Atopic dermatitis (also known as AD) is the most common type of eczema. In fact, more than 18 million American adults have atopic dermatitis — which often appears as a red, itchy rash normally on the cheeks, arms and legs.

Atopic dermatitis rash on an adult armSevere atopic dermatitis on an adult armAtopic dermatitis typically begins in childhood, usually in the first six months of a baby’s life. Even though it’s a common form of eczema, it’s also severe and long-lasting. When you or your child have atopic dermatitis, it may improve at times, but at others it may get worse. Often, atopic dermatitis disappears as a child grows older, though some children will have atopic dermatitis flares into adulthood.Atopic dermatitis exists with two other allergic conditions: asthma and hay fever (allergic rhinitis). People who have asthma and/or hay fever or who have family members who do, are more likely to develop AD. We don’t know the exact cause of atopic dermatitis. Researchers do know that a combination of genetics and other factors are involved. When a substance from inside or outside the body triggers the immune system, it over-reacts and produces inflammation. It is this inflammation that causes the skin to become red, rashy and itchy.Research also shows that some people with eczema, especially atopic dermatitis, have a mutation of the gene responsible for creating filaggrin. Filaggrin is a protein that helps our bodies maintain a healthy, protective barrier on the very top layer of the skin. Without enough filaggrin to build a strong skin barrier, moisture can escape and bacteria, viruses and more can enter. This is why many people with atopic have very dry and infection-prone skin.