Naltrexone overview
Naltrexone is a medicine that blocks opioid receptors in the brain and other tissues. It is used as part of a medically supervised treatment plan, rather than as a stand-alone solution. In Sweden, treatment should be assessed by a qualified prescriber who can consider the person’s diagnosis, treatment goals, and medical history.
The active ingredient is naltrexone, commonly supplied as naltrexone hydrochloride in tablet formulations. It is an opioid antagonist, meaning it reduces or prevents the effects of opioid medicines and illicit opioids at receptor sites. It does not produce opioid-like effects and is not intended to relieve acute opioid withdrawal.
Naltrexone is generally prescribed alongside counselling, psychosocial support, and follow-up care where appropriate. The most suitable treatment approach varies between individuals. A pharmacist or prescribing clinician can explain how naltrexone fits into a broader recovery plan.
Approved uses and clinical role
Naltrexone may be used to support treatment of alcohol dependence by helping reduce the rewarding effects associated with drinking. It can also be used after opioid detoxification to help prevent relapse, provided the person is no longer physically dependent on opioids. The exact approved indications and local practice may differ between products and healthcare settings in Sweden.
For alcohol-related treatment, naltrexone is not designed to make alcohol safe or to remove the health risks of heavy drinking. It may reduce cravings or help some people drink less when used within a structured care plan. Continued support and regular clinical review remain important.
For opioid-use treatment, naltrexone should only be started after an adequate opioid-free period confirmed by a clinician. Taking it too soon after opioids can trigger sudden, severe withdrawal. It is not a substitute for emergency care, detoxification support, or overdose prevention planning.
Origin and development of naltrexone
Naltrexone was developed during research into medicines that could block opioid receptor activity. It emerged from work on related opioid-antagonist compounds in the mid-twentieth century. Its development provided clinicians with a longer-acting oral option than some earlier opioid-blocking medicines.
Over time, clinical research explored naltrexone in alcohol dependence and in relapse prevention following opioid detoxification. Regulatory approvals and treatment protocols have differed across countries. Modern use is guided by product information, clinical evidence, patient assessment, and local regulations.
The medicine has been studied for decades, but long-standing availability does not mean it is appropriate for everyone. Liver health, opioid exposure, pregnancy considerations, and mental health history can all affect suitability. Individual clinical assessment is therefore essential before treatment begins.
How naltrexone works
Naltrexone attaches to opioid receptors without activating them. By occupying these receptors, it can block or lessen the effects of opioid substances. This receptor blockade is also thought to contribute to its role in reducing alcohol-related reward for some patients.
The medicine does not reverse an opioid overdose in the way that naloxone can. Naltrexone is a maintenance treatment, while suspected overdose requires urgent emergency action. In Sweden, call 112 immediately if overdose is suspected.
Because opioid receptors are involved in pain treatment, naltrexone can make opioid pain medicines less effective. Patients should tell dentists, surgeons, emergency teams, and other healthcare professionals that they take naltrexone. Medical-alert information may be useful where recommended by a clinician.
Forms and commonly used strengths
Naltrexone is commonly available as oral tablets, often in a 50 mg strength. The formulation, pack size, and licensed strengths supplied may vary between pharmacies and manufacturers. A prescription should specify the appropriate product and directions.
Long-acting injectable naltrexone exists in some markets, but its availability and authorisation may not be the same in Sweden. Injectable treatment is administered by trained healthcare professionals. It should not be confused with oral naltrexone tablets.
Some websites discuss low-dose naltrexone for conditions outside its approved indications. Such use may be off-label and requires specialist clinical judgement. Patients should not alter tablets, split doses, or seek compounded products without clear advice from a prescriber and pharmacist.
Taking naltrexone safely
Take naltrexone exactly as directed on the prescription label and in the patient leaflet. It may be taken with food if stomach upset occurs, unless a clinician has advised otherwise. Do not take extra doses to compensate for a missed tablet.
Before starting treatment for opioid dependence, the prescriber must establish that opioids have been stopped for long enough. The required opioid-free interval depends on the opioid used, the formulation, and the person’s clinical circumstances. This assessment is important because precipitated withdrawal can be medically serious.
If a dose is missed, follow the instructions provided by the prescriber or pharmacist. Do not restart treatment after opioid use without seeking clinical advice. Keeping scheduled follow-up appointments helps clinicians monitor benefits, adverse effects, and any changes in other medicines.
