Naltrexone (A complete guide)


Author bio

Page last updated: 21/11/2022


Naltrexone is a drug that is used to prevent relapses into drug or alcohol abuse.

The brand names for naltrexone are Vivitrol and Revia. 

What is naltrexone?

Naltrexone is used to help narcotic dependents, who have stopped taking opiates, to stay drug-free. It is also used to help alcoholics stay alcohol-free.

The medicine is not a cure for addiction.

It is used as part of an overall program that may include counseling, attending support group meetings and other treatment recommended by your doctor.

How does naltrexone work? 

Naltrexone is not a narcotic. It works by blocking the effects of narcotics, specifically the opioid receptor in the brain that is responsible for the euphoric and sedative effects of opioids such as morphine, and codeine.

It especially blocks the “high” feeling that makes you want to use them. It also may block the “high” feeling that may make you want to use alcohol.

It will not produce any narcotic-like effects or cause mental or physical dependence.

It will not prevent you from becoming impaired while drinking alcohol.

Naltrexone blocks the opioid receptor in the brain that gives euphoric and sedative effects of opioids.

If someone who is suffering from opioid use disorder relapses and uses the drug naltrexone will prevent the feeling of getting high. 

What is some important information to know before taking naltrexone? 

People using naltrexone should not use any other opioid or illicit drug, drink alcohol, or take sedatives, tranquilizers or any other drug. 

Naltrexone can reduce tolerance to opioids, and if patients discontinue naltrexone they may be in great danger if they take the same dose of opioids that they were previously used to taking.

Thus, the risk for opioid-induced respiratory arrest and circulatory collapse is heightened, which are both life-threatening. 

What are the side effects of naltrexone?

When a doctor prescribes this medication, it is because they have judged the benefit is greater than the risk of side effects.

However, some people can experience:

·      nausea

·      headache

·      dizziness

·      anxiety

·      tiredness

·      insomnia.

In a small number of people, mild opiate withdrawal symptoms may occur, including abdominal cramps, restlessness, bone/joint pain, muscle aches and runny nose.

If any of these effects persist or worsen, tell your doctor or pharmacist immediately.

Naltrexone (A complete guide)

Sudden opiate withdrawal symptoms can occur within minutes after taking naltrexone.

Tell your doctor right away if any of these withdrawal symptoms occur: 

·      abdominal cramps

·      nausea/vomiting

·      diarrhea

·      joint/bone/muscle aches

·      mental/mood changes (e.g., anxiety, confusion, extreme sleepiness, visual hallucinations)

·      runny nose.

Is naltrexone addictive?

There is potential for abuse with naltrexone. As a medication assisted treatment, is to be prescribed as part of a comprehensive treatment plan.

What conditions are treated by naltrexone?

Opiate addiction and alcohol misuse are the two conditions treated by naltrexone, among other medications.

Opioid addiction is a long-lasting (chronic) disease that can cause major health, social and economic problems.

Opioids are a class of drugs that behave in the nervous system to produce feelings of pleasure and pain relief.

Some opioids are legally prescribed for severe and chronic pain.

Commonly prescribed opioids include oxycodone, fentanyl, buprenorphine, methadone, oxymorphone, hydrocodone, codeine and morphine.

Naltrexone is used to treat both opioid addiction and alcohol abuse.

Opioid addiction is characterized by a powerful, compulsive urge to use opioid drugs, even when they are no longer required medically.

Opioids have a high potential for causing addiction in some people, even when the medications are prescribed appropriately and taken as directed.

Many prescription opioids are misused or diverted to others.

Individuals who become addicted may prioritize getting and using these drugs over other activities in their lives, often negatively impacting their professional and personal relationships.

It is unknown why some people are more likely to become addicted than others.

Opioids change the chemistry of the brain and lead to drug tolerance, which means that over time the dose needs to be increased to achieve the same effect.

Taking opioids over a long period of time produces dependence, such that when people stop taking the drug, they have physical and psychological symptoms of withdrawal (such as muscle cramping, diarrhea, and anxiety).

Dependence is not the same thing as addiction; although everyone who takes opioids for an extended period will become dependent, only a small percentage also experience the compulsive, continuing need for the drug that characterizes addiction.

Opioid addiction can cause life-threatening health problems, including the risk of overdose.

Overdose occurs when high doses of opioids cause breathing to slow or stop, leading to unconsciousness and death if the overdose is not treated immediately.

Both legal and illegal opioids carry a risk of overdose if a person takes too much of the drug, or if opioids are combined with other drugs (particularly tranquilizers called benzodiazepines).

Alcohol misuse is when you drink in a way that’s harmful, or when you’re dependent on alcohol.

To keep health risks from alcohol to a low level, both men and women are advised not to regularly drink more than 14 units a week.

A unit of alcohol is 8g or 10ml of pure alcohol, which is about:

·      half a pint of lower to normal-strength beer/cider (ABV 3.6%)

·      a single small shot measure (25ml) of spirits (25ml, ABV 40%)

·      a small glass (125ml, ABV 12%) of wine contains about 1.5 units of alcohol.

Alcohol misuse is when you drink in a way that’s harmful

Frequently asked questions (FAQs) about naltrexone: 

What is naltrexone used for?

