Seborrheic DermatitisCraig Kraffert, MD
Seborrheic (seb-o-re’ik) dermatitis is a common skin rash that tends to occur on oily skin areas such as the scalp, ears, and face as well as occasionally on the chest, back, arms and legs. It responds readily to treatment and is not contagious. Seborrheic dermatitis typically arises after puberty and tends to become milder later in 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 to treat seborrheic dermatitis, but there is no way to prevent or cure it. Seborrheic dermatitis 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 vs. Seborrheic Dermatitis
Even more common than seborrheic dermatitis is dandruff, an exceptionally common scalp condition characterized by flaking and scaling. It 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. 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 of dandruff.
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 and tends to worsen during periods of stress. It is not in any way related to skin cancer or other skin diseases.
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, on the lower-mid forehead, on the lower sides of the nose and laugh lines. On the trunk, redness and scaling may occur on the skin between the shoulder blades and the skin 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.
Cause of Seborrheic Dermatitis
The main cause of seborrheic dermatitis is believed to be overgrowth of normal skin yeast called Malassezia. 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 Head & Shoulders, Selsun Blue and Nizoral shampoos are recommended to control yeast growth. Topical cortisone solutions are often recommended to control itching and redness. The medicated shampoos are lathered and allowed to sit for five minutes prior to rinsing. Cream rinses can be used afterward (or on top of) if desired. The scalp solutions are applied to clean dry areas of itchy or inflamed scalp as needed. The topical cortisone products available by prescription are more potent versions of the over the counter cortisones. Most cases of seborrheic dermatitis and dandruff can be controlled with over the counter products.
Facial and other non-hairy areas can be treated by the use of cortisone-based or anti-yeast based shampoos and creams. Many people chose to lather these shampoos not only on the scalp but also the affected areas of non-hairy skin 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 on red scaly skin areas, usually provides excellent control.
Diagnosis of Seborrheic Dermatitis
Seborrheic dermatitis is typically diagnosed by its appearance. Laboratory tests are not generally required. Many people are aware of the nature of their seborrheic dermatitis diagnosis and opt for self-treatment with over the counter products. Dermatologists can be particularly helpful whenever there is a question regarding the diagnosis of seborrheic dermatitis or if over the counter medication is not working as expected within a couple weeks.