Eczema is a chronic skin condition affecting about 10 percent of the U.S. population.
Eczema, also called atopic dermatitis, is a group of inflammatory skin conditions that cause swelling, dryness, itchiness, and rashes. It commonly affects the face, elbows, knees, hands, and feet.
The term “eczema” originates from the Greek word meaning “to boil” and refers to red, dry, and itchy skin.
While not contagious, eczema varies from person to person and can appear on different areas of the body. Common symptoms include dry, itchy, scaly, or rough patches that can lead to intense itching and scratching, sometimes causing the skin to bleed.
It often results in inflammation or swelling, and in some cases, oozing or crusting of the affected areas.
Skin discoloration is also common, varying by skin tone and appearing as pink, red, purple, brown, or gray.
Symptoms specific to atopic dermatitis—the most common form of eczema—include thickened skin with light or dark patches, a condition known as lichenification, resulting from repeated scratching or rubbing that makes the skin appear leathery.
The distribution of atopic dermatitis rashes varies with age:
- Infants often experience widespread, dry, red, and scaly rashes, especially on the face and cheeks.
- In older children, rashes typically appear on the wrists, elbows, ankles, and knees.
- In school-aged children and adults, eczema commonly affects the folds of the elbows and knees.
Additional symptoms may include blisters and sores, which can become infected with bacteria or viruses.
Although its exact cause is not fully understood, atopic eczema is believed to be caused by a combination of factors, including:
Genetics
A family history of eczema, asthma, or allergies increases the risk. Certain genes, such as the filaggrin gene, play a key role in maintaining the skin barrier. Mutations in these genes can make the skin more sensitive to irritants. Other genes related to skin barrier function, lipid production, and immune system response may also contribute to the condition.
Environmental Factors
People with atopic eczema have a weakened skin barrier, making their skin prone to dryness and irritation.
Common triggers that can cause flare-ups and worsen symptoms include:
- Soaps
- Detergents
- Dust mites
- Pet dander
- Certain foods, such as eggs, milk, and peanuts
- Stress
- Weather changes
- Hormonal changes, such as those during pregnancy
- Skin infections, such as staph
- Sweat
- Scratchy clothing
Immune System Overactivation
Atopic eczema is also linked to an overactive immune system, in which the body responds too strongly to environmental triggers, leading to inflammation and, in turn, itchy, painful skin symptoms. However, atopic eczema is not an autoimmune disorder.
Other risk factors for atopic eczema include:
- Age: Atopic dermatitis can develop at any age, but it most commonly begins in childhood, typically within the first six months of life. Approximately 65 percent of cases develop before age 1, and about 90 percent occur before age 5.
- Allergies: People with eczema often also have asthma and allergies such as allergic rhinitis (hay fever). These conditions, known as “atopic” conditions, occur in people who are highly sensitive to environmental allergens.
- Race: Non-Hispanic black children are at a higher risk for atopic dermatitis than other populations.
- Obesity: Excess fat tissue releases pro-inflammatory cytokines, which can disrupt the immune balance in the skin, making it prone to the exaggerated immune response that characterizes eczema.
- Vitamin or nutrient deficiency: Deficiencies in nutrients such as zinc—which has anti-inflammatory properties—may contribute to eczema by increasing the production of pro-inflammatory mediators.
- Urban living: Air pollutants can affect both local and systemic immune responses, potentially skewing the immune system towards eczema. Research has shown a link between higher levels of particulate matter and an increased risk and severity of eczema.
- Climate with low humidity: Low humidity increases the risk and severity of eczema by drying out the skin, compromising the skin barrier, and making it more susceptible to irritants and allergens.
