Eczema is a skin condition that affects 30 million Americans. It is characterized by a rash that may blister, peel, or itch. It can be located anywhere, but it is most common on the elbows or behind the knees. Allergies are a common trigger of eczema, and unfortunately, not all allergens are easy to spot. Food allergies in particular can be easy to overlook. However, with up to one third of eczema sufferers also having an underlying food allergy, this may be an avenue worth exploring.

What foods can cause eczema to flare up?

There are a wide variety of foods that can cause eczema to flare up. Lactose, which is an enzyme found in dairy, is a common trigger. Egg allergies, although rare, typically present in the form of eczema. This is more common in babies and children than in adults. Wheat, peanuts, soy, and fish are also known to exacerbate symptoms.

Determining if a food allergy is causing your eczema

It can take a lot of patience to determine if a food allergy is behind your eczema. Your doctor may give you a few different test options.

Skin testing involves injecting very small amounts of an allergen into the skin. If you test negative for a food allergy, you will have no reaction. Any kind of skin irritation near the injection site is indicative of an allergy, but this isn't always accurate—in fact, skin testing gives a false positive 50-60% of the time.

Blood testing is another possible method. A sample of blood is taken and tested in a lab for a reaction to a variety of potential allergens. This has a similar success rate to skin testing. It won't provide a false negative, but false positives are common.

Food elimination diets may be an effective way of testing for food allergies. With these tests, typically you will cut out many foods—your doctor will help you decide what is okay to keep eating. The idea is for your eczema symptoms to decrease while you are on this restricted diet. You will then gradually add suspected trouble foods back in, and see if any of them cause an increase in your symptoms. Your doctor may also perform skin testing or a blood test in conjunction with the elimination diet to help confirm their diagnosis.

Although removing problematic foods from your diet won't cure your eczema, it may help keep your symptoms in check. If you suspect that a food allergy may be making your eczema worse, talk with your doctor to discuss your eczema treatment options.