If you’ve started looking into naltrexone, it’s usually because something else hasn’t worked. Willpower, dry months, switching to lower-strength drinks, promising yourself you’ll stop at two: most people who end up reading about naltrexone have tried the obvious things first. The good news is the obvious things failing isn’t a character flaw. Alcohol does something specific to your brain’s reward system, and naltrexone does something specific to interrupt it.
This guide walks through how naltrexone works for alcohol, the two main ways people use it (daily versus targeted), what to expect from side effects, and how to get a prescription if you decide it’s worth trying. It’s long because the topic deserves it. There’s no version of this where 400 words gets you what you need.
# What naltrexone actually is
Naltrexone is an opioid antagonist. It was originally developed in the 1960s for opioid addiction, but in 1994 the FDA approved it for alcohol use disorder after trials showed it reduced heavy drinking days and helped people who wanted to drink less actually drink less. It’s been on the market for thirty years. It’s generic. A month’s supply costs less than most takeaway dinners.
The mechanism is the interesting part. When you drink alcohol, your brain releases endorphins. These are your body’s own opioids, and they’re a big part of why drinking feels good and why your brain wants more of it. Naltrexone blocks the receptors those endorphins land on. The drink still gets you drunk, but the reward signal that your brain learns from is muted. Over time, drinking on naltrexone teaches your brain that alcohol isn’t actually as compelling as it remembered.
This is why naltrexone is usually described as working slowly. You don’t feel different on day one. What changes is the conditioning your brain has built around alcohol over years or decades. Each drink while taking naltrexone is, in a small way, undoing some of that conditioning.
# Who naltrexone is for
The people naltrexone tends to help fall into a few overlapping groups.
Heavy drinkers who want to drink less but not necessarily stop. The original trials specifically measured “heavy drinking days” rather than total abstinence. Naltrexone reliably reduces those.
People who can stop drinking for periods (a dry month, a holiday) but find themselves drifting back to old patterns within weeks of starting again. The relapse curve is what naltrexone is designed to flatten.
People for whom the first drink leads to ten problem dominates. If you can usually have one drink without trouble but occasionally lose the brakes, naltrexone is well-targeted at that pattern.
People in early recovery who want pharmacological support alongside therapy or peer groups. Naltrexone is not incompatible with AA, SMART Recovery, or any other framework. It’s a tool, not a worldview.
It’s worth being honest about who it doesn’t suit as well. People taking opioid pain medication can’t take naltrexone, because the two block each other directly. People with active liver disease need careful screening because naltrexone is metabolised by the liver. And people whose drinking is primarily driven by social ritual rather than craving may find the effect underwhelming. Naltrexone works on the reward circuit, and if your reward isn’t really alcohol-driven (you drink because everyone else is, you stop without much fuss when you decide to), there isn’t much for it to work on.
# The two main ways people take naltrexone
This is where naltrexone splits into two genuinely different approaches, and the choice matters.
# Approach one: daily naltrexone
The conventional approach is one 50mg tablet every day, regardless of whether you plan to drink. The idea is to keep the opioid receptors blocked continuously, so any drink at any time loses its full reward value. This is how the drug was originally trialled and how most prescribing doctors will start you off.
Daily dosing has the advantage of simplicity. One tablet, same time each day, usually with breakfast. You don’t have to plan, predict, or remember anything beyond the daily routine. For people who drink regularly or unpredictably, this is the simplest fit.
The downside is that you’re medicating every day even on days you weren’t going to drink anyway. Side effects, when they happen, happen daily. The first two weeks of nausea and headaches that some people experience apply seven days a week regardless of what you’re doing.
# Approach two: the Sinclair Method (targeted dosing)
The alternative is the Sinclair Method, named after Dr John David Sinclair, the researcher who developed it. You only take naltrexone before you drink. Specifically: one tablet roughly an hour before your first drink, and only on days you intend to drink. On dry days you take nothing.
The mechanism that makes this work is called pharmacological extinction. Each drinking session on naltrexone weakens the brain’s learned association between alcohol and reward. Over months, the urge to drink reduces because the conditioning that drove it is being unwound, drink by drink. Sinclair’s published success rate (defined as significant reduction in drinking or full abstinence) is roughly 78% in compliant patients, which is genuinely high for any addiction intervention.
The Sinclair Method has some real advantages. You take less medication overall, so cumulative side effects are lower. You don’t medicate on dry days. The mechanism (every drink while medicated weakens the habit, every drink without it strengthens it again) gives you a clear principle to follow.
It also has a real disadvantage: discipline. You have to actually take the tablet an hour before drinking every single time. Forget once and you’ve reinforced the old pattern that day instead of weakening it. People who can’t reliably plan an hour ahead, or who drink impulsively at unpredictable moments, struggle with TSM. People who can manage that one-hour window almost always do well.
# Which to choose
If you’re working with a doctor who prescribes both, the choice usually comes down to whether your drinking is predictable enough for the Sinclair Method to be practical. If you can reliably know an hour ahead of time when you’re going to start drinking, TSM is a strong choice. If your drinking is more spontaneous (someone suggests a pub, you say yes, you’re drinking thirty minutes later), daily dosing removes the timing problem.
