The excessive flaking of dead skin that forms on the scalp is referred to as dandruff. Though it is normal for dead cells to die and flake off, there is unusually rapid cell turnover in some people. The dead skin cells are replaced every two weeks in some people in a normal cycle once a month. When this happens, large clumps of small, unsightly white, grayish patches known as dandruff loosen and fall off.

Though there are many causes for dandruff, the most common is probably the fungus Malassezia furfur. Commonly found in areas such as the scalp, face and upper part of the body, this fungus disturbs the natural renewal of cells, thereby causing dandruff and itching. Other factors include overactive sebaceous glands, food allergies, excessive perspiration, usage of alkaline soaps, yeast infections, seasonal changes, exposure to UV light, dust, cold and dryness in the atmosphere, harsh shampoos, dyes, poor nutrition, and, above all, stress.

To treat dandruff, one needs to regularly wash one's hair with an anti-dandruff shampoo. An anti-dandruff shampoo removes the dead skin before it can build up. Most of the anti- dandruff ingredients are either acids, which break down the oils on the scalp, or fungicides, which kill the Malassezia fungus, ensuring better hair hygiene and health.

There are various shampoo brands and the treatments specifically available for treating dandruff. The definitive standard of treatment is a tar shampoo that contains salicylic acid. Shampoos like Head and Shoulders, which contain Zinc Pyrithione; Selsun Blue, which contains Selenium Sulfide; Neutrogena and T-Gel, which contain coal tar; and, shampoos that contain Ketoconazole, such as Nizoral, are also effective in controlling and treating dandruff.