Introduction
Seborrheic Dermatitis_Disease BackgroundSeborrheic dermatitis (SD) is a chronic relapsing inflammatory skin disorder mostly confined to areas where sebaceous glands are prominent. Malassezia (formerly known as Pityrosporum ovale) infection is common in seborrheic dermatitis.
Epidemiology
Seborrheic dermatitis has a global estimated prevalence of 4-5%, with biphasic incidence occurring in infants between the ages of 2 weeks and 12 months and during adolescence and adulthood. In the 2025 Global Burden of Disease (GBD) study, which covers the years 1990-2021, the global age-standardized incidence rate of seborrheic dermatitis was approximately 1,700 per 100,000 individuals. Seborrheic dermatitis is more common in men than women in all age groups due to hormonal differences. The prevalence is increased among individuals with human immunodeficiency virus and may be a presenting sign of the disease.
Seborrheic dermatitis prevalence varies globally, with South Africa reporting the highest rate, followed by the United States and Turkey, while India showed the lowest prevalence based on multiple studies.
Pathophysiology
While the exact pathogenesis is not known, seborrheic dermatitis is usually caused by inflammatory responses (eg T cell depression, complement pathway activation) to Malassezia sp proliferation in the stratum corneum. Malassezia sp also contribute by breaking down sebum and utilizing saturated fatty acids, which disrupts the normal lipid balance on the skin surface. Studies also cited skin barrier dysfunction as a possible cause of the development of seborrheic dermatitis in individuals.
Risk Factors
Seborrheic dermatitis is more frequently seen in individuals with neurologic or psychiatric disorders such as Parkinson disease, mood disorders, and stroke, as well as in those with immunodeficiency conditions like HIV/AIDS, hepatitis, and cancer. Immunosuppression promotes the proliferation of Malassezia sp, contributing to disease development. Recent evidence also associates obesity and metabolic syndrome with increased risk. The condition is more common during the winter season and periods of heightened stress. Medications that have been linked to seborrheic dermatitis include Auranofin, Buspirone, Chlorpromazine, Cimetidine, Ethionamide, 5-FU, Griseofulvin, Haloperidol, Interferon alfa, Lithium, Methoxsalen, Methyldopa, Phenothiazines, psoralens, Thiothixene and Trioxsalen.