Classification of Exogenous Factors Contributing to the Itch Response

Itch is a common sensation and a component of numerous disease states. Itch can be classified according to its origin and may be modulated by both endogenous and exogenous factors. Recent research has led to a better understanding of the mechanisms of itch, but there are still many areas to be explored. The purpose of this article is to classify the common causes of exogenous itch in humans. To facilitate this, a Medline literature review was conducted using the MeSH search term ‘pruritus’ along with relevant associated subheadings to identify articles dealing with exogenous factors related to itch. Factors relevant to exogenous itch were classified into mechanical, chemical, and environmental components. A better understanding of the various mechanisms of pruritus is critical to effective research into the treatment of itch.