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What is dermatitis?

The term “dermatitis” refers to a group of diseases that involve skin inflammation. It is also known as “eczema”. Dermatitis can be caused by allergies, infections, and irritating substances.1 The most common types of dermatitis are atopic dermatitis and contact dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease which usually appears in childhood, and is often accompanied by allergic diseases such as asthma and allergic rhinitis. Atopic dermatitis affects 15-20% of children and 1-3% of adults worldwide.2 In the U.S. in 2003, the prevalence of AD ranged from 8.7-18.1% in children3 and from 2-10% in adults.4 Atopic dermatitis is most common in East Coast states. 5

Contact dermatitis (CD) is an acute skin inflammation resulting from contact with one or more irritating substances. According to data collected by the National Health and Nutritional Examination Survey over a one year period, the prevalence of CD in the U.S. is roughly 1.4%.6

What are the common symptoms?

The most common symptoms of both AD and CD are (in order of frequency)2,7:

  • Dry and scaly skin
  • Itchy skin
  • Skin rashes
  • Bleeding or oozing rashes after scratching

What are the causes?

Dermatitis can have many origins, but is usually caused by skin barrier dysfunction. Dysfunction can result from genetic mutations, exposure to humidity, aggressive hygiene in susceptible areas, and more.1 Repeated and prolonged exposure to irritating substances – such as detergents, fabrics, cosmetics, nickel sulfate, and fragrances – can also lead to the development of dermatitis.2,8

The main risk factors for dermatitis are (in order of relevancy)2,8:

  • Genetics
  • Dry skin
  • Skin irritants
  • Allergens
  • Extreme temperatures
  • Tobacco smoke
  • Diet
  • Antibiotic use

How does this topic relate to my microbiome?

Healthy individuals have higher skin bacterial diversity than AD patients.5,9 Recent studies show that certain skin microbes, such as Staphylococcus epidermidis, help maintain a healthy skin barrier by providing antigens to immune cells, and causing skin cells to produce antimicrobial peptides.15,16

On the other hand, there’s evidence that the gut microbiota of healthy patients contain more Bifidobacterium and less Staphylococcus than patients with AD.10 In comparison to healthy individuals, the gut microbiome of children who developed AD had less of the beneficial Bifidobacterium and Bacteroides, and higher counts of Clostridium. Furthermore, children with AD were more likely to have Staphylococcus aureus in their guts.11,12,13

An antigen is a toxin or foreign substance that induces an immune response in the body.
Antimicrobial peptides are peptides produced by skin cells to protect the surface of the skin from microbes and initiate the immune response against external agents.

Which diseases/topics are related to dermatitis?

Other diagnoses that may be considered with dermatitis include14:

  • Dermatophyte infection
  • Lichen planus
  • Psoriasis
  • Skin and soft-tissue infection

Dermatitis can also occur alongside other conditions. When AD occurs alongside asthma and allergic rhinitis, this is called ‘the atopic triad’, which is more common in children than in adults.15 Other related conditions are1,16:

  • Animal allergy
  • Drug allergy
  • Food allergy
  • Seasonal allergy
Also known as “tinea” infection, dermatophyte infection is caused by fungi in the skin, hair, and nails. It is characterized by redness and scaling in the affected area, and occasionally, blister formation.
Lichen planus is an inflammatory condition affecting the skin, hair, nails, and/or mucous membranes. In the skin, it occurs as purplish, flat-topped, and itchy bumps. In mucous membranes like the mouth or vagina, it appears in white patches.

How can people take action?

For proper examination and treatment, consult your healthcare provider. You can usually prevent CD by avoiding exposure to allergens, humidity, and pollution.8 For example, for some people, it helps to avoid jewelry containing nickel, or laundry detergent containing fragrances.

Because AD is so common in children, preventive measures are recommended during their first year of life. Breastfeeding and exposure to farm environments and animals during the first two years of life can be preventative, as well.2

Skin moisturizer can protect the skin barrier for both AD and CD. It is a powerful way to avoid skin breakdown and prevent dermatitis from advancing.2,9


1. Nedorost, S. T. (2012). Generalized Dermatitis in Clinical Practice (Illustrate). London: Springer London.

2. Nutten, S. (2015). Atopic dermatitis: Global epidemiology and risk factors. Annals of Nutrition and Metabolism, 66, 8–16.

