An Excerpt from the Introduction to
Principles of Analgesic Use
in the Treatment of Acute Pain and Cancer Pain

Fifth Edition

I. Introduction and Definitions

Pain has been described as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage," or described in terms of such damage. While it is unquestionably a sensation in part or parts of the body, it is always unpleasant and, therefore, an emotional experience.

Pain is always subjective. Objective observations such as grimacing, limping, or tyachycardia may be helpful in assessing patients, but these signs are often absent in patients with chronic pain caused by structural lesions. No neurophysiological or laboratory test can measure pain. The clinician must accept the patient's report of pain.

The most common reason for unrelieved pain in American healthcare systems is the failure of staff to routinely assess pain and pain relief. Many patients silently tolerate unrelieved pain, especially if they are not specifically asked about it.

Because pain is identified principally through self-reports, patients who have difficulty communicating with clinicians are at particular risk of undertreatment. These include infants and children, people who speak a language different than their clinician's  language, those whose cultural backgrounds differ greatly from their clinicians', some elderly individuals, and those who are developmentally delayed, cognitively impaired, or severly emotionally disturbed.