When atopic dermatitis occurs during infancy and childhood, it affects each child differently in terms of both onset and severity of symptoms. In infants, atopic dermatitis typically begins around 6 to 12 weeks of age. It may first appear around the cheeks and chin as a patchy facial rash, which can progress to red, scaling, oozing skin. The skin may become infected. Once the infant becomes more mobile and begins crawling, exposed areas, such as the inner and outer parts of the arms and legs, may also be affected. An infant with atopic dermatitis may be restless and irritable because of the itching and discomfort of the disease. The skin may improve by 18 months of age, although the infant has a greater than normal risk of developing dry skin or hand eczema later in life.

In childhood, the rash tends to occur behind the knees and inside the elbows; on the sides of the neck; around the mouth; and on the wrists, ankles, and hands. Often, the rash begins with papules that become hard and scaly when scratched. The skin around the lips may be inflamed, and constant licking of the area may lead to small, painful cracks in the skin around the mouth.

In some children, the disease goes into remission for a long time, only to come back at the onset of puberty when hormones, stress, and the use of irritating skin care products or cosmetics may cause the disease to flare.

Although a number of people who developed atopic dermatitis as children also experience symptoms as adults, it is also possible for the disease to show up first in adulthood. The pattern in adults is similar to that seen in children; that is, the disease may be widespread or limited to only a few parts of the body. For example, only the hands or feet may be affected and become dry, itchy, red, and cracked. Sleep patterns and work performance may be affected, and long-term use of medications to treat the atopic dermatitis may cause complications. Adults with atopic dermatitis also have a predisposition toward irritant contact dermatitis, where the skin becomes red and inflamed from contact with detergents, wool, friction from clothing, or other potential irritants. It is more likely to occur in occupations involving frequent hand washing or exposure to chemicals. Some people develop a rash around their nipples.

These localized symptoms are difficult to treat. Because adults may also develop cataracts, the doctor may recommend regular eye exams.