The short answer
Naltrexone is a prescription medicine that blocks opioid receptors in the brain, which dulls the reward from alcohol and can reduce cravings. Trials show it lowers the risk of returning to heavy drinking, and Australian guidelines recommend it for moderate to severe alcohol use disorder. It's PBS-subsidised for alcohol dependence, and the PBS now allows a goal of controlled drinking as well as abstinence. It isn't suitable if you use or may need opioids, and it works best alongside regular support.
On this page
What is naltrexone?
Naltrexone is a prescription-only (Schedule 4) medicine from a group called opioid antagonists [1]. In Australia it's used for two things: alcohol dependence, and opioid dependence once a person has fully withdrawn from opioids [1]. For alcohol, it's taken as a tablet and is subsidised on the PBS [2].
The Australian Guidelines for the Treatment of Alcohol Problems recommend naltrexone to prevent relapse to heavy drinking, with the highest grade of evidence (Level A) [3]. Despite that, naltrexone is prescribed for fewer than 3% of Australians with alcohol use disorder, even though many patients are interested in medication options [4].
How does naltrexone work for alcohol?
Naltrexone blocks mu-opioid receptors in the brain. According to the Australian guidelines, this lowers levels of dopamine, the brain's main reward chemical, which in turn reduces how much people drink [2]. The Alcohol and Drug Foundation describes it as reducing both the rewarding effects of alcohol and cravings [1].
It doesn't work by making you sick when you drink. Naltrexone doesn't change how your body absorbs or breaks down alcohol, although some people notice nausea if they drink while taking it [2]. You'll still be impaired if you drink, so the usual driving rules apply [1].
Does naltrexone work?
Yes, with modest but meaningful effects. The key evidence:
- Cochrane review (50 trials, 7,793 people). Naltrexone reduced the risk of heavy drinking to 83% of the risk on placebo, cut drinking days by about 4%, and reduced the amount people drank [5]. Its effect on returning to any drinking just missed statistical significance [5].
- 2023 JAMA meta-analysis (118 trials, 20,976 people). For every 11 people treated with naltrexone, one fewer returned to heavy drinking. For every 18 treated, one fewer returned to any drinking [6].
Australian GP experts point out that these numbers only capture the effect of the drug itself, so they understate the overall benefit of treatment [4]. Both the Alcohol and Drug Foundation and the Australian guidelines note that naltrexone may be better at preventing heavy drinking than at producing complete abstinence [1][2]. It's more likely to help when you have good support and a strong reason to change [1].
In the large US COMBINE trial, people who took naltrexone with "medical management" (regular, structured check-ins with a health professional) had better drinking outcomes than those on placebo [7].
Is naltrexone on the PBS?
Yes. Naltrexone 50 mg tablets are PBS-listed for alcohol dependence as a streamlined authority [8]. As at the November 2026 PBS Schedule, the restriction reads: "The treatment must be part of a comprehensive treatment program with the goal of maintaining abstinence/controlled consumption" [8].
That "controlled consumption" wording matters. Recent PBS changes expanded naltrexone's use to include the goal of drinking less, not just stopping altogether [4]. Australian GP guidance also notes that regular GP review satisfies the comprehensive treatment program requirement, and that someone who declines counselling can still be eligible [4].
Do you have to stop drinking before starting naltrexone?
Not necessarily. Recent guidance in the Australian Journal of General Practice says abstinence isn't required before or during treatment, and naltrexone may suit people who want to cut down gradually [4]. Some doctors also use a targeted approach, where naltrexone is taken ahead of situations where drinking is expected [4]. That's a plan to work out with your GP, not something to try on your own.
If you're stopping completely, the Australian guidelines suggest starting naltrexone as soon as possible after any withdrawal has finished, usually 3 to 7 days after your last drink [2]. The guidelines also note that sustained abstinence is the best outcome for most people with alcohol dependence [3], so your goal is worth talking through.
