Please note: The information given on this page is not medical advice. Individuals who want medical advice about naltrexone should consult a health professional.
Naltrexone is a prescription drug. It belongs to a group of drugs known as opioid antagonists. These block the effects of heroin and other opioid drugs. Naltrexone is used in pharmacotherapy, in which a drug of dependence is replaced with a prescribed drug. Pharmacotherapy helps to stabilise people's lives and reduce the harms related to drug use.1
Naltrexone may be used:
How is it used?
Naltrexone is taken as a tablet. The length of the course will depend on each person's needs and situation.
It can also be administered via an implant. Treatment with naltrexone implants is permitted in Australia under the requirements of the TGA Special access scheme.
To be eligible for the treatment for opioid dependence, a person must:
Alcohol and naltrexone
Naltrexone can be prescribed to people with alcohol dependence. Its use in that context works in several ways:
Regular blood tests to monitor liver function both before and during naltrexone treatment are recommended.6
How effective is it?
Naltrexone may not work for everyone, so it is important to consult a doctor or drug counsellor to find the best approach.
Naltrexone treatment is more likely to be successful if it is part of a comprehensive treatment program that includes counselling, alternative therapies and the development of a positive network of peers, friends and a support group.
Some studies suggest that many clients don't remain on naltrexone and return to heroin use. Future studies may provide a clearer picture of the drug's effectiveness.
In terms of its use to treat alcohol dependence, naltrexone may be more effective for preventing relapse to heavy or problem drinking and reducing high levels of alcohol consumption than for maintaining abstinence from alcohol.6
There is no safe level of drug use. Use of any drug always carries some risk – even medications can produce unwanted side effects. It's important to be careful when taking any type of drug.
Naltrexone affects everyone differently, based on:
Naltrexone has few side effects, and these usually go away after the medication is taken for a few days.
The reported side effects include:
Large doses of naltrexone may cause liver damage. Seek medical advice immediately if any of the following symptoms are experienced:
Risk of heroin overdose
Naltrexone will lower a person's tolerance to heroin. This means that there is a serious risk of overdose if they use heroin after a missed dose of naltrexone or after treatment has finished.3
People who plan to use heroin after being on naltrexone should consider themselves 'new' users.
Using naltrexone with other drugs
The effects of taking naltrexone with other drugs – including over-the-counter or prescribed medications – can be unpredictable and dangerous. In particular:
Naltrexone + opioid painkillers: the naltrexone will stop opioid painkillers from working.3
In cases where a person on opioid painkillers is likely to be given naltrexone (or vice versa), medical staff will need to be informed so that a different kind of painkiller can be prescribed. An emergency wallet card is a good way of alerting staff in the event that the person is not able to tell them.
People who are taking naltrexone will need both emotional and practical support.
Those who are to give support should decide, in collaboration with the person undergoing treatment, exactly what the support will entail. This might include whether they will inform a doctor if problems arise.
It could also include:
People can stop taking naltrexone at any time. They will not experience withdrawal symptoms.
Reducing the risks
ADF SEARCH – Find other credible websites and apps on naltrexone.
1. Brands, B., Sproule, B., & Marshman, J. (Eds.) (1998). Drugs & drug abuse. (3rd Ed.). Ontario: Addiction Research Foundation.
2. Substance Abuse and Mental Health Services Administration. (2009). The facts about naltrexone for treatment of opioid addiction.
3. Galanter, M. & Kleber, H. (Eds.). (2008). Textbook of substance abuse treatment. (4th ed.). Washington, DC: American Psychiatric Publishing, Inc.
4. REVIA®. (2013.). Naltrexone hydrochloride Consumer Medicine Information. Melbourne. Better Health Channel.
5. Family Drug Support. (2007). Other pharmacotherapies.
6. Haber, P., Lintzeris, N., Proude, E., & Lopatko, O. (2009). Guidelines for the treatment of alcohol problems, Australian Government Department of Health and Ageing.
Last updated: 20 May 2016