The journey to overcome alcohol or opioid dependence is a courageous one, but it can feel like an uphill battle against cravings and the risk of relapse. It’s a path that requires support, strength and the right set of tools. For many, a crucial part of this toolkit is a medication called Naltrexone.

Naltrexone is a prescription medication used in medication-assisted treatment (MAT) for Alcohol Use Disorder (AUD) and Opioid Use Disorder (OUD). It belongs to a class of drugs known as opioid antagonists. Importantly, Naltrexone is not a cure, nor is it addictive or a substitute for another substance. Instead, it is a well-established, non-narcotic medication that works by helping to break the cycle of craving and reward, making it easier for individuals to focus on their recovery when used alongside counseling and behavioral therapy.

What does Naltrexone do?

Naltrexone is approved by the U.S. Food and Drug Administration (FDA) to help people who have stopped drinking or using opioids to remain abstinent. Its function differs slightly depending on the substance use disorder being treated.

• For Alcohol Use Disorder (AUD): Naltrexone helps reduce the rewarding, pleasurable effects of drinking alcohol. It can also significantly decrease alcohol cravings. For individuals who do have a drink, it may help them drink less and prevent a “slip” from turning into a full-blown relapse.
• For Opioid Use Disorder (OUD): Naltrexone works by blocking the euphoric and sedative effects of opioids like heroin, morphine, and prescription painkillers. If a person uses opioids while taking Naltrexone, they will not feel “high.” This helps to remove the incentive for using opioids and supports the goal of preventing relapse.

It is critical to understand that a person must be completely free of all opioids for at least 7 to 10 days before starting Naltrexone to avoid severe withdrawal symptoms. Clinical studies have shown that when integrated into a comprehensive treatment program, Naltrexone can be highly effective in reducing relapse rates and supporting long-term recovery (Substance Abuse and Mental Health Services Administration, 2024).

How does Naltrexone work?

To understand how Naltrexone works, it helps to know about the brain’s reward system. When you consume alcohol or use opioids, these substances trigger the release of endorphins, which are the body’s natural “feel-good” chemicals. These endorphins then bind to specific sites in the brain called opioid receptors, creating feelings of pleasure and euphoria. This powerful reward reinforces the desire to use the substance again.

Naltrexone is an opioid antagonist. This means it works by binding to these same opioid receptors and blocking them. Think of Naltrexone as a key that fits perfectly into the receptor’s lock but doesn’t turn it. By occupying the receptor, it prevents endorphins (from alcohol) or opioid drugs from binding to it.

This blocking action is key to its clinical effect. For alcohol, it dampens the rewarding feedback loop, making drinking less appealing. For opioids, it forms a barrier that prevents the drugs from producing a high, thereby reducing the motivation to use. Naltrexone itself does not cause any pleasurable feelings, dependence or withdrawal, making it a safe and valuable tool for recovery.

Naltrexone side effects

Like all medications, Naltrexone can cause side effects. Most are mild and tend to decrease as your body adjusts to the medication.

Common side effects may include:

• Nausea, vomiting or stomach cramps
• Headache
• Dizziness
• Fatigue or difficulty sleeping
• Anxiety or nervousness
• Joint and muscle pain

A critical risk is precipitated withdrawal. If you take Naltrexone before your body is fully clear of opioids, the medication will immediately strip the opioids from your receptors, triggering sudden and severe withdrawal symptoms. For this reason, your doctor will ensure you have been opioid-free for a sufficient period before starting treatment.

Serious side effects are less common but require medical attention. Naltrexone can potentially cause liver damage, especially at higher-than-recommended doses. Your doctor may monitor your liver function with blood tests. People with acute hepatitis or severe liver disease should not take Naltrexone. In rare cases, it can be associated with depression or suicidal thoughts. Contact your doctor right away if you experience signs of an allergic reaction (hives, trouble breathing, swelling) or severe abdominal pain.

Naltrexone dosage

Naltrexone comes as a daily oral tablet (formerly ReVia) or a monthly intramuscular injection (Vivitrol), offering options for patient adherence.

Before starting Naltrexone, your doctor will perform a medical evaluation, possibly including blood and urine tests, to ensure the medication’s safety and suitability. Naltrexone treatment should always be part of a comprehensive program with counseling and support.

Does Naltrexone have a generic version?

Yes, the oral tablet form of Naltrexone is widely available as a generic medication. The FDA ensures that generic versions are bioequivalent to their brand-name counterparts, meaning they are just as safe, effective and high-quality (FDA, 2021). The long-acting injection is currently only available under the brand name Vivitrol. The availability of generic oral Naltrexone can make this important treatment more affordable and accessible.

Conclusion

Naltrexone is a powerful, non-addictive medication that serves as a vital support in the journey of recovery from alcohol and opioid use disorders. By blocking the rewarding effects of these substances, it helps to reduce cravings and prevent relapse, giving individuals the stability they need to engage fully in therapy and rebuild their lives.

While it is not a standalone cure, Naltrexone is a proven and effective component of a comprehensive treatment plan. Working closely with a qualified healthcare provider will help you determine if it is the right choice for your recovery, empowering you to take a confident step forward on your path to lasting health and well-being.

References

1. Substance Abuse and Mental Health Services Administration (SAMHSA). (2024). Naltrexone. https://www.samhsa.gov/medications-substance-use-disorders/medications-counseling-related-conditions/naltrexone
2. U.S. Food and Drug Administration (FDA). (2021). Generic Drug Facts. https://www.fda.gov/drugs/generic-drugs/generic-drug-facts
3. National Institutes of Health. (2022). Naltrexone. MedlinePlus. https://medlineplus.gov/druginfo/meds/a685041.html