Test Your Knowledge

There are several types of eczema, but most people use the term to refer to atopic dermatitis, the most common variety.

Atopic dermatitis is a condition that may occur in association with allergies and frequently runs in families with a history of asthma or hay fever. It typically begins in infancy, where it is often related to food allergies. It is rarely present when a child is born, but often develops over the first six weeks of a baby’s life. Almost all cases occur by the time a child is 5.

There are two main forms of atopic dermatitis:

• Chronic, with symptoms lasting for long periods of time
  
  
• Episodic, with symptoms more likely to come and go in periodic flare-ups

Atopic dermatitis does not usually occur in the diaper area, as the moisture in this region helps in prevention. However, it can affect all other areas of the body. It tends to vary in severity during childhood and adolescence. Certain conditions (e.g., colds, infections) and seasons (either dry winter weather or hot, humid summer weather) tend to cause flare-ups. Atopic dermatitis may become less troublesome in adulthood. However, exposures to certain allergens (e.g., pollen, molds, dust) or irritants (e.g., tobacco smoke, certain fabrics) can trigger an outbreak later in life. Stress can also exacerbate atopic dermatitis. Although some children outgrow the condition, individuals who have had eczema during childhood may continue to have dry, sensitive skin. 

Other types of eczema include:

• Contact dermatitis. Results from direct skin contact with various irritants (irritant contact dermatitis) or allergens (allergic contact dermatitis). Irritants include laundry soap, skin soaps or detergents, and cleaning products. Allergens include rubber, metals such as nickel, jewelry, perfume, cosmetics, hair dye, weeds such as poison ivy, and neomycin, an ingredient often found in topical antibiotic creams. A brief exposure to a small amount of allergen can cause contact dermatitis. However, it takes a more significant amount of an irritant – and a longer period of exposure – to trigger irritant contact dermatitis.
  
  
• Neurodermatitis. Occurs when a tight garment or insect bite irritates the skin, leading to chronic scratching or rubbing and a subsequent rash that is dull red to brown, thickened and slightly scaly. Common locations include ankles, wrists, outer forearms or arms, and the back of the neck.
  
  
• Seborrheic dermatitis. Common in people with oily skin or hair, it involves an overproduction of skin cells and the skin’s natural oil (sebum). Also known as cradle cap, it is most likely to appear during infancy before disappearing between the ages of 8 months to 12 months. Cradle cap usually affects the scalp but may occasionally affect the infant’s entire body. It may reoccur depending on the season of the year or whether the patient is under stress. Adults who have neurologic conditions (e.g., Parkinson's disease) or who are immunocompromised (e.g., HIV patients) also are at risk for this form of eczema. Seborrheic dermatitis is often an inherited condition. It is readily treated with mineral oil.
  
  
• Perioral dermatitis. Often associated with conditions such as rosacea, acne or seborrheic dermatitis of the skin around the mouth or nose. The precise cause is unknown, but exposure to makeup, moisturizers and dental products may be involved. This type of eczema rarely occurs in children.
  
  
• Latex dermatitis. Occurs when the skin comes into contact with latex, a fluid produced by rubber trees and found in gloves, balloons, condoms and other products.
  
  
• Dyshidrotic dermatitis. An intensely itchy, chronic form of eczema that typically appears on the palms, fingers and soles of the feet. The cause of dyshidrotic dermatitis is unknown but may include allergies, exposure to irritants and stress. It often progresses to small, fluid-filled bumps, which peel off after one or two weeks. This leaves cracks in the skin that resolve slowly over time. This type of eczema occasionally occurs in teenagers.