What is it used for?

• Reversing breathing problems (respiratory depression) caused by opioids, for example following surgery, or in people taking high doses to control cancer pain.
• Reversing breathing problems (respiratory depression) in newborn babies whose mothers were given opioids during labour.
• Diagnosing and treating opioid overdosage.

How does it work?

• Naloxone is a type of medicine called an opioid antagonist. It blocks the actions of opioid medicines such as morphine, diamorphine, codeine, pethidine, dextropropoxyphene and methadone.
• Opioids are similar to morphine in structure and are commonly used for their potent painkilling properties. Other illegal opioids such as heroin have similar effects, but are more likely to cause dependence or addiction. High doses of opioids, excessive opioid intake, or abuse or overdose with these drugs can cause reduced lung function and slow, shallow breathing (respiratory depression), which can be life threatening.
• Naloxone is used to treat respiratory depression caused by opioids. Opioids produce their effects by acting on opioid receptors in the brain and nervous system. Naloxone works by blocking these opioid receptors, thus stopping opioids from acting on them. This reverses the effects of the opioid.

Naloxone may be given by injection into a vein, muscle or under the skin, or via a drip into a vein (intravenous infusion).

Use with caution in

• Disease involving the heart and blood vessels (cardiovascular disease)
• People taking medicines that can have side effects on the heart
• People who have received very large doses of opioids or are physically dependent on opioids, as this medicine could result in severe withdrawal symptoms.

Not to be used in

• Allergy to any ingredient.
• This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

Pregnancy and breastfeeding

• The safety of this medicine for use during pregnancy has not been established. It should only be used when considered essential by your doctor. Seek medical advice from your doctor.
• It is not known if this medicine passes into breast milk. It should be used with caution in breastfeeding mothers, and only if the expected benefit to the mother is greater than any possible risk to the nursing infant. Seek medical advice from your doctor.

Side effects

• Nausea and vomiting
• Sweating
• Increased heart rate (tachycardia)
• Hyperventilation
• Increased blood pressure
• Reversal of pain relief if larger than necessary doses are given
• Irregular heart beat (ventricular arrhythmias)
• Low blood pressure (hypotension)
• Accumulation of fluid in the lungs (pulmonary oedema)

The side effects listed above may not include all of the side effects reported by the drug's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

References:

https://harmreduction.org/issues/overdose-prevention/overview/overdose-basics/understanding-naloxone/

https://www.netdoctor.co.uk/medicines/respiratory/a8006/naloxone/

https://www.drugs.ie/resources/naloxone/

https://en.wikipedia.org/wiki/Naloxone

https://www.drugsandalcohol.ie/25499/

https://www.drugabuse.gov/related-topics/opioid-overdose-reversal-naloxone-narcan-evzio