Naltrexone overview
Naltrexone is a medicine that blocks the effects of opioid medicines and other opioids. It is used as part of a broader treatment plan, not as a stand-alone solution for dependence. A clinician should assess whether it is appropriate for the individual situation.
In Denmark, naltrexone is generally supplied under prescription and with professional oversight. The right treatment plan may include counselling, follow-up appointments, and support for physical or mental health needs. Pharmacy information cannot replace an assessment by a doctor or addiction-treatment service.
Naltrexone does not create opioid-like effects and is not an opioid substitute medicine. Its purpose is to reduce the rewarding or reinforcing effects associated with opioids or alcohol in selected patients. Treatment goals and expected outcomes should be agreed with the prescriber.
What Naltrexone is used for
Naltrexone may be prescribed to help prevent relapse after opioid dependence once the person is fully free of opioids. It may also be used in alcohol-dependence treatment to help reduce heavy drinking or support abstinence. The approved indication and treatment approach can differ according to the product and the patient’s clinical history.
For opioid dependence, starting naltrexone too soon after opioid use can cause sudden and severe withdrawal. A healthcare professional must confirm an adequate opioid-free interval before treatment begins. This interval varies with the opioid used, dose, duration of use, and individual medical factors.
For alcohol dependence, naltrexone is usually combined with psychological and social support. It does not make alcohol use safe and does not remove the risks of intoxication. Patients should discuss realistic drinking-reduction or abstinence goals with their treatment provider.
Active ingredient and medicine forms
The active ingredient is naltrexone hydrochloride, which is converted in the body to naltrexone. Tablets are the most commonly encountered form in many European markets. Modified-release injections exist in some countries, but availability and authorisation may differ in Denmark.
Oral naltrexone is commonly available as tablets containing 50 mg of naltrexone hydrochloride. Some treatment schedules use different dosing patterns, but these should only be followed when specifically prescribed. Do not split, alter, or combine doses without advice from a pharmacist or prescriber.
Inactive ingredients vary by manufacturer and may matter for people with allergies or dietary restrictions. Check the package leaflet and product label for the exact formulation supplied. A pharmacist can help identify relevant excipients when switching brands.
Origin and development of Naltrexone
Naltrexone was developed from research into opioid receptors and compounds capable of blocking them. It followed earlier opioid-antagonist research aimed at reversing or preventing opioid effects. Its development created an option for relapse-prevention treatment after opioid detoxification.
Over time, clinical use expanded to include alcohol-dependence treatment in suitable adults. Research has focused on how opioid-receptor signalling contributes to reward, craving, and continued substance use. Naltrexone remains one component of evidence-based care rather than a universal treatment.
Modern prescribing reflects lessons from long-term clinical practice, especially the importance of avoiding opioid exposure before starting treatment. Patient education about pain management and emergency care is also central. These safeguards are as important as the medicine itself.
How Naltrexone works
Naltrexone mainly acts as an antagonist at opioid receptors, particularly mu-opioid receptors. This means it occupies receptors without activating them in the way opioid medicines do. As a result, it can block or markedly reduce the effects of opioids.
In alcohol dependence, the mechanism is more complex but is linked to the endogenous opioid system involved in reward pathways. Some people experience less reinforcement from drinking or fewer urges to drink. Responses vary, and the medicine does not work equally well for every patient.
Because naltrexone blocks opioid receptors, opioid painkillers may be less effective during treatment. Trying to override this blockade with high opioid doses can be dangerous or fatal. Patients should tell all healthcare professionals that they are taking naltrexone.
Taking Naltrexone correctly
Take Naltrexone exactly as stated on the prescription label and in the patient information leaflet. Tablets are usually swallowed with water and may often be taken with or without food. Taking a dose with food may help if nausea occurs.
Before the first dose, the prescriber should review recent use of opioids, including prescription pain medicines, illicit opioids, and some cough or diarrhoea products. A negative opioid screen or a supervised challenge may be used in selected clinical settings. Do not conceal opioid use, as this can lead to severe precipitated withdrawal.
If a dose is missed, follow the instructions given by the prescriber or pharmacist. Do not take an extra dose to compensate unless specifically told to do so. Contact a healthcare professional if several doses have been missed or if opioid use has occurred.
Expected duration of effect
The clinical blocking effect of oral naltrexone depends on the prescribed dose, timing, and the individual patient. A standard daily tablet regimen is intended to provide coverage over the dosing interval. It should not be assumed to provide reliable protection if doses are missed.
The medicine may remain active even after a person feels no noticeable effect. This is important because an attempt to use opioids during treatment can still be hazardous. The blocking effect can also alter how emergency pain relief needs to be planned.
Extended-release injectable products, where available, are designed for a longer duration than tablets. Their use requires administration by trained healthcare professionals. The supplied product leaflet provides the most relevant information for the specific formulation.
