Researchers at the Perelman School of Medicine at the University of Pennsylvania report that adults with seborrheic dermatitis in a large US cohort had higher odds of multiple epithelial barrier diseases across skin, respiratory, gastrointestinal, and ocular systems, and lower odds of chronic obstructive pulmonary disease and pulmonary hypertension.
Seborrheic dermatitis affects oily areas of the skin and creates red, flaky patches that show up on the face, scalp, and other areas with high sebaceous gland activity. The condition affects approximately 5% of the population worldwide.
Epithelial barrier context
Previous studies have proposed mechanisms that include colonization by Malassezia yeast, lipase-mediated breakdown of keratinocyte lipids, changes in the skin lipid matrix, and downstream cytokine-driven inflammation.
Epithelial barrier theory proposes that weakened barriers in the skin, airways, gut, or eyes allow germs, allergens, and pollutants to slip through, stir up the immune system, and create long-lasting inflammation.
Previous electron microscopy findings of disorganized stratum corneum packing and functional studies showing increased transepidermal water loss further support barrier disruption in seborrheic dermatitis cases, while links to other respiratory, gastrointestinal, and ocular conditions remain unclear.
In the study, “Epithelial Barrier Diseases Among Adult Patients With Seborrheic Dermatitis,” published in JAMA Dermatology, researchers conducted a retrospective cohort study to explore the association between seborrheic dermatitis and epithelial barrier diseases.
Investigators used claims from multiple US health care centers and care settings between 2016 and mid-2022. Among 20,274,189 patients, 733,776 individuals (3.62%) had at least one seborrheic dermatitis diagnosis recorded.
Exposure was a diagnosis of seborrheic dermatitis recorded at any time during the observation window. Outcomes were diagnoses of epithelial barrier diseases during the same period, also defined by at least one associated ICD-10 code. Negative control conditions with no known association to seborrheic dermatitis included hand fracture, sebaceous cyst, appendicitis, influenza, and astigmatism.
Key findings across diseases
Strong positive associations appeared between seborrheic dermatitis and several dermatologic epithelial barrier diseases in fully adjusted models. Odds ratios (OR) included 3.21 for atopic dermatitis, 4.02 for alopecia areata, 2.25 for contact dermatitis, 3.26 for psoriasis, and 4.52 for rosacea.
Additional positive associations included food allergy with an OR of 1.21, hidradenitis suppurativa 1.63, chronic spontaneous urticaria 1.35, pemphigus vulgaris 1.48, and bullous pemphigoid 1.60.
Beyond the skin surface, seborrheic dermatitis showed positive associations with several epithelial barrier diseases. Rhinosinusitis had an OR of 1.24, celiac disease 1.36, irritable bowel syndrome 1.32, ocular allergy 1.39, and dry eye 1.48.
Higher prevalence of many of these conditions was found in patients with seborrheic dermatitis compared with those without. Associations with several other respiratory, gastrointestinal, and ocular conditions, along with hand fracture, appendicitis, influenza, and astigmatism, fell within a prespecified clinically insignificant range.
Interpretation and next steps
Authors interpret the clustering of seborrheic dermatitis with diverse inflammatory skin conditions involving varied inflammatory markers and pathways as support for epithelial barrier theory, suggesting it is a “shared driver in the pathogenesis,” and that epithelial dysfunction in seborrheic dermatitis may align with increased frequency of inflammatory skin disease across multiple immunologic pathways.
Positive associations with rhinosinusitis, celiac disease, irritable bowel syndrome, ocular allergy, and dry eye are presented as further support for a model in which disruption at one epithelial barrier can relate to inflammatory conditions at other epithelial surfaces.
It is a bit of a leap from a comorbidity pattern to suggest directionality or any form of causality from epithelial barrier issues as a “shared driver,” even if compatible with the epithelial barrier theory.
Prospective and mechanistic studies are needed to determine whether skin barrier dysfunction is upstream of, downstream of, or simply co-occurring with these other conditions and whether barrier-targeted interventions can modify risk of related conditions elsewhere in the body.
Written for you by our author Justin Jackson, edited by Sadie Harley, —this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive.
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More information:
Sabrina Meng et al, Epithelial Barrier Diseases Among Adult Patients With Seborrheic Dermatitis, JAMA Dermatology (2025). DOI: 10.1001/jamadermatol.2025.4313
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