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We currently do NOT offer treatment with Naltrexone implants. We offer treatment with tablets. You will find explanations for this below. If, after reading this page you are still looking for Naltrexone implants UK-based, please contact a Naltrexone implant clinic.

Naltrexone for Relapse Prevention

What is Naltrexone?

Naltrexone, an opioid antagonist, is a safe and effective medication. Its blocking mechanism means that heroin, methadone (Physeptone) and all other opiates such as morphine, codeine, DF118 and Temgesic will no longer produce their desired effects such as the intense feeling of pain relief and euphoria. The removal of these desired effects effectively reduces the desire to take these drugs.

How does it work?

Naltrexone enters the brain and nervous system and attaches itself to small areas called receptor sites. For heroin to produce its effects, it must attach to the same receptors, but Naltrexone blocks it for reaching them for up to three days after an oral dose. These receptors are part of the complex reward mechanisms that motivate us and lead to repetitive behaviour. If the reward is blocked, the craving and dependence reduces and new behaviours establish over time. It works well for relapse prevention in opiate addiction after a detox or in-patient rehabilitation.

Does Naltrexone block the effects of alcohol?

Naltrexone works often, but less predictably, in alcohol dependence. In Alcohol Use Disorders (AUD), naltrexone acts by binding to the endorphin receptors in the body and blocking the ‘high’ from alcohol. As a result, it can help minimise alcohol cravings by blocking the reward mechanism. As such, only individuals who are not physically dependent on alcohol are suitable for Naltrexone treatment. 

Who may not be suitable for Naltrexone treatment?

Naltrexone can be used to treat both alcohol and opioid use disorders once detoxed, however treatment with Naltrexone should no take place if:

  • There is a latent addiction to opioids

  • There are opioid withdrawal symptoms

  • Opioid medicines are being use

  • Surgery or dental work is scheduled

  • The patient is under the age of 18


Why consider Naltrexone?

The OAD Clinic offers naltrexone treatments to prevent opiate relapse. The medication should be taken after the body has been fully detoxified from opiates, otherwise strong withdrawal symptoms may be experienced. It is part of our comprehensive opiate addiction treatment programme that includes counselling, monitoring and lifestyle changes. It is an option to consider as a relapse prevention strategy following an in-patient rehab or a detoxification. Learn more about our drug treatment programmes.


Naltrexone can also be effectively used in alcohol treatment programmes. It blocks opioid receptors responsible for the euphoric effects of alcohol mediated by endorphins (brain reward system), reducing the desire to drink. Naltrexone works best as part of a treatment programme that includes psychosocial support such as counselling and therapy. Learn more about our alcohol treatment programmes.

We currently do not offer Naltrexone implant treatment due to research findings on relative high risk of infection. If you are looking for Naltrexone implant treatments in the UK, please contact us and we will provide you with more information on specialist Naltrexone implant clinics in the UK. 

Naltrexone Formulations

Naltrexone is available in three forms.

Naltrexone Implants

A Naltrexone implant is an opiate blocker implant. It is a specially formulated, sterilised preparation for insertion under the skin during a 20-30 minute minor surgical procedure. Its effects last up to 6 months. The OAD Clinic does not currently provide treatments based on a Naltrexone implant for alcohol addiction. Keep in mind that there can be side effects to a Naltrexone Implant alcohol based treatment, so it’s important that you understand the possible risks and complications, which can include nausea, dizziness, fatigue, and more.

Naltrexone Implants do not have a product licence in the UK and are still regarded as experimental. Learn more about Naltrexone Implants.

Naltrexone Tablets

These are usually swallowed daily and it is best that consumption is supervised. If not taken for a couple of days, relapse to opiate use is possible. They do have a product licence.

Naltrexone Depot Injections

This is a liquid preparation of Naltrexone for injection into deep muscle, slowly released over approximately one month. The advantage of this formulation is that no surgical procedure is needed, with no visible lump or scar. Compared to Implants, the disadvantage is its shorter duration, requiring more commitment from the patient to have it repeated monthly, without relapsing in between. If you are looking for Naltrexone injection UK, The OAD Clinic unfortunately cannot offer this form of treatment at this time. Currently, this formulation does not have a product licence in the UK.

