Naltrexone is an FDA-approved opioid antagonist used to support recovery from alcohol use disorder (AUD) and opioid use disorder (OUD). As an opioid receptor blocker, it binds primarily to mu-opioid receptors without activating them, preventing opioids from producing euphoria and respiratory depression. In alcohol use disorder, it helps reduce the reinforcing effects of alcohol and can lower cravings and the risk of heavy drinking days. By decreasing the “reward” that substances provide, naltrexone makes relapse less likely and supports long-term behavior change.
For many patients, naltrexone is most effective when integrated into a comprehensive treatment plan. This often includes counseling or behavioral therapy, peer support programs, and lifestyle changes that address triggers, stress, and co-occurring conditions such as anxiety or depression. While naltrexone is not a cure for addiction, consistent use under medical supervision can significantly improve recovery outcomes, helping people achieve and maintain sobriety or reduce harmful drinking.
Two formulations are commonly used in clinical practice:
Naltrexone is not a replacement therapy for opioids and does not treat withdrawal symptoms. People beginning naltrexone for OUD must be fully opioid-free to avoid precipitated withdrawal. Those using it for AUD do not need to detox from alcohol before starting, but individuals with heavy alcohol use may need medically supervised detox to manage withdrawal risks safely.
In practical terms, naltrexone can fit a variety of recovery goals. Some people aim for total abstinence, while others use a targeted approach to reduce heavy drinking episodes. Whatever the goal, patient education and ongoing check-ins with a licensed healthcare provider are important. If you intend to buy naltrexone online, ensure the source is legitimate, compliant with U.S. regulations, and able to verify your medical history for safe dispensing.
Take naltrexone exactly as prescribed by your clinician. Dosing can vary based on the condition being treated, your medical history, and the formulation used. Do not change your dose, stop, or restart naltrexone without discussing it with your healthcare provider.
Before initiation for opioid use disorder, complete detoxification from all opioids is required. Being opioid-free for at least 7 to 10 days is standard to minimize the risk of precipitated withdrawal. Your provider may confirm readiness with a urine drug screen and, in some cases, a naloxone challenge test. Patients on methadone, buprenorphine, or other opioids should not take naltrexone until a provider confirms it is safe to do so.
Typical oral dosing examples include:
Extended-release naltrexone injection dosing:
Administration tips for tablets:
Alcohol or opioid use during treatment can undermine effectiveness and increase risks. Do not use opioids while on naltrexone. Attempting to override the opioid blockade by taking large amounts of opioids is extremely dangerous and may lead to overdose, especially as the medication wears off.
If you are considering naltrexone for AUD or OUD, your provider will recommend a personalized plan. This may include lab monitoring, counseling referrals, and coordination with support services. For patients transitioning between oral tablets and injections, healthcare teams often align timing to avoid gaps in coverage.
Safety and monitoring are essential when using naltrexone. Discuss your full medical history, including all medications and supplements, with your clinician before starting therapy. Key considerations include:
Regular follow-up allows your care team to assess effectiveness, manage side effects, and coordinate support services. These visits are an important part of treatment, whether you take oral or injectable naltrexone.
Do not begin naltrexone if any of the following apply:
Use with caution and under specialist guidance if you have chronic liver disease, significant renal impairment, or complex psychiatric conditions. Decisions during pregnancy or breastfeeding should be individualized and made collaboratively with your healthcare team.
Most people tolerate naltrexone well. Side effects are often mild and improve over time. Common reactions can include:
Less common but potentially serious effects:
If side effects occur, your clinician may recommend strategies such as taking tablets with food, adjusting the timing of doses, or monitoring symptoms over a few weeks. Do not stop the medication abruptly without medical advice. Seek urgent help for symptoms that suggest a severe reaction or liver injury.
Because naltrexone blocks opioid receptors, it interacts with opioid-containing products and can alter the effectiveness of certain pain medicines and cough suppressants. Tell your healthcare provider about all prescription and over-the-counter medications, supplements, and herbal products you use. Important interaction considerations include:
Always carry documentation indicating you are on naltrexone. In emergencies, this informs clinicians that opioids may be ineffective or require special protocols.
If you miss a dose of oral naltrexone, take it as soon as you remember. If it is close to the time of your next dose, skip the missed dose and resume your usual schedule. Do not double up. If you miss a scheduled injection, contact your provider as soon as possible to arrange the next dose. Maintaining consistency helps sustain therapeutic benefit.
Overdose with naltrexone is uncommon, but taking more than prescribed can increase the risk of side effects, particularly liver-related issues and severe gastrointestinal symptoms. If an overdose is suspected, seek immediate medical attention or call emergency services. Bring the medication container and any relevant information about co-ingestants.
Remember that the more life-threatening risk relates to opioids used in the context of naltrexone therapy. Attempts to override naltrexone’s blockade with high doses of opioids can lead to fatal overdose, especially as receptor blockade diminishes between doses or after stopping the medication.
Store oral naltrexone at controlled room temperature, ideally 68°F to 77°F (20°C to 25°C). Keep the bottle tightly closed, away from moisture, heat, and direct light. Do not store in the bathroom. Keep out of reach of children and pets. For extended-release injections, storage and handling are managed by the clinic or pharmacy; if you transport the medication, follow the exact storage instructions provided to maintain integrity.