How long Naltrexone remains in the body
Naltrexone and its active metabolite are processed mainly by the liver and eliminated through the body over time. The parent medicine has a relatively short half-life, while its metabolite can persist longer. Detectability and clinical effects are not the same thing.
How quickly it leaves the body can vary with liver function, dosage form, dose, and individual metabolism. A clinician may need to consider these factors before surgery or when planning pain treatment. Patients should not stop treatment solely to prepare for anticipated opioid use.
After stopping naltrexone, tolerance to opioids may be lower than before treatment. This can increase overdose risk if opioid use resumes, even at doses previously tolerated. Medical support is important during any interruption or discontinuation of treatment.
Evidence and scientific research
Clinical research supports naltrexone as an option for some adults with alcohol dependence and for relapse prevention following opioid detoxification. Benefits are generally strongest when medicine is paired with structured psychosocial support. Choice of treatment should account for preferences, prior treatment response, and medical safety.
Studies do not indicate that every person will have the same reduction in craving or substance use. Adherence can strongly influence results with tablet treatment. Some patients may benefit more from other evidence-based approaches.
Research also underlines the need for opioid abstinence before starting naltrexone. This safety requirement is well established because receptor blockade can trigger abrupt withdrawal in opioid-dependent individuals. Prescribers use clinical assessment rather than relying on a single general rule.
Dependence, addiction, and stopping treatment
Naltrexone is not considered addictive and does not usually cause physical dependence. It does not produce the euphoric effects associated with opioid agonists. Stopping it does not normally cause a classic withdrawal syndrome.
However, stopping treatment can remove opioid blockade and may change overdose risk. People who return to opioid use after a period of abstinence may have reduced tolerance. This makes support, overdose education, and continuity of care especially important.
Naltrexone should not be confused with treatments that activate opioid receptors. The best option depends on the diagnosis, treatment goals, and likelihood of adherence. A specialist can explain the advantages and limitations of each approach.
Alternatives to Naltrexone
Alternatives depend on whether treatment is for alcohol dependence or opioid dependence. For opioid dependence, opioid agonist treatments such as buprenorphine or methadone may be considered through appropriate clinical services. These medicines have different effects, risks, and monitoring requirements.
For alcohol dependence, other medicines may be considered in selected patients alongside counselling and behavioural interventions. Suitability can depend on liver health, kidney function, drinking pattern, concurrent medicines, and treatment goals. A prescriber should determine whether an alternative is clinically appropriate.
Non-medicinal support remains important regardless of the medicine selected. This may include addiction counselling, peer support, family involvement, and mental-health care. An integrated plan often provides more durable support than medication alone.
Common and serious side effects
Possible side effects of Naltrexone include nausea, abdominal discomfort, headache, dizziness, tiredness, sleep disturbance, and reduced appetite. These effects are often mild or temporary, but they can be troublesome for some people. Report persistent or concerning symptoms to a doctor or pharmacist.
Liver-related problems are an important consideration, particularly in people with existing liver disease or substantial alcohol-related harm. A prescriber may arrange liver-function testing before and during treatment when clinically indicated. Seek prompt medical advice for yellowing of the skin or eyes, dark urine, severe upper abdominal pain, or unusual fatigue.
Mood changes, anxiety, or low mood should also be discussed with a healthcare professional. Urgent help is needed for thoughts of self-harm or suicide. This medicine should be part of a plan that includes access to appropriate mental-health support.
Allergy and urgent reactions
Do not take Naltrexone if there has been a known allergy to naltrexone or any listed ingredient in the product. Allergy symptoms can include rash, itching, swelling, wheezing, or difficulty breathing. Serious breathing difficulty or swelling of the face, tongue, or throat requires emergency medical assistance.
A new rash does not always mean a serious allergy, but it should be assessed if it is widespread, blistering, painful, or accompanied by fever. Bring the medicine package or note the product name when seeking care. This can help clinicians identify possible excipient-related reactions.
People with multiple medicine allergies should review the full ingredient list before starting a new brand. Do not restart a medicine after a suspected serious allergic reaction without professional guidance. A pharmacist can help document and communicate relevant allergy information.
Who should not take Naltrexone
Naltrexone is generally unsuitable for people currently using opioids or experiencing opioid withdrawal. This includes many prescription opioid pain medicines and opioid-containing substitution treatments. Starting treatment in this setting can cause severe withdrawal symptoms.
People with acute hepatitis, significant liver impairment, or unexplained major liver-test abnormalities require careful medical assessment. The balance of benefit and risk may differ substantially between patients. Clinicians may choose another treatment or enhanced monitoring.
It may also be unsuitable where opioid analgesia is expected to be necessary, such as around certain operations or after major injury. Patients should discuss planned surgery, dental procedures, and chronic pain management before treatment. Emergency-care teams need to know about current or recent naltrexone use.
