All
humans shed skin all the time. If it is shed in visible quantities
from the scalp it is known as “dandruff”. About 50% of individuals have dandruff. The main cause, in the majority, is an extremely common condition, pityriasis capitis, which is associated with the presence of the yeast, pityrosporum. Dandruff is usually shed but, sometimes, particularly in the condition seborrhoeic dermatitis (aka. seborrhoic eczema), it can build up into crusty layers. The same yeast is implicated in seborrhoeic dermatitis but, in this condition, there are pathological changes in the skin and an abnormal build up of sebum (skin oil). Seborrhoeic dermatitis is also marked by the presence of a rash on the face, particularly round the mouth, eyes and sides of the nose. Simple dandruff is a condition in which the social context is important. It is more troublesome, for example, to the black-suited waiter than the sheep farmer.
Various shampoos are available that claim to remove dandruff and can be tried in turn. Medically the commonest used products have contained tar products or selenium sulphide. More recently, however, preparations have appeared that, at least temporarily, get rid of the pityrosporum yeast. These products can be obtained without prescription. If the dandruff is associated with a build-up of scaling, or a facial rash, it is worth consulting the doctor. In these circumstances it is most likely to be seborrhoeic dermatitis but it could be one of the chronic skin conditions such as psoriasis. |
