You are looking for clear, safe answers. You might be weighing up a prescription you already have. Or you want to know if naltrexone fits into a plan for alcohol or opioid dependence. This recovery focused guide keeps things practical. You will see what naltrexone is, how it works, common side effects, what to avoid and how to access it in the UK. I think small, steady steps help most people. Let’s keep it simple and honest.
What is naltrexone
Naltrexone is a medicine that blocks the effect of opioids at brain opioid receptors. In plain words, it stops opioid drugs from triggering reward signals. It also reduces the rewarding pull of alcohol for many people. In the UK the licensed form is a 50 mg oral tablet on prescription only, usually taken once daily. National guidance places it within structured treatment, never as a solo fix [1].
You will hear two broad dose ranges.
- Standard dose. Usually 25 mg as a first test dose on day one then 50 mg once daily. This is the licensed UK approach for alcohol or for relapse prevention after opioid detox [2].
- Low dose naltrexone or LDN. Much smaller doses, often 1 to 4.5 mg, used off label for pain or immune conditions in research settings. Evidence is growing in some areas like fibromyalgia, with early data suggesting symptom improvement and a good safety profile, yet it remains investigational in the UK and should be supervised by a clinician who understands both benefits and limits.
Conditions naltrexone can help treat
Alcohol dependence
Naltrexone can reduce heavy drinking days and craving. It supports people who aim to stay alcohol free after detox and it can help people reduce harmful drinking within a broader plan. High quality reviews show a meaningful effect, especially on return to heavy drinking, when the 50 mg daily dose is combined with psychological support [1].
Opioid dependence
Naltrexone helps prevent relapse after you complete detox. It blocks opioid effects, so using heroin or codeine while on naltrexone does not produce the usual reward. NICE recommends naltrexone as an option for detoxified adults who want relapse prevention, within a structured programme that includes psychosocial support [2].
Off label use at low dose
LDN is being explored for fibromyalgia and some immune related conditions. A recent meta analysis reported pain improvement in fibromyalgia with low rates of serious adverse events, which is promising, yet larger studies are still needed. If you consider LDN, treat it like any prescription medicine. Use a reputable prescriber, check drug interactions and agree monitoring up front [7].
How naltrexone works
Opioids and alcohol engage the brain reward system. Naltrexone sits on the receptors that would otherwise be activated, so the same dose of an opioid is mostly blocked and the dopamine surge linked to alcohol is softened. The result tends to be fewer urges and less reward if you do drink or try opioids. The effect is pharmacological. Your work on goals and routines still matters, probably more than anything else [1, 2].
Naltrexone side effects
Most people tolerate naltrexone. That said, bodies differ. Go slow if you can.
Common effects
- Nausea or tummy discomfort
- Headache
- Dizziness
- Tiredness or low energy
- Insomnia or vivid dreams
These usually settle in the first few weeks. Taking the tablet with food or moving the dose to morning can help. Your clinician may start with 25 mg on day one to test tolerance then move to 50 mg daily [3].
Less common but important
- Raised liver enzymes on blood tests
- Itching or rash
- Mood change
Serious liver injury appears rare at standard doses. Large safety reviews describe low rates of enzyme elevations and very few cases of clinically apparent liver injury. Your team will check baseline liver tests and repeat them if indicated. If you develop right upper abdominal pain, dark urine, yellowing of eyes or skin or severe fatigue, seek care the same day [4].
When to seek urgent help
- You use opioids and start to feel sudden severe withdrawal after a dose
- You have a severe allergic reaction with swelling of face or tongue or difficulty breathing
- You have new confusion, fainting or severe vomiting
I know it is easy to wait and see. Please call 111 if unsure or 999 for life threatening symptoms.
What to avoid when taking naltrexone or LDN
Naltrexone is an opioid blocker. That single fact explains most practical do and do not items.
- Do not take opioid medicines. That includes codeine, dihydrocodeine, tramadol, morphine, oxycodone, fentanyl. Many cold and cough syrups contain codeine. Some antidiarrhoeal and pain products rely on opioid like actions. Ask your pharmacist to check everything before you buy it.
- Tell every clinician you see that you take naltrexone. Carry the naltrexone information card that services provide. In emergencies, opioid pain relief can be difficult and needs specialist planning.