A safety note: if you drink heavily every day, cutting down or stopping suddenly can bring on withdrawal, and in some people withdrawal can cause seizures [4]. Most withdrawal can be managed safely outside hospital with the right support [3], so talk to a doctor first. If someone has a seizure or becomes severely confused, call 000.
Who shouldn't take naltrexone?
| Situation | Why it matters |
|---|---|
| Taking opioids, or likely to need opioid pain relief | Naltrexone blocks opioid pain relief and can trigger sudden withdrawal [1][2]. The Australian guidelines say it's contraindicated with current or recent opioid use [2]. |
| Recently stopped opioids | People coming off opioids usually need to be opioid-free for 7 to 10 days first [1]. |
| Planned surgery | Your doctor will usually stop naltrexone a few days before any procedure where opioid pain relief might be needed [2]. |
| Acute hepatitis or severe liver failure | Naltrexone is contraindicated in these conditions [2]. |
| Pregnant or breastfeeding | Safety data are limited, so it's an individual decision with your doctor [1][4]. |
Make sure your doctors, dentist and pharmacist know you take naltrexone, especially if opioid pain relief might be needed [1].
Overdose risk after stopping. Naltrexone lowers your tolerance to opioids. If you use opioids during or after a course of naltrexone, the risk of overdose is serious [1].
What about the liver? Doctors check liver function before starting and during treatment [2]. Australian GP guidance says early concerns about liver damage came from high-dose studies in the 1980s, and the largest study in people with cirrhosis found no evidence of naltrexone-induced liver injury [4]. Its safety in severe acute hepatitis is still unknown [4]. Your GP weighs this against the very real harm alcohol does to the liver.
What are the side effects of naltrexone?
Most side effects are mild and settle within days [2]. In the Cochrane review, nausea affected about 10 more people in every 100 on naltrexone than on placebo, and daytime sleepiness about 9 more in every 100 [5]. Other common effects include headache, dizziness, stomach pain, reduced appetite, nervousness, restlessness and sweating [1].
Doctors often start low and adjust to help with nausea [4]. Naltrexone isn't addictive. There's no evidence it causes tolerance, and no withdrawal syndrome is known when you stop [1][2].
Naltrexone vs naloxone: what's the difference?
The names are similar, and both block opioid receptors, but they do very different jobs.
| Naltrexone | Naloxone | |
|---|---|---|
| What it's for | Ongoing treatment to reduce drinking or prevent relapse [1] | Emergency reversal of an opioid overdose [1] |
| How it's used | Taken regularly as a course of treatment [2] | Given in an emergency. Its effect is temporary, so call 000 as well [1] |
| How you get it | Prescription, PBS-subsidised for alcohol dependence [8] | Free under the Take Home Naloxone program, no prescription needed [1][9] |
| Who gives it | You take it yourself | Anyone, including a bystander [1] |
If you think someone has overdosed on opioids, give naloxone if you have it and call 000 [1].
How does naltrexone fit with counselling and support?
Medication works best as part of a wider plan. The Australian guidelines recommend cognitive behaviour therapy as a first-line psychological treatment for alcohol dependence, and say its benefit is enhanced when combined with medication [3]. Motivational interviewing helps in the short term, and peer support programs such as Alcoholics Anonymous and SMART Recovery are effective too [3].
In practice, support might include:
- regular GP reviews to check progress, side effects and liver tests [2][4]
- counselling or psychology sessions, if you want them
- peer support groups
- the National Alcohol and Other Drug Hotline on 1800 250 015 [1].
Drinking often overlaps with low mood, anxiety and sleep problems. If you're also on an antidepressant, see our guide to antidepressants and alcohol. Another medicine, acamprosate, is recommended to help people maintain abstinence [3]. Read our acamprosate guide to compare.
How long do people take naltrexone for?
A course usually runs for 3 to 6 months, and sometimes up to 12 months [2]. Whether to keep going is decided case by case, looking at side effects, past relapses and your circumstances [2]. Support to prevent relapse continues after the medication stops [2].
