What Naltrexone Does in the Brain
Naltrexone is a medication that helps treat alcohol use disorder by targeting the brain’s opioid system, specifically, by blocking mu-opioid receptors. These receptors are involved in the release of dopamine, the chemical responsible for feelings of reward and reinforcement. When you drink alcohol, your brain typically releases a surge of dopamine, making the experience more pleasurable and encouraging repeat use. Naltrexone blunts this effect, making alcohol feel less rewarding.
Unlike disulfiram, naltrexone does not cause illness if you drink while taking it. Instead, it gradually reduces the desire to drink by weakening alcohol’s ability to deliver the expected “buzz.” This mechanism supports a wide range of recovery goals, including complete abstinence or reduced drinking. Naltrexone doesn’t work instantly, it’s most effective when paired with behavioral therapy, peer support, or structured programs. But by dampening the brain’s reward loop, it helps many people regain control over their drinking behavior.
Evidence at a Glance: Drink Less vs. Quit Completely
Naltrexone has been extensively studied in people with alcohol use disorder (AUD), and clinical trials consistently show that it can reduce heavy drinking and help patients maintain abstinence, but its impact depends on the treatment goal. Some individuals aim for complete sobriety, while others seek to cut down on harmful drinking. Naltrexone supports both paths by reducing cravings and making alcohol less reinforcing. According to the American Psychiatric Association’s guidelines, naltrexone is one of the most effective medications for lowering the number of heavy drinking days and extending the time to relapse.
A recent 2025 randomized trial published in JAMA Internal Medicine compared oral and extended-release naltrexone in hospitalized patients with AUD. Both formulations significantly reduced relapse rates, though the injectable version had higher adherence and fewer missed doses, especially after discharge.
Importantly, naltrexone doesn’t work for everyone and it doesn’t create instant abstinence. But for those who respond, it can lead to meaningful reductions in alcohol intake, even without total abstinence. These improvements are associated with lower risks of injury, liver disease, and other complications.
As the WHO’s 2023 report highlights, treatment goals should be individualized, and reduction in use is a valid and measurable outcome.
Oral Naltrexone (50 mg/day): Pros, Cons, Adherence Tricks
Oral naltrexone is typically prescribed as a 50 mg tablet taken once daily. It’s a convenient and affordable option, widely available in generic form. For people newly starting treatment or those who prefer flexibility, oral naltrexone offers a non-invasive way to begin managing alcohol cravings. However, daily dosing requires consistent adherence. Missing doses can reduce its effectiveness and increase the risk of relapse. Some patients benefit from using reminder apps, linking the pill to a daily routine (like brushing teeth), or involving a trusted person for support. It’s best suited for motivated individuals, especially those in early recovery or exploring medication-assisted treatment for the first time.
Extended Release Naltrexone Injection (Vivitrol®)
The extended-release form of naltrexone, often known by the brand name Vivitrol®, is given as a 380 mg intramuscular injection once every four weeks. It delivers steady medication levels and eliminates the need for daily pills, which can be especially helpful for individuals with adherence challenges. It must be administered by a healthcare provider and requires at least 7–10 days of opioid-free status to avoid withdrawal. The injection is often used after inpatient detox or in structured outpatient settings. Although more expensive than oral forms, it may improve outcomes for those with frequent lapses or difficulty sticking to a daily routine.
Side Effect Profile and Safety Labs
Naltrexone is generally well tolerated, but like all medications, it can cause side effects. The most common include nausea, headache, dizziness, and fatigue. These are usually mild and resolve with continued use. Some patients also report sleep disturbances or muscle aches. For those receiving extended-release injections, injection site reactions such as pain, swelling, or irritation can occur. Serious reactions are rare but may include allergic responses or skin necrosis.
Both oral and injectable forms of naltrexone carry a risk of liver toxicity, especially at higher doses. As a precaution, clinicians typically order baseline liver function tests (LFTs) before starting treatment. Mild elevations in liver enzymes may not preclude use, but ongoing monitoring is advised in patients with preexisting liver disease or those taking other hepatotoxic medications.
Naltrexone is contraindicated in individuals who use opioids, as it can precipitate withdrawal. A careful medication history and opioid-free period are essential before initiation.
With proper screening and follow-up, naltrexone is considered a safe and effective treatment option for many people with alcohol use disorder.
Real-Life Success Stories & FAQ
Medication-assisted treatment isn’t about erasing willpower it’s about giving people a fair chance to heal. Many individuals using naltrexone find it helps them regain stability and resist the urges that previously led to relapse.
Tom, a 42-year-old engineer, started oral naltrexone after three inpatient stays. With support from a therapist and his partner, he created a morning ritual: take the pill, drink coffee, review a recovery goal. Over the next year, his cravings decreased, his sleep improved, and he rebuilt trust at work. For Tom, the medication wasn’t magic but it made success possible.
Lena, a single mother in early recovery, found oral pills too easy to skip. After a missed dose triggered a return to drinking, her clinician recommended extended-release naltrexone. With monthly injections, she no longer had to negotiate with herself each morning. She described it as “one less decision to make when I was already exhausted.”
Frequently Asked Questions:
- Can I drink while on naltrexone?
Yes, but you may find the experience duller. Naltrexone doesn’t make you sick like disulfiram it simply blocks the “high,” which helps reduce binge urges. - How fast does it work?
Some patients notice reduced cravings within a few days, while others see steady improvement over 2–4 weeks. It works best when paired with therapy or structured recovery plans. - What if I miss a dose or injection?
For oral tablets, take it as soon as you remember. For injections, contact your provider quickly gaps in coverage may lead to relapse risk. If staying consistent is hard, discuss switching formulations. - Can I use naltrexone if I have liver problems?
Mild liver enzyme elevations aren’t always a barrier, but naltrexone isn’t recommended for those with acute hepatitis or liver failure. Liver function tests are done before and during treatment. - Is naltrexone addictive or habit-forming?
No. Naltrexone is not addictive, doesn’t produce euphoria, and has no potential for misuse. It can be safely stopped under medical guidance.
References
1. American Psychiatric Association. (2018). Practice guideline for the pharmacological treatment of patients with alcohol use disorder. Psychiatric News, 53(4), 8–10. https://psychiatryonline.org/doi/10.1176/appi.pn.2018.pp1b4
2. JAMA Internal Medicine. (2025). Oral vs extended-release naltrexone for alcohol use disorder in hospitalized patients: A randomized clinical trial. JAMA Internal Medicine. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2832702
3. World Health Organization. (2023). Global status report on alcohol and health 2023. https://www.who.int/publications/i/item/9789240096745
