Which comes first: atopic dermatitis or food allergy?

In food allergy circles, we usually think of symptoms and side effects as results of food allergies, not the other way around. In many cases that’s true. One exceptional pair is food allergies and atopic dermatitis.

Science has shown links between these two, especially for moderate-to-severe atopic dermatitis, and especially in infants and young toddlers. (Atopic dermatitis is a form of eczema.) This article explores the science of which comes first for patients with both food allergies and atopic dermatitis.

Dr. Jon Hanifin, a respected dermatologist, recently gave a talk to colleagues. He discussed the link between food allergies and atopic dermatitis. The research he presented suggests that sometimes atopic dermatitis comes first, acting as a precursor to food allergies. For other patients, certain foods can trigger or worsen atopic dermatitis, and may or may not be true allergens.

Atopic dermatitis is often one of the first signs that caregivers notice in their child that helps lead to a food allergy diagnosis. As Dr. Hanifin explained, about 6-10% of children get an atopic dermatitis diagnosis, and of those with moderate-to-severe cases, about a third will get a food allergy diagnosis. That begs the question: If atopic dermatitis comes before a food allergy diagnosis, could atopic dermatitis cause food allergies?

What We Know:

  • In cases of food allergy, offending foods cause reactions in the body that involve the immune system.
  • Immunoglobulin-E (IgE) antibodies are immune substances that are normally in our bodies at low levels, but levels are higher with food allergy.
  • Allergy signs and symptoms often involve the skin, an important barrier that keeps most outside “things” from getting inside. This includes our digestive tract, which is like our skin-on-the-inside.
  • One factor in atopic dermatitis is gaps or “holes” in the barrier our skin provides.

What Dr. Hanifin Proposed:

In the past we thought that food allergies came first, causing both high IgE levels and contributing to atopic dermatitis symptoms. Dr. Hanifin suggested that gaps in the skin barrier cause atopic dermatitis in some patients (likely due to genetics). This is a way that foreign substances could enter the skin and cause adverse reactions. He thinks that proteins that get through these gaps could lead the body’s immune system to become sensitive to certain foods. That sensitivity is food allergies.

What does all of this mean? A big message here is that patients with atopic dermatitis, especially under five years of age, may have food allergies and may need testing to confirm them. An allergist should advise you whether or not testing is necessary. While avoiding food allergens may not help improve atopic dermatitis for everyone, it can certainly help some, and is always necessary if food allergies are present.

The second message is that food allergies and atopic dermatitis often occur together. However, more research is need to study the causes of atopic dermatitis and its relationships to food allergies. Any research that leads to better health, by helping us understand atopic dermatitis and/or food allergies, is good research!

Tell us about your experience: Was atopic dermatitis the first sign that you saw of your child’s food allergy?

Rob McCandlish, RDN

Rob McCandlish is a registered dietitian nutritionist (RDN) who joined the Nutricia team in 2010. He has years of experience at Nutricia following food allergy research, working with Neocate products, talking with Neocate families and learning about the science behind Neocate and food allergies. Rob has two nephews who both used Neocate for their cow milk allergies!

Last updated February 13, 2019

Published: 03/17/2011
Rob McCandlish
Hi Valerie, sorry to hear you're both having to deal with this, yikes! Skin conditions like atopic dermatitis can be triggered by foods, but also by many, many other factors. 2 days may not be long enough to see possible improvement from removing foods, but since it's severe you probably shouldn't wait any longer. Definitely schedule a visit with her pediatrician, and be ready for them to possibly refer you to a dermatologist and maybe also an allergist. Hang in there!
My daughter has broken out in a severe rash, but we have no idea what from. She is on solids and formula. We started solids back in october with baby oatmeal and she did fine, so we started adding fruits and veggies as time went on. Then came January and she broke out with this rash, initially starting just on her knee cap and now its taken over her body. I just don't know what else to do. We eliminated the foods that we thought maybe caused that were within 2 weeks of the first outbreak, which were turkey, squash and this banana sweet potato mixture...its only been 2 days but still no progress. I have lost my mind and i feel so bad for her. Help?
Rob McCandlish
Hi Brooke, great question. If nothing else in his routine or your diet has changed and you had been avoiding dairy, it's certainly possible that your son's rash could be related to changes in your diet. Protein fragments of foods a lactating mother eats can make their way into her breast milk. And there's definitely a sibling link when it comes to allergies: having an older sibling with allergies is common when younger children are diagnosed with allergies! However, those are common body sites for rashes that can have other causes. The best thing to do would be to ask his healthcare team how you can safely continue breastfeeding, possibly under medical supervision (in case you must avoid certain foods/ingredients and to get all the nutrients you need). Good luck!
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