Itch is an unpleasant sensory experience.

Abstract

The International Association for the Study of Pain (IASP) defines pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. In a note attached to that definition (http://www.iasppain.org.terms-p.html#Pain), the IASP further states that “unpleasant, abnormal experiences (dysesthesias) may also be pain but are not necessarily so because, subjectively, they may not have the usual sensory qualities of pain.” While everyone would agree that itch does not have the sensory qualities of pain, for those patients with intense, unrelenting itch the sensory and emotional experiences can be as unpleasant as pain. Clinical colleagues have told me anecdotal stories of patients with itch due to spinal intrathecal opioid administration who indicated a desire to stop the opioid administration because they would rather experience the pain than the itch. It is difficult to define the number of patients whose quality of life is adversely impacted by uncontrolled itch. However, as suggested in Table 1 by a partial list of dermatologic and systemic diseases that are associated with itch, it is likely that the number is quite high. Because itch does cause unpleasant sensory and emotional experiences in a large number of humans, it seems appropriate to focus more attention on efforts to understand the physiology of itch. In addition, because most current treatments for itch are quite inadequate, it also seems appropriate to attempt to develop better treatment modalities for patients suffering with intense, unrelenting itch. This topic is also of potential interest