Naltrexone for Alcohol in the UK: What Is It, and How Does It Actually Work?
By Rethink Drink. For UK adults. Reviewed November 2026.
Naltrexone is a prescription medicine that blocks the brain's opioid receptors.
That matters with alcohol... because part of the reward you get from a drink runs through those same receptors.
In the UK, it's licensed to help people who have stopped drinking to stay stopped. The Sinclair Method uses it in a different way, and that use is off-label here.
Maybe you're just starting to look into this. Or maybe you've already tried a lot... AA, rehab, an app, a detox. Maybe even naltrexone itself, bought online and taken on your own.
You might be holding it all together, just. Looking fine from the outside... and quietly feeling you've lost your off switch. And you'd love to have that choice again.
This page won't promise you that. It will tell you, honestly, what this medicine is and isn't... including why it sometimes doesn't work.
We're conditioned to expect a medicine to do the job for us... Paracetamol for a headache. Take it, and the problem drifts away.
Alcohol doesn't work like that. And naltrexone can be used in:
Two completely different ways, with
Two completely different kinds of support, for
Two completely different goals.
This page explains a medicine. It doesn't recommend one. Whether it's right for you is a decision for a prescriber who knows your health.
In short
One medicine, two methods. On the NHS, it's taken daily once you've stopped drinking, to stay stopped. The Sinclair Method uses it before drinking, so the desire can weaken over time and you drink less, or stop if you choose to. Only the first matches its UK licence.
It doesn't stop you getting drunk, and it isn't addictive.
It isn't for everyone. Not with opioids, including some common painkillers, and not with some liver and kidney problems.
Does it work? It has a real, modest effect in trials. It varies from person to person, and support seems to matter.
Feeling rough early on isn't always the tablet. Drinking less can bring its own poor sleep and anxiety.
Check first: if your body depends on alcohol, stopping or cutting down too fast can be dangerous. Speak to your GP or local alcohol service before you change anything...
...Our free units calculator and AUDIT-C check give you a starting picture in a couple of minutes. They can't tell you whether your body depends on alcohol; a doctor can.
What is naltrexone?
Naltrexone is a prescription-only medicine, taken as a tablet.
It's what's called an opioid antagonist.
In plain words... it sits on the brain's opioid receptors and blocks them. While it's there, the body's own opioid-like chemicals have almost nowhere to land, which is how the reward cycle is interrupted.
It isn't a "makes you sick if you drink" medicine either. That's a different drug, disulfiram. The UK product information describes naltrexone as non-aversive: it doesn't cause a reaction when alcohol is drunk.
How does naltrexone work on alcohol?
When you drink, your brain releases endorphins: its own feel-good, opioid-like chemicals. They land on opioid receptors... And that provides a reward.
In a brain-scan study of 25 people (13 heavy drinkers and 12 who weren't), alcohol triggered endorphin release in the brain's reward areas. The more endorphins released, the more pleasure the drinkers reported (Mitchell and colleagues, 2012).
That reward is how drinking becomes learned. Every drink that pays out teaches your brain the same lesson... Drink equals a reward.
Naltrexone blocks the receptors those endorphins use, so the reward is dampened. You still feel the alcohol. You can still get drunk (being drunk isn't the reward; many people confuse this). What goes is the reward.
More on the biology: alcohol and endorphins.
How do you take naltrexone? Every day?
It depends which method you mean. Whichever it is, your prescriber decides how and when you take it.
On the NHS: daily, to stay stopped
Here, naltrexone is taken daily, after you've stopped drinking.
The NHS describes it as a medicine that helps reduce alcohol cravings. And if a drink does happen, the reward is muted, which can make it easier for one drink not to become many.
On The Sinclair Method: before drinking, to drink less over time
Here, naltrexone is taken before drinking, at a time your prescriber sets, while you're still drinking.
It's important to note: it's not the medication itself that makes the method, it's the protocol of how to take it.
The idea came from the late Dr David Sinclair. If drinking happens while the reward is blocked, the learned behaviour stops being rewarded... and the relationship with alcohol can gradually weaken. He called this pharmacological extinction.
Think of a job you're no longer paid for.
How long would you keep turning up?
It only applies to drinks taken while the reward is blocked, and it happens over time, not overnight. More on how extinction works and how long it usually takes.
Which raises the question most pages skip...
If you keep drinking while it works, who's keeping an eye on how it's going?
We'll come back to that.
Does naltrexone work for alcohol?
For some people, yes, modestly. Not for everyone. Here's what the evidence actually says.
One Cochrane review brought together 50 trials, with nearly 8,000 people. Naltrexone lowered the risk of going back to heavy drinking compared with a placebo (to 83% of the placebo group's risk). Its effect on whether people drank at all was less clear (Rösner and colleagues).
A real effect. Not a large one. And it varies from person to person.
