the analgesic effect of opioids is due to their
Opioid Opioids are substances that act on opioid receptors to produce morphine-like effects.[2] Medically they are primarily used for pain relief, including anesthesia.[3] Other medical uses include suppression of diarrhea, treating opioid use disorder, reversing opioid overdose, suppressing cough, and suppressing opioid induced constipation.[3] Extremely potent opioids such as carfentanil are only approved for veterinary use.[4] Opioids are also frequently used non-medically for their euphoric effects or to prevent withdrawal.[5]
International Association for the Study of Pain The IASP definition of pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage"[7] is derived from a 1964 definition by Harold Merskey,[8] and it was first published in 1979 by IASP in PAIN, number 6, page 250.