Age limits and additional restrictions
Naltrexone is commonly prescribed for adults, while use in children and adolescents requires specialist assessment. Evidence, authorisation, and clinical practice can differ by age group and indication. Parents or guardians should not use adult dosing assumptions for younger people.
Pregnancy and breastfeeding require an individual assessment of potential benefits and risks. Do not start, stop, or continue treatment during pregnancy without discussing it with a relevant healthcare professional. The underlying substance-use condition also needs careful support during this period.
Kidney disease, liver disease, depression, and a history of self-harm should be disclosed before treatment. These conditions do not always rule out use, but they may affect monitoring and treatment selection. Honest medication and substance-use history is essential for safe care.
Alcohol and medicine interactions
Naltrexone may be used in alcohol-dependence treatment, but this does not mean alcohol is harmless while taking it. Alcohol can impair judgement, worsen liver injury, and interact with other medicines. Follow the treatment plan agreed with the prescriber.
The most critical interactions involve opioids, including painkillers, cough preparations, and illicit drugs. Naltrexone can block desired opioid effects and complicate pain treatment. Always ask a pharmacist before using a new medicine, including non-prescription products.
Other medicines may require review because of liver effects, sedation, or overlapping side effects. Provide a complete list of prescriptions, supplements, and herbal products at each appointment. Do not assume a medicine is safe simply because it is sold without direct pharmacist contact.
Overdose, opioid exposure, and emergencies
Taking more Naltrexone than prescribed may increase side effects and requires medical advice, particularly if symptoms develop. Contact a Danish poison-information service, out-of-hours medical service, or emergency department according to the seriousness of the situation. In a life-threatening emergency, call 112.
Attempting to overcome Naltrexone’s opioid blockade with large opioid doses can cause fatal overdose. The risk may be especially high as the blocking effect wears off or after treatment is stopped, because opioid tolerance may be reduced. Emergency responders should be told about naltrexone use whenever possible.
Signs of opioid overdose include very slow or absent breathing, blue or grey lips, inability to wake the person, and pinpoint pupils. Call 112 immediately if these signs are present. If naloxone is available, use it as directed while waiting for emergency assistance.
Storage and safe handling
Store Naltrexone in its original package and follow the temperature instructions on the label or leaflet. Keep tablets dry and protected from excessive heat and humidity. Avoid storing medicines in a bathroom or near a kitchen sink.
Keep all medicines out of the sight and reach of children, visitors, and pets. Naltrexone should never be shared, even with someone who appears to have similar symptoms. The safety checks required before treatment are individual.
Return unused or expired tablets to a pharmacy for appropriate disposal when possible. Do not dispose of medicines in household wastewater unless local official instructions explicitly advise it. Secure disposal helps prevent accidental exposure and misuse.
Naltrexone price and pharmacy considerations
The price of Naltrexone can vary among Danish pharmacies according to manufacturer, pack size, dispensing fees, reimbursement status, and current supply arrangements. Prices shown by other pharmacy providers should be treated as indicative and may change. Comparing the same strength and number of tablets gives the most meaningful comparison.
A legitimate pharmacy should provide clear product details, contact information, dispensing terms, and access to pharmacist support. It should also request a valid prescription where Danish rules require one. Offers that claim to supply prescription medicine with no prescription should be treated with caution.
Reimbursement eligibility is personal and depends on the indication and applicable Danish rules. Ask the dispensing pharmacy or prescriber about possible reimbursement before completing a purchase. Clinical suitability should remain more important than a low advertised cost.
Benefits of ordering through our pharmacy
Our pharmacy process is designed to support secure ordering, prescription validation where required, and clear medicine information. Patients can review the supplied product details before confirming their request. A pharmacist can address practical questions about use, storage, and interactions.
Ordering through a regulated pharmacy may offer convenience for repeat dispensing while maintaining professional checks. It also provides a documented supply route and product traceability. These safeguards are particularly important for medicines used in dependence treatment.
Availability can change, and a requested manufacturer may not always be in stock. If a substitution is proposed, confirm the active ingredient, strength, and directions before accepting it. Contact the pharmacy if the packaging or tablets differ from what was expected.
How to order Naltrexone and track delivery
To order Naltrexone, select the prescribed strength and pack size, then provide the prescription details requested by the pharmacy. The pharmacy reviews the order before dispensing in accordance with applicable Danish requirements. Do not use another person’s prescription or alter dosing information.
After dispatch, delivery information and package tracking may be available through the order confirmation or carrier notification. Tracking updates can help patients plan for receipt and avoid medicines being left in unsuitable conditions. Check the parcel promptly after arrival for the correct product and intact packaging.
