Seborrheic
Dermatitis and Dandruff
(Sept 1999)
Seborrheic (seb-o-re’ik) dermatitis is a common skin rash that tends to occur on oily areas of the skin. It responds readily to treatment and is not contagious. Seborrheic dermatitis typically develops on the scalp, ears, and face as well as occasionally on the chest, back, arms and legs.
Seborrheic dermatitis typically arises after puberty and tends to become milder during later life. A variant of seborrheic dermatitis called cradle cap occurs in newborns and usually goes away without treatment during the first year of life. Safe and effective medicines are available that provide excellent control of seborrheic dermatitis, but there is no way to prevent or cure it. This condition tends to worsen during periods of stress. It occurs in all racial and ethnic groups but is particularly common in people of Celtic heritage. Approximately three percent of adults in the United States have seborrheic dermatitis; dandruff is even more common. The vast majority of people with seborrheic dermatitis are otherwise healthy, but Parkinson’s disease and other brain disorders may trigger it in some cases. Seborrheic dermatitis is also seen more frequently and extensively when the immune system becomes weakened. It is not in any way related to skin cancer or other skin diseases.
Dandruff is the term used to describe an exceptionally common scalp condition characterized by flaking and scaling. Intermittent episodes of fine, dry, white flaking and mild itching of the scalp are the hallmark of dandruff. Contrary to popular belief, regular washing of the scalp and hair actually results in improvement of the dryness and scaling (dandruff products). Dandruff can be thought of as either a mild variant of seborrheic dermatitis or a separate condition that is capable of worsening into true seborrheic dermatitis. The key distinction between dandruff and seborrheic dermatitis is that there is no visible inflammation associated with dandruff.
Seborrhea is a term used to describe skin that is excessively oily. It is only when irritation, redness and scaling develop on oily skin that seborrheic dermatitis is present.
Seborrheic dermatitis of the scalp is very common and characterized by scaling, itching and redness. Although this redness develops initially around hair follicles, seborrheic dermatitis has not been shown to cause permanent hair loss. Behind the ears, seborrheic dermatitis causes redness and greasy scaling. It also commonly causes itchy red ear canals. On the face, the most common areas of involvement are the eyebrows near the nose, the lower mid forehead, the lower sides of the nose and the laugh lines. On the trunk, redness and scaling may occur on the skin between the shoulder blades and overlying the chest bone. Seborrheic dermatitis can also occur in skin folds, especially under the arms and in the groin folds where crusting and open splits may develop.
The main cause of seborrheic dermatitis is now believed to be overgrowth of normal skin yeast called M. Ovale. This conclusion is based upon the facts that the organism is found on people with the condition, can be grown outside of the body, and when placed on unaffected skin can cause the condition to develop. The way in which this yeast causes redness and scaling is not entirely known.
There are many options, both prescription and over the counter, for treating seborrheic dermatitis. The medicines used to treat this condition work either by slowing the growth of the causative yeast or by decreasing the inflammation. Often a combination of treatments is recommended for optimum control. For the scalp, products such as Nizoral shampoo or zinc containing shampoos are recommended to control yeast growth and topical cortisone solutions are often recommended to control itching and redness (dermatologist recommended shampoos). The shampoos are lathered up and allowed to sit for five minutes prior to rinsing. Cream rinses can be used afterward if desired. The scalp solutions are applied to clean dry areas of itchy or inflamed scalp by hand as needed. The products available by prescription are generally just more potent versions of the over the counter products. Most cases of seborrheic dermatitis and dandruff, however, can be very well controlled with over the counter products.
Facial and other non-hairy areas can be treated by the use of cortisone based or Nizoral based creams. Many people chose to lather not only the scalp but also the affected areas of non-hairy skin with Nizoral shampoo for five minutes two or more times weekly. This regimen, particularly when coupled with once or twice daily application of hydrocortisone or other mild cortisone based creams to red scaly skin areas usually provides excellent control.
Seborrheic dermatitis is diagnosed by its appearance. Laboratory tests are not generally required. Many people are aware of the nature of their problem and opt for self-treatment with over the counter products. Dermatologists are helpful whenever there is any question regarding the diagnosis of seborrheic dermatitis or if over the counter medication is not working as expected within a couple weeks.
Craig Kraffert, M.D.
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