Naltrexone
Naltrexone blocks opioid receptors and is used alongside behavioural and clinical support for alcohol or opioid dependence. It is also an ingredient in a specific combination medicine for weight management.
Key points
- Starting naltrexone while opioids are still in the body can trigger sudden, severe withdrawal.
- It blocks opioid pain medicines and changes overdose risk, so all treating clinicians need to know it is being used.
- Breathing difficulty, severe withdrawal, collapse or suspected opioid overdose needs emergency care.
Listings are for comparison only. Suitability and supply depend on clinician and pharmacy checks, stock, destination rules and prescription requirements.
What Naltrexone is used for
Naltrexone may support treatment for alcohol dependence or opioid dependence after appropriate assessment. In a specific combination, it may be used as part of a broader weight-management plan.
How it works
Naltrexone blocks opioid receptors. This prevents opioids from producing their usual effects; it does not itself treat acute withdrawal and does not make opioid use safe.
Important safety checks
Current or recent opioid use (including some pain, cough and diarrhoea medicines) must be reviewed before treatment. Liver health, pregnancy and plans for surgery or emergency pain relief also matter. Trying to overcome the opioid blockade can cause fatal overdose, and opioid tolerance may be lower after naltrexone is stopped.
When to seek urgent care
Call emergency services for slow or stopped breathing, blue-grey lips or skin, inability to wake, collapse or suspected overdose. Seek urgent assessment for severe precipitated withdrawal, yellow skin or eyes, severe abdominal pain or a serious allergic reaction.