Duration of effect and elimination
After a standard oral dose, opioid-receptor blocking effects may last about 24 hours, although the clinical effect varies by dose and individual factors. Some prescribed regimens use different dosing intervals under medical supervision. The product leaflet and prescriber’s directions should take priority over general estimates.
Naltrexone itself is cleared relatively quickly, while an active metabolite remains in the body longer. As a general pharmacokinetic guide, most of the medicine and its metabolites are expected to decline substantially over several days. Liver function, dose, and repeated use can influence this timeline.
Feeling that the effect has worn off does not mean it is safe to use opioids. Opioid tolerance can be reduced after abstinence or treatment interruption, increasing overdose risk if opioids are resumed. Discuss discontinuation or any planned change in treatment with a healthcare professional.
Evidence and treatment expectations
Clinical research supports naltrexone as one evidence-based option for selected people with alcohol dependence or opioid dependence after detoxification. Benefits are most meaningful when treatment is matched to the individual’s circumstances and combined with appropriate support. Results can vary, and no medicine guarantees abstinence or prevents relapse in every patient.
Research has also identified practical limitations, including the need for consistent adherence and the need to avoid opioids before initiation. Monitoring is particularly relevant for patients with liver disease or complex medication regimens. A prescriber may arrange tests or follow-up based on clinical need.
Naltrexone treatment should be reviewed if goals are not being met, side effects become troublesome, or opioid pain relief may be needed. Alternative therapies may be more suitable for some people. Decisions should be made with a clinician familiar with addiction medicine and the patient’s wider health needs.
Dependence, addiction, and stopping treatment
Naltrexone is not an opioid and is not generally considered to cause physical dependence or addiction. It does not create the euphoric effects associated with opioid agonists. However, it should still be used only under professional guidance.
Stopping naltrexone does not usually cause a characteristic withdrawal syndrome. The key concern is that opioid tolerance may be lower after treatment, abstinence, or reduced opioid use. A previously tolerated opioid dose may therefore become dangerous or fatal if resumed.
People taking naltrexone for alcohol dependence may still need support when treatment changes or ends. Cravings, stress, and relapse risk can continue even after medication is stopped. A treatment plan should address behavioural support and emergency contacts where appropriate.
Side effects and allergic reactions
Possible side effects include nausea, abdominal discomfort, headache, dizziness, tiredness, sleep disturbance, or reduced appetite. These effects are often mild, but they can be persistent for some people. Report troublesome or unexpected symptoms to a pharmacist or prescriber.
More serious concerns can include signs of liver problems, such as yellowing of the skin or eyes, dark urine, unusual tiredness, or persistent upper abdominal pain. Seek prompt medical assessment if these symptoms occur. Patients with known liver disease need careful medical evaluation before and during treatment.
Allergic reactions are uncommon but can be serious. Urgent help is needed for swelling of the face or throat, breathing difficulty, widespread rash, or faintness. Anyone with a known allergy to naltrexone or any listed ingredient should not take the product.
Who should not take naltrexone
Naltrexone is not suitable for people currently using opioids, physically dependent on opioids, or experiencing opioid withdrawal. This includes opioid-containing pain medicines, opioid substitution treatments, and some cough or diarrhoea medicines. A clinician must review all medicines and non-prescribed substances before treatment starts.
It may be unsuitable in acute hepatitis or significant liver impairment, depending on the clinical assessment and product information. People with kidney problems, depression, suicidal thoughts, or other significant health conditions should discuss these issues openly with their prescriber. Extra monitoring may be required.
Pregnancy and breastfeeding require individual medical advice because the balance of benefit and risk is personal. Children and adolescents should only receive naltrexone when a qualified specialist determines that it is appropriate. Age limits and licensed indications can vary by formulation and local guidance.
Alcohol, medicines, and other interactions
Naltrexone is sometimes prescribed for alcohol dependence, but alcohol can still impair judgement and cause harm while treatment is being used. Avoid assuming that naltrexone protects against intoxication, accidents, or alcohol-related illness. Discuss alcohol-reduction goals and safety planning with a healthcare professional.
The most important interactions involve opioids, including prescription analgesics and opioid-containing combination products. Naltrexone can block pain relief and may lead a person to take unsafe amounts of opioids in an attempt to overcome the blockade. This can cause life-threatening overdose, especially as naltrexone levels fall.
