Naltrexone can help in the treatment of alcohol and opioid addiction, but it can cause depression and dangerously low opioid tolerance, among other things.

What Is Naltrexone?

Naltrexone is an opioid antagonist often used as part of a treatment program for opioid and/or alcohol dependence.

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), this drug works primarily by blocking the intoxicating effects of alcohol, the sedative effects of opioids, and the euphoric effects of both. This helps to motivate people to stop abusing these drugs. Naltrexone is a pure opioid antagonist. There is no evidence that it causes physical or psychological dependence of any kind. This means it is not addictive, and a person should not experience any withdrawal symptoms from naltrexone itself.

It can still very much lead to opioid withdrawal symptoms if taken improperly.

Before Taking Naltrexone

It is important to be opioid-free for a minimum of seven to 10 days before taking naltrexone. Otherwise, the withdrawal of the drug causes can be serious.

While it is not a major concern for people who abuse only alcohol, naltrexone is an opioid antagonist, and as such, it can cause serious negative effects in people who have opioids in their systems.

As with all prescription drugs and most drugs in general, it is important to talk to a doctor before using naltrexone. It is especially important, to be honest about all opioid abuse during these discussions. If opioids are still in your system, you are endangering yourself if you do not disclose that information.

Naltrexone for Opioid Abuse

When used in the treatment of opioid addiction, naltrexone should only be used after at least seven to 10 days of being free from opioids. If the person is still experiencing withdrawal symptoms from opioids, naltrexone can worsen them.

Generally, a person taking naltrexone (often in tablet or capsule form) will first be given a dose of 25 mg (milligrams) a day.

This initial dose is intentionally low and meant to allow a doctor to monitor for the signs of dangerous withdrawal symptoms.

If no symptoms occur, then the dose is eventually raised to 50 mg.

When taken for opioid abuse, naltrexone is primarily for people who are already doing well in their treatment.

While the exact statistics are unknown, there is strong evidence that more vulnerable people who are addicted to opioids tend to stop taking naltrexone if they are at risk of relapsing.

While true for all people addicted to drugs, it is especially important in the case of opioid addiction to seek a comprehensive treatment program. These programs could lead a person to a place where naltrexone is a good option even if it was not when treatment began.

Naltrexone for Alcohol Abuse

While signs of withdrawal will still be monitored, naltrexone should not exacerbate alcohol withdrawal symptoms. As such, if a person has problems with abusing alcohol and does not abuse opioids or similar drugs, they will usually be prescribed a 50 mg dose to be taken daily.

As noted by RxList, naltrexone (specifically, in this case, the brand of naltrexone hydrochloride tablets ReVia) has been evaluated as effective as part of a 12-week regimen in reducing alcohol dependence. It has not been well-studied beyond that.

Several studies have noted that naltrexone is more effective than no drug at all in the treatment of alcoholism. Its effects also seem to be comparable to other drugs used in treatment, such as acamprosate.

However, the data vary on exactly how effective naltrexone is, with no immediately clear consensus. More research is needed in this area.

Negative Side Effects

Naltrexone can have side effects such as:

  • Upset stomach
  •  Vomiting
  •  Headache
  •  Nervousness
  •  Sleep problems or drowsiness
  •  Joint and muscle pain

If you experience these side effects, do not stop taking naltrexone. Talk to your doctor to see how serious the situation is and whether there should be a change to your dose, or if naltrexone is not the right treatment for you.

Seek help right away if you experience liver damage since naltrexone can damage the liver. Any reaction at injection sites (if taking naltrexone injections rather than tablets) and symptoms of pneumonia are additional reasons to call your doctor.

Two of naltrexone’s more serious side effects are that it increases vulnerability to opioid overdose, and it has the potential to cause depression and suicidality. Both must be taken into account before trying naltrexone.

A person should never take opioids while on naltrexone and should understand they are likely less tolerant of opioids after the treatment. If they go back to abusing opioids, they should not take the drugs at the doses they had before treatment.

Opioid overdose is particularly likely with a return to use after a period of abstinence.

Always disclose any medications you are on and any medical conditions you have before beginning naltrexone. If you ever feel serious side effects, even if they are not mentioned above, talk to a doctor about them to make sure naltrexone is working as intended.


If you are already depressed or vulnerable to suicidal thoughts, you should not take naltrexone.

When on naltrexone, if you feel a desire to attempt suicide (even if you do not act on that desire), report it to your doctor immediately. You are in danger, and your doctor can help you deal with those dangerous feelings.

In the event you feel you are in danger of attempting suicide or other forms of self-harm, call the National Suicide Prevention Hotline at 1-800-273-8255 if you live in the United States or an equivalent if you live outside the United States. Many resources are available to guide you to a better tomorrow.

The Importance of a Treatment Program

White capsule pills spilling out of a blue containerNo treatment drug, no matter how helpful, is going to fully address serious addiction or dependence on its own. This is especially true with opioids and alcohol. These drugs are notoriously addictive and can cause serious psychological and physical dependence.

This is not to say naltrexone does not help combat dependence on these drugs. It can be a helpful tool in the recovery process.

If you are addicted to either opioids or alcohol, you will need to enroll in a drug treatment program to get the best results and the highest chances of recovery.

This type of program will include the use of both medications and therapy for a well-rounded approach to recovery.

The exact nature of a drug treatment program varies widely. Some are quite intensive and have you live at a facility, while others might just involve you attending a weekly support group or therapy sessions.

It largely depends on what is best for you, determined through a discussion with a professional.

Making the Best Treatment Decision

Treating addiction is rarely easy, and naltrexone is admittedly not without its downsides. It can even be dangerous for some people. As long as you are honest and have a clear discussion about the drug with your doctor, they should be able to determine if it will be safe to try.

For many people, naltrexone can be part of a bigger treatment program that leads them out of opioid or alcohol addiction. These are serious addictions, but they can be effectively managed.

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