Dandruff is the shedding of excessive amounts of flakes of dead skin from the scalp. It is a cosmetic problem experienced by hundreds of millions of people in the world but it is not contagious. It is often accompanied by itchiness of the scalp. Dandruff is sometimes confused with dry scalp but it differs from it in that it improves when one shampoos more often.
Skin cells are constantly renewing themselves. When skin cells on the scalp at renewed, the old ones are pushed to the surface, leaving the scalp. In a normal healthy scalp environment this renewal process is unnoticeable. With dandruff, the skin renewal speeds up , so that a bigger amount of dead cells are shed in clumps, which are big enough to be seen with the naked eye as embarrassing white flakes.
There are several types of dandruff and each is a result of a different medical condition. Common dandruff is believed to be related to a fungus known as malassezia, which normally lives in the human scalp. In some cases, the sudden proliferation of this fungus results in the flakiness of the skin characteristics of dandruff. The reasons for this overgrowth of fungus are unclear.
Severe dandruff may lead to scalp psoriasis.