What is "eczema"?
Eczema is a term that describes a type of scaly, thickened, itchy skin condition. There are many reasons that eczema might occur, but treatment is similar regardless of the cause. However, in order to prevent eczema, it is important to identify the triggers whenever possible. The distribution (pattern or locations on the body) can give us clues as to what the most likely causes could be. This is where your allergist may be able to supplement a treatment plan with some good detective work that will look for the root cause.
What does the pattern of eczema tell you?
Atopic dermatitis, otherwise known as "infantile eczema", is a long term very itchy, scaly skin disorder that is often on the cheeks of the face, scalp, hands and feet, and on the outer surfaces of the arms and legs of babies; these areas shift as the child gets older, with the most common places for atopic dermatitis in a toddler being the creases of the inner aspect of the elbow, and behind the knees. Sometimes there are other clues such as involvement of only exposed areas of the body, or only those areas under clothing. These are generally more likely to be due to a contact allergy to a product used on the skin or to launder clothing, sheets, and towels.
What are the causes of eczema?
While atopic dermatitis is not technically "caused" directly by food allergies, these can trigger a flare of the eczema. If it is a contact allergy type eczema, sensitization takes several days or weeks or even months, and the eczematous skin eventually will flare with exposure to the offending substance.
Stress, very hot or cold dry weather, oily skin, and infrequent washing of the hair or skin are among the triggers for seborrheic dermatitis, one common type of nonallergic eczema. You may recognize this on the scalp of babies as "cradle cap".
Do kids eventually "grow out of" their eczema?
With atopic dermatitis in infants and children under age 3, there is a strong possibility of food allergies as a trigger. This likelihood decreases with age of onset, with children over age 5 at onset of eczema being far less likely to have a food allergy trigger. If the offending food is discovered through allergy testing and can be completely avoided for long enough -- sometimes only 6-12 months -- then the sensitivity to that food may decrease and eventually disappear. If not avoided, however, the food allergy will tend to persist and continue to worsen chronic eczema. Most adults do lose their skin sensitivity with time.
Are all eczema types triggered by food allergies?
No, some are due to contact allergies to skin or hair care products, dyes, rubber, metals, etc., and some are not allergic at all but more associated with extremely dry skin, chronic rubbing of an area of skin, or in the case of seborrheic dermatitis, an over production of skin oil and irritation from a yeast called malessizia.
Is eczema inherited? Does it run in families?
The tendency to be an allergic child is inherited from one or both parents, but the type of allergic condition the child will have is not predictable. For example, a child may have atopic dermatitis due to a food allergy, while his parent might have nasal allergies or asthma instead, or other "atopic" (allergic) conditions. Seborrheic dermatitis appears to run in families.
Is there any test for eczema causes?
Yes, food allergy skin testing is possible, to give you a starting point for what foods may need to be avoided in order to allow the skin condition to come under control. Mild or moderate allergy skin test results usually require elimination for a few weeks, followed by challenge with one of these foods per week. Avoidance of a significant food allergen can lead to rapid improvement of eczema.
Patch testing is more appropriate when looking for triggers of a contact allergy. This can be done testing your own hair or skin care products, as well as a standard panel of common ingredients of everyday products.