naloxone hydrochloride at a glance
Medicine class
Opioid antagonist and antidote
Main role
Reverses opioid-related breathing and central nervous system depression
Administration
Given by intravenous or intramuscular injection, or intravenous infusion, depending on the clinical setting
Important limitation
Its effect may wear off before the opioid, so continued observation is essential
What is naloxone hydrochloride used for?
The selected injection is licensed for:
Complete or partial reversal of breathing and central nervous system depression caused by natural or synthetic opioids.
Helping diagnose suspected acute opioid overdose or intoxication.
Reversing opioid-related breathing and central nervous system depression in a newborn whose mother received opioids.
How does naloxone hydrochloride work?
Naloxone competes with opioids at opioid receptors and displaces them. This can restore breathing and consciousness, but it does not reverse unconsciousness caused solely by alcohol, sedatives or other non-opioid substances.
naloxone hydrochloride preparations and strengths
Injection
Route: Parenteral
Strengths: 400 micrograms/mL, 1 mg/mL
How to take naloxone hydrochloride
This injection is administered by a trained healthcare professional into a vein or muscle, or as an infusion into a vein. The solution should be clear, colourless and free from visible particles; each ampoule is for single use.
Food does not affect this injected treatment.
People supplied with take-home naloxone should follow their product-specific training and still call 999 whenever it is used.
naloxone hydrochloride side effects
Common or expected effects
- Nausea or vomiting
- Dizziness or headache
- Fast heartbeat
- Raised or lowered blood pressure
- Return of pain after reversal of postoperative opioid effects
Get urgent medical advice
- Severe allergic reaction, including facial swelling, breathing difficulty or collapse
- Serious abnormal heart rhythm or cardiac arrest
- Fluid on the lungs or severe breathing difficulty
- Seizure
- Severe, abrupt opioid withdrawal with marked agitation, sweating, vomiting or cardiovascular effects
naloxone hydrochloride in pregnancy
Human pregnancy information is limited. The selected product should be used only when clearly necessary after clinical assessment; it crosses the placenta and may precipitate withdrawal in an opioid-dependent fetus or newborn. Pregnancy should always be disclosed to the treating team.
naloxone hydrochloride while breastfeeding
It is unknown whether naloxone passes into breast milk. The selected product advises avoiding breastfeeding for 24 hours after treatment; obtain advice from the treating clinician or a breastfeeding medicines specialist about expressing milk and restarting.
naloxone hydrochloride interactions
The clinical response depends particularly on the opioid involved and any other substances taken.
Opioids and opioid agonists
Naloxone reverses their effects and can trigger acute withdrawal in someone who is physically dependent.
Buprenorphine
Reversal of respiratory depression may be incomplete, so respiratory support and close monitoring may still be required.
Alcohol or sedatives
Naloxone does not directly reverse their effects, and recovery may be slower in mixed intoxication.
Common questions about naloxone hydrochloride
Answers are fully visible for fast scanning and source review.
What does naloxone hydrochloride reverse?
It reverses central nervous system and breathing depression caused by opioids, including heroin and opioid medicines.
Does naloxone hydrochloride work for alcohol or benzodiazepine overdose?
No. It blocks opioid effects but does not directly reverse alcohol, benzodiazepines or other non-opioid depressants.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.