We can provide Buvidal depot injections (prolonged-release buprenorphine injection)as an alternative opioid blocker with the same purpose as a Naltrexone injection.

Side Effects of Naltrexone

While Naltrexone’s mechanism of action works by blocking desired opioid side effects and results in a reduction of cravings, there are still side effects that must be considered. These include:

  • Anxiety

  • Abdominal pain

  • Skin rash

  • Headaches

  • Fatigue/drowsiness 

  • Dizziness 

  • Constipation or diarrhoea 

  • Vomiting and nausea

  • Loss of Appetite 

These symptoms will typically go away on their own once stabilised on a suitable Naltrexone dose. The clinical team at The OAD Clinic will be monitoring symptoms and any serious allergic reactions closely for the first 24 to 48 hours. There are rare cases of serious side effects as a result of Naltrexone treatment. You will need to seek immediate medical attention if you experience any of the following:

  • Severe diarrhoea and/or vomiting

  • Blurred or impaired vision

  • Hallucinations

  • Swollen lips, throat, face, eyes and difficulty breathing (allergic reaction)

  • Yellowing of eyes or skin (jaundice)

Before using Naltrexone, patients should wait at least 7 to 14 days after their last use of opioids to reduce the risk of opioid withdrawal symptoms. 

Using Naltrexone for Opioid Use Disorder

Naltrexone can be used as a treatment for opioid use disorder (OUD). The mechanism of action is the blockage of opioid receptors. Before using Naltrexone, patients should wait at least 7 to 14 days after their last use of opioids to reduce the risk of opioid withdrawal symptoms. 
When taking Naltrexone for OUD, individuals must not:

  • Use opioids

  • Drink alcohol

  • Take sedatives, tranquilisers or other drugs

Before starting treatment, you must inform your clinician about any medications you are currently taking. Patients who have taken Naltrexone are likely to have a decreased tolerance to opioids, meaning that taking opioids, even in the same or lower doses, can be life-threatening. Discontinuing use against medical advice is not recommended.

Using Naltrexone for Alcohol Use Disorder

Does Naltrexone block the effects of alcohol? While Naltrexone can be used as part of OUD treatment, it can also be used to treat alcohol use disorder (AUD), binding to the endorphin receptors in the body and blocking the ‘high’ from alcohol. As a result, it can help minimise alcohol cravings.


Only individuals who are not physically dependent on alcohol are suitable for Naltrexone treatment. Therefore, Naltrexone is usually administered after an alcohol detox process to avoid severe side effects like vomiting. This means that Naltrexone therapy is often used to assist

patients in maintaining their sobriety. Treatment can last up to four months. 

Safety Precautions when Administering Naltrexone

Before starting Naltrexone, you should speak with your clinician about:

  • Existing medical conditions, including liver or kidney problems

  • Pregnancy or if you plan to become pregnant/are breastfeeding

  • All medications you are currently taking, as well as vitamins and herbal supplements and any opioid-containing medicines

  • Whether you are already being treated for OUD or AUD

  • Allergies - including whether you are allergic to Naltrexone or any of its ingredients 

Naltrexone Dosage Guide

There is a risk of accidental overdose when taking Naltrexone. Always tell a close family member or friend about your risk of overdose and increased sensitivity to opioids when on Naltrexone.

As Naltrexone blocks the effects of opioids, do not attempt to overcome this effect by taking larger amounts of opioids. This can lead to coma, injury, or even death. 

Likewise, sensitivity to opioids can increase when taking Naltrexone. Using opioids at the dose you have used in the past, or even lower amounts, can lead to overdose and possibly death. 
Never take more or less Naltrexone than what has been prescribed by your clinician and follow their strict instructions. Your Naltrexone dosage might change throughout your treatment, but this will be done accordingly by your clinician. Naltrexone tablets are often prescribed as one tablet per day (50 mg) for AUD and half a tablet (25 mg) to one tablet (50 mg) per day for OUD. 

