Altered level of consciousness, respiratory depression (typically a very slow respiratory rate with a maintained tidal volume), miosis, hypothermia.
Treatment:
Naloxone 0.2-0.4 mg IV and repeat every 2-3 minutes. May need up to 10 mg (maximum dose). If no response after 10 mg then question diagnosis.
Monitoring essential as the effect of naloxone can wear off before that of the opioid (the t½ of naloxone is ~1 hour which is shorter than most opioids). Repeat doses are often required. The patient should be observed for evidence of returning narcosis (especially for long acting narcotics like methadone). An infusion of naloxone 0.4 mg per hour may be required.
Naloxone will reverse all the actions of the narcotic including analgesia.
May bring about an agitated 'withdrawal' state in an addict so reverse in small aliquots to achieve spontaneous respiration without full reversal.