Some people start on daily and switch to TSM after a few months once they’re feeling better and want to reduce their cumulative dose. Others go the other way: try TSM, find the timing too hard, switch to daily for the simplicity.
There’s no one-right-answer here. Both work. The right one is the one you’ll actually stick to.
# Dosing details
The standard dose is 50mg once daily, or 50mg one hour before drinking on TSM. That’s been the trial dose for decades and it’s where most prescribers start. A few practical points:
The tablet is small and easy to swallow. There’s no special diet or timing requirement beyond the one-hour pre-drink rule for TSM. You can take it with food (some people find this helps with first-week nausea) or on an empty stomach.
If you forget a dose on daily, take it when you remember unless it’s nearly time for the next one. Don’t double up.
If you forget a dose on TSM and have already started drinking, taking it mid-session doesn’t really work. The pharmacological extinction principle relies on the receptors being blocked from the first drink. Taking a tablet at drink three doesn’t undo what the first two drinks did to your conditioning. Better to skip it for that session and resume next time.
A few people are prescribed lower doses (25mg) initially to ease side effects, then ramp up to 50mg over the first week or two. This is fine and worth asking about if you’re nausea-prone.
There’s also low-dose naltrexone (LDN), typically 1.5–4.5mg, which is sometimes prescribed off-label for autoimmune conditions, fibromyalgia, and a few other things. LDN is a different protocol with different mechanisms and is not the same as low-dose-for-alcohol. If a doctor offers you LDN for alcohol, ask them specifically about the evidence: the standard alcohol dose is 50mg, full stop.
# Side effects: what to actually expect
Most people get something. Very few people get something serious.
The most common side effects in the first one to two weeks: mild nausea (about a third of trial patients), headache (roughly a quarter), some dizziness (around one in eight), and trouble sleeping (about one in seven). These almost always fade within two weeks as your body adjusts. Taking the tablet with food helps. Hydration helps. So does taking it earlier in the day if sleep becomes an issue.
The full breakdown of what to expect, when to worry, and how to manage the first month is in our dedicated guide: Naltrexone Side Effects: What’s Normal and What’s Not.
The serious-but-rare effects worth knowing about: liver enzymes can rise, especially at the much higher doses originally used in obesity studies (100–300mg). At 50mg this is genuinely uncommon, but most prescribers will run baseline liver function tests and recheck at one and three months. Mood changes including new or worsening depression are listed as a side effect; if you notice your mood dropping after starting, tell your doctor sooner rather than later. Severe allergic reactions are rare but possible (as with any medication).
The one absolutely critical safety point: naltrexone blocks opioid receptors completely. If you’re on it and you take an opioid (prescription painkillers, codeine cough medicine, anything else that works on those receptors), the opioid won’t work. Worse, if you keep taking more to try to get an effect, you can hit a dangerous overdose point because your tolerance has changed. Tell every doctor and dentist you’re on naltrexone before any procedure, and stop the medication 24–72 hours before any planned surgery so opioids will be available if needed.
# How to get a naltrexone prescription
This is the part most people find frustrating, because it varies enormously by country and by individual doctor.
In the UK, naltrexone is available on the NHS for alcohol use disorder, but in practice access depends heavily on your GP’s familiarity with it. Some GPs will prescribe it directly. Others will refer you to a community alcohol service or specialist. The wait for the latter can be weeks or months in many areas. Private GPs and online prescribers (Boots Online Doctor, several private services) can prescribe it same-week if cost isn’t an issue. Expect to pay £40–80 for an initial consultation and £20–40 for the medication itself per month.
In the US, naltrexone is FDA-approved and prescribable by any doctor, but the same variability applies. Some primary care doctors prescribe it routinely. Others will only refer to addiction specialists. Telehealth services (Ria Health, Workit Health, several others) specialise in naltrexone for alcohol and can prescribe nationwide. Insurance coverage varies; the medication itself is cheap (under $30/month generic at most pharmacies) so even if insurance balks, paying out of pocket is feasible.
In Australia, naltrexone is on the PBS for opioid dependence but not formally for alcohol, which means doctors have to prescribe it off-label. Most GPs comfortable with addiction medicine will do this. Some won’t. The Australian arm of SMART Recovery maintains a list of friendly prescribers.
The conversation to have with your doctor is direct and informational. Tell them what your drinking looks like in practical terms (drinks per week, drinks per session, how long it’s been a problem, what you’ve tried). Tell them what you’re hoping naltrexone will do (reduce heavy drinking days, support a quit attempt, manage the first-drink-leads-to-many problem). Ask them to consider it. If they’re not familiar, point them at the American Psychiatric Association’s pharmacotherapy guidelines, which list naltrexone as first-line for alcohol use disorder.
If your first doctor declines, getting a second opinion is reasonable. Naltrexone is well-studied, off-patent, low-cost, and has a thirty-year safety record. There’s no good reason for it to be hard to get, even though sometimes it is. We have a country-by-country walkthrough in How to Get a Naltrexone Prescription (US, UK, AU), with specifics on each route.
# Naltrexone alongside everything else
A few notes on how naltrexone fits with other things you might be doing.
