Giving up drugs and alcohol can be a gruelling process, with powerful cravings and withdrawal symptoms causing many people to relapse. Various medications can assist individuals with different aspects of the recovery process, but naltrexone is one of the most effective for alleviating cravings. Naltrexone can play a pivotal role in making both alcohol and opioid cravings more manageable and preventing relapse during this difficult stage. For anyone who is considering naltrexone treatment as part of their addiction treatment programme, understanding its benefits, risks and safe usage can ensure its effectiveness and avoid potential dangers.

What is naltrexone?

Naltrexone is a medication from the opioid antagonist class. It was first synthesised in 1963 and approved by the FDA in 1984 for the treatment of opioid addiction and for alcohol addiction treatment in 1995. Its primary function is to block the effects of addictive substances in the brain, thereby reducing the powerful cravings that emerge when a physically dependent individual stops using alcohol or opioids.

Naltrexone is marketed under several brand names, including:

    Vivitrol

    Trexan
    ReVia
    Adepend
    Depade
    Abernil
    Nalerona
    Naltrexona

Naltrexone is also being studied for its promising effects on gambling addiction, kleptomania and porn and sex addiction.

Like all addiction treatment medications, naltrexone is not a standalone solution for addiction. It is most effective when used as part of a comprehensive treatment plan that includes a therapy programme, lifestyle changes and ongoing aftercare and support. However, when used in the early stages of recovery, naltrexone can be a highly effective medical aid.

How is naltrexone used in addiction treatment?

Excessive alcohol and opioid use changes the brain’s chemistry and functioning, leading to physical and psychological dependence. When a dependent individual stops using these substances, these brain changes cause intense cravings and withdrawal symptoms, which are significant barriers to recovery.

Naltrexone’s effectiveness in treating alcohol and opioid addiction lies in its action at the neuronal level, specifically its interaction with the brain’s opioid receptors. Opioid receptors are part of the central nervous system and play a crucial role in regulating pain, reward and addictive behaviours. When opioids or alcohol are consumed, they activate these receptors, leading to the release of dopamine and subsequent feelings of pleasure and euphoria, reinforcing the cycle of addiction.

Blocking opioid receptors
Naltrexone functions as an opioid receptor antagonist. This means it binds to the mu, kappa and delta opioid receptors in the brain but does not activate them. Instead, naltrexone effectively blocks these receptors, preventing opioids from creating their euphoric effects. For individuals addicted to opioids, this blockade diminishes the rewarding aspects of drug use, reducing cravings and the likelihood of relapse.
Reducing alcohol cravings
The mechanism by which naltrexone reduces alcohol cravings is slightly different but is also thought to involve the opioid receptors. Alcohol consumption increases the release of endorphins, which bind to opioid receptors and contribute to the rewarding properties of alcohol. By blocking these receptors, naltrexone reduces the pleasurable effects of alcohol, diminishing the desire to drink and helping individuals reduce or cease their alcohol consumption.
Breaking the cycle of pleasure and reward

Naltrexone’s ability to block opioid receptors also impacts the brain’s reward pathways. By interfering with the normal operation of these pathways, the drug permanently alters the neurological response to alcohol and opioids, effectively “decoupling” the association between substance use and the pleasurable reward. This disruption is crucial for breaking the cycle of addiction and supporting recovery efforts.

Extended-release formulations

The development of extended-release formulations like Vivitrol (injectable Naltrexone) has enhanced the practical application of this medication in addiction treatment. By providing a steady level of Naltrexone in the body for a month at a time, these formulations ensure consistent receptor blockade, which is particularly beneficial for maintaining abstinence in the critical early stages of recovery.

Who can naltrexone benefit?

Naltrexone offers significant benefits to individuals navigating the complex journey of withdrawal and addiction recovery. These include:

  • Individuals who have completed opioid detox: Naltrexone can help maintain sobriety by reducing cravings and blocking the euphoric effects of opioids.
  • Individuals who are dependent on alcohol: Naltrexone has been shown to decrease the desire to drink and can reduce the amount of alcohol consumed by those who do drink.
  • Individuals looking for a non-addictive opioid medication: Unlike methadone or buprenorphine, naltrexone does not have addictive properties, making it a suitable choice for those worried about swapping one addiction for another

It is important to note that naltrexone is not appropriate for everyone. Patients with acute hepatitis or liver failure, those who are currently using opioids or individuals who have not fully detoxified may not be suitable candidates for naltrexone treatment. A thorough medical assessment, including liver function tests and an evaluation of the individual’s substance use history, is essential before starting naltrexone.