How to Store and Dispose of Naltrexone

Naltrexone tablets should be stored at room temperature, or 20°C to 25°C. Keep out of reach of children and ensure it is tightly closed in its container. 
Unused Naltrexone should be disposed of safely - speak with your clinician or local pharmacist for additional guidance on how to safely dispose of Naltrexone or other medications. Do not flush Naltrexone down the toilet.

Before Taking Naltrexone

There are several considerations to make before taking Naltrexone. In particular, before using Naltrexone, you should:

  • Not take opioids - including opioid medications (Vicodin, fentanyl, and more) and opioid street drugs

  • Not use opioids up to 14 days before starting Naltrexone 

  • Understand that you will have an increased sensitivity to opioids after treatment 

  • Speak with your prescriber

What to tell your prescriber

Before starting Naltrexone, you must speak with your prescriber and tell them if you:

  • Are allergic to Naltrexone or other medications

  • Are taking any opioid medications or street drugs 

  • Are taking any other medications, as well as vitamins, or supplements

  • Have kidney disease 

  • Have or had depression 

  • Are pregnant, breastfeeding, or plan to become pregnant 

  • Require medical treatment or surgery 

How to use Naltrexone

Naltrexone is available as oral tablets or as an intramuscular injection. At The OAD Clinic, we can only provide oral Naltrexone tablets for our patients. 

Before starting treatment, it is recommended that you do not use short-acting opioids for up to at least 10 days to prevent opioid withdrawal symptoms. 

To use Naltrexone tablets properly, you should take them as directed by your prescriber. This is often once a day but can differ depending on the patient. 

The amount of time that you will be on Naltrexone is decided by your prescriber. 

Taking Naltrexone while Pregnant or Breastfeeding

If you are pregnant or breastfeeding, consult your prescriber. There has not been much research conducted on Naltrexone and the extent of harm on your unborn baby. Naltrexone tablets have been shown to pass into breast milk - you should not breastfeed and take Naltrexone tablets. 
Also, speak with your prescriber if you plan to become pregnant. Furthermore, if you become pregnant while taking Naltrexone, tell your prescriber immediately. 

Remember these Facts before taking Naltrexone

Before starting treatment, opioids including opioid medications (OxyContin, Vicodin, paracetamol, fentanyl and morphine among others) should not be taken for up to 14 days prior to starting treatment. Increased sensitivity to opioids after treatment may also be a side effect of treatment.

Naltrexone Clinic

If you are interested in a specific Naltrexone treatment for opiate detoxification and curbing alcohol cravings in the form of tablets, do not hesitate to get in touch with us for more information.


Am I suitable for Naltrexone treatment?

Naltrexone can be used to treat both AUD and OUD. However, not everyone is suitable for Naltrexone treatment. Particularly, you should not use this medication if you are addicted to opioids, are experiencing opioid withdrawal symptoms, are currently using opioids, require surgery or dental work and/or are under the age of 18.

Do I need to follow special dietary instructions?
You can continue with your normal diet unless otherwise instructed by your doctor.

What do I do if I miss a dose?
Take the missed dose as soon as possible unless it is almost time for your next dose. In this case, skip the missed dose and continue as normal. Do not take a double dose. If in doubt, contact our clinic.

I think I’ve overdosed - what should I do?
If you have overdosed, please contact your doctor or dial 999 for the ambulance service immediately. If possible, have someone take you to the closest A&E. 

What do I need to avoid when taking Naltrexone?
Naltrexone side effects include sleepiness and dizziness. Do not drive, operate machinery or engage in dangerous activities while you are on Naltrexone.

What active ingredients are contained in Naltrexone?

The active ingredient in Naltrexone treatment is Naltrexone hydrochloride. Inactive ingredients can vary between different brands - read the product label for a complete list of the ingredients in your Naltrexone tablets. 

How do I store Naltrexone?
Naltrexone tablets should be stored at 20°C to 25°C, or room temperature, out of reach for children. 

What other medication affect Naltrexone treatment?
Approximately 337 drugs are known to interact with Naltrexone. Speak to us about medication, vitamins, and supplements you are currently taking for a better understanding of whether you need to eliminate certain ones from your routine when taking Naltrexone. Medication containing opioids could affect your Naltrexone treatment, especially if you are already being treated for
opioid use disorders.

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