Naltrexone

How is naltrexone used?

Naltrexone is taken as a tablet and usually taken daily. The length of the course will depend on each person’s needs and situation.

Naltrexone can also be administered via an implant, an unregistered form of naltrexone treatment which is yet to be supported by high quality evidence. It can be accessed in Australia under the TGA Special Access Scheme.

Naltrexone for alcohol or opioid dependence

To be eligible for naltrexone treatment, a person must:

• not be currently using any opioids* or require opiate-based pain relief
• have no existing liver conditions, such as acute hepatitis
• seek advice if they are pregnant or breastfeeding as naltrexone may not be safe for use during pregnancy.⁶

* If using naltrexone for opioid dependence a person typically needs to be free of opioids for 7–10 days before starting naltrexone treatment; otherwise they may experience instant withdrawal. Sometimes people are tested to confirm they are no longer using opioid drugs before beginning treatment. An example is the Naloxone Challenge Test (NCT), where naloxone is administered to understand a person’s current level of physical dependence on opioids.³

Regular blood tests to monitor liver function both before and during naltrexone treatment are recommended.¹

How effective is it?

Naltrexone may not work for everyone, so it’s important to consult a doctor or alcohol and other drug (AOD) counsellor to find the best approach.

Generally naltrexone treatment is more likely to be effective if a person has good social support and they are highly motivated to change.^7,8

When treating alcohol dependence, naltrexone may work better at reducing heavy drinking and overall alcohol use than at helping people stay completely alcohol-free.⁹

Effects of naltrexone

Use of any drug always carries some risk. It’s important to be careful when taking any type of drug.

Naltrexone affects everyone differently, based on:

• size, weight and health
• whether the person is used to taking it
• whether other drugs are taken around the same time
• the amount taken.

Side effects

Naltrexone has few side effects, and they are usually mild. Side effects may be reduced by taking naltrexone with food and often go away once your body gets used to the medication.¹⁰

Common side effects include:

• nausea
• headache
• dizziness
• drowsiness
• stomach pain
• reduced appetite
• nervousness
• restlessness
• sweating.^11,12

Less common side effects include:

• feeling energetic
• thirst
• diarrhoea, constipation
• skin rashes
• delayed ejaculation
• irritability
• chills.¹²

Overdose

Naltrexone lowers a person’s tolerance to opioids. This means there is a serious risk of overdose if a person uses an opioid during or after naltrexone treatment finishes.¹

If opioids have been taken during or immediately after naltrexone treatment, call triple zero (000) and request an ambulance if you or someone else has any of the following symptoms (emergency services are there to help and can provide instructions over the phone):

• slow breathing, abnormal breathing or not breathing at all
• slow or no heartbeat and pulse
• cool, pale or clammy (wet and sweaty) skin
• vomiting
• choking or gurgling sounds
• small pupils.¹³

Mixing naltrexone with alcohol and other drugs

Mixing naltrexone with other drugs can have unpredictable effects and increase the risk of harm.

Naltrexone and alcohol: if a person drinks alcohol while using naltrexone, they will still experience the impairment effects of alcohol. Their judgement, coordination and ability to do things like drive a car or operate machinery will still be affected.¹⁴

Naltrexone and opioids (codeine, heroin, oxycodone): naltrexone lowers a person’s tolerance to opioids, and makes an overdose more likely if opioids like heroin are used after missing a naltrexone dose or stopping treatment.

If you are taking naltrexone:

• inform medical staff if you are likely to be given opioid painkillers (such as codeine or oxycodone) so they can care for you properly
• always start with a small amount if you plan to use heroin, oxycodone, or other opioids, to prevent the risk of overdose and keep naloxone nearby.^12,15

Use of more than one drug or type of drug at the same time is called polydrug use.

Reducing harm

There are ways you can reduce the risk of harm when taking naltrexone:

• Follow your doctors’ instructions on how and when to take naltrexone. Do not stop taking naltrexone or change the dose without talking to your doctor.
• Naltrexone may affect your alertness and/or coordination. Avoid driving or using machinery if you feel affected.
• Do not use naltrexone if you have used opioids within 7-10 days.
• Do not use naltrexone if you have liver disease or liver failure.
• If you experience any side effects or discomfort, talk to your doctor to make sure that naltrexone is right for you.
• Naltrexone has the potential to interact with several drugs and medications. Talk with your doctor about the other drugs and medications you use.
• Tell your doctor if you are pregnant or breastfeeding, or plan on becoming pregnant, while taking naltrexone.¹²

Getting Help

If your use of alcohol or other drugs is affecting your health, family, relationships, work, school, financial or other life situations, or you’re concerned about a loved one, you can find help and support.

• Call the National Alcohol and Other Drug Hotline on 1800 250 015 for free and confidential advice, information and counselling about alcohol and other drugs
• Help and Support Services search
  Find a service in your local area from our list. Simply add your location or postcode and filter by service type to quickly discover help near you.

If you’re looking for other information or support options, send us an email at druginfo@adf.org.au