- Avoid starting naltrexone if you have used opioids in the last 7 to 10 days. A urine screen or a naloxone challenge is sometimes used if there is any doubt. Taking naltrexone too soon can precipitate severe withdrawal.
- If you drink alcohol while on naltrexone, you will not get an aversive reaction like with disulfiram. The medicine reduces reward rather than causing sickness. Services often advise staying on the tablet through a slip to reduce the risk of a full return to heavy drinking. You still aim for fewer or zero drinks based on your plan.
- For LDN specifically, all the opioid cautions still apply. Even low doses can block opioids enough to cause problems. Check any new medicines or supplements with your pharmacist. Keep the same liver test plan you would use for standard dose, unless your prescriber sets a different schedule based on your history.
A quick thought. Many people keep a short wallet note that lists naltrexone, dose, GP details and a contact. Simple, yet helpful.
How effective is naltrexone
The short version. Naltrexone improves outcomes when used with structured psychological support. It reduces return to heavy drinking and helps with craving. It also prevents opioid effects after detox and can lower relapse risk when combined with recovery work.
- For alcohol use disorder, a 2023 review found oral naltrexone at 50 mg daily lowered return to heavy drinking compared with placebo, with a clear clinical benefit when combined with therapy [5].
- A Cochrane review supports opioid antagonists for people aiming to cut down harmful drinking within a wider plan. This includes naltrexone and nalmefene where appropriate [6].
- For opioid dependence, NICE recommends naltrexone after detox as one option to prevent relapse for motivated adults, within a programme that includes psychosocial support and regular follow up.
No medicine replaces support, routines and boundaries. Think of naltrexone as a tool that makes the hard work a little more doable.
Who can and cannot take naltrexone
You can probably take naltrexone if you are an adult without current opioid use and your liver tests are acceptable. Your prescriber will assess the full picture. Some situations need extra care.
- Do not start if you have used opioids in the last week to ten days or if you screen positive for opioids. You might need a naloxone challenge first.
- Avoid if you have acute hepatitis or liver failure. Mild to moderate liver disease needs case by case advice with baseline and follow up tests. Serious liver injury from naltrexone is rare at standard doses, yet caution is sensible if you have chronic liver disease.
- Pregnancy and breastfeeding require specialist advice. Data are limited. Clinicians weigh potential benefit against theoretical risk and consider safer established options first. If you are planning pregnancy, tell your prescriber early.
Pre treatment assessment
- Full medical history and medicines check
- Baseline liver blood tests then repeat tests if indicated
- Alcohol goals agreed in writing or confirmed opioid detox status
- Safety planning, including the information card and overdose education for people at risk of returning to opioids.
Getting a naltrexone prescription in the UK
NHS pathways
Start with your GP or your local drug and alcohol service. You do not need to manage this alone. In England, free local services are available and you can self refer. Your team can arrange assessment therapy and discuss medicines like naltrexone if suitable [8].
- England. Find local support through FRANK. It lists NHS commissioned services you can access near you.
- Scotland, Wales, Northern Ireland. Local NHS boards and government sites list services and helplines. Your GP can guide you to the right team.
Expect a full assessment, a discussion of goals, blood tests and a plan for regular follow up. NICE suggests monthly contact for at least six months when using acamprosate or naltrexone for alcohol dependence, which fits with good practice in most services.
Private clinics and regulated online services
Private prescribers and online clinics can also provide naltrexone where clinically suitable. If you choose an online route, use Care Quality Commission regulated prescribers and a pharmacy that is listed on the General Pharmaceutical Council register. Check the GPhC links and look for the EU common logo or UK distance selling logo where applicable [10].
Cost and availability
On the NHS in England the standard prescription charge is £9.90 per item for 2025 to 2026 unless you are exempt. Prescription prepayment certificates can reduce costs if you need regular items. Scotland, Wales and Northern Ireland have different arrangements with no charge at the point of dispensing for most residents [11].
Private costs vary and depend on consultation fees, dispensing fees and follow up. Ask for total monthly cost before you start.
What to expect during the prescription process
- A first appointment for history, goals and safety
- Blood tests before starting in most cases
- A test dose on day one if you are starting standard dosing
- Clear written advice on what to avoid
- A review plan. Early reviews are usually more frequent then monthly
If you are using naltrexone following opioid detox, your team may add a family member or trusted person into safety planning. It helps with reminders and with quick help if stress builds.
