Understanding Dandruff - the Basics

What Is Dandruff?

Dandruff - those dry, white flakes of skin you constantly find yourself brushing off your collar or shoulders - typically poses no health risk whatsoever. But it can be a source of embarrassment, and the itchiness that may come with it is a genuine nuisance. Many people incorrectly assume that the problem has something to do with hygiene and how often you wash your hair. Although it's true that shampooing infrequently can aggravate an existing case of dandruff, it will not bring one on. What actually lies behind dandruff is a simple difference between people in a natural process we all undergo every day: shedding skin cells. The difference is that some of us shed more than others.

Skin cells that grow and die off too fast are the cause of dandruff, but doctors do not know why this happens.  One possible cause is a fat-eating fungus called Pityrosporum ovale, which is present in most people but to excess in dandruff sufferers.  This fungus lives on the scalp of most healthy adults without causing any problems.  Sometimes its numbers grow out of control and it feeds on the oil made by hair follicles.  This causes irritation, which leads to an increase in skin cell shedding. 

This abundance of fungus in some can be due use of alkaline soaps, infrequent shampooing, hormonal fluctuations, certain neurological disorders like Parkinson's, a weakened immune system, and stress. Even the season of the year can contribute to the problem: Cold, dry winters are notorious for bringing on dandruff or making it worse.

If dandruff flakes are greasy and yellow, the probable cause is the skin condition known as seborrheic dermatitis; seborrhea is usually associated with redness as well. Dry, thick lesions consisting of large, silvery scales may be traced to the less-common psoriasis of the scalp. These scaly conditions become a hazard only if you scratch to the point of causing breaks in the skin, which can place you at greater risk for infections, particularly from staph and strep bacteria.