Dandruff and Seborrheic Dermatitis

W. Steven Pray, PhD, RPh, Professor of Nonprescription Products and Devices, School of Pharmacy, Southwestern Oklahoma State University, Weatherford, OK

US Pharmacist. 2001;26(4) 

In This Article

Seborrheic Dermatitis

Seborrheic dermatitis is a more severe condition than dandruff. The scales appear to have an oily consistency, and borders of the affected area are indistinct. The age of onset is usually at puberty, and it is common to have pruritus associated with the condition.

Proponents of the proliferative etiology point out that cell turnover is so rapid in dandruff that some cells still retain their nuclei, and that in seborrheic dermatitis, the process is further accelerated, with a correspondingly higher ratio of cells retaining the nuclei.

Seborrheic dermatitis was long thought to result from overproduction of sebum, hence the name. Part of the reason is that the sites most often affected are those in which sebum production is heaviest, due to a greater concentration of sebaceous glands, such as the scalp, eyebrows, eyelashes, the external ear canal, behind the ears, in the nasal folds, the midchest, in the armpits, between the shoulder blades, and the pubic area and groin.[6] However, later researchers have demonstrated that patients with seborrheic dermatitis do not produce more sebum than age-matched controls.

The distribution of seborrheic dermatitis lends credence to the fungal theory, in that P. ovale cannot synthesize fatty acids of C12 or longer chain lengths.[4] Thus it is dependent on gaining these fatty acids from its surroundings. As it metabolizes these fats, it may cause skin damage by producing irritant metabolites.

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