allergy to that food.
If they are now eating that food then this is great news and they should continue to eat it. If they have not started eating the food you should talk to your doctor before introducing it as it might need to be done under medical supervision. This is known as a “food challenge”.
Allergy tests are of no value in children with delayed milk allergy.
7: “My 7 month old infant developed hives on her face after eating scrambled egg. Should I avoid all foods containing egg?”
No! Most infants (>85%) with doctor proven egg allergy can tolerate egg in baked foods such as cake, scones, pancake and egg pasta. If your infant is already tolerating any of these then they should be kept in their diet because this will help them grow out of the allergy.
If not already eating them, then you should start by giving your child small amounts of egg that’s been baked in cake or muffin.
8: “My 8 month old infant had an anaphylactic reaction to egg in a pancake. Should I try and introduce baked egg into their diet?”
No, best not to! Any infant who has had a reaction to egg that has caused them to have difficulty breathing or caused them to collapse should not have any egg introduced into their diet until they have first been seen by a doctor with expertise in food allergy.
9: “My son has a peanut allergy. Will allergy testing tell me how bad his reactions will be?”
No! Allergy testing does not predict how severe a food allergy reaction will be. Doctors with experience in allergy know that listening to the story of your child’s reactions is more helpful but even then there is no definite way of predicting exactly what type of reaction your child will experience. It is often said that reactions get worse with each successive one. This is actually not true.
Children who have had an anaphylactic reaction in the past can go on to have subsequent milder reactions. Good control of any asthma symptoms is important in reducing the risk of a severe allergic reaction.
10: Is peanut allergy the most dangerous allergy?
This is a tough question, and is debated widely. It is a fact that peanut causes more cases of anaphylaxis than any other food but the reasons are complex. It Is better to be aware that any food allergy can potentially trigger a life threatening allergic reaction.
11: Does food allergy cause eczema?
No! Eczema is a genetic skin problem caused by a defect in the skin barrier. It is not an allergy. There is no magic bullet to cure eczema. Food should not be removed from infant’s diets to try and fix their eczema. Removing a food to fix eczema is rarely successful, and affects your child’s nutrition.
12: “I breast feed my baby. I heard that I should take cow’s milk out of my diet to treat my infant’s eczema. Is this correct?”
No! Eczema is a genetic skin problem caused by a defect in the skin barrier. It is not an allergy.
Eczema is best treated with bathing, emollients and topical steroids.
- if your infant is also experiencing a combination of tummy symptoms such as diarrhoea, vomiting, blood in their stools, is unsettled and very difficult to feed, then they may have delayed cow’s milk protein allergy (see question 1) and in this case a short trial of dairy exclusion (2-4 weeks) can be tried
- if you notice sudden eczema flares always associated with a breast feed, then this may be the first sign of immediate cow’s milk protein allergy and a short trial of dairy exclusion (2-4 weeks) can be tried
- all long term dairy exclusion should be supervised by a registered dietitian to protect your bone health and to ensure you and your baby’s nutrition needs are met.
13: Is there an association between food allergy and eczema?
Yes! Infants and children with eczema, particularly those with eczema that appeared very early in life (less than 6 months of age) and also severe eczema are more likely to develop immediate food allergy than those with normal skin.
14: “My child has eczema. Should I have them allergy tested?”
There may be some role for allergy testing, however, under no circumstances should your child have extensive allergy testing to all the foods already in their diet that they are able to eat.
These large “allergy screening panels” are often offered in the private sector but are completely pointless. No foods should ever be removed from a child’s diet merely because of a positive food allergy test.
Allergy doctors mostly use allergy tests as a guide to getting important foods back into children’s diets, rather than taking them out. If your child has eczema and is not already eating nuts then allergy testing may be helpful before they are introduced into their diet.
15: “My 1 year olds face becomes red and itchy after eating tomato but their allergy test was negative. What does this mean?”
This is a very common finding. Foods such as tomato, citrus and berry fruits, act as irritants when they contact with the face of infants, especially those with eczema around their face. This will settle as their skin condition improves.
16: “My first child has eczema and food allergy. Is there anything I can do prevent my next child developing food allergy?”
Recent studies have shown that delaying introduction of allergic foods into infant’s diets increases their risk of developing food allergy, especially if they have eczema. Infants actually have to eat foods in order to become tolerant to them.
Introducing peanut regularly (3 times a week) into infants diets as soon as they begin to wean will significantly reduce their risk of developing peanut allergy. Infants with severe eczema should have an allergy test before giving them peanut.
This test can be performed as early as 5-6 months of age. Current international advice also says other allergenic foods (e.g. egg, fish, sesame, shrimp, tree nuts – in safe spreadable forms, not as nuts or nut fragments) should be introduced without delay.
This is a revolution of medical advice and may be why you are even reading this fact sheet!
17: Do food allergies ever go away?
Yes! It is the norm (>80% by 5 years) for milk and egg allergy to get better and this is helped by early introduction of baked egg and baked milk (see questions 7 and 8). However peanut, tree nut and fish allergies rarely go away (only 20% of cases).
Allergy review and testing over a few years can help identify the small number of children who may recover from their nut allergy. They may need to have a medically supervised food challenge to prove they have become tolerant.
18: Do all children with food allergy need to carry adrenaline pens?
No! Most egg and milk allergic children do not need such kits. In contrast, most peanut and tree nut allergic children do need them, eventually, especially when of school age, and maybe not until then. This is another area of medical debate that will keep evolving.
19: “My child has peanut allergy. I am worried about taking him on a plane”.
Plane journeys are generally very safe for food allergic people. It is important to follow a few simple rules.
- Always prepare food for your child to eat on the plane.
- Do not buy them any food on the plane.
- Let the air stewards know that your child has an allergy.
- Make sure to clean the tray tables and the seat belts before your child sits down.
- Always carry your adrenaline pens in your carry-on luggage as the hold is too cold for them.
20: Are there any cures coming for food allergy?
Yes! Studies have been carried out looking at how best to gradually introduce allergic foods in order to “desensitise” the immune system. This is called Immunotherapy. Foods such as egg, milk and nuts have been studied. Many other studies are still in progress.
An immunotherapy peanut tablet called Palforzia has recently been licensed in USA. This is not yet licensed in Europe.
Other forms of immunotherapy still being studied include skin patches and nasal sprays.
It is dangerous to consider doing this yourself and be aware that deaths have occurred in settings where alternative practitioners have done this.