• Naloxone is a pure opioid antagonist that exerts its effect by competitive inhibition at the opioid receptor sites. It prevents or reverses the effects of opioids, including respiratory depression, sedation and hypotension. In the absence of opioids, it exhibits essentially no pharmacological activity.

Pharmacology Review

  • Reversal of respiratory depression in a suspected narcotic overdose.
  • Hypersensitivity to Naloxone
Precautions / Notes
  • Polypharmacy overdose.
  • Half-life of naloxone is < 1 hour; repeat doses may be required to maintain effect with longer acting opioids and those with active metabolites (e.g. methadone, diphenoxylate, codeine). Observe patients who respond to naloxone for 2-3 hours after administration for signs of re-narcotisation.
  • Response to Naloxone is rapid; reconsider diagnosis if there is a failure to respond to 2 mg Naloxone.
  • Patients may be aggressive post Naloxone and administration due to hypoxia. Scene safety and personal safety are paramount.
  • IN naloxone is only for EMT scope only, unless no other routes available. For more information, see here.


  • IM/IV/IO:
    • 0.4-0.8 mg (400-800 microg) repeat dose every 2 minutes as required, titrated to clinical response to a maximum of 10 mg.
  • IN: 
    • One spray (1.8 mg) of Nyxoid® into nostril.
    • Repeat at 2 minutes in opposite nostril if the patient does not respond.


  • IM/IV/IO:
    • 0.01 mg/kg (10 microg/kg, maximum dose 0.4 mg (400 microg), repeat every 2-3 minutes minutes as required, titrated to clinical response.
    • If high suspicion of overdose, a 0.1 mg/kg (100 microg/kg) dose (maximum 2 mg) may be given following a lack of response to initial dose.
  • IN: 
    • One spray (1.8mg) of Nyxoid® into nostril.
    • Repeat dose after 2 minutes if patient does not respond.
Special Considerations

Withdrawal symptoms such as:

  • Aggression
  • Agitation
  • Nausea/vomiting
  • Dilated pupils and lacrimation

Take-Home-Naloxone (THN)

  • Total dispensed amount (3.6 mg - 2x 1.8 mg Sprays + Box with Instructions)
  • For patients that have required Naloxone, every attempt should be made to convince the 'at risk' patient to be transported to a healthcare facility.
  • Where attempts prove futile, IN Naloxone - Nyxoid® could be left with the patient. This is to avoid the risk of opioid related respiratory depression due to the short half-life of Naloxone.
  • In such circumstances please ensure to document leaving Nyxoid® with the person or a responsible other person in the PnT / ePCR.
  • Due to our SASA requirements, clinicians cannot supply scheduled medicines to persons who are not St John WA patients.


0.4 mg (400 microg) in 1 mL vial


Each device of Nyxoid nasal spray contains one spray (100 µL). Each dose of 100 µL contains 1.8 mg naloxone.
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