Causes of eczema

Eczema typically runs a chronic course with flare-ups (exacerbations) and remissions. 

A variety of "trigger factors" may exacerbate eczema. These include irritants (e.g. soap, harsh chemicals, wool, heat and humidity, stress and anxiety), and allergens (e.g. foods, house dust mites, moulds).

In children, a number of external factors may precipitate or aggravate the eczema, such as food allergens, house dust mites etc., whereas in adults, the cause is often not found.

Diet-related causes

In babies, eczema may present soon after birth – usually as a result of allergens being transferred through the mother’s milk. Sometimes it is due to skin lotions containing allergens or chemicals. Food is one of the most common aggravating factors in children with eczema, compared to adults where food is hardly ever related to their eczema.

Food allergy does not cause eczema, but may precipitate or exacerbate the condition. A baby with eczema is more likely to be allergic to food than other children. There is up to a 35% chance that food allergies may be triggers in a child with eczema. The foods responsible for 90% of these reactions are egg, peanuts, milk, soy, wheat, fish, nuts and shellfish, but any food may be the culprit. A baby's eczema may improve if the breast-feeding mother avoids these types of foods.

The skin of the majority of children with food allergy will become intensely itchy with large hives. Depending on the cause of the hives, this could occur within an hour or less of eating. Sometimes babies will have more subtle symptoms such as irritability or a slightly worse rash after a feed.

Food additives can also aggravate eczema in older children. Certain foods may aggravate eczema, even if the person is not food allergic.

Common triggers include spicy foods, curries, alcohol (especially red wine), citrus fruit, strawberries, tomatoes, pineapple and the food colouring tartrazine.

Other aggravating factors

These include the following

  • House dust mites are one of the most common aggravating factors of eczema. Appropriate measures should be taken to minimise the exposure to house dust mites.
  • Other common aggravators are smoking, pet hair, pollens and moulds.
  • Stress and anxiety also play a big role in the aggravating of eczema, and in some children this may be due to the introduction of a food-elimination diet, so caution and balance is required before excluding foods from a diet.
  • Household items which may aggravate eczema include enzyme-enriched washing powders, fabric softeners, dishwashing liquid, bleach, soaps containing perfumes or alcohol, harsh chemicals and perfumes.
  • Swimming pool chlorine may also irritate and dry out the skin.
  • Local household skin irritants include wool, mohair, nylon and feathers.
  • Remember that parents who work with chemicals or foods as an occupation or hobby can indirectly cause these substances to come into contact with their children, usually via their clothes.
  • Environmental factors that affect eczema are hot, humid and cold, dry weather, as well as excessive sweating. Do not overdress your child. 

Read more: 

Treating eczema 

What is eczema? 

Can eczema be outgrown? 

Reviewed by Professor Sharon Kling, Clinical Unit Head, General Paediatrics, Intensivist at Tygerberg Hospital and Associate Professor, Department of Paediatrics and Child Health at Stellenbosch University. February 2015.

Original article by Dr Harris Steinman, May 2007.

Read more on: eczema health

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