Acute pain: Pain that is limited in duration and is associated with a specific cause. (Chapter 11.2)

Addiction: A term used in many countries to describe severe problems related to compulsive and habitual use of substances. However, it is no longer a diagnosis by the American Psychiatric Association because of its potentially negative connotation.^[1] (Chapter 11.2)

Adjuvant: Medication that is not classified as an analgesic but has been found in clinical practice to have either an independent analgesic effect or additive analgesic properties when administered with opioids. (Chapter 11.4)

Analgesics: Medications used to relieve pain. (Chapter 11.4)

Chronic pain: Pain that is ongoing and persistent for longer than six months. (Chapter 11.2)

Misuse: Taking prescription pain medications in a manner or dose other than prescribed; taking someone else’s prescription, even if for a medical complaint such as pain; or taking a medication to feel euphoria (i.e., to get high). (Chapter 11.2)

Nociceptor: A sensory receptor for painful stimuli. (Chapter 11.2)

Opioid intoxication: Significant behavioral or psychological changes (e.g., apathy, dysphoria, psychomotor agitation or retardation, or impaired judgment) that occur during or shortly after opioid use. Symptoms of opioid intoxication include drowsiness or coma, slurred speech, or impairment in attention or memory.^[2] (Chapter 11.2)

Overdose: The biological response of the human body when too much of a substance is ingested. (Chapter 11.2)

Pain: An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. (Chapter 11.2)

Patient-Controlled Analgesia (PCA): A method of pain management that allows hospitalized clients with severe pain to safely self-administer opioid medications using a programmed pump according to their level of discomfort. (Chapter 11.4)

Physical dependence: Withdrawal symptoms that occur when chronic pain medication is suddenly reduced or stopped because of physiological adaptations that occur from chronic exposure to the medication. (Chapter 11.2)

Referred pain: Pain perceived at a location other than the site of the painful stimulus. For example, pain from retained gas in the colon can cause pain to be perceived in the shoulder. (Chapter 11.2)

Substance use disorder: An illness caused by repeated misuse of substances (including opioids). When taken in excess, these substances have a common effect of directly activating the brain reward system and producing such an intense activation of the reward system that normal life activities may be neglected.^[3] (Chapter 11.2)

Tolerance: A diminished effect with continued use of the same amount of an opioid, or a need for increased amounts of opioids to achieve the desired effect or intoxication. (Chapter 11.2)

Withdrawal: Symptoms that cause significant distress after stopping or reducing the use of substances (including opioids), with symptoms such as dysphoric mood, nausea, vomiting, muscle aches, rhinorrhea or lacrimation, pupillary dilation, piloerection, sweating, diarrhea, yawning, fever, or insomnia. (Chapter 11.2)