Dandruff is a common chronic scalp condition marked by itching and flaking of the skin on your scalp. Although dandruff isn’t contagious and is rarely serious, it can be embarrassing and sometimes difficult to treat.
The good news is that dandruff usually can be controlled. Mild cases of dandruff may need nothing more than daily shampooing with a gentle cleanser. More stubborn cases of dandruff often respond to medicated shampoos.
The exact cause of seborrhea isn’t known, although some researchers believe it can be caused by an overproduction of skin oil (sebum) in the oil glands and hair follicles. A type of yeast, or fungus, called malassezia can grow in the sebum along with bacteria. This may be another factor in the development of seborrhea.
1. 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 dandruff. Flakes from dry skin are generally smaller and less oily than those from other causes of dandruff, and you’ll likely have symptoms and signs of dry skin on other parts of the body, such as your legs and arms.
2. Irritated, oily skin (seborrheic dermatitis). This condition, one of the most frequent causes of dandruff, is marked by red, greasy skin covered with flaky white or yellow scales.
3. Not shampooing often enough. If you don’t regularly wash your hair, oils and skin cells from your scalp can build up, causing dandruff.
4. 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.
5. Eczema. If you have eczema anywhere on your body, it could also be on your scalp, possibly leading to the development of dandruff.
6. Sensitivity to hair care products (contact dermatitis). Sometimes sensitivities to certain ingredients in hair care products or hair dyes, especially paraphenylene diamine (PPD), can cause a red, itchy, scaling scalp. Shampooing too often or using too many styling products also may irritate your scalp, causing dandruff.
7. 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, which then die and fall off in clumps from your hair and scalp, making them appear white and flaky.