Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Eczema

What Is It?

Dermatitis is a skin inflammation. Eczema is the most common type of dermatitis.

Eczema first appears as an episode of itching and redness of the skin. You also may have tiny bumps or blisters.

When eczema develops into a long-term condition, it is called chronic eczema. This leads to:

• Thickening of the skin

• Scaling

• Flaking

• Dryness

• Color changes

There are many types of eczema. The type depends on the cause, shape and location of the rash.

Most eczemas are related to allergies or to contact with irritating substances. Some are associated with fluid retention in the legs.

Following are types of eczema:

• Atopic eczema (atopic dermatitis) — This type of eczema comes and goes repeatedly. It usually occurs in people with an inherited tendency to allergies. These allergies may include allergic asthma, hay fever or food allergies.

Atopic eczema appears early in life, usually by 18 months. In babies, atopic eczema primarily affects the:

• Face

• Neck

• Ears

• Torso

• Tops of feet or outside of elbows (less commonly)

Atopic eczema in older children, teenagers and adults usually involves the:

• • Skin inside the creases of the elbow

  • Knee

  • Ankle or wrist joints

  • Hands

  • Upper eyelids

• Contact dermatitis — When irritants touch the skin, they can produce two types of contact dermatitis. Irritant contact dermatitis is the direct irritation of the skin. It can be caused by prolonged contact with irritants such as:

  • Detergents

  • Bubble bath

  • Harsh soap

  • Sweat

  • Saliva

  • Urine

The second type of contact dermatitis is allergic contact dermatitis. This is an allergic reaction in the skin. This type occurs in people who have an allergy to a specific substance. The most common allergens are poison ivy, poison oak and poison sumac.

Other substances that can trigger skin allergies include:

• • Some building materials

  • Cleaning products

  • Deodorants

  • Cosmetics

  • Medications

  • Nickel in earrings

  • Chemicals in:

    • Fragrances

    • Skin cream and lotions

    • Shampoos

    • Shoes

    • Clothing

• Hand eczema — Hand eczema is limited to the hands. It can be related to atopic eczema. Or it can result from repeated hand washing or exposure to strong detergents. Occasionally, it is caused by an allergy, such as to latex.

• Nummular eczema — This eczema causes coin sized patches of irritated skin. It typically appears on the legs, arms or chest. It usually occurs in adults. It can be related to atopic dermatitis and, less often, allergic contact dermatitis.

• Sometimes, it is an allergic reaction to a fungal infection such as athlete's foot. It still appears on the arms, legs or chest, even if the fungal infection is elsewhere on the body.

• Asteatotic eczema — This eczema dries the skin, causing fine cracks. It often first involves the lower legs. It commonly occurs in the elderly. It is common during winter months spent indoors in low humidity environments.

• Stasis dermatitis — This type appears on the calves, ankles and feet. It occurs in people who have poorly functioning veins in the lower legs. The veins cause blood to collect in the legs (stasis). This leads to leg swelling, which leads to the signs of stasis dermatitis:

  • Itching

  • Fine red bumps

  • Skin redness or darkening

  • Weeping sores

• Lichen simplex chronicus — This eczema is a reaction to repeated scratching or rubbing of the skin. A nervous scratching habit can lead to thickened, discolored skin. Skin picking can lead to smaller bumps of the same type of rash.

• Seborrheic dermatitis — This type creates a greasier rash than usual for eczema. This scaly dermatitis commonly appears on the scalp of infants (as cradle cap). In adults, it appears as dandruff. It commonly affects the face or neck around the nose and at the scalp line.