Naltrexone side effects

Naltrexone is generally well-tolerated, but like all medications, it can cause side effects in some individuals. These side effects vary from mild to severe, so users and healthcare providers must understand the risks.

Common naltrexone side effects include:

  • Nausea and vomiting: These are among the most frequently reported side effects, often occurring early in treatment and diminishing over time.
  • Headache: A common side effect that can range from mild to moderate in intensity.
  • Dizziness and drowsiness: These symptoms can affect an individual’s ability to drive or operate machinery and usually decrease as the body adjusts to the medication.
  • Insomnia: Difficulty sleeping is a potential side effect, which can sometimes be managed with adjustments to the timing of naltrexone administration.
  • Anxiety and nervousness: Some individuals may experience increased feelings of anxiety or nervousness, which should be monitored and managed through supportive care or adjustment of the treatment plan.


Less common but more serious naltrexone side effects may include:

  • Liver toxicity: Naltrexone can cause liver damage, particularly at high doses. Liver function tests are recommended before and during treatment to monitor for signs of liver injury.
  • Severe opioid withdrawal: If someone takes naltrexone with physical dependence on opioids, it can precipitate severe withdrawal symptoms and increase the risk of overdose. It is, therefore, crucial to ensure that individuals are opioid-free for a minimum period before starting naltrexone.
  • Depressed mood: Naltrexone may also be associated with depression or worsening of pre-existing depression. Close monitoring and mental health support are essential for individuals at risk.

Users should tell their doctor or healthcare provider if they experience any naltrexone side effects, as adjustments to the dosage or the treatment plan may be necessary. In most cases, the benefits of naltrexone in supporting recovery from addiction may outweigh the risks of side effects, but this determination should be made on an individual basis, in consultation with a medical professional.

Potential naltrexone drug interactions

Naltrexone can interact with various other medications, substances and even herbal supplements, potentially altering its effectiveness or increasing the risk of naltrexone side effects. Being informed about these interactions can help ensure the safe and effective use of naltrexone. Potential naltrexone drug interactions include:

Opioid-based medications
The most significant interaction is with opioid drugs, including prescription painkillers, heroin and methadone. Naltrexone blocks the effects of opioids, which can lead to severe withdrawal symptoms in individuals who are still dependent on these substances, and also significantly reduces tolerance, so there is a higher chance of overdose if the person uses excessive doses of opioids again. Individuals should, therefore, be opioid-free for a specified period before starting naltrexone to avoid precipitated withdrawal and overdose risks.
Alcohol
While naltrexone is used to reduce the craving for alcohol, the use of alcohol does not directly interact with naltrexone. However, individuals being treated for alcohol dependence should avoid alcohol consumption to reduce the risk of liver damage and enhance the effectiveness of their treatment plan.
Certain medications for diarrhoea, cough or pain
Some over-the-counter and prescription medications contain small amounts of opioids and could potentially lead to an interaction with naltrexone.
Herbal supplements
Certain herbal supplements may interact with naltrexone, affecting liver enzyme levels and potentially altering the metabolism of naltrexone.
Medications that affect liver enzymes
Some drugs can affect the enzymes that metabolise naltrexone in the liver, potentially altering its effectiveness. These include certain antibiotics, antifungal medications and drugs used to treat seizures or HIV.

Individuals should inform their healthcare providers about all medications, supplements and substances they are using to ensure that naltrexone is safe and effective for them. Regular monitoring and open communication with doctors can help manage potential drug interactions and contribute to a successful recovery journey.

Get help for addiction today

If you or someone you know is struggling with addiction, it is crucial to seek professional help. Addiction is a complex condition, but with the right support and treatment, recovery is possible. Reaching out to your GP or a professional addiction treatment to take the first step toward recovery. These professionals can provide guidance on the best treatment options, including the use of medications like naltrexone, and help you find a plan that addresses your needs.

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