For The Sinclair Method, you'll see a 78% figure quoted, including by us. It comes from Dr Sinclair's own clinics in Finland, not a controlled trial. Controlled trials show a smaller, real effect, and results vary. The whole picture, including what that figure can't tell you: what the research really shows.
And one finding keeps coming back... support matters. More on that below.
What is naltrexone licensed for in the UK?
In the UK, naltrexone is licensed as an add-on treatment, taken daily, as part of a programme that includes psychological support. It's used:
For alcohol dependence: to help people who have stopped drinking stay stopped.
For opioid dependence: to help people who have come off opioids stay off them.
Not every UK product carries both licences: an NHS supply notice in 2024 said using an opioid-only one for alcohol would be off-label.
NICE says that after a successful withdrawal from alcohol, people with moderate or severe dependence can be offered acamprosate or naltrexone, alongside one-to-one psychological support. The UK clinical guidelines call naltrexone a first-line treatment for preventing relapse.
The Sinclair Method is different. Taking naltrexone before drinking is outside its UK licence and UK guidelines. Doctors can prescribe outside a licence, but the General Medical Council says they must be satisfied there's enough evidence, and they take responsibility for it.
...And a myth worth clearing up. You may have read that the NHS prescribes naltrexone for gambling, but not for alcohol. Not so: NICE recommends it for alcohol, to help people stay stopped, while its 2025 gambling guideline says only to consider it once talking therapy hasn't helped, and noted that use was off-label.
Can I get naltrexone from my GP or the NHS?
For its licensed use, yes. Usually through a local specialist alcohol service (usually secondary care), sometimes continued by your GP (General Practitioner).
For The Sinclair Method, it's uncommon. And that's rarely about you. It's off-label, it's a specialist subject, and GPs are generalists by design... So if yours hadn't heard of it, that's common.
It also means drinking while you're on it, which needs someone keeping an eye on things week by week. A ten-minute GP appointment every few weeks can't support that.
How to walk in prepared: Can I get naltrexone from my GP or the NHS?
...And if they've already said no: My GP said no. What now?
Can you buy naltrexone online in the UK?
Yes, legally... with a prescription. Naltrexone is a prescription-only medicine, so the legal routes are the NHS, or a private prescriber (online or in person) after a consultation, with the medicine dispensed by a registered pharmacy.
Check the pharmacy is on the General Pharmaceutical Council's register. The GPhC says that's the only way to confirm a pharmacy is legally operating in Great Britain.
A website that sells it with no prescription is a different thing altogether. There's no way to know the tablets are genuine... And nobody is checking your liver, your other medicines or whether it's safe for you.
Privately, there's no single price, because you're usually paying for a few separate things: a prescriber's consultation, the medicine from a pharmacy, sometimes blood tests, and the support.
How it works in practice, including what to ask about cost: Where to get naltrexone in the UK. Rethink Drink's programmes, and prices, can be found here.
Does naltrexone make you feel ill?
Like any medicine, it can cause side effects, although not everybody gets them. The UK patient leaflet lists nausea, headache, trouble sleeping, anxiety, restlessness and feeling weak among the very common ones. Liver problems are less common, which is why the blood tests matter.
The full list, in plain English: Naltrexone side effects (UK). And if you've heard it blocks all pleasure... Does naltrexone block all pleasure?
I tried naltrexone and it didn't work, or I didn't like how it felt. Why?
It's one of the most common messages we get. Sometimes it simply isn't the right medicine for that person, and some people do get side effects.
Often, too, it was bought online, taken in a way that matched neither method, or taken with nobody alongside.
And a common point where people think it's not working is a plateau: drinking comes down, then stalls. Often that's because the habit hasn't been worked on yet.
If side effects are bothering you, speak to your prescriber; if they're severe, stop and get medical advice. Whether to try again, or try something else, is their decision.
...I tried naltrexone and it didn't work. Why?
Is it the tablet, or is it cutting down?
Honestly? It can be hard to tell.
When you drink less, your body notices. The NHS lists difficulty sleeping, anxiety and nausea among the symptoms of alcohol withdrawal.
The naltrexone leaflet lists sleeplessness, anxiety and nausea too.
Same symptoms. Two possible causes. Sometimes both at once.
And passing out isn't sleep.
Drinkaware explains that alcohol might help you drop off, but it cuts the REM stage of sleep, so you wake less refreshed... and that temporary insomnia is a common side effect of withdrawal. So the first nights with less alcohol can leave you shattered. And it's easy to blame the newest thing in your life: the tablet.
Feeling flat works the same way. It can be the tablet, but it can also be part of cutting down.
So:
Note what you feel, and when.
Tell your prescriber. Working out which is which is their job.
Don't change how or when you take it, or stop, without your prescriber. The leaflet says to take it exactly as your doctor has told you. If side effects are severe, stop and get medical advice.
Feeling rough in the first weeks isn't a verdict on you. It's information, and it belongs with your prescriber.
