Eczema is a red, itchy rash that can be triggered by food or other allergies. Because of this, some people ask: Is eczema an allergic reaction or is it a separate skin condition?
Eczema is not just one single skin condition. It is a broad name for different types of conditions. Most of these are not considered to be allergic reactions. However, the symptoms of eczema can flare because of an allergic reaction.
Part of the confusion as to the relationship between eczema and allergies comes from what doctors refer to as “the atopic march.” Children who develop eczema early, often before their first birthday, may later be diagnosed with food allergies, allergic rhinitis (hay fever) and then asthma.
This common occurrence shows a link between eczema and allergies. Almost 40 percent of children with eczema have food allergies. According the American College of Allergy, Asthma and Immunology, “it is recommended that children under the age of five who have moderate to severe eczema be evaluated to milk, egg, peanut, wheat and soy allergies.”
How allergies trigger eczema symptoms
Even though there is a close relationship between eczema and allergies, the rash from eczema is not an allergic reaction in most cases. The exception is when a rash that develops as a direct result of the skin being exposed to an allergen, such as poison ivy. In most cases, however, the rash from eczema is a result of a reaction from the immune system, not the allergen itself.
Eczema is thought to be caused by a breakdown in the skin’s barrier. This causes the skin to dry out and allergens are then able to penetrate the skin easily. Once this happens, the immune system is triggered, trying to fight off the intruder (allergen). The immune system focuses on the skin and a rash develops.
In the case of food allergies, the immune system does the same thing, but is triggered on the inside. In both cases, the immune system targets the skin.
It can sometimes be difficult to determine the trigger or allergen, as the eczema rash might not show up for 24- to 48-hours after you have been exposed to the allergen. This is because it takes a while before the immune system is triggered and starts to fight off what it sees as an attack. Some common environmental triggers include:
- Dust mites
- Chemicals found in clothing or hair dyes
- Soaps and other cleaning products
While many people find that the eczema rash develops around where the contact to the allergen occurred, it can also appear on other parts of the body.
Your doctor can conduct patch tests to determine what substances cause an allergic reaction. A patch test involves placing a patch that contains a common allergen on your back and then checking the area after 48 hours to see if there is any skin reaction. If this type of test doesn’t help, your doctor might remove a small piece of the affected skin and send it to a laboratory for additional testing.
Evaluation of Food Allergy in Patients with Atopic Dermatitis: The Journal of Allergy and Clinical Immunology