Treatment & Safety
Naltrexone Contraindications: Opioids, Withdrawal, and Label Checks
Current opioid use, opioid dependence, acute withdrawal, specified test results, and prior hypersensitivity can make naltrexone unsafe to start.
Understand naltrexone—and what to ask next
If you are considering naltrexone for alcohol or opioid use disorder, start with the questions that matter: what it can do, when it is unsafe to start, which form you are discussing, and how to find care where you live.
What are you trying to work out?
Choose the question closest to yours. You do not need to read the site in order.
What does naltrexone do?
See how it blocks opioid receptors, why that can help with alcohol or opioid treatment, and what it does not do.
Is it safe to start now?
Recent opioid use is the first issue to raise. Even some pain, cough, and diarrhoea medicines can matter before the first dose.
Tablet or monthly injection?
Compare daily oral naltrexone with extended-release Vivitrol without treating them as interchangeable products.
How do I access treatment?
Country guides show the product, funding, and care routes we could verify—and the questions only a local service can answer.
Access guides by country
A medicine can be clinically recognised yet difficult to find, unfunded, or available only in a different formulation. Pick your country for the practical route.
Four distinctions worth knowing
These clear up many of the confusing or contradictory claims found online.
- Naltrexone blocks opioid receptors: Not detox. It does not treat acute withdrawal and can make withdrawal much worse if started too soon.
- Tablet and extended-release injection: 2 forms. They share an active drug but differ in approved uses, administration, and access.
- Standalone naltrexone is a different product: Not Contrave. Contrave also contains bupropion and is used for chronic weight management.
- Price and supply need a country check: Local. A registry listing alone cannot tell you what a nearby pharmacy has today.
How we handle uncertain answers
We use official labels, guidelines, medicine registers, funding schedules, and published studies. Then we explain what each source can actually tell you in normal language.
The exact product matters
A claim about a 50 mg tablet is not automatically true of a monthly injection or a naltrexone-bupropion combination.
The country matters
Approval, prescribing, funding, stock, and patient cost are separate questions. Our country pages date facts that can change.
Safety is not boilerplate
We keep the warnings that affect a real decision—especially recent opioid use, overdose vulnerability, liver symptoms, and urgent reactions.
Questions people ask before treatment
Focused guides to starting safely, comparing medicines, and understanding evidence without the medical-journal voice.
Treatment & SafetyStarting Naltrexone After Opioids: Why the Opioid-Free Interval Matters
Naltrexone can trigger severe withdrawal if opioids are still present. The minimum interval is not a self-assessment rule and may be longer after buprenorphine or methadone.
Treatment & SafetyNaltrexone Side Effects: Expected Effects and Urgent Safety Signals
Nausea, headache, dizziness, and tiredness are reported with naltrexone. Vivitrol also has injection-site effects; certain symptoms need prompt clinical review.
Treatment & SafetyVivitrol Injection Administration: What Patients Should Know
Vivitrol is prepared and given only by a healthcare provider as a deep gluteal injection. This guide explains the patient-facing safety essentials.
Start with your real-world access route
Choose your country to see which product and care pathway are documented, then use the page’s questions when you speak with a clinician, pharmacist, or insurer.