You may also see "low-dose naltrexone" discussed online for other conditions. That's a different, off-label use and isn't what this page is about.
When should you see a GP about drinking?
Australian guidelines recommend healthy adults drink no more than 10 standard drinks a week and no more than 4 on any one day [10]. It's worth talking to a GP if you regularly drink more than that, you've tried to cut back and found it hard, you get cravings, or you feel shaky, sweaty or anxious when you don't drink.
If you'd like to talk to a GP about your drinking, without judgement, you can request an appointment. Our GPs can refer you to a psychologist or psychiatrist when needed. A consultation doesn't guarantee a prescription. Your GP decides what's clinically appropriate. You can read more on our alcohol page.
If you're in crisis or thinking about suicide, call Lifeline on 13 11 14 or 000 in an emergency.
This page is general information, not medical advice.
Common questions
Can I get naltrexone in Australia?
Do I have to stop drinking before starting naltrexone?
Not necessarily. Recent Australian GP guidance notes that you don't need to be abstinent to start, and naltrexone may suit people cutting down gradually [4]. If you're stopping completely and going through withdrawal, guidelines suggest starting soon after withdrawal has finished [2]. Talk to a doctor before stopping suddenly if you drink heavily every day.
Can you drink alcohol on naltrexone?
What's the difference between naltrexone and naloxone?
Is naltrexone bad for your liver?
Naltrexone shouldn't be used in acute hepatitis or severe liver failure, and doctors check liver function before and during treatment [2]. That said, recent Australian GP guidance says early liver concerns came from high-dose studies, and the largest study in people with cirrhosis found no evidence of liver injury from naltrexone [4].
References
- Alcohol and Drug Foundation. Naltrexone. Published 7 October 2026. Accessed November 2026. adf.org.au/drug-facts/naltrexone
- Guidelines for the Treatment of Alcohol Problems (4th ed). Chapter 10: Naltrexone. Accessed November 2026. alcoholtreatmentguidelines.com.au/frontline-pharmacotherapy-tgaapprove
- Haber PS, Riordan BC, Winter DT, et al. New Australian guidelines for the treatment of alcohol problems: an overview of recommendations. Med J Aust. 2021;215(Suppl 7):S3-S32. pubmed.ncbi.nlm.nih.gov/34601742
- Deyo C, Membrey D, Conigrave KM, et al. Naltrexone: a safe and effective standard of care in treating alcohol use disorder. Aust J Gen Pract. 2026;55(1-2). www1.racgp.org.au/ajgp/2026/january-february/naltrexone
- Rösner S, Hackl-Herrwerth A, Leucht S, et al. Opioid antagonists for alcohol dependence. Cochrane Database Syst Rev. 2010;(12):CD001867. pubmed.ncbi.nlm.nih.gov/21154349
- McPheeters M, O'Connor EA, Riley S, et al. Pharmacotherapy for alcohol use disorder: a systematic review and meta-analysis. JAMA. 2023;330(17):1653-1665. pubmed.ncbi.nlm.nih.gov/37934220
- Anton RF, O'Malley SS, Ciraulo DA, et al. Combined pharmacotherapies and behavioral interventions for alcohol dependence: the COMBINE study: a randomized controlled trial. JAMA. 2006;295(17):2003-17. pubmed.ncbi.nlm.nih.gov/16670409
- Pharmaceutical Benefits Scheme. Naltrexone 50 mg tablet (item 8370M), alcohol dependence, streamlined authority. Schedule effective 1 November 2026. pbs.gov.au/medicine/item/8370M
- Australian Government Department of Health, Disability and Ageing. Take Home Naloxone program. Accessed November 2026. health.gov.au/our-work/take-home-naloxone-program
- National Health and Medical Research Council. Australian guidelines to reduce health risks from drinking alcohol. Accessed November 2026. nhmrc.gov.au/health-advice/alcohol
Published by Mental Health Clinic. Last updated 6 November 2026. This page is general information only and isn’t a substitute for advice about your own situation. If you or someone else is in danger, call 000.