Seborrheic dermatitis is a chronic eruption with erythema and scaling, involving typically the scalp, external ear canals, eyebrows, central face and the central anterior chest. The etiology of seborrheic dermatitis appears to be on the basis of a host response to an overgrowth of a normal skin yeast, Pityrosporum ovale. Seborrheic dermatitis occurs in oilier areas of the skin. Some central nervous system abnormalities such as Parkinson's disease appear to result in increased skin oiliness with increased seborrheic dermatitis. Patients with AIDS can have more severe seborrheic dermatitis. The scaling of the scalp is also termed dandruff.
- Removal of the yeast is highly effective. Zinc pyrithione, selenium sulfide, and ketoconazole shampoos are highly effective.
- Because the yeast is a normal skin organism, cessation of therapy generally results in a recurrence of the problem. Ongoing treatment is usually required.
- Tar shampoos are moderately effective.