Pruritus shares many features and pathways with pain but is a separate sensation from pain with its own precipitants and blockers. For example, loss of touch sensitivity dose not stop itching(e.g.,tabes dorsalis), however, in an area insensitive to pain, itching does not occur(e.g.,syringomyelia, leprosy). Unlike pain, specific receptors for pruritus and clear pathways for its transmission have not yet been identified. Until now, it has not been possible to isolate a universal mediator to explain pruritus. There are a wide variety of chemical substances known to be the mediators of pruritus. Well known among these is histamine, but in most cases of generalized pruritus is is not the main cases of generalized pruritus it is not the main mediatro. Our lack of understanding of the mechanism of pruritus is reflected by the inefficiency of many of the available antipruritic agents.

I herein present an update review of the pathophysiology of pruritus, possible causes of generalized pruritus, the differential diagnosis and the basic principles of treatment.