Atopic dermatitis is chronic, itchy inflammation of the upper layers of the skin that often develops in people who have hay fever or asthma and in people who have family members with these conditions.
Atopic dermatitis is one of the most common skin diseases, particularly among urban areas or developed countries, affecting about 15 to 30% of children or adolescents and 2 to 10% of adults worldwide. Almost 66% of people with the disorder develop it before age 1, and 90% by age 5. Atopic dermatitis that develops during childhood frequently goes away or lessens greatly by adulthood.
Doctors do not know what causes atopic dermatitis, but people who have it usually have many allergic disorders, particularly asthma, hay fever, and food allergies. The relationship between the dermatitis and these disorders is not clear because atopic dermatitis is not an allergy to a particular substance. Atopic dermatitis is not contagious.
Many conditions can make atopic dermatitis worse, including emotional stress, changes in temperature or humidity, bacterial skin infections, certain airborne particles (such as dust mites, molds, and dander), some cosmetics, and contact with irritating clothing (especially wool). In some infants, food allergies may provoke atopic dermatitis.
Infants may develop red, oozing, crusted rashes on the face that spread to the scalp, diaper area, hands, arms, feet, or legs. Large areas of the body may be affected. In older children and adults, the rash often occurs (and recurs) in only one or a few spots, especially on the hands, upper arms, in front of the elbows, or behind the knees.
Although the color, intensity, and location of the rash vary, the rash always itches. The itching often leads to uncontrollable scratching, triggering a cycle of itching-scratching-itching that makes the problem worse. Scratching and rubbing can also tear the skin, leaving an opening for bacteria to enter and cause infections.
In people with atopic dermatitis, infection with the herpes simplex virus, which in other people usually affects a small area with tiny, slightly painful blisters (see see Herpes Simplex Virus Infections), may cause a serious illness with widespread dermatitis, blistering, and high fever (eczema herpeticum). People with atopic dermatitis may also develop viral skin infections (such as common warts and molluscum contagiosum) and fungal skin infections.
Diagnosis and Treatment
A doctor makes the diagnosis based on the typical appearance of the rash and often on whether other family members have allergies. Occasionally, doctors apply substances to the skin or do blood tests to determine which substances are triggering attacks.
No cure exists, but itching can be relieved with topical drugs or drugs taken by mouth (see see Treatment). Certain other measures can help. Avoiding contact with substances known to irritate the skin or foods that the person is sensitive to can prevent a rash. The skin should be kept moist, either with commercial moisturizers or with petroleum jelly or vegetable oil. Moisturizers are best applied immediately after bathing, while the skin is damp. Parents should cut their children's fingernails short to minimize scratching and thus reduce the risk of infection.
Certain measures can help reduce exposure to common household triggers:
Specific treatments include applying a corticosteroid ointment or cream. To limit the use of corticosteroids in people being treated for long periods, doctors sometimes replace the corticosteroids with petroleum jelly for a week or more at a time. Ointments or creams containing an immune system‒modulating drug, such as tacrolimus or pimecrolimus, also are helpful and can limit the need for long-term corticosteroid use. Some doctors prescribe such drugs first. Corticosteroid tablets are a last resort for people with stubborn cases.
Phototherapy (exposure to ultraviolet light) may help adults (see see Phototherapy: Using Ultraviolet Light to Treat Skin Disorders). This treatment is rarely recommended for children because of its potential long-term side effects, including skin cancer and cataracts.
For severe cases, the immune system can be suppressed with cyclosporine, azathioprine, or mycophenolate mofetil taken by mouth, or injections of interferon gamma.
Last full review/revision October 2012 by Karen McKoy, MD, MPH