Dandruff is an excessive flaking of skin on the scalp, with some skin flakes caught amongst the hair. Shedding of surface skin cells is normal, as they are gradually replaced by cells formed at the base of the epidermis which then move towards the surface. This process takes about a month. An increase in the number of cells being shed, which tend to clump together, is called dandruff.
Dandruff does not occur in children so hormones are thought to play a part in causing the concern. Recent research indicates that the yeast pityrosporum is the causative agent in seborrheic dermatitis (a form of dandruff). If the scalp is excessively dry, the dandruff will appear as dry, flaking skin. Seborrheic dermatitis differs from a dry scalp as it includes oiliness, severe flaking with redness, itching and inflammation. Other concerns, such as psoriasis and eczema may also affect the scalp.