What are allergens? (for the topic of Atopic Dermatitis / Eczema) (From medicinenet.com)

Info source: http://www.medicinenet.com/atopic_dermatitis/page8.htm


What are allergens?

Allergens are substances from foods, plants, or animals that provoke an overreaction of the immune system and cause inflammation (in this case, the skin).

Inflammation can occur even when the person is exposed to small amounts of the allergen for a limited time. Some examples of allergens are pollen and dog or cat dander (tiny particles from the animal's skin or hair).

When people with atopic dermatitis come into contact with an irritant or allergen to which they are sensitive, inflammation-producing cells permeate the skin from elsewhere in the body.

These cells release chemicals that cause itching and redness. As the person scratches and rubs the skin in response, further damage occurs.

Certain foods act as allergens and may trigger atopic dermatitis or exacerbate it (cause it to become worse).

Food allergens clearly play a role in a number of cases of atopic dermatitis, primarily in infants and children.

An allergic reaction to food can cause skin inflammation (generally hives), gastrointestinal symptoms (vomiting, diarrhea), upper respiratory tract symptoms (congestion, sneezing), and wheezing.

The most common allergy-causing (allergenic) foods are eggs, peanuts, milk, fish, soy products, and wheat.

Although the data remain inconclusive, some studies suggest that mothers of children with a family history of atopic diseases should avoid eating commonly allergenic foods themselves during late pregnancy and while they are breastfeeding the baby.

Although not all researchers agree, most experts think that breastfeeding the infant for at least four months may have a protective effect for the child.

If a food allergy is suspected, it may be helpful to keep a careful diary of everything the patient eats, noting any reactions.

Identifying the food allergen may be difficult and require supervision by an allergist if the patient is also being exposed to other allergens.

One helpful way to explore the possibility of a food allergy is to eliminate the suspected food and then, if improvement is noticed, reintroduce it into the diet under carefully controlled conditions.

A two week trial is usually sufficient for each food. If the food being tested causes no symptoms after two weeks, a different food can be tested in like manner afterward.

Likewise, if the elimination of a food does not result in improvement after two weeks, other foods may be eliminated in turn.

Changing the diet of a person who has atopic dermatitis may not always relieve symptoms. A change may be helpful, however, when a patient's medical history and specific symptoms strongly suggest a food allergy.

It is up to the patient and his or her family and physician to judge whether the dietary restrictions outweigh the impact of the disease itself.

Restricted diets often are emotionally and financially difficult for patients and their families to follow. Unless properly monitored, diets with many restrictions can also contribute to nutritional problems in children.