Eczema is a common skin disease that causes itchy, painful lesions that most people find challenging not to scratch. If a person scratches the skin eczema affects, it may thicken and become red and painful. Scratching can also lead to infection and scarring.

The National Eczema Association notes that the causes of eczema may have links to certain environmental triggers and genetics, although they are not sure of the exact causes of the disease.

Factors outside and inside the body trigger people with eczema’s overactive immune systems, causing inflammation. The inflammation is responsible for the itchy rashes that people associate with eczema.

In this article, we examine why eczema itches and how to help prevent it. We also look at what happens to the skin when someone scratches their eczema and the possible treatment options.

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Eczema is an allergic skin disease that commonly begins during childhood. It is a common disease that affects more than 31 million people in the United States.

Typical symptoms of eczema include patches of dry, itchy skin that can be red and painful. If a person scratches their skin, it can become flaky, scaly, and thick.

Experts are not entirely sure of the exact causes of the disease, but suggest that certain factors may play an important role in it. These include:

  • a family history of eczema, allergies, or asthma
  • a lack of a specific protein called filaggrin
  • the environment a person lives and works in
  • whether a person has exposure to pollution, stress, smoke, or chemicals

About half of all people with moderate to severe eczema also have hay fever, food allergies, and asthma.

Everyone who has eczema will experience some degree of itching. There are various reasons why eczema causes itching. These include:

Flare-ups

When a person has an eczema flare-up, something triggers the interactive network between the immune system, the nervous system, and the skin. The skin becomes sore, red, and has inflammation, which causes itching.

A variety of chemical mediators affect inflammation, including substance P, which is a neuropeptide. The inflammation increases a person’s blood flow, which also contributes to itching.

Changes to the skin barrier

People with eczema have alterations to the skin barrier in the topmost layer of the epidermis, the stratum corneum. The skin is structurally different due to changes in the filaggrin gene, which controls the skin barrier structure.

Because of these structural changes, the cells are unable to retain water, and they shrink. As natural moisturizing factors decrease, the skin becomes dry, and gaps open up between cells.

There is also a breakdown of lipid lamellae, a membrane of tissue that plays a role in water diffusion in the skin. This further contributes to dry skin and a defective skin barrier, which means irritants can enter the skin, and water disappears through it, known as transepidermal water loss (TEWL).

Researchers have found that TEWL increases during the night, explaining why people with eczema often experience worse itching at night.

Chemical mediators

Chemical itch mediators are substances in the body that communicate messages.

Chemical mediators act on the nerve endings in the upper layers of the skin or indirectly through cells that affect itching.

Researchers have identified various chemical itch mediators in eczema, one of which includes a neuropeptide named substance-P.

Sweating

Perspiration, or sweating, can aggravate eczema and worsen itching.

Experts indicate this is due to changing sensations in sweat gland nerve endings in the skin and an increase in the number of chemical mediators called neuropeptides.

Many environmental trigger factors may cause itching in eczema due to allergic reactions or irritants. These may include:

  • perfumes
  • soaps
  • pet dander
  • household cleaning products
  • detergents
  • synthetic and wool clothing
  • changes in temperature
  • contact allergy to latex, cement, or metal
  • dust
  • grass and trees
  • chemical substances
  • humidity
  • stress
  • cold and flu
  • certain foods

People experiencing a flare-up of eczema often experience an “itch-scratch cycle.” This is when a person is itchy, and they scratch their eczema, which causes more inflammatory mediators to release, which in turn causes more itchy dry skin. The dry skin leads to more itching, and so the cycle continues.

Scratching, not eczema itself, is one of the main causes of skin damage. Scratching can lead to painful, red skin, which may break and bleed.

If a person’s skin breaks, they are at higher risk for infection. Broken skin also makes it easier for irritants and allergens, such as dust and pet dander, to enter the skin barrier and cause eczema to flare.

Scratching can also cause the skin to become thick and leathery through a process called lichenification, which may cause changes to skin color. It may take weeks or months for the skin to return to its typical appearance.

Some people with eczema may have itchy lumps that may become thick and dark if they scratch them. This is called nodular prurigo. If this occurs in someone with a darker skin tone, there is an increased risk of the skin areas having permanent discoloration.

Scratching can also lead to scarring in the skin.

The best way to stop skin damage with eczema is to stop scratching. A person may be better able to help prevent scratching by treating or taking steps to help prevent the itch.

A person may help prevent flare-ups in a variety of ways, including:

  • using dye-free and fragrance-free skin products and detergents
  • moisturizing regularly
  • avoiding extreme temperatures and climates
  • wearing loose clothes made from breathable fabric
  • bathing in lukewarm water

A person can receive treatment for their eczema from a dermatologist, which often includes:

  • oral and topical medications
  • skin care advice
  • light therapy, or phototherapy

A person should contact a doctor or dermatologist about their eczema if:

  • the lesions cover a substantial amount of the body
  • it is affecting their daily living
  • over-the-counter products are not helping it
  • the lesions have an infection, produce pus, and have red streaks

Eczema is a common allergic skin disease. It causes itching for various reasons, including:

  • triggering an inflammatory reaction in the immune system
  • altering the skin barrier
  • releasing chemical mediators
  • increasing sweating
  • being sensitive to environmental triggers

Triggers for itching in eczema include:

  • dust
  • detergents
  • soaps
  • perfumes
  • pet dander
  • stress
  • extreme temperatures

When a person scratches eczema, they often end up in an itch-scratch cycle, where itching causes more scratching, and vice versa.

Scratching eczema can also lead to a higher risk of:

  • infection
  • broken skin
  • greater risk of irritants and allergens entering the skin
  • a thickening of the skin called lichenification
  • changes to skin color
  • scarring

Treatments and prevention for itchy eczema include avoiding triggering factors such as wool, perfumes, and dye, and contacting a dermatologist for treatment.

A person should contact a doctor if their eczema is severe or shows signs of infection.