Naltrexone is an opioid antagonist, which means that it blocks opioid receptors in the brain that are responsible for the sedative and euphoric effects experienced by opioid users.

Naltrexone prevents these effects and decreases the desire to take opioid drugs. 

2.    What happens if you drink alcohol while taking naltrexone?

Naltrexone may reduce the feelings of intoxication from alcohol and reduce the desire to drink more.

It does not, however, reduce the effects that alcohol has on motor coordination and judgement. 

3.    Is naltrexone used for weight loss?

Naltrexone has been prescribed off-label for weight loss, meaning, in the US, that it has not been FDA approved to be taken for weight loss.

If you are obese or overweight discuss with your doctor to see if naltrexone is an option for you. 

4.    Does naltrexone help with anxiety?

Low doses of naltrexone can help with anxiety, but it is not approved to be prescribed specifically to treat anxiety.

5.    Does naltrexone improve mood?

The relation between depressive symptoms and poor adherence to taking the prescription of naltrexone may be bidirectional, i.e. improving either depressive symptoms or sticking to the prescription may assist in the improvement of the other. 

Drug dependencies must be stopped at least seven days prior to starting naltrexone.

1.    Does naltrexone make you sleepy?

Naltrexone may cause people to become dizzy, drowsy, or less alert than they normally are.

If any of these side effects occur, do not drive or operate heavy machinery. 

2.    What happens when you stop naltrexone? 

Even if you feel better, it is extremely important not to stop taking naltrexone. 

3.    Can you get drunk on naltrexone? 

Naltrexone usually decreases the effects of alcohol-induced intoxication and decreases the desire to drink.

One of the ways by which it decreases the desire to drink is by blocking the pleasurable effects of alcohol.

It does not, however, decrease the risks that alcohol poses to motor coordination and judgement. 

4.    Does naltrexone work immediately?

Naltrexone’s effects on blocking opioids occur shortly after taking the first dose.

Findings to date suggest that the effects of naltrexone in helping patients remain abstinent and avoid relapse to alcohol use also occur early.

5.    Does naltrexone work for everyone?

No, naltrexone does not work for everyone. Naltrexone should not be used by pregnant women, people with severe liver or kidney damage or by patients who cannot achieve abstinence for at least five days prior to initiating medications.

Also, people who are dependent on opioid drugs, must stop their drug use at least seven days prior to starting naltrexone.

Naltrexone (A complete guide)

For some more information about opioid or alcohol addition try the following books:

This Naked Mind: Control Alcohol, Find Freedom, Discover Happiness & Change Your Life

Many people question whether drinking has become too big a part of their lives, and worry that it may even be affecting their health.

But, they resist change because they fear losing the pleasure and stress-relief associated with alcohol, and assume giving it up will involve deprivation and misery.  

This Naked Mind offers a new, positive solution.

Here, Annie Grace clearly presents the psychological and neurological components of alcohol use based on the latest science, and reveals the cultural, social and industry factors that support alcohol dependence in all of us. 

Packed with surprising insight into the reasons we drink, this book will open your eyes to the startling role of alcohol in our culture, and how the stigma of alcoholism and recovery keeps people from getting the help they need.

With Annie’s own extraordinary and candid personal story at its heart, this book is a must-read for anyone who drinks.

The Cure for Alcoholism: The Medically Proven Way to Eliminate Alcohol Addiction

Featuring new and updated information and studies, including an introduction by actress Claudia Christian, the second edition of The Cure for Alcoholism delivers exactly what millions of alcoholics and families of alcoholics have been hoping for: a painless, dignified, and medically proven cure for their addiction.

Backed by 82 clinical trials and research that extends back to 1964, The Sinclair Method deploys an opiate-blocking medication in a very specific way in combination with ongoing drinking to extinguish the addictive software in the brain.

The de-addiction process rolls back the addictive mechanism in the brain to its original pre-addicted state – before the first drink was consumed, making this program an actual cure for alcoholism.

Opiate Addiction – The Painkiller Addiction Epidemic, Drug Addiction and the Way Out

Opiate addiction has reached epidemic proportions around the world, and the problem shows no signs of slowing.

Overcoming addiction is tough and, with opiates, many find it nearly impossible.

Overdose deaths from prescription painkillers have more than quadrupled over the last fifteen years, and this is just a fraction of the problem. In fact, with prescription opiate addiction now shown to be a gateway drug, the issue is only getting worse.

Last year alone, 11.5 million Americans abused some type of opioid, and more than 660,000 have used narcotic in the past year. 

If you or someone you love is addicted to opiates, Opiate Addiction, now in its 6th Edition, offers a powerful message balanced with both useful information and hope for a way out from its stifling grip.

There is no doubt that addiction is a cunning and cruel disease that robs its victims of nearly everything.

Those suffering from opiate addiction are often baffled by its effects on their lives and the devastation that can be wrought in such a short period of time.

Loved ones feel helpless and hopeless as they are forced to stand by and watch as someone they care about erodes before their eyes. 


Naltrexone. Substance Abuse and Mental Health Services Administration (SAMHSA). September 2019

Naltrexone (oral route) – Mayo Clinic – February 2020

Opioid addiction US National Library of Medicine – April 2020