A medicine to reduce heavy drinking
Nalmefene
An opioid-blocking medicine taken on at-risk days to reduce craving and heavy drinking.
What is Nalmefene?
Nalmefene is a medicine that helps reduce craving and heavy drinking in people who want to cut down rather than stop completely. It is taken on days when there is a risk of drinking, ideally a little before, to lessen the urge and the amount drunk. It works best alongside support that helps people reduce their alcohol use, tailored to the person. Importantly, it is an opioid-blocker, so it must not be used by anyone who needs opioid painkillers, as it can block their effect or trigger withdrawal. Common effects include nausea, dizziness, sleep problems and feeling unwell, which often ease over the first days.
Education and reference only. This is a plain-language guide to Nalmefene — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Nalmefene is a medicine used to help people reduce heavy drinking, aimed at those who want to cut down their alcohol use rather than stop altogether straight away. It is taken as needed, on days when there is a risk of drinking, rather than every single day. It is prescribed alongside support that helps reduce alcohol consumption, and it is meant for people who are still drinking heavily but do not need immediate detox. It is taken by mouth as a tablet.
How it works
Nalmefene works on the brain's opioid receptors, which are part of the reward system that alcohol acts on. By blocking and adjusting this system, it dampens the pleasurable 'reward' and the craving linked to drinking, which can make it easier to stop after fewer drinks and to drink less overall. Because it is an opioid-blocker, the same action means it interferes with opioid painkillers, blocking their effect or causing withdrawal in anyone dependent on opioids, which is why it must not be combined with them.
Company & origin
Originated / developed by: Generic (long-established).
A medicine used in the UK to help reduce alcohol craving and heavy drinking, taken on days when there is a risk of drinking.
Practical use
How to take Nalmefene
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take one tablet on each day you feel there is a risk of drinking, ideally one to two hours before you might start.
- If you have already started drinking without taking it, take it as soon as you can that day.
- Do not take it if you are using opioid painkillers or are dependent on opioids, as it can block them or cause withdrawal.
- Tell any healthcare professional you take nalmefene before any surgery or strong pain relief is planned.
- Use it alongside the support you have been offered, as the two together help reduce drinking most.
Weighing it up
Advantages & disadvantages of Nalmefene
Advantages
- Helps reduce craving and heavy drinking for people who want to cut down.
- Taken only on days when there is a risk of drinking, rather than every day.
- Works alongside support and suits people who are not aiming to stop completely at once.
Disadvantages
- Must not be used with opioid painkillers or by people dependent on opioids, as it blocks them or causes withdrawal.
- Commonly causes nausea, dizziness, headache and sleep problems, especially early on.
- It is not suitable for people who need immediate, complete alcohol withdrawal.
Practical use
Good to know
Nalmefene is designed for reducing drinking, taken on at-risk days, ideally one to two hours before drinking might start, and it works best with support that helps people change their drinking. The single most important caution is that it is an opioid-blocker: it must not be used by anyone taking opioid painkillers (such as codeine or morphine) or who is dependent on opioids, because it can stop those medicines working or cause sudden withdrawal; this also matters before any planned surgery or strong pain relief. Common early effects include nausea, dizziness, headache, tiredness and trouble sleeping, which often settle within the first days. It is not intended for people who need to stop alcohol completely and immediately or who have severe withdrawal, and the liver and kidneys are considered before it is prescribed.
Who should not take it / use with caution
- Anyone taking opioid painkillers, or who is dependent on opioids or in opioid withdrawal, must not use it.
- It is not for people who need to stop alcohol completely and immediately or who have severe alcohol withdrawal.
- Used with caution, or avoided, in significant liver or kidney problems, which are assessed first.
Monitoring
- Reviewing how much drinking is reducing and whether to continue treatment.
- Checking that no opioid painkillers are needed, including before any surgery.
- Considering liver and kidney function and overall tolerability.
Side effects
- Nausea, dizziness, headache, tiredness and difficulty sleeping are common, especially in the first days.
- Feeling sick or unwell, a faster heartbeat or restlessness can occur.
- Less often, mood changes or confusion, which should be discussed with your prescriber.
Key interactions
- It blocks opioid painkillers such as codeine and morphine, so they will not work normally while taking it.
- In someone dependent on opioids it can trigger sudden withdrawal.
- Care is needed with other medicines that affect mood or the nervous system, so tell your prescriber what you take.
Available as: Tablets taken by mouth.
Answers
Nalmefene: frequently asked questions
Do I take nalmefene every day?
No. It is taken only on days when you think there is a risk of drinking, ideally one to two hours before you might start, rather than every single day.
Why can't I use it with painkillers?
Nalmefene is an opioid-blocker, so it stops opioid painkillers such as codeine or morphine from working and can cause withdrawal in anyone dependent on opioids; tell your team before any surgery or strong pain relief.
Is nalmefene for stopping drinking completely?
It is mainly designed to help reduce heavy drinking rather than to stop completely and immediately, and it works best alongside support that helps you cut down.
Will it make me feel unwell?
Nausea, dizziness, headache, tiredness and sleep problems are common in the first days and usually settle; tell your prescriber if they are troublesome.
Does it work on its own?
It works best as part of a wider plan with support to reduce drinking, tailored to you, rather than relying on the medicine alone.
The wider class
About Alcohol-craving reducer
Nalmefene belongs to the alcohol-craving reducer class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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