Tell the prescriber and pharmacist about all medicines, herbal products, supplements, and recreational substances. This includes medicines obtained abroad or through other providers. Never conceal recent opioid use, as accurate information is crucial for safe initiation.
Overdose and urgent situations
Taking more naltrexone than prescribed may increase the risk of adverse effects, including nausea, abdominal symptoms, dizziness, and possible liver-related complications. There is no safe self-management method for a suspected overdose. Contact the Swedish Poisons Information Centre or seek urgent medical advice for guidance.
Call 112 immediately if someone has collapsed, has difficulty breathing, has a seizure, or cannot be awakened. If opioid overdose is suspected, emergency services are required even if naltrexone treatment is known. Naloxone may be used by trained responders or according to local emergency guidance, but it does not replace emergency care.
Bring the medicine package or provide the product name, strength, amount taken, and time of ingestion when seeking help. Do not induce vomiting unless a healthcare professional instructs you to do so. Keep medicines out of reach of children and people for whom they were not prescribed.
Alternatives to naltrexone
Alternatives depend on whether treatment is for alcohol dependence or opioid dependence. For alcohol-related care, clinicians may consider psychosocial interventions and other authorised medicines when suitable. The best choice depends on health history, goals, liver function, and previous response to treatment.
For opioid dependence, opioid agonist treatments such as buprenorphine-based or methadone-based care may be appropriate for many patients. These options have different mechanisms, monitoring needs, and overdose considerations from naltrexone. A specialist service can explain the relative benefits and limitations.
Non-medication support remains important regardless of the chosen treatment. Counselling, peer support, family involvement, housing support, and mental-health care can all contribute to recovery. Medication changes should never be made abruptly without professional input.
Prescription access in Sweden
Naltrexone is a prescription medicine, and access should follow Swedish healthcare and pharmacy requirements. A legitimate web pharmacy must verify a valid prescription before dispensing where required. Requests to obtain naltrexone without prescription should be declined for patient safety and legal compliance.
To buy naltrexone safely, use a pharmacy that provides identifiable contact details, pharmacist support, secure payment procedures, and clear medicine information. Avoid sellers that offer prescription medicines without medical review or make unrealistic promises. Products from unverified sources may be counterfeit, incorrectly stored, or unsuitable for the patient.
A clinician can assess whether naltrexone is appropriate and issue a prescription when indicated. The pharmacy can then confirm available strength, manufacturer, pack size, and collection or delivery options. Availability may vary, and some products may need to be obtained through standard pharmacy supply channels.
Costs and responsible purchasing
The amount paid for naltrexone can vary with the prescribed formulation, pack size, manufacturer, reimbursement status, and pharmacy service. Costs displayed by other Swedish web pharmacies may change over time and should be checked at the point of dispensing. A pharmacist can help clarify whether a listed product matches the prescription.
Do not choose a medicine source solely because it appears inexpensive. Legitimate dispensing includes prescription review, quality-controlled supply, appropriate packaging, and access to professional advice. These safeguards are particularly important for medicines used in alcohol- or opioid-dependence treatment.
Before completing a request, check the medicine name, strength, quantity, patient details, and delivery address carefully. Ask about substitutions only if permitted by the prescriber and pharmacy. Retain the receipt and package information in case follow-up is needed.
How web-pharmacy fulfilment and tracking work
After a valid prescription is received and checked, the pharmacy prepares the medicine for dispensing. A pharmacist may contact the patient if information is missing or a safety question needs clarification. Dispatch should occur only after the required clinical and legal checks are complete.
Delivery tracking is normally provided through the selected carrier once a parcel has been handed over for transport. Tracking updates show delivery progress but do not replace checking that the correct medicine has arrived. Contact the pharmacy promptly if the package is damaged, delayed, or appears tampered with.
Store naltrexone in its original package, protected from moisture and excessive heat, and follow the temperature instructions on the carton or leaflet. Keep it securely away from children and others. Do not use tablets that are expired, damaged, or no longer identifiable, and ask a pharmacy about safe disposal.
Frequently asked questions about Naltrexone
Why must recent opioid use be checked before starting Naltrexone?
Naltrexone can rapidly trigger severe withdrawal if opioids are still active in the body. A clinician will assess recent use of prescription opioids, illicit opioids, opioid-containing cough products, and opioid-based pain medicines before treatment begins. The required opioid-free interval depends on the opioid involved and the individual situation.
