Atopic dermatitis is very common, particularly in developed countries and among people who have a tendency to develop allergies.
Infants tend to develop red, oozing, crusted rashes on the face, scalp, hands, arms, feet, or legs.
Older children and adults tend to develop one or a few spots, usually on the hands, upper arms, in front of the elbows, or behind the knees.
Doctors base the diagnosis on the appearance of the rash and the person's family medical history.
Treatment includes keeping the skin moist, avoiding triggers, applying corticosteroids to the skin, and sometimes using ultraviolet light therapy or immune system‒modulating drugs.
(See also Overview of Dermatitis.)
Atopic dermatitis is one of the most common skin diseases, particularly in urban areas or developed countries, affecting about 20% of children or adolescents and 1 to 3% of adults in developed countries. Most people develop the disorder before age 5, and many people develop it before age 1. Atopic dermatitis that develops during childhood frequently goes away or lessens greatly by adulthood.
Doctors do not know what causes atopic dermatitis, but it is related to genes and often runs in families along with asthma and hay fever. Atopic dermatitis is not an allergy to a particular substance, but having atopic dermatitis increases the likelihood of also developing asthma and hay fever (what doctors call an atopic triad). Atopic dermatitis is not contagious.
Many conditions can trigger atopic dermatitis flare-ups, including emotional stress, changes in temperature or humidity, presence of the bacterium Staphylococcus aureus on the skin, certain airborne particles (such as dust mites, molds, and dander), some skin care products (such as cosmetics, fragrances, harsh soaps), sweating, and contact with irritating clothing (especially wool). In some infants, food allergies may provoke atopic dermatitis.
Atopic dermatitis usually begins in infants (usually less than 4 months old).
In the early (acute) phase, red, oozing, and crusted areas develop, and sometimes blisters. This phase lasts 1 to 2 months.
In the chronic (later) phase, scratching and rubbing creates areas that appear dry and lichenified.
In infants, rashes on the face spread to the neck, scalp, hands, arms, feet, and legs. Large areas of the body may be affected.
In older children and adults, a rash often occurs (and recurs) in only one or a few spots, especially on the front of the neck, the inner folds of the elbows, and behind the knees.
Although the color, intensity, and location of the rash vary, the rash always itches. In older children and adults, intense itching is the main symptom. The itching often leads to uncontrollable scratching, triggering a cycle of itching-scratching-itching that makes the problem worse. Continuous scratching causes the skin to thicken (lichenification).
Scratching and rubbing can also tear the skin, leaving an opening for bacteria to enter and cause infections of the skin, tissues below the skin, and nearby lymph nodes. Widespread inflammation and scaling of the skin (exfoliative dermatitis) also can develop.
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, may cause a serious illness with widespread dermatitis, blistering, and high fever (eczema herpeticum).
People who have had atopic dermatitis for a long time may develop clouding of the lens of the eye (cataracts) in their 20s or 30s.
A doctor makes the diagnosis of atopic dermatitis based on the typical appearance of the rash and often on whether other family members have allergies.
Sometimes, doctors do skin prick testing or patch tests or do blood tests (the radioallergosorbent test [RAST]) to determine which substances may be triggering attacks.
Atopic dermatitis often lessens by the time children are 5 years of age. However, flare-ups are common throughout adolescence and into adulthood. Girls and people who developed atopic dermatitis at an early age, have severe disease, have a family history, and have rhinitis or asthma are more likely to have atopic dermatitis for a long time. Even in these people, however, atopic dermatitis frequently resolves or lessens significantly by adulthood. Because the symptoms of atopic dermatitis are visible and sometimes disabling, children may develop long-term emotional problems as they face the challenge of living with the disease during their developmental years.
Avoiding contact with substances known to irritate the skin or foods that the person is sensitive to can prevent a rash.
Certain measures can help reduce exposure to common household triggers:
Using synthetic fiber pillows and impermeable mattress covers
Washing bedding in hot water
Removing upholstered furniture, soft toys, carpets, and pets (to reduce dust mites and animal dander)
Using air circulators equipped with high-efficiency particulate air (HEPA) filters in bedrooms and other frequently occupied living areas
Using dehumidifiers in basements and other poorly aerated, damp rooms (to reduce molds)
Applying the antibiotic mupirocin inside the nostrils and taking baths with diluted bleach to decrease the numbers of S. aureus on the skin, thus lessening the severity of atopic dermatitis
People should also try to reduce their emotional stress.
No cure exists, but itching can be relieved with topical drugs or drugs taken by mouth. Treatments of itching can usually be given at home, but people who have exfoliative dermatitis, cellulitis, or eczema herpeticum may need to be hospitalized.
Certain skin care measures are helpful:
Using soap substitutes instead of regular soap
Keeping the skin moist, either with commercial moisturizers or with petroleum jelly after exposure to water
Applying moisturizers immediately after bathing, while the skin is damp
Bathing only once a day
Bathing in water diluted with added colloidal oatmeal
Blotting or patting the skin dry after bathing rather than rubbing
Parents should cut their children's fingernails short to minimize scratching and thus reduce the risk of infection. If a skin infection does occur, antibiotics may be given by mouth, applied to the skin, or both.
Specific treatments include applying a corticosteroid ointment or cream. To limit the use of corticosteroids in people being treated for long periods (because long-term use can lead to thinning of the skin), doctors sometimes replace the corticosteroids with petroleum jelly or noncorticosteroid treatments for eczema, 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 (for example, possibly crisaborole ointment).
Phototherapy (exposure to ultraviolet light) may help, especially therapy using narrowband ultraviolet B light.
For severe cases, wet wraps (corticosteroid or immunomodulator applied to wet skin, wrapped with a moist layer and then a dry layer) are helpful. Also, the immune system can be suppressed with cyclosporine, azathioprine, or mycophenolate mofetil taken by mouth, or injections of biologics such as dupilumab.
Eczema herpeticum is treated with the antiviral drug acyclovir.