Opioids and Overdose

  • Opioids are drugs related to opium poppies like heroin, morphine, fentanyl, codeine, methadone, and oxycodone.
  • Opioid overdose occurs when an individual stops breathing due to the effects of the drugs.
  • Naloxone (Narcan) reverses the effects of opioids, allowing an individual experiencing an opioid overdose to breathe normally.
  • Naloxone does not work for overdoses of benzodiazepines, cocaine, methamphetamine, or alcohol.
  • In a mixed overdose (opioids and benzos, heroin and cocaine, etc), naloxone will help reverse the effects of the opioids, but will not have any effect on other substances present.

Naloxone (Narcan)

  • CLASS:
    • Opioid Antagonist
  • INDICATIONS:
    • opioid overdose, altered mental status of unknown origin
  • CONTRAINDICATIONS:
    • no absolute contraindications
  • PRECAUTIONS:
    • Naloxone has a duration of action which is shorter than most opioids. "Re-overdose" may occur after 30-90 minutes.
    • Reversal of overdose in a person who is dependent on opioids may produce signs and symptoms of withdrawl.
    • Reversal of overdose may un-mask complications of underlying medical conditions, e.g. cardiac arrythmias.
    • Reversal of overdose in pregnancy may cause withdrawl symptoms in the fetus. The patient should be evaluated in a hospital with OB capabilities.
    • Anaphylaxis is a theoretical risk.
    Possible dependency (including newborns). It also has a half-life that is shorter than that of most narcotics; hence the patient may return to the overdose state.
  • ONSET:
    • 3-5 minutes IN/IM (IV is faster)
  • DURATION OF ACTION:
    • 30-90 minutes
  • DOSAGE/ROUTE:
    • Initial adult dose: 0.4 mg IV/IM or 2 mg IN, repeat every 2 minutes up to a total dose of 10 mg or adequate respiratory effort
    • Initial pediatric dose: 0.1 mg/kg IV/IM or 2 mg IN, repeat every 2 minutes up to a total dose of 10 mg or adequate respiratory effort
      • (pediatric patients may require larger doses of naloxone than adults due to the relatively higher opioid dose per kg of body weight)

Naloxone Mechanism


Opioids bind to opioid receptors to cause their effects. They can help relieve pain, but also cause sedation and hypoventilation.


Opioid receptors in the body have a higher affinity for naloxone than most opioids. Naloxone "pushes" opioids off the receptors, thereby reversing their effects, and blocks futher binding.