- Naltrexone is an FDA-approved opioid antagonist that reduces alcohol cravings and the pleasurable effects of drinking
- Available as a daily oral tablet (50 mg) or monthly injection (Vivitrol, 380 mg) — the injection removes daily adherence concerns
- It works by blocking endorphin receptors, reducing the "buzz" and reward that alcohol normally provides
- Clinical trials show naltrexone reduces heavy drinking days by approximately 25% compared to placebo
- Unlike disulfiram, naltrexone does not make you sick if you drink — it simply reduces how rewarding alcohol feels
- It can be started while still drinking, making it accessible to people not yet ready for complete abstinence
How Naltrexone Works for Alcohol Addiction
When you drink alcohol, your brain releases endorphins — natural opioid peptides that produce feelings of pleasure and reward. These endorphins bind to mu-opioid receptors in the brain's reward circuit, reinforcing the behavior of drinking. Over time, the brain learns to associate alcohol with this opioid-mediated reward, creating powerful cravings.
Naltrexone blocks these mu-opioid receptors. When a person taking naltrexone drinks alcohol, the endorphins are still released, but they cannot bind to their receptors and produce the usual pleasurable sensation. Drinking becomes less rewarding — the person may still feel some effects of alcohol (impairment, sedation) but the euphoric "buzz" is significantly diminished.
Over weeks and months, the brain gradually unlearns the association between alcohol and reward. This process — called pharmacological extinction — weakens the craving pathways that drive compulsive drinking. Many patients describe the experience as "alcohol just doesn't do it for me anymore."
Oral Naltrexone vs. Vivitrol Injection
Oral Naltrexone (ReVia, generic): 50 mg tablet taken once daily. Advantages include flexibility (dose can be adjusted, easy to start and stop) and lower cost. The main disadvantage is adherence — patients must remember to take it daily, and some skip doses intentionally before planned drinking.
Vivitrol (Extended-Release Injectable Naltrexone): 380 mg intramuscular injection administered monthly by a healthcare provider. Advantages include elimination of daily adherence decisions (the medication works continuously for 4 weeks) and potentially higher effectiveness in real-world settings due to consistent medication levels. Disadvantages include higher cost, injection site reactions, and the need for monthly office visits.
The Sinclair Method Connection
The Sinclair Method (TSM) is a specific protocol using naltrexone that has gained significant attention. Rather than taking naltrexone daily regardless of drinking, TSM instructs patients to take naltrexone 1-2 hours before any drinking occasion and not to take it on days they do not drink. The theory is that drinking on naltrexone produces pharmacological extinction (weakening the reward association), while drinking without naltrexone would re-strengthen it.
TSM has shown promising results in some studies, though it remains controversial in mainstream addiction medicine. Most clinical guidelines still recommend daily or continuous naltrexone use rather than targeted dosing.
What to Expect When Starting Naltrexone
Week 1-2: Nausea is the most common early side effect (affects 10-15% of patients) and usually resolves within a few days. Some patients experience headache, dizziness, or fatigue. Starting with a lower dose (25 mg) for the first few days can reduce nausea.
Week 2-4: Cravings begin to diminish. Patients report that alcohol "doesn't taste as good" or "doesn't give me the same feeling." Drinking occasions may still occur but tend to be shorter and less heavy.
Month 1-3: Progressive reduction in drinking frequency and quantity. Many patients naturally shift toward lower consumption without forcing it. The decision not to drink becomes easier as the reward pathway weakens.
Month 3-6: Significant sustained reduction in alcohol consumption. Some patients achieve full abstinence, while others maintain controlled, moderate drinking. Both outcomes represent treatment success.
Who Naltrexone Helps Most
Naltrexone is most effective for people who experience strong alcohol cravings, find that once they start drinking they have difficulty stopping, have a family history of alcohol use disorder (genetic variation in opioid receptor genes may predict response), want to reduce heavy drinking even if not ready for complete abstinence, and are compliant with daily medication or willing to receive monthly injections.
Naltrexone is NOT appropriate for individuals currently taking opioid medications or using opioids (it will precipitate severe withdrawal), those with acute hepatitis or liver failure, or people who have recently used opioids (a 7-14 day opioid-free period is required before starting).
FAQ
Can I still drink on naltrexone?
Naltrexone does not prevent you from drinking and does not make you sick if you drink (unlike disulfiram). You can physically drink alcohol while taking naltrexone. However, the experience will be different — the pleasurable buzz will be reduced. The purpose is to weaken the reward that drives compulsive drinking, gradually reducing consumption over time. Many patients naturally drink less and less as the reward diminishes.
How long do I need to take naltrexone?
Most treatment guidelines recommend a minimum of 3-6 months. Some patients take naltrexone for a year or more. The decision to discontinue should be based on stability in recovery, coping skills, and support system strength — not an arbitrary timeline. Some patients find that discontinuing naltrexone after sustained abstinence does not lead to relapse, while others prefer to continue it as long-term maintenance.
Does naltrexone have side effects?
The most common side effects are nausea (usually temporary, resolves in a few days), headache, dizziness, fatigue, and decreased appetite. Vivitrol injections may cause injection site reactions (pain, hardness, itching). Serious side effects are rare but include liver damage (at very high doses) — liver function monitoring is recommended. Naltrexone is generally well-tolerated and most patients report minimal side effects after the first week.
References:
- Volpicelli, J.R. et al. (1992). Naltrexone in the Treatment of Alcohol Dependence. Archives of General Psychiatry.
- National Institute on Alcohol Abuse and Alcoholism. (2024). Naltrexone for Alcohol Use Disorder.
- Garbutt, J.C. et al. (2005). Efficacy and Tolerability of Long-Acting Injectable Naltrexone (Vivitrol). JAMA.
- Sinclair, J.D. (2001). Evidence About the Use of Naltrexone. Alcohol and Alcoholism.
Valley Spring Recovery Center Editorial Team
This article was reviewed by the Valley Spring Recovery Center editorial team, comprising licensed therapists, medical professionals, and addiction specialists dedicated to providing accurate, evidence-based information about substance use disorders and treatment options.