How Do You Figure Out if a Rash is Actually a Sign of Food Allergy?

Published: December 17, 2018
Photo: Getty

Q: We suspect our 3.5-year-old, who has severe eczema and a milk allergy, is developing more food allergies. Although she avoids dairy, her eczema rash recently has begun to flare at times after eating, and there have been episodes of vomiting and some hives. Our child is itchy with rash, though we have started a wet wrap therapy. We’re in the process of getting to see a new allergist, but I’m not sure how he’ll figure out the trigger. Our daughter has a wide diet, that includes potential culprits like nuts (which we just stopped), soy, eggs and wheat. Plus, my wife is certain the eczema rash worsens after beef is eaten. Have you any insights as to how the source of her problems can be figured out?

Dr. Sicherer: It can be very tricky to determine whether food is causing eczema rash and flares. In eczema, or atopic dermatitis, the skin is irritable, dry and prone to infection and inflammation. Most of the time when a food is a suspected trigger, the relationship is disproved with medically supervised feeding tests. This is no surprise because scratching, infection, changes in temperature, exposure to allergens in the air, and even changes in mood, can result in eczema rash and flares.

People with eczema are at risk for food allergies, but the foods often cause immediate allergic reactions (hives, wheezing) rather than the baseline rash or flares. Also, it is not common for tolerated foods that are part of the diet to become allergic triggers.

Eczema Rash Trigger Tips

While it is not easy to identify allergic triggers, there are some “ground rules” that can be helpful:

• Don’t assume this eczema rash is primarily a result of food allergy. It is important to have a skin-care regimen in place to keep the skin in the best shape possible, taking into consideration that atopic dermatitis has many triggers. Talk to your doctor about such a regimen, and often different skin-care approaches will need to be tried to find a plan that works.

• Take action to address typical food allergy symptoms. If you are seeing symptoms other than flares of eczema, such as hives and vomiting with a meal, it is much more likely that an ingredient in that meal is a problem. Treat the reaction, make a note of all the ingredients, and speak to your allergist promptly. Your allergist may be able to help you identify the trigger from a careful history and confirmatory skin or blood testing.

• Don’t remove foods from the diet on your own when a relationship with the eczema rash is not clear. Removing foods may cause your child social and nutritional problems. As well, sometimes a food that was part of the diet, then was removed for a prolonged period, can trigger anaphylactic reactions.

• Come to the doctor’s visit prepared to give details. Keep notes or a diary. The history is often the best “test”; more informative than blood or skin tests. Your doctor will want to know your suspicions, details of symptoms, and meal ingredients. For example, you mention a dairy allergy, and roughly l0 percent of children with a severe milk allergy react to beef, especially if it is undercooked. Your doctor can use that knowledge. Random testing is often misleading, but the history is extremely important.

Managing food allergy and eczema is complicated. Do work with your allergist to get specific advice.

Dr. Scott Sicherer is a practicing allergist, clinical researcher and professor of pediatrics. He is Director of the Jaffe Food Allergy Institute and Chief of Pediatric Allergy and Immunology at the Icahn School of Medicine at Mount Sinai in New York. He’s also the author of Food Allergies: A Complete Guide for Eating When Your Life Depends On It.

Submit a Question