Blocks; it does not replace opioids
Naltrexone is different from methadone and buprenorphine. It does not activate opioid receptors or prevent opioid withdrawal symptoms.
Start here
What is naltrexone?
Naltrexone is a prescription medicine that blocks opioid receptors. It is used in treatment for alcohol use disorder and, after opioid withdrawal, opioid use disorder. It is not an opioid, a detox medicine, or an overdose treatment.
The short version
Naltrexone sits on opioid receptors without activating them. For alcohol use disorder, that can reduce some of alcohol's rewarding pull and lower heavy-drinking outcomes for some people. For opioid use disorder, it can block opioid effects after a person has completed withdrawal.
The timing matters. Starting naltrexone while opioids are still present can trigger sudden, severe withdrawal. It also changes overdose risk during and after treatment. That is why the first useful conversation is not simply ‘Can I get a prescription?’ but ‘Is naltrexone suitable, and is it safe for me to start now?’
What it does—and what it does not do
These distinctions prevent many of the most dangerous misunderstandings.
Can support alcohol treatment
It may reduce heavy drinking or help prevent return to drinking for some people. It does not stop intoxication, impaired judgement, or alcohol poisoning.
Requires an opioid-free interval
Recent opioid exposure—including some pain, cough, and diarrhoea medicines—needs to be reviewed before the first dose or injection.
Works best as part of care
A medicine can support a goal, but it does not replace follow-up, behavioural support, overdose planning, or treatment of other health needs.
Oral naltrexone and extended-release Vivitrol are not interchangeable
| Oral naltrexone | Extended-release Vivitrol | |
|---|---|---|
| Form | Commonly a 50 mg tablet | 380 mg suspension for injection |
| Routine | Taken on the schedule set by the prescriber | Given every four weeks or once monthly under the US label |
| Who gives it | Usually taken by the patient | Healthcare professional only |
| Practical trade-off | No injection appointment, but each scheduled dose can be missed | No daily tablet, but requires a visit and injection-site monitoring |
| Availability | Verified in several—not all—countries covered here | Strongest current access evidence on this site is from the United States |
Useful orientation
The exact label and treatment plan still depend on the product and country.
- Alcohol use disorder
- AUD
- Opioid use disorder
- OUD
- Common oral tablet strength
- 50 mg
- US Vivitrol presentation
- 380 mg
Oral and extended-release forms are used in treatment, depending on jurisdiction
Treatment begins only after an adequate opioid-free interval
A product strength, not a personal dosing recommendation
A healthcare-provider-administered monthly injection
Questions people often ask
Is naltrexone addictive?
Naltrexone does not produce opioid euphoria or physical dependence. Its important risks are different: precipitated withdrawal if it is started too soon, attempts to overcome the blockade, and overdose vulnerability after missed or stopped treatment.
Will I still feel alcohol?
Yes. Naltrexone does not prevent intoxication, poor coordination, impaired decisions, sedation, or alcohol poisoning. Some people experience less reward or craving; response varies.
Can I take opioid pain relief while using it?
Opioid pain medicines may work poorly or differently, and trying to override the blockade is dangerous. Tell every treating professional that you use naltrexone, especially before surgery, dental work, or emergency pain care.
What about the liver?
Current labels include hepatitis and liver-dysfunction warnings. A clinician can interpret symptoms, history, other medicines, alcohol exposure, and tests together; a single web rule cannot decide suitability.
Is Contrave the same treatment?
No. Contrave combines naltrexone with bupropion for chronic weight management. It has a different dose, indication, label, and safety profile.
How long does treatment last?
There is no duration that fits everyone. A useful plan names the goal, follow-up date, adherence support, safety plan, and what would prompt a change.
Sources
- Current US oral naltrexone prescribing information (DailyMed)
Indications, contraindications, opioid blockade, and safety warnings.
- SAMHSA: medication for alcohol use disorder
Clinical guide covering oral and extended-release naltrexone alongside other alcohol-treatment medicines.
Turn the overview into a useful conversation
Next, check the safety guide and your country page. Take the exact product name and a complete medication list to the appointment.
Content and sources reviewed