Dandruff can have several causes, including:
- Dry skin. Simple dry skin — the kind you get during winter when the air is cold and rooms are overheated — is the most common cause of itchy, flaking skin. Flakes from dry skin are generally smaller and less oily than those from other causes of dandruff.
- Irritated, oily skin (seborrheic dermatitis). This condition, a frequent cause of dandruff, is marked by red, greasy skin covered with flaky white or yellow scales. Seborrheic dermatitis affects not only your scalp but also other areas rich in oil glands, such as your eyebrows, the sides of your nose and the backs of your ears, your breastbone, your groin area, and sometimes your armpits.
- Not shampooing often enough. If you don’t regularly wash your hair, oils and skin cells from your scalp can build up, causing dandruff.
- Psoriasis. This skin disorder causes an accumulation of dead skin cells that form thick silvery scales. Psoriasis commonly occurs on your knees, elbows and trunk, but it can also affect your scalp.
- Eczema. If you have eczema on your scalp, it’s possible you could develop dandruff.
- Sensitivity to hair care products (contact dermatitis). Sometimes sensitivities to certain hair care products or hair dyes can cause a red, itchy, scaling scalp. Shampooing too often or using too many styling products also may irritate your scalp, causing dandruff.
- A yeast-like fungus (malassezia). Malassezia lives on the scalps of most healthy adults without causing problems. But sometimes it grows out of control, feeding on the oils secreted by your hair follicles. This can irritate the skin on your scalp and cause more skin cells to grow. The extra skin cells die and fall off, clumping together with oil from your hair and scalp, making them appear white, flaky and visible in your hair or on your clothes.Exactly what causes an overgrowth of malassezia isn’t known, although having too much oil on your scalp; changes in your hormones; stress; illness; neurological disorders, such as Parkinson’s disease; a suppressed immune system; not shampooing often enough; and extra sensitivity to the malassezia fungus may contribute to the development of dandruff.
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