3. Williams, H. C. (2013). Epidemiology of human atopic dermatitis – seven areas of notable progress and seven areas of notable ignorance. Veterinary Dermatology, 24(1).

4. Eckert, L., Gupta, S., Amand, C., Gadkari, A., Mahajan, P., & Gelfand, J. M. (2017). Impact of atopic dermatitis on health-related quality of life and productivity in adults in the United States: An analysis using the National Health and Wellness Survey. Journal of the American Academy of Dermatology, 77(2), 274–279.e3.

5. Eichenfield, L. F., Ellis, C. N., Mancini, A. J., Paller, A. S., & Simpson, E. L. (2012). Atopic Dermatitis: Epidemiology and Pathogenesis Update. Seminars in Cutaneous Medicine and Surgery, 31(3 SUPPL.), S3–S5.

6. Hogan, D., & Ledet, J. J. (2009). Impact of Regulation on Contact Dermatitis. Dermatologic Clinics, 27(3), 385–394.

7. Diepgen, T. L., & Coenraads, P. J. (1999). The epidemiology of occupational contact dermatitis. International Archives of Occupational and Environmental Health, 72(8), 496–506.

8. Cashman, M. W., Reutemann, P. A., & Ehrlich, A. (2012). Contact Dermatitis in the United States: Epidemiology, Economic Impact, and Workplace Prevention. Dermatologic Clinics, 30(1), 87–98.

9. Lynde, C. W., Andriessen, A., Bertucci, V., McCuaig, C., Skotnicki, S., Weinstein, M., Wiseman, M., & Zip, C. (2016). The skin microbiome in atopic dermatitis and its relationship to emollients. Journal of Cutaneous Medicine and Surgery, 20(1), 21–28.

10. Watanabe, S., Narisawa, Y., Arase, S., Okamatsu, H., Ikenaga, T., Tajiri, Y., & Kumemura, M. (2003). Differences in fecal microflora between patients with atopic dermatitis and healthy control subjects. Journal of Allergy and Clinical Immunology, 111(3), 587–591.

11. Björkstén, B., Naaber, P., Sepp, E., & Mikelsaar, M. (1999). The intestinal microflora in allergic Estonian and Swedish 2-year-old children. Clinical and Experimental Allergy : Journal of the British Society for Allergy and Clinical Immunology, 29(3), 342–346.

12. Björkstén, B., Sepp, E., Julge, K., Voor, T., & Mikelsaar, M. (2001). Allergy development and the intestinal microflora during the first year of life. Journal of Allergy and Clinical Immunology, 108(4), 516–520.

13. Kalliomäki, M., Kirjavainen, P., Eerola, E., Kero, P., Salminen, S., & Isolauri, E. (2001). Distinct patterns of neonatal gut microflora in infants in whom atopy was and was not developing. Journal of Allergy and Clinical Immunology, 107(1), 129–134.

14. Pallin, D. J., Espinola, J. A., Leung, D. Y., Hooper, D. C., & Camargo, Jr, C. A. (2009). Epidemiology of Dermatitis and Skin Infections in United States Physicians’ Offices, 1993–2005. Clinical Infectious Diseases, 49(6), 901–907.

15. Kapoor, R., Menon, C., Hoffstad, O., Bilker, W., Leclerc, P., & Margolis, D. J. (2008). The prevalence of atopic triad in children with physician-confirmed atopic dermatitis. Journal of the American Academy of Dermatology, 58(1), 68–73.

16. Brunner, P. M., Silverberg, J. I., Guttman-Yassky, E., Paller, A. S., Kabashima, K., Amagai, M., Luger, T. A., Deleuran, M., Werfel, T., Eyerich, K., Stingl, G., Bagot, M., Hijnen, D.J., Ardern-Jones, M., Reynolds, N., Spuls, P., & Taieb, A. (2017). Increasing Comorbidities Suggest that Atopic Dermatitis Is a Systemic Disorder. Journal of Investigative Dermatology, 137(1), 18–25.