Ask the Doctor: ‘My 3-year-old has eczema and a dairy allergy — will my newborn have these issues too?’

”I have a child (3) who has eczema and a dairy allergy. I am pregnant again and wonder if that means this child will have the allergy too or is there anything I should be aware of/avoid when she is born?”

Answer from Dr Emma Ruth, Consultant Paediatrician, Beacon Hospital

This is quite a common scenario (affecting 4-5% Irish children) and parents who have one child with food allergy understandably hope to prevent its occurrence in subsequent siblings.

Milk allergy is classified as either IgE-mediated or non IgE-mediated. IgE-mediated milk allergy results in rapid onset of typical symptoms – rash (usually hives), lip and/or eye swelling, abdominal pain and vomiting, and in more severe cases, breathing difficulty and collapse. This occurs within a maximum of 2 hours after ingestion of the food and occurs on every subsequent exposure. A small amount of food can cause significant reactions.

Non IgE-mediated milk allergy causes skin problems such as eczema and abdominal symptoms, including colicky abdominal pain, vomiting and loose (sometimes bloody) stools. Symptoms may not appear for more than 24 hours after exposure. A small dose may be tolerated but larger doses are not.

We know that having eczema predisposes children to developing food allergies. This is because their immune system can be exposed to food allergens in early infancy through their defective skin barrier. This pathway of exposure promotes development of an allergic response rather than the tolerant response seen when the immune system meets food allergens for the first time through the gastrointestinal tract. About 20% of children with moderate to severe eczema will have food allergies.

In small children, food allergies can exacerbate pre-existing eczema. However, there is no justification for manipulating a child’s diet until skin care with topical emollients and steroids is optimised. There is no evidence that avoidance of food allergens in pregnancy will prevent the development of food allergies. Where possible, all infants should be exclusively breastfed until 6 months of age and breastfeeding should be encouraged and supported.

Upon weaning to solids, early introduction of allergenic foods (with concurrent breastfeeding if possible) is recommended. Milk, egg and peanut should all be introduced as soon as weaning begins.

It is recommended to avoid supplementing breast-fed infants with cow’s milk formula in the first week of life as this can act as a sensitising event leading to the development of cow’s milk allergy later in infancy. There is no evidence that the use of extensively hydrolysed formulas, pro- or prebiotics can prevent the development of food allergy.

In summary, early introduction of food allergens is the single best approach to prevent food allergy.

Further information on food allergies can be found here.

Have a question for the professionals you’d like answered? Get in touch with sarah.gill@image.ie with the subject headline ‘Ask The Doctor’.