Seborrheic Dermatitis

Seborrheic dermatitis is a common inflammatory skin condition that is highly treatable but incurable.

Seborrheic dermatitis (also known as seborrhea) is a chronic inflammation of the skin that typically waxes and wanes. It produces a red scaling, occasionally weepy, oozy eruption.

Seborrheic dermatitis commonly involves portions of the scalp, brows, mid-face, ears, mid-chest, and mid-back. It is not unusual for it to affect the skin of infants and young children where it often involves the scalp (cradle cap) and the diaper area.

Picture of seborrheic dermatitis on the forehead; photo courtesy of Gary W. Cole, MD, FAAD

Since both of these conditions can affect the scalp with an itchy scaling dermatitis, it can sometimes be difficult to distinguish one from the other. Aside from scalp involvement, psoriasis typically involves anatomically different areas of skin than seborrheic dermatitis. In addition, seborrheic dermatitis is eczematous dermatitis producing a weepy, oozing appearance.

Psoriasis produces papules and plaques of scaling red skin. A pathological examination of a skin biopsy is rarely necessary to distinguish these two conditions.

Dandruff flakes represent scales from the scalp.

Dandruff is simply a sign of the excessive production of the skin. It can be seen in several inflammatory skin diseases, including seborrhea and psoriasis.

Medical professionals have a poor understanding of the causes of seborrheic dermatitis. There are some newly recognized genetic influences in seborrheic dermatitis. Eleven gene mutations or protein deficiencies appear to be more common in individuals with seborrheic dermatitis. Most of the genes play a role either in the immune response or epidermal differentiation.

Since this condition tends to occur in areas of heavy sebum production, it is felt that oily skin may be a factor leading to seborrheic dermatitis. In addition, it seems that many patients with seborrheic dermatitis have an abundant growth of normal skin yeast (Pityrosporum or Malassezia) in the affected areas. The fact that topical antifungal medications are effective in controlling seborrheic dermatitis has led some to conclude fungi may play a role in causing this disease. Whether these normal members of the cutaneous microbiome play a causal role in seborrheic dermatitis remains to be determined.

Patients with severe central nervous system disease (dementia and traumatic brain injuries) seem to have more trouble with seborrheic dermatitis. It is unclear if the nervous system plays a role in causing seborrhea or if it is simply a lack of normal hygiene.

Is seborrheic dermatitis contagious?

Seborrheic dermatitis is not contagious.

Although almost all patients with seborrheic dermatitis are generally healthy, there does seem to be an association between diseases of the central nervous system and AIDS (HIV).

Seborrheic dermatitis is characterized by spontaneous remissions and exacerbations (flare-ups).

The rash itself is characteristically red and scaling but occasionally can become weepy and oozy. The scaling can be extensive enough to produce significant dandruff, which is usually a patient's major complaint.

The distribution of this rash is often of great help in making the diagnosis. In adults, areas commonly involved include the scalp, the outer ear, and external auditory canal, the forehead, the eyebrows, the eyelids, the cheeks adjacent to the nose, including the folds that extend from the nose to the sides of the mouth, and less commonly the armpits, the mid-chest, and mid-back regions. In babies, the rash causes a scalp eruption commonly called "cradle cap." It can also be more extensive and involve the diaper area as well.

Although the rash may have no symptoms in both adults and children, it commonly causes itching, especially on the scalp.

Most primary care physicians, pediatricians, internists, and family doctors can diagnose and treat seborrheic dermatitis. Occasionally, it may be necessary to refer patients to a dermatologist for a diagnosis.

The diagnosis of seborrheic dermatitis is usually made clinically, meaning that the doctor recognizes it based on its appearance. Occasionally, a scraping of skin scales treated with potassium hydroxide is examined using a microscope to exclude fungal infection. A skin biopsy is rarely required for diagnosis.

Treatment of hair-bearing areas, like the scalp, often includes the use of over-the-counter shampoos that may contain one or more of the following ingredients:

• Tar (DHS Tar, Neutrogena T/Gel)
• Ketoconazole (Nizoral requires a prescription)
• Ciclopirox
• Zinc pyrithione (Head & Shoulders, Dermazinc)
• Selenium sulfide (Selsun Blue)
• Salicylic acid (Neutrogena T/Sal)
• 10% sodium sulfacetamide and 5% sulfur solution (Novacet, Sulfacet R lotion)

In addition, the application of a prescription-strength topical steroid lotion or solution of weak to moderate potency is effective such as desonide (Desonate, DesOwen, LoKara, Verdeso), clobetasol (Clobex, Cormax), betamethasone valerate (Valisone), fluocinolone (Capex, Synalar), hydrocortisone, and triamcinolone (Aristocort, Aristocort HP, Kenalog, Triderm).

For non-hair-bearing areas, the application of a weak to moderately potent topical steroid or topical antifungal cream is frequently effective. The use of topical calcineurin inhibitors, tacrolimus (Protopic) or pimecrolimus (Elidel) ointments, can be effective but is quite an expensive alternative. Patients may also use ketoconazole-containing creams for the treatment of seborrheic dermatitis.

It needs to be stressed that since this condition is incurable but easily controlled; if the disease is active and the treatment is stopped, one should expect seborrheic dermatitis to recur. One should also use effective medications just frequently enough to control the symptoms. Excessive treatment of apparently normal skin is economically wasteful as well as potentially risky.

There is little compelling evidence that any of the following substances taken either orally or used topically are of any significant benefit in the control of seborrheic dermatitis: coconut oil, apple cider vinegar, tea tree oil, aloe vera, fish oil supplements, or biotin.

On the other hand, 1% hydrocortisone, which is inexpensive and easily available without a prescription, is likely to be very effective in controlling seborrhea. It can be helpful to apply olive oil or fluocinolone topical oil to the scalp to soften and loosen flaky or scaly patches; follow up by thoroughly brushing and washing your hair.

Since seborrheic dermatitis generally is not associated with any serious problems, one way of looking at the prognosis would be optimistic. On the other hand, although treatment almost always results in an excellent response, it is unlikely to result in any durable, permanent resolution of the disease.

There are a few complications attributable to this condition. Most problems seem to be related to misdiagnosis or mistreatment. Rarely, certain superficial cutaneous (dermatophyte) fungal infections of the face and scalp can resemble seborrheic dermatitis.

• If dermatophyte infections are mistakenly treated with anti-inflammatory medications (topical steroids), more extensive involvement could be encouraged.
• The overuse of potent topical steroids in an ill-conceived attempt to cure this condition, especially on the face and armpits, can result in many undesirable skin changes including skin thinning.
• Severe seborrheic dermatitis can occasionally produce thinning or loss of hair, in great part probably related to excessive scratching. As the disease is controlled, regrowth is expected.

 Seborrheic dermatitis is not preventable.