What causes dandruff?

The cause of dandruff is usually a fungus called Pityrosporum ovale (P. ovale). While the name may sound intimidating, P. ovale is really a common and naturally occurring yeast-like organism found on the scalp and other parts of human skin.

In small numbers, this fungus causes no harmful effects. However, when triggered by certain changes in climate, hormonal or stress levels, the P.ovale fungus tends to concentrate on the scalp for a very good reason - the scalp is where the largest concentration of sebaceous glands can be found. These are the glands that produce your skin's natural oil, called sebum, which contributes to the growth of the P. ovale fungus.

As the fungus grows in size and numbers, it causes increased skin irritation and accelerates the rate at which old skin cells are shed and replaced. The result: dandruff.

Dandruff is usually limited to the scalp and typical symptoms include white or gray flakes and mild skin irritation.

Severe dandruff, or seborrheic dermatitis (seborrhea), is most often found on the scalp but can also appear in the area around the eyebrows, cheeks, behind ears or on the chest. Seborrhea is usually recognized by the appearance of oily yellow flakes and moist red patches on the scalp.