Dandruff--also known as seborrhea or seborrheic dermatitis--is a common condition that affects the scalp. Popular telltale signs of dandruff include itchy scalp and white or yellow flakes in the hair and on clothing. If another condition is causing dandruff, treating that condition may help cure or improve your condition.
Dry Skin
Dandruff is often caused by a simple case of dry skin. Dry skin is common in the winter or when you are in a room that is overheated. Flakes from dandruff caused by dry skin tend to be smaller and less oily.
Oily Skin
Oily skin--or seborrheic dermatitis--is another common cause of drandruff. Seborrheic dermatitis causes the skin of the scalp to become red and greasy, with white or yellow scales that flake.
Lifestyle
Oil can build up and cause dandruff if you do not wash your hair often enough. The reverse is also true--shampooing too often can irritate and dry out your scalp. Dandruff can also occur if your scalp is sensitive to certain chemicals in hair care products or dyes. A diet that lacks zinc, vitamin B and certain fats can increase the risk of developing dandruff. Stress could also contribute to the condition.
Psoriasis
Psoriasis is a skin condition in which dead skin cells form thick silvery scales. Psoriasis is often found on the knees, elbows and trunk in addition to the scalp. Eczema is another skin condition that can cause dandruff.
Malassezia
The Mayo Clinic states that malassezia is a yeast-like fungus that naturally lives on the scalp. This fungus often does not cause problems; however, malassezia can grow out of control, which causes more skin cells to grow and die off. The cause of malassezia overgrowth is not known. The Mayo Clinic suggests that hormone changes, stress, illness, neurological disorders, a suppressed immune system, not shampooing often enough and being sensitive to the malassezia fungus--all common causes of dandruff--may contribute.
Neurological Diseases
According to the U.S. National Library of Medicine, neurological conditions including Parkinson's disease, head injury and stroke may be associated with seborrheic dermatitis.
Impaired Immune System
Human immunodeficiency virus (HIV) and patients who are receiving chemotherapy are also susceptible to dandruff.