Support and recovery beyond medication
Medicine is one piece. People do better when they add evidence based support. If one method does not click, try another. That is normal.
- Psychological therapies. Cognitive behavioural therapy, relapse prevention work, motivational strategies
- Peer groups. Alcoholics Anonymous, SMART Recovery, local recovery communities
- Practical supports. Sleep, nutrition, movement, money advice
- Family and couple sessions when relationships are under strain
UK help you can reach today.
- NHS 111 for urgent advice when you are unsure what to do next [8].
- FRANK for local drug and alcohol services in England [12].
- Samaritans 116 123, free from any phone, when you need someone to listen without judgement at any hour [9].
I have seen people make progress when they put two or three supports together. Medicine plus one therapy, plus one peer group. Simple rhythm. It is not about being perfect. It is about staying in the game.
Practical tips for day to day success
- Take naltrexone at the same time every day
- Keep a medicines list on your phone and show it at every appointment
- Ask your pharmacist to screen your over the counter choices for codeine or other opioids
- Set a clear alcohol goal with your team and track it
- Book reviews ahead so you do not run out
- If you stop naltrexone, remember your opioid tolerance will be lower. The risk of overdose increases if you return to use. Carry that fact with care and speak to your team about overdose prevention and support.
Frequently asked questions
For alcohol dependence, services often start naltrexone around the time of planned withdrawal or soon after. Some people start it while still drinking to reduce heavy drinking. Your clinician will match the plan to your goals and medical history.
Tell the team you take naltrexone. Non opioid plans can work well. If opioids are needed, this requires specialist planning and close monitoring. Carry your naltrexone card and inform staff early.
Early trials and a recent meta analysis in fibromyalgia suggest good tolerability, with vivid dreams reported more often than placebo. LDN remains off label. Use a clinician who can explain benefits and gaps, check your medicines and monitor appropriately.
At standard doses it rarely causes serious liver injury. Services still check baseline liver tests and repeat if needed, especially if you have existing liver disease. Heavy alcohol use is usually a greater risk to the liver than naltrexone, which is one reason it can be a helpful tool when used carefully.
Closing thoughts
If you are reading this, you are already doing the hard part. You are looking for facts and a plan. Naltrexone can support your goals in the UK when used with the right safeguards and the right supports. Speak with your GP or local service, decide on clear steps and let people help you. You do not need to get everything right at once. You only need to move one step forward today.
References
- National Institute for Health and Care Excellence. Alcohol use disorders: diagnosis, assessment and management of harmful drinking and alcohol dependence. Treatments for adults who misuse alcohol. https://www.nice.org.uk/guidance/cg115/ifp/chapter/treatments-for-adults-who-misuse-alcohol
- National Institute for Health and Care Excellence. Naltrexone for the management of opioid dependence. Technology Appraisal TA115. https://www.nice.org.uk/guidance/ta115
- British National Formulary. Naltrexone hydrochloride. https://bnf.nice.org.uk/drugs/naltrexone-hydrochloride/
- LiverTox. Naltrexone. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.ncbi.nlm.nih.gov/books/NBK548583/
- McPheeters M et al. Pharmacotherapy for alcohol use disorder. JAMA. 2023. https://jamanetwork.com/journals/jama/fullarticle/2811435
- Cochrane Library. Naltrexone and nalmefene for alcohol dependent patients. 2022. https://www.cochrane.org/evidence/CD001867_naltrexone-and-nalmefene-alcohol-dependent-patients
- Efficacy and safety of low dose naltrexone in fibromyalgia. Annals of Medicine and Surgery. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12055162/
- NHS. Drug addiction: getting help. https://www.nhs.uk/live-well/addiction-support/drug-addiction-getting-help/
- Samaritans. How to contact Samaritans. https://www.samaritans.org
- Medicines and Healthcare products Regulatory Agency. FakeMeds campaign. https://fakemeds.campaign.gov.uk/
- Community Pharmacy England. NHS prescription charges frozen for 2025 to 2026. https://cpe.org.uk/our-news/nhs-prescription-charges-frozen-for-2025-26/
- FRANK. Find drug and alcohol support near you. https://talktofrank.com/get-help/find-support-near-you
