About 1 percent of all children's visits to doctors is for atopic dermatitis. It affects from 1 percent to 10 percent of infants. About 27 percent of infants whose mothers have allergies develop atopic dermatitis. One-half of infants who have eczema before they are one year old have no more symptoms by age two.

Atopic dermatitis usually goes away during childhood, or by the age of 25. But for some people, it is lifelong. Adults can also develop atopic dermatitis.

Researchers have found that atopic dermatitis can be triggered by a number of factors, including allergy and emotional stress. It involves high levels of immunoglobulin E (IgE), the major allergy antibody.

It is related to the development of other allergies, such as allergic rhinitis and asthma, in most children. In one study of adults who had atopic dermatitis as children:

• About 35 percent had no skin problems but had asthma or hay fever.
• Only 20 percent still had the condition.
• About 15 percent had both atopic dermatitis and asthma or hay fever.

In infants, atopic dermatitis appears as an itchy rash, called pruritus. It appears first as small white pimples with red centers over the infant's cheeks, neck and scalp. As the itchiness becomes annoying, the infant may scratch the rash. This can cause the area to become infected, ooze fluid and spread over a wider area. The rash can also appear on the outside surfaces of the arms and legs. It often does not appear in the diapered area.

In older children, the rash appears on the inner forearm, behind the knees, and opposite the elbows. Skin that is chronically covered with the rash over time will become dry, thickened and more brown in color. Some children get the rash on the eyelids, palms of the hand and soles of the feet. Teenagers and young adults get the rash most often in the bend of the elbow, back of the knees, ankles and wrists, and on the face, neck, chest, and palms of the hands and soles of the feet.

In some people, inhaled substances (such as dust mites, animal allergens and pollen) can cause flare-ups of atopic dermatitis. A bacterial, fungal or viral infection also can cause a flare-up. Food allergies may trigger an episode in children, but rarely in adults.

Atopic dermatitis is not contagious. Sometimes, though, scratching can lead to a bacterial infection. A Staphylococcus aureus bacterial infection of an area covered by eczema can cause impetigo, a skin infection that is contagious. (Other causes of impetigo are infections following poison ivy or an allergy to soap or makeup.) Most often impetigo occurs on the face, especially around the mouth and nose. It begins with tiny blisters that burst and may ooze fluid, then become crusted.

To diagnose atopic dermatitis, the doctor will take a careful medical history, looking especially at allergy among other family members. If food is the suspected cause of a child's eczema, the doctor may delete milk, egg, peanut, or other suspected foods from the child's diet to see if symptoms go away. If there is a history of atopic dermatitis among other family members, the doctor may suggest that solid foods be withheld from infants until they are at least six months old.

Skin testing can help confirm that a food allergy is triggering flare-ups. An extract of the suspected food substance is used to scratch or prick the skin. If the patient is allergic, the area becomes red and swollen. But some people may have a positive reaction to a food that is not causing the eczema.

Skin tests also can be difficult if the patient already has a rash. In such cases, a blood test such as the RAST (radioallergosorbent test) is used to detect food-specific antibodies in the blood. Another lab test analyzes a blood sample for the presence of eosinophils, cells that cause inflammation.

A food challenge can confirm that atopic dermatitis is triggered by food. Suspected foods are removed from the diet, then they are added back in, first in small amounts then in increasing quantities, and the patient is watched to see if symptoms recur.

• Treatment begins with efforts to reduce the itching and inflammation, hydrating the skin and removing the "flare factors" such as infections and exposure to allergens and irritants:
• Bathe in warm water not hot water for no more than 3-5 minutes. Use superfatted, unscented soap or soap substitute. Pat the skin dry, then promptly apply a moisturizer. This will help keep the skin hydrated. If the area has become thick, moisturizing ointments are used.
• Trim fingernails to reduce problems from scratching. At night, patients can wear cotton socks on their feet or gloves on their hands to prevent scratching while asleep. If the rash is oozing, doctors may prescribe a lotion to dry the rash and an antibiotic to treat infection.
• If the rash is on the face, do not use a corticosteroid product.
• Stay indoors, in air conditioning in hot weather. This avoids sweating and the itchiness it causes.
• Use a humidifier in the winter to keep skin from drying out.
• Avoid wool, polyester, wrinkle-resistant, flame-retardant or scratchy fabrics in clothes and bedding. Wear open-weave, loose fitting cotton or cotton blend garments. Wash new clothes before wearing.
• Reduce indoor allergens, particularly dust mites, by
• washing bedding in hot water, removing rugs, stuffed furniture, stuffed toys and curtains where possible.
• When doing housework, wear plastic or rubber gloves or latex gloves lined with cotton.
• Avoid stress, which can add to flare-ups. Patients often feel angry and frustrated by the chronic itching. Parents need to find ways to let children with atopic dermatitis express feelings. Professional counseling may help. Know that with proper treatment the condition can be controlled and it will improve with age. Many methods to reduce stress are available.
• If a link with food has been diagnosed, eliminate it from the patient's diet. This will reduce symptoms, but not always get rid of them.
• Use liquid laundry detergent that is unscented and mild. Avoid fabric softeners (liquid and dryer sheets). Rinse clothing and bedding thoroughly after washing to remove detergent residue.
• Avoid chemicals and extreme heat or cold, which can worsen the condition.
• Use cosmetics lightly and seldom. Avoid products with perfume and dyes, and ingredients such as urea, lactic acid or other alphahydroxy acids.

Topical steroids are key medications for controlling the itching and inflammation. Used immediately after bathing, they also help keep the skin hydrated. Most steroids require a prescription. Systemic corticosteroids (tablets, shots or liquids) should seldom be used. They cause flare-ups when the medications are discontinued.

Antihistamines may help relieve itching, often sedating the patient. They are most useful when given at bedtime. Antianxiety medications may also help relieve itching.

Antibiotics will treat complicating skin infections. Allergy shots will not help. In fact, they can cause the condition to worsen.

Impetigo is usually treated with oral antibiotics or, if the case is mild, topical antibiotics. Healing should begin in three days.

Keep in mind that the disease can be controlled. It often takes awhile to find out the cause and the best treatment for it, though. Keep in mind also that the condition nearly always improves over time.

New drugs that prevent the skin from becoming inflamed show promise. An immunosuppressive agent (tacgolimus) has shown promise in both adults and children with atopic dermatitis.