Dermatitis - Seborrheic Dermatitis
More than just dandruff
Seborrheic (seb-o-REE-ik) dermatitis is a common skin disorder affecting millions of Americans. Although it can be uncomfortable and may cause embarrassment, it is not contagious. Oasis asked Lawrence E. Gibson, M.D., a dermatologist at Mayo Clinic, Rochester, Minn., about this condition.
Oasis: What are the symptoms of seborrheic dermatitis
Dr. Gibson: The affected skin is usually red and greasy. On top of that there is a white or yellowish scale that often flakes off. The most common sites are the scalp, in and between the eyebrows, along the sides of the nose, behind the ears, the external ear canal, over the breastbone, in the groin area, and sometimes in the armpits. It is usually asymptomatic (causes no symptoms) but may cause itching and occasional soreness, especially in the groin area.
Oasis: Dandruff, seborrheic dermatitis and psoriasis are similar enough that many people confuse them. How do they differ
Dr. Gibson: Dandruff is a lay term describing excessive scaling. It can be caused by excessive dryness or by seborrheic dermatitis, psoriasis or another skin disease. Seborrheic dermatitis and psoriasis can be difficult to tell apart. psoriasis tends to have a whiter scale, and affected areas will bleed fairly easily if they are plucked or picked or scratched. plaques or patches of psoriasis also tend to be thicker and more persistent. Although both can produce dandruff, I would say most dandruff is due to seborrheic dermatitis, not psoriasis, because seborrheic dermatitis is much more common. A few people have both conditions, however, which can make diagnosis difficult.
Oasis: Are there other disorders or diseases associated with seborrheic dermatitis
Dr. Gibson: Rarely, seborrheic dermatitis will become infected, a condition known as impetigo. Besides psoriasis, other conditions associated with seborrheic dermatitis are parkinson's disease, spinal cord injuries and other neurological conditions. Another disease that seems to lead to outbreaks of seborrheic dermatitis is AIDS. However, the vast majority of people with seborrheic dermatitis have no associated conditions.
Oasis: What causes seborrheic dermatitis
Dr. Gibson: It's thought to be due to an abnormality of the oil (sebaceous) glands and hair follicles. people with seborrheic dermatitis seem to have increased sebum or oil production. Secondarily, a yeast, called pityrosporum, may grow in the sebum, along with bacteria, making the dermatitis more persistent. The effectiveness of anti-fungal treatments such as ketoconazole seems to bear out the idea that yeast is a contributing factor.
Oasis: Can seborrheic dermatitis be prevented, and how is it treated
Dr. Gibson: prevention and basic treatment are similar and consist of using shampoos containing one of five FDA-approved active ingredients: salicylic acid, coal-tar, zinc pyrithione, selenium sulfide and sulfur. They are non-prescription shampoos. Nizoral, the shampoo containing the anti-fungal ketoconazole, is a prescription shampoo. You may need to try several shampoos to find the one that works best for you, and then rotate between a medicated shampoo and regular shampoo or switch from one medicated type to another because they often seem to lose effectiveness after a while. It's important to massage the shampoo onto the scalp and other affected areas and leave it in place for a few minutes and then rinse thoroughly. If these shampoos aren't working, the next step is to rub on a topical 1 percent or 2.5 percent hydrocortisone cream once or twice a day. If you're still having trouble, then we usually go to a coal-tar preparation that you leave on overnight. We sometimes also use a stronger corticosteroid preparation.
Oasis: Can seborrheic dermatitis be cured
Dr. Gibson: Unfortunately, no. It may start in infancy as cradle cap, then go away during childhood. It may start again during adolescence when the oil glands become active, and you have it for a long time, often into old age. But it can usually be controlled using the treatments I described.