Skin cells are produced continuously on the scalp, so flaking—the shedding of dead skin cells—is actually a normal process. With dandruff, however, skin cells are shed at a faster rate than normal. Oil coming from the scalp causes these skin cells to form and clump together, appearing as white flakes.
A number of factors can cause dandruff, including dry skin, sensitivity to hair products, and skin conditions such as psoriasis, seborrheic dermatitis, or eczema. Poor hygiene, lack of sleep,
inadequate shampooing and rinsing of the hair, cold weather, dry environment, or excessive heat can also lead to dandruff.
According to experts at the Mayo Clinic, seborrheic dermatitis is one of the most frequent causes of dandruff. It is marked by red, greasy skin covered with flaky white or yellow scales. This condition may affect not only the scalp, but also other body parts with oil-rich glands, such as eyebrows, the sides of the nose and the backs of ears, breastbone, groin area, and sometimes the armpit. The flakes associated with psoriasis appear like silver scales, which may also be commonly seen on the ears, extremities, palms, and soles.
Another common cause of dandruff is sensitivity to hair care products or contact dermatitis. Sometimes, people who are sensitive to certain ingredients found in hair care products or hair dyes, especially paraphenylene diamine (PPD), can have red, itchy, scaling scalp. Using too many styling products or shampooing the hair too often may also irritate the scalp and cause dandruff.
The growth of yeast called Malassezia can also cause dandruff. It thrives on the scalp of most healthy men and women without causing any trouble. But with uncontrolled growth, it feeds on the oils secreted by the hair follicles. Thus, the scalp can get irritated and lead to the growth of more skin cells. And when they die and fall off, the dead cells clump with the oil in the hair and on the scalp, making them appear white and flaky in one’s hair or clothes. The overgrowth of these yeast cells can be caused by stress, hormonal changes, too much oil on the scalp, or problems in the immune system or other illnesses.
What causes dandruff?