As humans, we constantly form new epidermal cells. When these cells get closer to the surface of the skin, the cell slowly dies and the visual manifestation of this is flakes. This is a normal process that happens to everyone all the time. In some people, the rate of epidermal cell development is accelerated.
Dandruff and seborrheic dermatitis are conditions involving the increased rate of shedding of the topmost layer of the skin called the epidermis. The most common form of seborrheic dermatitis which only involves the scalp is dandruff. Dandruff can be asymptomatic or cause mild flaking and itching. The best way to treat dandruff is to use over the counter (OTC) medicated shampoos like pyrithione zinc, ketoconazole, or selenium sulfide. These meds can be left on for a few minutes and then rinsed off. They can be used daily or 2-3 times per week until the symptoms are gone. Recurrence can be prevented by continuing to use one of these products 2-3 times per week.