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Dandruff
Dandruff is a common condition involving an increased rate of shedding of dead epidermal (outer layer of the skin) cells of the scalp that causes dry, flaky, white to grayish scales to form, and is usually accompanied by itching. People with oily scalps tend to suffer most from dandruff. Dandruff is not contagious.
Scalp cells replenish themselves in a pattern similar to that of hair, but more rapidly. The skin of the head renews itself about once a month. Dead scalp cells are constantly being pushed from the deepest layer of the epidermis to the skin's surface, where they gradually die. Usually the scalp sheds them in a nearly invisible way. But for reasons that are still unclear, cell turnover sometimes becomes unusually rapid, and dead cells are shed as the visible flakes called dandruff.
Joseph P. Bark, M.D., chairman of dermatology at St. Joseph's Hospital in Lexington, Kentucky says that dandruff has its bright side: "If the scalp doesn't shed its dead skin cells, the human scalp would be tremendously thick. But when the cell turnover goes too far and increases, then you get not only visible excess scaling, but redness and itching. Redness and itching is actually seborrheic dermatitis, and it frequently occurs around the folds of the nose and the eyebrow areas, not just the scalp."
Do not confuse simple dandruff with other conditions that also cause flaking of the scalp like Seborrheic Dermatitis or Psoriasis. Psoriasis is a condition of the scalp or body characterized by irritation, itching, redness, and "extreme" excess shedding of dead epidermal cells. Seborrheic dermatitis is a condition of the scalp or body characterized by irritation, itching, redness, and excess shedding of dead epidermal cells.
Treatment for Dandruff
Washing your hair more often means you remove dandruff flakes that otherwise would remain on the head. Wash hair daily, using an over-the-counter (OTC) dandruff shampoo, sold in stores everywhere. Dandruff shampoos are drugs because they treat dandruff and itching. Regular shampoos only make your hair cleaner. Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, ketoconazole, or selenium. Shampoos or lotions containing selenium, ketoconazole, or corticosteroids may be prescribed for severe cases. To apply shampoos, part the hair into small sections, apply to a small area at a time, and massage into the skin. If on face or chest, apply medicated lotion twice per day.
In 1990, FDA banned 27 ingredients in dandruff shampoos because they were not proven safe and effective. Today dandruff can be treated with OTC drug products containing ingredients FDA has verified as safe and effective. Ingredients for dandruff treatment are available in shampoos, rinses, or in products that users apply and leave on the scalp. Each works in different ways to control dandruff symptoms like scaling or itching.
Treatment of Dandruff with 5 Percent Tea Tree Oil Shampoo
Dandruff appears to be related to the yeast Pityrosporum ovale. Tea tree oil has antifungal properties with activity against P ovale and may be useful in the treatment of mild to moderate dandruff. 5 percent tea tree oil appears to be effective and well tolerated in the treatment of dandruff.
If you have mild to moderate dandruff, you can usually take care of it with an over-the-counter (OTC) dandruff shampoo containing salicylic acid. Use it for several weeks, and if you don't see a clear-cut improvement in the scaling, consult a dermatologist. A dermatologist can diagnose whether you have a fungus infection of the scalp, seborrheic dermatitis, or some other disorder.
Coal Tar
Coal tar, one ingredient in OTC dandruff products, is a byproduct of treated bituminous coal. In constant exposure to concentrated solutions in industrial settings over long periods (20 to 25 years), coal tar has been associated with skin cancer. But coal-tar products are considered safe for topical use in shampoos because contact with the scalp is only for a short duration.
For body seborrheic dermatitis and psoriasis, however, products containing coal tar remain on the skin for longer periods. There are no well-defined, long-term studies that demonstrate how long coal-tar products can be used safely. FDA has noted that prolonged use of such products may not be completely risk free due to possible cancer-causing effects.
Coal tar also produces photosensitivity reactions (reactions that occur with exposure to sunlight). Residual amounts of coal tar may remain on the scalp, hair, or surrounding areas after using. So if you're going out in the sun after shampooing with these products, you may want to take extra precautions.
FDA requires OTC dandruff products that contain coal tar to state on their labels, "Do not use for prolonged periods without consulting a doctor. Use caution in exposing skin to sunlight after applying this product. It may increase your tendency to sunburn for up to 24 hours after application."
Coal-tar shampoos also tend to give an orange tinge to light-colored hair.
References:
1) United State Food and Drug Administration - Controlling Dandruff - Audrey T. Hingley - www.fda.gov
2) International Bibliographic Information on Dietary Supplements (IBIDS) - National Institutes of Health (NIH) - Office of Dietary Supplements (ODS) - USDA Agricultural Research Service - National Agricultural Library (NAL) - December 2002 - grande.nal.usda.gov/ibids/index.php
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