"Atopic" refers to a group of conditions that can run in families and usually occur together. These include asthma, hay fever, and atopic dermatitis. This is known as the "atopic triad." Children who outgrow atopic dermatitis may later develop seasonal allergies or asthma. Atopic dermatitis does not cause asthma or allergies, however.

About 65% of people with atopic dermatitis develop symptoms in the first year of life. Nearly 4 in 5 (85%) develop symptoms before the age of 5. Atopic dermatitis can go into permanent remission by the time a child reaches adulthood. But in about half of the cases, it continues into adulthood. Occasionally, it shows up for the first time later in life. In adults, atopic dermatitis can show up after the skin is exposed to harsh conditions.

When the condition worsens, that period is called a flare or exacerbation. When it improves or clears up entirely, that period is called a remission. In some people, this cycle of flares and remissions may be seasonal in very hot or very cold weather. A flare can be caused by an irritant or an allergen.

Eczema is a general term for many types of dermatitis (inflammation of the skin). Atopic dermatitis is the most common type of eczema. Acne is a different kind of skin disease. Pimples are a symptom of acne. Like eczema, psoriasis is a chronic skin disease, but it is caused by a different disorder of the immune system.

Certain triggers can make this condition worse. For example, stress, hot or cold temperature, dry conditions, certain fabrics, metals, or detergents can cause a flare-up.

Symptoms vary from person to person. Other symptoms include cracks behind the ears and a rash on the cheeks, arms and legs. Scratching and rubbing the skin make the condition worse. The other answers are symptoms for other types of eczema.

Thick, leathery skin, called lichenification, can develop because of constant scratching and rubbing. Red, scaly skin can develop when the immune system in the skin becomes over-activated.

The epidermis, or outer layer of skin, is divided into two parts. The inner part contains moist, living cells. The outer part contains dry, dead cells. For a person with normal skin, the outer part acts as a barrier, protecting the inner layer from damage. The skin of a person with atopic dermatitis loses too much moisture. This reduces its protective abilities. It is more vulnerable to certain infections. People with eczema are more likely to have a severe and possibly life-threatening reaction to smallpox vaccination. Those with eczema also can develop eczema herpeticum, a herpes infection in the skin that can be life-threatening.