Eczema is a general term for many types of skin inflammation, also known as dermatitis. The most common form of eczema is atopic dermatitis (some people use these two terms interchangeably). However, there are many different forms of eczema.
Eczema can affect people of any age, although the condition is most common in infants, and about 85% of people have an onset prior to 5 years of age. Eczema will permanently resolve by age 3 in about half of affected infants. In others, the condition tends to recur throughout life. People with eczema often have a family history of the condition or a family history of other allergic conditions, such as asthma or hay fever. Up to 20% of children and 1%-2% of adults are believed to have eczema. Eczema is slightly more common in girls than in boys. It occurs in people of all races.
Eczema is not contagious, but since it is believed to be at least partially inherited, it is not uncommon to find members of the same family affected.
Some forms of eczema can be triggered by substances that come in contact with the skin, such as soaps, cosmetics, clothing, detergents, jewelry, or sweat. Environmental allergens (substances that cause allergic reactions) may also cause outbreaks of eczema. Changes in temperature or humidity, or even psychological stress, can lead to outbreaks of eczema in some people.
Eczema most commonly causes dry, reddened skin that itches or burns, although the appearance of eczema varies from person to person and varies according to the specific type of eczema. Intense itching is generally the first symptom in most people with eczema. Sometimes, eczema may lead to blisters and oozing lesions, but eczema can also result in dry and scaly skin. Repeated scratching may lead to thickened, crusty skin.
While any region of the body may be affected by eczema, in children and adults, eczema typically occurs on the face, neck, and the insides of the elbows, knees, and ankles. In infants, eczema typically occurs on the forehead, cheeks, forearms, legs, scalp, and neck.
Eczema can sometimes occur as a brief reaction that only leads to symptoms for a few hours or days, but in other cases, the symptoms persist over a longer time and are referred to as chronic dermatitis.
Atopic dermatitis
Atopic dermatitis is a chronic skin disease characterized by itchy, inflamed skin and is the most common cause of eczema. The condition tends to come and go, depending upon exposures to triggers or causative factors. Factors that may cause atopic dermatitis (allergens) include environmental factors like molds, pollen, or pollutants; contact irritants like soaps, detergents, nickel (in jewelry), or perfumes; food allergies; or other allergies. Around two-thirds of those who develop the condition do so prior to 1 year of age. When the disease starts in infancy, it is sometimes termed infantile eczema. Atopic dermatitis tends to run in families, and people who develop the condition often have a family history of other allergic conditions such as asthma or hay fever.
Contact eczema
Contact eczema (contact dermatitis) is a localized reaction that includes redness, itching, and burning in areas where the skin has come into contact with an allergen (an allergy-causing substance to which an individual is sensitized) or with a general irritant such as an acid, a cleaning agent, or other chemical. Other examples of contact eczema include reactions to laundry detergents, soaps, nickel (present in jewelry), cosmetics, fabrics, clothing, and perfume. Due to the vast number of substances with which individuals have contact, it can be difficult to determine the trigger for contact dermatitis. The condition is sometimes referred to as allergic contact eczema (allergic contact dermatitis) if the trigger is an allergen and irritant contact eczema (irritant contact dermatitis) if the trigger is an irritant. Skin reactions to poison ivy and poison sumac are examples of allergic contact eczema. People who have a history of allergies have an increased risk for developing contact eczema.
Seborrheic eczema
Seborrheic eczema (seborrheic dermatitis) is a form of skin inflammation of unknown cause. The signs and symptoms of seborrheic eczema include yellowish, oily, scaly patches of skin on the scalp, face, and occasionally other parts of the body. Dandruff and “cradle cap” in infants are examples of seborrheic eczema. It is commonplace for seborrheic dermatitis to inflame the face at the creases of the cheeks and/or the nasal folds. Seborrheic dermatitis is not necessarily associated with itching. This condition tends to run in families. Emotional stress, oily skin, infrequent shampooing, and weather conditions may all increase a person’s risk of developing seborrheic eczema. One type of seborrheic eczema is also common in people with AIDS.
Nummular eczema
Nummular eczema (nummular dermatitis) is characterized by coin-shaped patches of irritated skin — most commonly located on the arms, back, buttocks, and lower legs — that may be crusted, scaling, and extremely itchy. This form of eczema is relatively uncommon and occurs most frequently in elderly men. Nummular eczema is usually a chronic condition. Neurodermatitis
This form of eczema results in scaly patches of skin on the head, lower legs, wrists, or forearms. Over time, the skin can become thickened and leathery. Stress can exacerbate the symptoms of neurodermatitis.
Stasis dermatitis
Stasis dermatitis is a skin irritation on the lower legs, generally related to the circulatory problem known as venous insufficiency, in which the function of the valves within the veins has been compromised. Stasis dermatitis occurs almost exclusively in middle-aged and elderly people, with approximately 6%-7% of the population over 50 years of age being affected by the condition. The risk of developing stasis dermatitis increases with advancing age.
Dyshidrotic eczema
Dyshidrotic eczema (dyshidrotic dermatitis) is an irritation of the skin on the palms of hands and soles of the feet characterized by clear, deep blisters that itch and burn.