Food Allergies and Eczema
Can Food Allergies Cause Eczema?
No. Children are born with the tendency to have eczema, and many things can make their eczema worse. These are known as 'triggers' for the eczema. Foods can be a trigger for eczema in some cases but DO NOT CAUSE eczema. If food does trigger the eczema it is often only one or two food types, rather than many. Removal of these foods will sometimes result in a significant improvement, but will not cure the eczema.
The foods most commonly found in both delayed and immediate reactions are cows' milk, egg, wheat and peanuts.
There are two main ways a food allergy may make the eczema worse:
- Immediate reaction with redness and itching of the skin developing within 2 hours of eating the food. Children with these reactions will usually have a positive skin prick test or IgE antibody blood test. The reactions are thought to be due to the food reacting with the IgE antibody in most cases
- Delayed reaction in this case the eczema may gradually get worse (more redness and itch) over 24-48 hours after ingesting the food. These reactions are thought to be due to immune cells in the skin reacting against the food. They are not caused by IgE antibodies and therefore tests for these antibodies (skin prick test or blood test) are not very helpful in predicting the reactions
There are no good skin prick tests or blood tests to determine whether foods cause a delayed reaction. Your doctor will decide whether the history suggests a particular food might be involved, and if so may recommend trial of eliminating that food from the child’s diet. If there is significant improvement the food should continue to be avoided. Often, the effect of removing a food is unclear and it may be necessary to re-challenge with the suspected food.
Why Not Just Remove all the Foods That Show Up on an Allergy Test?
Many children with a positive allergy test can eat that food without a problem. Removing many common foods such as wheat, milk, soy and egg from the diet may mean your child’s diet is no longer adequate to meet their nutritional needs. Such a limited diet also is difficult to manage, particularly as the child grows older. In general, foods do not trigger eczema in older children, so it is important not to avoid a food indefinitely just on the basis of an allergy test unless there is a clear worsening of the eczema when the food is eaten.
There is another reason why it may not be a good idea to remove every food that shows up on an allergy test. We now know that removing a food from the diet of a child who regularly eats that food just because of a positive allergy test, can cause a severe allergic reaction when the child is subsequently re-exposed to that food. Thus, continuing to eat a food (so long as it does not trigger a reaction) – even if the allergy test is positive – might actually prevent a more severe allergy developing.
Many foods carry a warning on the label "may contain traces of ". This usually indicates that the food is made in a facility that also makes other foods which contain the listed food. Any possible trace or contamination would be so small that it is highly unlikely to make the eczema significantly worse. In general, foods labelled this way do not need to be avoided as part of an eczema diet. However, if your child has had a severe allergic reaction (anaphylaxis) to a food you should discuss what to do about these foods with your doctor.
Could Artificial Preservatives or Colourings or Natural Salicylates and Amines be Causing the Eczema or Making it Worse?
There is some suggestion that artificial colourings and preservatives may make eczema worse in a small proportion (< 3%) of children with eczema. There are no allergy tests for colourings and preservatives. There is no evidence that natural salicylates and amines should be avoided in children with eczema.
Last updated: March 2012