Pain, opioid tolerance and sensitisation to nociception in the neonate.

Pain is commonplace in newborn infants. Opioid analgesics have become increasingly used to reduce different types of pain in neonates, including pain from surgery, medical procedures and chronic conditions. Adverse effects of opioids include respiratory depression, hypotension and tolerance. These adverse effects can be minimised by utilising specific administration techniques and constant monitoring. Recent studies have demonstrated that untreated pain can have long-term effects on infant pain behaviours months beyond the events, thus, opioid analgesics may have a beneficial role that extends beyond the immediate painful event(s).