Will naltrexone make me feel out of control? Does it stop you getting drunk?
No, and no.
It doesn't give you a high. The UK product information says it doesn't lead to physical or psychological dependence.
And it doesn't make you sober. In a laboratory study of 19 social drinkers, naltrexone didn't change how the body processed alcohol, or people's coordination and reaction tasks (Swift and colleagues, 1994).
So alcohol still impairs you, and the drink-drive limit still applies. The product information also says naltrexone itself may affect driving, so ask your prescriber what that means for you.
Who shouldn't take naltrexone?
Your prescriber will check. The UK product information says it must not be used by people who:
Are taking opioids, or have recently. That includes codeine, tramadol, morphine and methadone.
Are dependent on opioids. Naltrexone can trigger sudden, severe withdrawal.
Have acute hepatitis, liver failure or severe liver problems.
Have severe kidney problems.
Are allergic to naltrexone.
That's down to your prescribing doctor to discuss with you.
Other considerations:
Other medicines. Some over-the-counter cough, cold and anti-diarrhoea medicines contain opioids. Tell your prescriber and pharmacist about everything you take: Does naltrexone interact with other medications?
Liver checks. Liver blood tests should be done before and during treatment.
Pregnancy and breastfeeding. UK guidelines advise avoiding it in pregnancy unless the benefit outweighs the risk, and not using it while breastfeeding.
Emergencies. If you ever need strong pain relief, the doctor treating you needs to know you take naltrexone.
If you have used opioids before. After naltrexone, your body can be more sensitive to opioids. Trying to override the block with opioids is dangerous and can be fatal.
Why is a prescription only the start?
However you get naltrexone, a prescription is the beginning. Not the end.
On the NHS, it comes with a treatment plan and psychological support. And the research points the same way.
In a key Finnish trial of people who were still drinking when they started, naltrexone beat a placebo for people who also had coping-skills sessions, but not for people given only general support (Heinälä and colleagues, 2001). Why support matters so much on The Sinclair Method.
And remember the question we left you with...
The Sinclair Method asks something the NHS route doesn't: you keep drinking while it works. Your drinking comes down over time, and someone needs eyes and ears on how that's going... Including the early weeks, when it's hard to tell what's the tablet and what's the change.
Over time, the medicine can quieten the desire...
...BUT taking a tablet cannot change our habits.
The Friday nights, the stress, the routines built around a drink over years... Your habits, triggers, mindset, environment. That's the real work. And it's where support makes the difference.
For Matt, our co-founder, one of the biggest was something he'd never noticed: he hadn't realised how much of a trigger his thirst and hunger actually were. Hydration and eating well became part of his routine... In his words, "I was taking care of myself for the first time in a long time."
And no one had walked him through that side of things... That's the point where Rethink Drink was born.
Talk it through with your prescriber and coach as you go.
And naltrexone isn't the only route. Abstinence, AA, other medicines and your local NHS service all help people every day: Alcohol treatment options in the UK.
Common questions
Do I have to stop drinking before taking naltrexone?
For its licensed NHS use, usually yes. The Sinclair Method doesn't ask you to stop first. Either way, if your body depends on alcohol, a doctor needs to look at that first: Do I need a detox first?
Can you drink alcohol on naltrexone?
It doesn't cause a reaction, and alcohol still affects you as normal. Drinking on it is how The Sinclair Method uses it, off-label, so your prescriber needs to know your plan.
How long do people take naltrexone for?
On the NHS, where it's taken daily after stopping, UK guidelines say it's commonly prescribed for around six months, or longer if it's helping. On The Sinclair Method, Dr Sinclair's advice was to keep using it whenever you drink; some people stop drinking altogether. Your prescriber decides, so don't stop or change it without them.
Is naltrexone the same as Ozempic?
No. Ozempic is semaglutide, licensed in the UK for type 2 diabetes, not alcohol, and its alcohol research is early (Hendershot and colleagues, 2025). Side by side: Ozempic vs naltrexone for alcohol
If you'd like support from us
Rethink Drink is a UK coaching service built around The Sinclair Method. Our programmes include a consultation with an independent prescriber, who decides whether treatment is suitable. Clinical oversight is provided by consultant psychiatrist Professor Jonathan Chick. Any prescription is dispensed by an independent partner pharmacy. Our coaches work with you, week by week, on everything around it.
And whatever happens, you can talk to someone today. Drinkline, the national alcohol helpline, is free and confidential: 0300 123 1110.
Please look after yourself
This page is here to help you understand your options. It isn't medical advice, and it can't replace a conversation with a doctor who can ask qualifying questions.
Before you change how much you drink or start any medication, speak to your GP or a prescriber.
We really hope this post helps. If you have any questions, you can contact us here.
The Rethink Drink team
Sources
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NHS North East London. Medicine supply notification MSN/2024/087: naltrexone tablets. August 2024.
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