How you take naltrexone for alcohol depends on your treatment approach. In the most common method, you take 50 mg once daily, every day, regardless of whether you plan to drink. In a targeted approach, you take it one to two hours before you expect to drink. Both methods reduce heavy drinking, but the timing and reasoning behind each differ significantly.
Daily Dosing: The Standard Approach
The standard protocol starts with 25 mg once a day for the first three days, then increases to 50 mg daily. This ramp-up period helps your body adjust and reduces stomach-related side effects like nausea. Many prescribers skip straight to 50 mg, but the gradual start tends to be easier on your system.
You take the pill at roughly the same time each day, typically in the morning or evening, with or without food. It doesn’t need to be timed around drinking because the medication stays active in your system throughout the day. If 50 mg isn’t producing results after about a week, your prescriber may increase the dose to 100 mg. For people who struggle with remembering a daily pill, an alternative schedule exists: 100 mg on Monday, 100 mg on Wednesday, and 150 mg on Friday. This provides the same weekly total with fewer doses to track.
Targeted Dosing: Taking It Before Drinking
Targeted dosing means taking naltrexone only on days you plan to drink, roughly one to two hours before your first drink. This gives the medication time to reach effective levels in your bloodstream before alcohol hits your brain’s reward system. The idea is that the pill blocks the pleasurable buzz from alcohol in real time, so over weeks and months, your brain gradually stops associating drinking with reward.
This approach is sometimes called the Sinclair Method, named after the researcher who studied it. It appeals to people who aren’t aiming for complete abstinence right away but want to reduce how much and how often they drink. A pilot study found that people using a combination of targeted and daily dosing (25 mg daily plus 25 mg before drinking) reduced their heavy drinking days from about 40% of the time down to roughly 18%. Those using targeted dosing alone also saw reductions, though somewhat smaller ones.
The key rule with targeted dosing: if you don’t take the pill before drinking, you lose the benefit for that session. Missing a dose before a drinking occasion means alcohol will feel rewarding again, which can reinforce the habit you’re trying to break.
How Naltrexone Changes Alcohol’s Effect
When you drink, alcohol triggers the release of your brain’s natural feel-good chemicals (endorphins) in the reward circuitry. Those endorphins then increase dopamine, the neurotransmitter responsible for the pleasurable, reinforcing feeling of a buzz. Naltrexone blocks the receptors where those endorphins land, so the chain reaction that produces the “reward” from drinking gets interrupted. You can still drink on naltrexone, and you’ll still feel some effects of alcohol, but that satisfying warmth or euphoria is dulled or absent.
This is why naltrexone works better at reducing heavy drinking than at promoting total abstinence. It doesn’t make you sick if you drink (that’s a different medication, disulfiram). Instead, it quietly removes the payoff, making it easier to stop after one or two drinks rather than continuing to chase a feeling that isn’t coming.
What to Expect in the First Week
The most common side effects are nausea, headache, and joint or muscle pain. These typically show up in the first few days and fade as your body adjusts. Starting at 25 mg for the first three days helps minimize these effects. Taking the pill with food can also reduce nausea.
Some people feel slightly “off” or low in mood during the first week. This makes sense given that naltrexone blocks receptors involved in your natural reward system. For most people, this settles within a week or two as the body recalibrates.
How Long You’ll Stay on It
Most guidelines recommend staying on naltrexone for at least three to four months. A review in the New England Journal of Medicine suggested that treatment for at least four months is effective, but many people relapse within months to a year after stopping. If you’re still having episodes of heavy drinking during that initial period, a longer course of treatment is worth discussing with your prescriber.
If you’ve been completely abstinent or drinking very lightly for the last several months of treatment, stopping naltrexone is reasonable. Monthly check-ins should continue for four to six months after you stop, because cravings can return. If they do, or if heavy drinking resumes, you can restart the medication without needing to go through any special process. Some people stay on naltrexone for a year or longer, and there’s no firm cutoff point that applies to everyone.
Liver Monitoring and Safety
Your prescriber will likely order a liver enzyme blood test before starting naltrexone and again about a month into treatment. From there, repeat testing every month or so during a standard four-month course is typical. Naltrexone can affect liver enzymes, and since heavy alcohol use already stresses the liver, monitoring both factors together matters. That said, research in Hepatology Communications found that naltrexone is a viable option even for people with existing liver disease, though those with more advanced liver damage need closer monitoring.
One Critical Safety Rule
If you currently use any opioid, whether prescription painkillers, heroin, or even tramadol, you must be completely opioid-free for at least 7 to 10 days before starting naltrexone. Because the medication blocks opioid receptors, taking it while opioids are still in your system triggers immediate, severe withdrawal symptoms. This applies to any opioid use, not just regular use. Be honest with your prescriber about recent opioid exposure, even if it was a one-time event, so you can time the start of naltrexone safely.