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Eczema types: Atopic dermatitis causes

What causes atopic dermatitis?

Exactly why people get atopic dermatitis, also called eczema, is still a bit of a mystery.

While studying atopic dermatitis, researchers have made important discoveries. We know that this condition is complex and that the following may play a role in causing it:

  • Your genes

  • Your immune system

  • What touches your skin

Here’s what likely takes place.

What happens to the skin barrier when someone has atopic dermatitis?

Our skin barrier is our outer layer of skin. Also called the stratum corneum, the job of the skin barrier is to protect us from everyday things that touch our skin — from pollution and dust mites to fragrances in skin care products and tobacco smoke. The skin barrier also helps keep the skin hydrated, so the skin doesn’t become dry, irritable, or itchy.

Atopic dermatitis causes gaps in the skin’s protective barrier
If you were to look at the skin barrier under a microscope, it would look like a protective brick wall. When someone has atopic dermatitis/eczema, you see gaps in this wall.

The gaps in the skin barrier that develop when someone has atopic dermatitis allow:

  • Too much moisture to escape from the skin, causing dryness

  • Everyday things in the environment from dust mites to fragrances to get inside the protective barrier, leading to inflammation

  • Germs like virus and bacteria to get inside the barrier, which can lead to an infection

While researchers have discovered that this happens, there are still unanswered questions about why it happens. Researchers, including dermatologists, continue to conduct studies.

Who gets atopic dermatitis?

This condition usually begins during childhood, with most children developing it by 5 years of age. Atopic dermatitis can also develop during puberty. Less often, people get it as an adult.

For many children, atopic dermatitis goes away by their teenage years. However, some see the disease return later in life. Atopic dermatitis can also continue into the teenage and adult years, becoming a lifelong disease. Board-certified dermatologists help people of all ages to control this condition.

What increases the risk of developing atopic dermatitis?

This condition develops in people of all ages and races. However, some people have a higher risk of getting it. Here’s what research shows can increase the risk.

  • Your race: In the United States, Black children are twice as likely as white children to develop atopic dermatitis, according to several studies.

  • Where you live: Around the world, people living in a city are more likely than people living in a rural area to develop atopic dermatitis. Several studies have found this to be true, and air pollution may be the reason. Living in a dry climate or far from the equator, where it’s cooler, may also increase your risk.

  • Genes you inherit: Many people who develop atopic dermatitis have one or more blood relatives with atopic dermatitis or an allergic disease like asthma or hay fever. Studies have found this to be true for 70% of patients with atopic dermatitis.

Atopic dermatitis increases risk of developing an allergic disease

In most cases, atopic dermatitis is not caused or triggered by a specific allergy. Still, many people who have atopic dermatitis develop an allergic disease.

Food allergies, seasonal allergies (sometimes called hay fever) or asthma can develop, usually after you get atopic dermatitis. Some people develop all these diseases, but it’s more common to get one. About one-third of children with atopic dermatitis later develop asthma, and two-thirds get hay fever.

When these allergic diseases develop one after another, it’s called the atopic march.

While many people develop an allergic disease, keep in mind that not everyone who has atopic dermatitis does.

It’s also important to know that some people develop asthma, hay fever, or another allergic disease before they get atopic dermatitis.

If you have atopic dermatitis, with or without an allergic disease, it’s important to see a board-certified dermatologist. These doctors have expertise in diagnosing and treating atopic dermatitis.

Treatment can prevent atopic dermatitis from worsening. Find out how dermatologists diagnose and treat it at: Atopic dermatitis: Treatment.

Getty Images

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Gabryszewski SJ, Dudley J, et al. “Patterns in the development of pediatric allergy.” Pediatrics. 2023 Aug 1;152(2):e2022060531.

Hoskinson C, Dai DLY, et al. “Delayed gut microbiota maturation in the first year of life is a hallmark of pediatric allergic disease.” Nat Commun. 2023 Aug 29;14(1):4785.

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Simpson EL, Leung DYM, et al. “Atopic dermatitis.” In: Kang S, et al. Fitzpatrick’s Dermatology. (ninth edition) McGraw Hill Education, United States of America, 2019:363-84.

Written by:
Paula Ludmann, MS

Reviewed by:
Elaine T. Kaye, MD, FAAD
Ata Moshiri, MD FAAD
J. Klint Peebles, MD, FAAD

Last updated: 10/10/23