What Causes Dandruff?

After numerous years of speculation on the causes of dandruff, in 2004, scientists finally determined the specific cause, at least of some types. Most of the itchiness and skin flaking, when other skin conditions like eczema are not present, is directly related to the presence of fungi or yeast, to the susceptibility of individuals, and to the presence of oil on the scalp. We all have a certain amount of the Malassezia fungus on our scalps, so dandruff is not due alone to this fungus. Whether or not we get large skin flakes tends to depend on the other related factors like presence of oil on the scalp, and how likely we are to negatively respond to the fungus, which varies among individuals.

Malassezia is a fungus that eats lipids, or oils or fats. Thus, theoretically, people with more naturally oily scalps would be prone to having more healthy populations of the fungus on their heads. The digestion process of Malassezia, and subsequent excretion by the yeast, can cause the skin to mature and flake rapidly, in much larger and more visible clumps than is normal. We all lose skin cells, all the time, but this is mostly not noticeable. Dandruff skin flakes tend to be held together by oil, and are lost in greater number and more quickly, causing the noticeable “flakes” of skin.

Information on the causes of dandruff, at least as scientists now view it, is further supported by looking at which shampoos are most effective. In general, shampoos that contain ketoconazole, an anti-fungal agent, tend to be most effective in reducing or eliminating the condition. In some rare cases though, people may have allergic dermatitis, and have more flaking instead of less as a result of shampoos with ketoconazole. So while the yeast Malassezia is responsible for many cases of “flakes” it isn’t responsible for all of them.

Under certain circumstances, other conditions may cause excessive skin flaking. Eczema, allergies to hair products, psoriasis, and sebhorreic dermatitis may also cause the condition. When dandruff shampoos don’t seem to work and the condition worsens or does not improve, it’s a good idea to see a physician to determine the cause. Further, some people confuse dandruff with head lice, since lice eggs or nits can look a little bit like skin flakes, though they are usually rounder and cleave more closely to the hair follicles.

In any case, when you can’t resolve dandruff with the many shampoos available, consider seeing a good dermatologist for diagnosis. There are a number of treatments available for flaking skin not based on fungal overload. These can help eliminate the issue for many people.