Naltrexone is usually taken as a daily pill or administered as a once-a-month injectable. It’s not addictive, and it usually only causes mild and short-lasting side effects.
Naltrexone can only be taken by individuals who have already stopped using alcohol or opioids for over a week. It cannot be used to treat withdrawal symptoms. It needs to be taken continuously in order to reduce cravings.
Created by Endo Laboratories in 1963, naltrexone was first developed to treat opioid addiction. It was approved by the FDA for this purpose in 1984.
During the 1980s, the drug showed promise in animal testing for its potential in treating alcohol abuse — promise that was proven in human clinical trials. The trails confirmed that, when combined with therapy, naltrexone reduced alcohol cravings and relapse rates.
Naltrexone is offered under the brand names ReVia and Depade (in pill form) and Vivitrol (as an injectable). As a pill, naltrexone is usually taken at a 25 to 50 mg dose once a day. As an intramuscular injectable in its extended-release formula, naltrexone is usually administered once a month, at a dose of 380 mg. Some people prefer Vivitrol since they don’t have to remember to take a pill regularly like they do with ReVia or Depade.
Naltrexone works by reducing cravings for alcohol and opioids. It does this by binding and blocking opioid receptors in the body. Thus, it works differently than commonly prescribed buprenorphine and methadone treatments, which trigger opioid receptors in order to reduce cravings.
When taken, naltrexone prevents the blissful and calming effects of opioids. It is also thought to block the pleasurable feelings associated with alcohol use and reduce alcohol cravings.
Naltrexone is not used to treat the immediate withdrawal symptoms associated with opioid or alcohol use disorder. Instead, it’s used to manage opioid and alcohol cravings and addiction. It’s used to help those who have already quit using alcohol or opioids, aiding them in remaining free from drugs and alcohol.
In any form (ReVia, Depade, or Vivitrol), naltrexone works by affecting the opioid system. There are opioid receptors in the brain, and these receptor sites are acted upon by naturally produced internal neurotransmitters (chemical messengers) that result in the release of painkilling chemicals. Opioid drugs bind to opioid receptors and mimic the effects of the naturally produced painkilling chemicals.
As an opioid antagonist, naltrexone works by blocking the opioid receptors. This limits the effect opioid drugs can have on a person and possibly reduces opioid cravings. As a result, it is very effective for treating opioid addiction.
For alcohol use disorder, the manner in which naltrexone works is not fully understood. However, it’s thought to be related to the opioid system as well as the neurotransmitter dopamine.
In animal testing, the administration of an opioid agonist (morphine) was shown to increase alcohol consumption, while the administration of an opioid antagonist (such as naltrexone) was shown to decrease alcohol consumption. This research indicates that the opioid system is involved in some way with the enjoyable or “rewarding” aspects of alcohol consumption.
Researchers agreed that the link between alcohol consumption and the opioid system was most likely due to the neurotransmitter dopamine, which plays a major part in the brain’s reward and motivation system. A meta-analysis of 19 studies found that, when compared to a placebo, naltrexone significantly reduced relapse rates of those in short-term treatment for alcohol use disorder.
Most side effects of naltrexone are mild and short-lasting, although some people may be more sensitive. These are some of the more common side effects:
More serious side effects are rare, but may include the following:
When taken in higher doses (higher than those prescribed clinically), naltrexone can cause liver failure and other serious problems. Stop taking naltrexone and seek medical care if any of the following effects are experienced:
Naltrexone is considered nonaddictive and non-habit-forming.
Although ReVia, Depade, and Vivitrol are considered safe and effective drugs for treating opioid use disorder and alcohol use disorder, there are some considerations to keep in mind about naltrexone.
Research has indicated that naltrexone is an effective tool for helping individuals with alcohol use disorder or opioid use disorder to control and reduce their cravings. However, substance use disorders are complex and often require a more holistic approach in order to provide an individual with a chance at sustained recovery.
There is no cure for addiction. It is a chronic condition that must be consistently managed over time.
Naltrexone is not a cure-all for addiction. Because naltrexone cannot be taken during withdrawal, an individual must get through what is perhaps the most difficult part of their recovery before they can even start taking it. Once they have gotten through withdrawal, they can begin taking ReVia or Vivitrol to control their cravings.
Support is critical during withdrawal and early recovery. You’ll reduce your chances of relapse if you detox in a structured program that offers medical supervision and psychological support. You may be given other medications during detox, including other forms of MAT or medications that treat individual withdrawal symptoms, such as medications to combat insomnia or nausea.
In this type of program, you’ll also receive psychological support around the clock, helping you to process what you’re going through and restricting your access to substances that could lead to relapse. If you attempt to detox at home on your home, relapse is highly likely.
If you return to use after a period of abstinence, your tolerance may be lower. Taking the same dose, or drinking the same amount, you were accustomed to before could more quickly result in overdose.
While it’s not a fast fix for addiction, naltrexone can play an important role in recovery for many individuals, particularly those engaged in a comprehensive treatment program with long-term plans for recovery. For most individuals with a substance use disorder, withdrawal is just the first step on a long journey. They need tools and skills to succeed in recovery and beyond.
Along with therapy where participants learn invaluable coping and life skills, medication-assisted treatment (MAT) can help to make everyday life more manageable and reduce the risk of relapse. Naltrexone may be an ideal choice for many because it isn’t habit-forming, and has generally mild side effects. It should be used as part of a comprehensive treatment program.