Therapy and peer support. Naltrexone is more effective combined with some form of behavioural support than alone. The original trials all included counselling. This doesn’t have to be formal therapy: AA, SMART Recovery, or even a regular check-in with a friend who knows what you’re trying to do all count. The medication handles the biology; the support handles the patterns and triggers.
Other alcohol medications. Acamprosate (Campral) works on a different mechanism (glutamate stabilisation) and is sometimes prescribed alongside naltrexone for compounding effect. Disulfiram (Antabuse) makes you violently ill if you drink, which is a fundamentally different approach: it relies on aversion rather than extinction, and most people find it harder to stick to long-term. Nalmefene is a close relative of naltrexone, prescribed in Europe specifically for as-needed use; it works similarly but isn’t widely available in the US or UK.
Diet and exercise. Nothing about naltrexone is diet-restrictive. There’s some evidence it modestly helps with weight loss in heavy drinkers, partly because alcohol calories drop and partly because it also reduces some food cravings (the same reward circuit overlaps). Don’t take it as a weight loss drug, but don’t be surprised if your weight shifts.
Pregnancy. Naltrexone is category C. Don’t take it if you’re pregnant or planning to become pregnant without specifically discussing the risks and alternatives with your obstetrician. Most prescribers will switch you off it during pregnancy.
# What to track while you’re on naltrexone
If you’re going to put a thirty-year-old generic medication into your body for several months, you might as well know whether it’s actually working.
The metrics that matter:
Drinking days per week. The fundamental signal. If it’s going down over months, the medication is doing its job.
Drinks per session. TSM in particular tends to lower this before it lowers session frequency. If you used to drink five and now drink three on a session, that’s a real change even before you have fewer sessions.
The “I could take it or leave it” feeling. The most consistent thing TSM users report is that drinking starts to feel optional in a way it didn’t before. The compulsion eases. This is hard to put on a graph but it’s the most meaningful signal.
Mood and sleep. Worth tracking because both can shift on naltrexone, and you want to spot changes early.
Logging this in AlcoLog handles drinks-per-session and drinks-per-week automatically. The medication card has a separate dose log with timestamps, so you can spot whether you took your tablet within the one-hour window for TSM.
Drinking patterns also feed a 0-100 health score the app calls AlcoScore, covering six pillars (frequency, intensity, trend, control, behaviour, recovery). The score is built from your drinking only. Tablet logs inform you, not your score.
# What naltrexone won’t do
Two honest framings worth keeping in mind.
Naltrexone won’t make you stop wanting alcohol. It changes the reward signal your brain gets from alcohol, but it doesn’t remove your habits, your triggers, your social patterns, or whatever underlying reasons you’ve been drinking. People who go in expecting “I’ll take this pill and not want to drink” usually don’t get that. People who go in expecting “this will help me drink less when I want to drink less” usually do.
Naltrexone won’t fix the things you drink to avoid. If you drink because of anxiety, the anxiety is still there. If you drink because of a difficult relationship, the relationship is still there. The medication makes alcohol less compelling as a coping mechanism, which is genuinely useful, but it doesn’t address the thing being coped with. Most people on naltrexone benefit from running the medication alongside whatever’s actually causing the drinking.
# A reasonable plan for trying naltrexone
If you’ve read this far and want to actually try it, here’s a sensible path.
- Decide whether you’re going daily or TSM. If you don’t know, default to daily, it’s simpler.
- Talk to your GP, primary care doctor, or telehealth service. Ask specifically for naltrexone for alcohol use disorder. If they decline or don’t know, ask for a referral or try a service that specialises in addiction medicine.
- Get baseline liver function bloods done. Re-check at one month and three months.
- Start at 25mg for the first three to seven days if you’re worried about side effects, then move to 50mg.
- Track your drinking honestly from day one. You need a baseline to compare against.
- Give it three months minimum before deciding whether it’s working. The mechanism is gradual; the first month often feels like nothing has changed.
- Plan for at least six months. Most people see meaningful change at three months and substantial change at six. Stopping after one month means stopping before the data was even in.
Naltrexone is one of the most well-evidenced, lowest-risk interventions for problem drinking we have. It’s also underprescribed, partly because doctors don’t always know about it, partly because patients don’t always ask. If you’ve tried the obvious things and they haven’t worked, it’s worth a conversation.
# How AlcoLog helps with naltrexone
AlcoLog includes a Medications card with dose logging for naltrexone (timestamp + amount), a configurable redose timer, and Pro-tier location reminders that fire when you arrive at or leave a saved location. The medication card sits alongside your drink log, so you can see what you took and when alongside what you drank.
AlcoScore, the 0-100 health score the app produces from your drinking patterns, is deliberately separate from medication tracking. The app’s view: medication is a tool you choose to use, not a behaviour the app should grade you on. Your dose log informs you, not your score.
All your data stays on your device. There’s no account, no email, and no login. CSV export of your sessions is free; Pro adds unlimited CSV and PDF reports if you want to share a printout with your doctor.
Privacy stays local. The dose log lives on your device, not on a server. If you want to share it with a doctor, the CSV export gives you a clean printout for an appointment.