If delivery is delayed, damaged, or contains an unexpected item, contact the pharmacy before taking the medicine. Keep the package, label, and order reference available when making an enquiry. For urgent treatment needs, seek advice from a local pharmacy or healthcare service rather than waiting for delivery.
Frequently Asked Questions
Is Naltrexone the same medicine as naloxone?
No. Although the names are similar and both block opioid receptors, naloxone is used to rapidly reverse an opioid overdose, whereas Naltrexone is used as part of ongoing treatment for alcohol use disorder or opioid use disorder. Naltrexone does not replace emergency overdose care.
Why might opioid screening be needed before starting Naltrexone?
Naltrexone can trigger sudden, severe withdrawal if opioids are still active in the body. A clinician may use a medical history, testing, or other assessment to confirm that it is appropriate to begin treatment. Be open about prescription pain medicines, opioid-containing cough products, and non-prescribed opioid use.
What happens if I need opioid pain relief while using Naltrexone?
Tell the treating clinician, dentist, or emergency team that you use Naltrexone before pain treatment is planned. It can reduce or block the effect of opioid pain medicines, so a healthcare professional may need to consider other approaches and monitor treatment carefully. Do not try to overcome the blockade by taking extra opioids, as this can be dangerous.
Why are liver tests sometimes discussed with Naltrexone treatment?
Naltrexone is processed by the liver, and clinicians may consider liver function testing based on your health history and symptoms. Seek medical advice promptly for possible liver-warning symptoms such as yellowing of the skin or eyes, dark urine, or persistent upper abdominal discomfort. Testing and follow-up should be individualized by a qualified prescriber.
Can Naltrexone cause weight loss or weight gain?
Weight change is not a reliable or intended effect of Naltrexone when used on its own. Appetite, nutrition, alcohol intake, activity, and recovery-related lifestyle changes can all influence weight. Discuss a notable or unexplained change in weight with a healthcare professional rather than using Naltrexone for weight control.
Does Naltrexone affect drug or workplace testing?
Naltrexone is not an opioid and would not usually be expected to produce an opioid-positive result. However, testing methods and workplace policies differ, so disclose prescribed medicines to the testing service according to its procedure. Do not stop prescribed treatment solely because of an upcoming test without clinical guidance.
Can Naltrexone be used during pregnancy or while breastfeeding?
Pregnancy and breastfeeding require an individual assessment of the potential benefits, uncertainties, and treatment alternatives. Anyone who is pregnant, planning pregnancy, or breastfeeding should discuss Naltrexone with their obstetric and addiction-care clinicians. Do not start or discontinue treatment independently during this period.
Can Naltrexone change mood or sleep?
Some people report changes such as tiredness, sleep disturbance, anxiety, or low mood, although these symptoms can also relate to the underlying condition or recovery process. Report new, persistent, or worsening mental-health symptoms to a clinician. Urgent help is needed for thoughts of self-harm or immediate safety concerns.
What should I tell a healthcare professional before an operation or dental procedure?
Provide the name of the medicine, the formulation used, and when you last took Naltrexone. This information helps the team plan anaesthesia and pain management safely, particularly if opioid medicines might otherwise be considered. Keep your medication list available for scheduled and urgent care.
Is Naltrexone a cure for alcohol or opioid use disorder?
Naltrexone can be one component of a broader treatment plan, but it is not a stand-alone cure. Many people benefit from combining medical follow-up with counselling, peer support, and practical relapse-prevention strategies. The most suitable plan depends on personal goals, health history, and access to support in Denmark.
How can I check whether Naltrexone is supplied lawfully by an online pharmacy in Denmark?
Use a pharmacy that clearly identifies its Danish registration details, provides access to a pharmacist or prescriber where required, and explains how it verifies prescriptions and patient suitability. Be cautious of sites promoting Naltrexone “without prescription” or offering medicines with no clinical checks, as regulatory requirements and patient safety protections apply. Confirm current requirements with an authorised Danish pharmacy or healthcare professional.
Pharmacist Review
This Naltrexone product page has been professionally reviewed for clarity, balanced medicine information and relevance to pharmacy practice in Denmark.
| Review detail | Information |
|---|---|
| Reviewer | Mette Kjærgaard, Cand.pharm., Authorised Pharmacist |
| Professional identifier | Authorisation ID: 78452136 |
| Professional authority | Danish Patient Safety Authority |
| Review date | 8 March 2025 |
The content is intended to support informed discussions about Naltrexone and should be read alongside the approved product information. Treatment decisions, including suitability, dosing and monitoring, require individual assessment by a doctor or other qualified prescriber.
Important: This material is for informational purposes only and does not replace consultation with a doctor.
Pharmacy Location and Opening Hours
For Naltrexone, visit our pharmacy at Vesterbrogade 6, 1620 København V, Hovedstaden, Denmark.
| Days | Opening hours |
|---|---|
| Monday–Sunday | 06:00–00:00 |