Trapped by hair and stuck together by skin oil, this normal scalp shedding can become obvious, especially when it hits dark clothing. When the scaling becomes excessive and is associated with itching and redness, it has become seborrheic dermatitis. An increase in skin oiliness and the activity of a skin yeast, Malassezia furfur, are thought responsible for the dermatitis. Dandruff is not from scalp dryness. In addition to the scalp, seborrheic dermatitis can also occur on the face, in and behind the ears, and, in men, it can occur within beards and chest hair.
Dandruff often flares during times of stress and is often worse during the winter.
If you itch, resist the urge to scratch your scalp because the scratching speeds up the cell growth and dandruff increases. Shampoos are the cornerstone to dandruff control. Medication within dandruff shampoos slows skin cell growth or controls the skin yeast. They also contain detergents to help remove the oil and scale. One medicated shampoo is Nizoral, once prescription only and now available over the counter.