What should I do if I miss a Naltrexone dose?
Do not double the next dose to make up for a missed one. Follow the instructions supplied with the medicine or contact the prescriber or pharmacist for guidance, particularly if several doses have been missed. The appropriate plan may differ between oral tablets and long-acting formulations.
How should planned surgery or dental treatment be managed while using Naltrexone?
Tell the surgeon, dentist, anaesthetist, and pharmacist that you use Naltrexone well before the procedure. It can block opioid pain medicines, so the clinical team may need to plan non-opioid options or a supervised pain-management strategy. Do not stop or restart treatment on your own to obtain opioid pain relief.
Should I carry information showing that I take Naltrexone?
A medication card, medical-alert entry, or updated medicines list can be helpful, especially when travelling or receiving urgent care. It should state the product name, formulation, dose schedule, prescriber details, and the date of the most recent dose or injection where applicable. This helps clinicians avoid ineffective or unsafe opioid treatment decisions.
Are blood tests sometimes needed with Naltrexone treatment?
A prescriber may request tests before or during treatment, particularly when there is a history of liver disease, substantial alcohol use, or symptoms that could suggest a medical concern. The type and timing of monitoring are individual rather than the same for every patient. Keep scheduled reviews and report unusual tiredness, dark urine, or yellowing of the skin or eyes promptly.
Can Naltrexone be used during pregnancy or breastfeeding?
Pregnancy and breastfeeding require an individual risk-benefit discussion with an appropriate clinician. Information may be limited, and the safest approach depends on the condition being treated, other medicines, and the risks of untreated alcohol or opioid use disorder. Do not start, stop, or change Naltrexone solely because of pregnancy without medical guidance.
Can I drive or operate machinery after taking Naltrexone?
Some people may experience dizziness, tiredness, headache, or reduced concentration, particularly when beginning treatment or after a dose change. Avoid driving, cycling in traffic, or operating machinery until you know how the medicine affects you. Alcohol and other sedating substances can further impair alertness.
Does Naltrexone affect drug screening tests?
Naltrexone is not an opioid and is not intended to produce an opioid-positive result. However, screening methods and workplace policies vary, so disclose prescribed medicines to the testing provider and keep suitable prescription documentation. A laboratory confirmation test may be needed if an initial screen is unclear.
How should Naltrexone be stored and disposed of?
Keep Naltrexone in its original packaging, away from moisture and excessive heat, and out of the sight and reach of children. Check the product leaflet for any formulation-specific storage instructions. Return unused or expired medicine to a pharmacy in Sweden rather than disposing of it in household waste or wastewater.
Can I take Naltrexone when travelling outside Sweden?
Carry the medicine in its original labelled packaging and take a copy of the prescription or a clinician’s letter, especially for international travel. Entry rules and documentation requirements can differ by destination, transit country, and formulation. Check the relevant embassy and airline guidance before departure, and pack essential medicines in hand luggage where possible.
Is Naltrexone the same medicine as naloxone?
No. Both medicines block opioid receptors, but they are used differently. Naloxone is generally used for rapid emergency reversal of opioid overdose, whereas Naltrexone is used as part of ongoing treatment plans under clinical supervision. They should not be substituted for one another.
Pharmacist Review
This Naltrexone product page has been professionally reviewed for clarity, balance, and responsible medicine information relevant to patients in Sweden.
| Review detail | Information |
|---|---|
| Reviewer | Elin Sjöberg, Licensed Pharmacist (Apotekare) |
| Professional identifier | HOSP ID: 5411592 |
| Professional authority | National Board of Health and Welfare (Socialstyrelsen) |
| Review date | 8 March 2025 |
The review considers appropriate prescription use, important contraindications, interaction risks, and the need for individual clinical assessment. Naltrexone should be used only as prescribed and with particular attention to current or recent opioid use.
Medical disclaimer: This material is provided for informational purposes only and does not replace consultation with a doctor.
Pharmacy Location and Opening Hours
For Naltrexone, visit our pharmacy at Klarabergsgatan 64, 111 81 Stockholm, Stockholm County, Sweden.
| Days | Opening hours |
|---|---|
| Monday–Friday | 07:00–00:00 |
| Saturday | 09:00–22:00 |
| Sunday | 10:00–22:00 |
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