What causes eczema?
Most eczema patients have an over-reactive immune system. When your immune system is triggered by something irritating - from inside or outside your body - it produces swelling, redness, pain and burning (inflammation). The inflammation causes relentless itching and can weaken the outer layer of the skin. Skin becomes less effective at protecting you from irritants and things you’re allergic to (allergens). Most eczema is caused by dry skin, an over-reactive immune system, or contact with a trigger (allergen) in your surroundings.
It can also be caused by a gene mutation (change) that’s responsible for creating a protein (filaggrin) that helps maintain a protective top layer of skin. Without the filaggrin layer, skin can become very dry, allowing germs to enter the skin, and infections to develop.
What can trigger eczema?
There’s no one eczema trigger for everyone because it affects people differently. Some of the most common triggers for eczema include:
- Skin that’s so dry that it becomes scaly, rough or tight
- Irritating substances including soaps and detergents, shampoo or body wash, make-up, fragrances, disinfectants and household cleansers, juice from foods, metals, tobacco smoke, latex, paint, certain fabrics, antibacterials, and poison ivy, oak or sumac
- Stress
- Raising your body temperature or sweating
- Temperature changes or a sudden drop in humidity
- Synthetic fabrics or wool
- Food allergies
- Animal dander
- Upper respiratory infections
Are there different types of eczema?
There are many types and each type has its own symptoms and triggers.
- Atopic dermatitis is a chronic condition requiring symptom management. This is the most common type, and many people also have asthma and hay fever. An itchy rash often develops in elbow and knee creases, and skin can change color or get thicker. Bumps may appear that leak clear fluid if scratched. In babies, the rash often develops on their scalp and cheeks.
- Contact dermatitis is caused by a reaction to something you’ve touched. If it’s caused by an allergic reaction your immune system causes the symptoms: itchy, red bumps that burn or sting (hives); fluid-filled blisters that ooze and crust over; and thickening, scaly skin over time.
- Dyshidrotic eczema causes small, fluid-filled blisters on fingers, hands, toes and feet that can itch or hurt. Your skin may crack or flake. This type of eczema can be caused by frequently having hands and feet in the water or long-term dampness. Allergies to nickel, cobalt and chromium salt as well as stress are also causes.
- Hand eczema is usually caused by working with chemicals that irritate hands, such as hair stylists, cleaners or healthcare workers. Hands become dry, itchy and red, often forming cracks or blisters.
- Neurodermatitis causes thick, scaly and itchy patches on arms, legs, neck, scalp, hands, feet or genitals. Stress is thought to be a trigger. It often develops in people who also have psoriasis or another type of eczema.
- Nummular eczema causes round, very itchy spots that can be triggered by insect bites, allergic reaction to chemicals or metals, or by very dry skin. It’s more common in people who also have another type of eczema.
- Seborrheic dermatitis occurs in areas where hair grows. Skin produces oil, and sebum is secreted. Skin becomes scaly, dry, red, with a rash and dandruff. It can be caused by a reaction to yeast in your skin. It’s also called seborrhea, cradle cap or sebopsoriasis.
- Stasis dermatitis occurs when fluid leaks out of weakened veins, causing itchy, red and painful skin. It can happen in people with blood circulation problems in their lower legs. Valves in your leg veins can malfunction, allowing blood to pool in lower legs, swelling and open sores. Varicose veins can develop, causing very dry, itchy skin over the affected veins.
- Eczema herpeticum is a serious infection caused by the herpes simplex 1 virus (oral herpes) that causes cold sores on the mouth. Sores can develop on other body parts, and cover large areas of skin, especially the face and neck. The skin develops clusters of small, itchy, painful blisters that are black, red or purple, oozing pus if cracked open. Patients may be sick with high fever, chills and swollen lymph nodes. It is very contagious, spreading by skin-to-skin contact. It’s more common in people with atopic dermatitis or other inflammatory skin diseases. It can take two weeks after contact with herpes simplex 1 virus for symptoms to develop.
Who’s at risk for eczema?
You may be more likely to develop eczema if you have asthma and hay fever. Or, if you have eczema, you’re more likely to develop asthma and hay fever. Most cases develop in infancy or childhood and go away with age.