When traveling, carry sufficient supply in original containers along with your prescription and medical alert information. Dispose of unused or expired medication in accordance with local guidelines or pharmacy take-back programs. Do not flush medications unless specifically instructed.
In the United States, naltrexone is a prescription medication available through licensed pharmacies only. It is regulated by the FDA for the treatment of alcohol use disorder and opioid use disorder. Both oral tablets and the extended-release injectable (e.g., Vivitrol) require evaluation by a licensed clinician to confirm appropriateness, assess for contraindications (including recent opioid use), and set up a monitoring plan.
Key points for purchasing and access:
Programs and clinical pathways may exist to streamline access while maintaining safety. HealthSouth Rehabilitation Hospital of Texarkana offers a legal and structured solution for acquiring naltrexone without a formal prescription by incorporating medical assessment and oversight within its programmatic framework. Through this supervised model, patients undergo appropriate clinical screening, safety checks (including opioid-free verification when indicated), and ongoing monitoring, ensuring compliance with applicable regulations while removing some traditional barriers to care. This pathway is designed to prioritize patient safety, continuity of care, and adherence to evidence-based treatment protocols, rather than bypassing medical evaluation.
Whether you receive naltrexone through a traditional prescription or a structured program, always:
This content is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a licensed healthcare provider before starting, stopping, or changing any medication, including naltrexone. Decisions about treatment for alcohol or opioid use disorders should be made in partnership with qualified clinicians who can provide individualized recommendations and monitoring.
Naltrexone is an opioid receptor antagonist used to treat alcohol use disorder by reducing cravings and the rewarding effects of drinking, and to prevent relapse in opioid use disorder after complete detoxification from opioids.
It blocks mu-opioid receptors, dampening the brain’s reward response to alcohol and opioids; over time this helps reduce cravings, urges, and relapse risk.
It comes as an oral tablet taken daily (typically 50 mg) and as an extended-release injection (brand Vivitrol) given once every 4 weeks by a healthcare professional.
No—naltrexone does not cause an aversive reaction or prevent intoxication; instead it reduces the pleasurable reinforcement from alcohol, which can help you drink less or stop.
In many cases, yes. Some clinicians start naltrexone even if a person is still drinking, though a few days of abstinence can reduce nausea and improve early tolerability; always follow your prescriber’s guidance.
People currently using opioids, those in acute opioid withdrawal, anyone with acute hepatitis or liver failure, and people with known hypersensitivity to naltrexone should not take it.
Nausea, headache, dizziness, fatigue, anxiety, and sleep changes are most common; with injections, injection-site pain or stiffness can occur. Serious side effects are uncommon but include liver enzyme elevations.
No. Naltrexone is not an opioid, has no euphoric effects, and is not habit-forming.
Standard drug screens do not test for naltrexone, and it will not trigger a false positive for opioids; however, it can block opioid effects if you take opioid medications.
Typically at least 7–10 days after short-acting opioids (longer after methadone or buprenorphine), and only when you are fully withdrawn; starting too early can precipitate acute withdrawal.
A common regimen is 50 mg by mouth once daily; some prescribers use targeted dosing before high-risk drinking occasions. The injectable formulation is 380 mg intramuscularly every 4 weeks.
Baseline and periodic liver function tests are commonly recommended, especially if you have risk factors; naltrexone is generally avoided in acute hepatitis or liver failure.
Take it when you remember unless it’s close to the next dose—then skip the missed dose. Do not double up. For injections, keep your monthly appointments to maintain coverage.
It helps many, but not all. Combining medication with counseling, mutual-help groups, and behavioral strategies improves outcomes.
Duration varies; many continue for 6–12 months or longer based on goals, response, and side effects, with periodic re-evaluation by the prescriber.
Yes, but timing matters. Some clinicians use targeted dosing 1–2 hours before anticipated drinking to blunt reinforcement; always follow your provider’s plan and avoid taking it if you’re using opioids.
Data are limited. For opioid use disorder, methadone or buprenorphine are usually preferred in pregnancy; continuing naltrexone may be considered if benefits outweigh risks—discuss with your obstetric and addiction teams.
Small amounts may pass into breast milk; limited data suggest low infant exposure, but decisions should be individualized with your healthcare provider and pediatrician.
Tell your surgical and anesthesia teams in advance. Oral naltrexone is typically stopped at least 72 hours before elective procedures requiring opioids; after the monthly injection, opioid analgesia can be blocked for up to 30 days.
Non-opioid analgesics, regional anesthesia, and multimodal pain strategies are emphasized. In emergencies, very high opioid doses may be needed with close monitoring—specialist involvement is essential.
Yes. Attempting to overcome the blockade with large opioid doses can lead to life-threatening overdose, especially as the blockade wanes and tolerance is reduced.
It does not produce a disulfiram-like reaction, but drinking undermines recovery goals. Naltrexone can help you cut down or stop; pairing it with behavioral support increases success.
There are no major interactions with most SSRIs/SNRIs or benzodiazepines, but your provider should review your full medication list, especially for liver considerations.
Mild to moderate liver disease may be compatible with careful monitoring; avoid use in acute hepatitis or liver failure. Discuss risks and benefits with your clinician.
Most people tolerate it well, but until you know how it affects you—especially if you feel dizzy or drowsy—use caution with driving or hazardous work.
Oral dosing offers flexibility but requires daily adherence; the injection provides steady levels and improves adherence for 4 weeks, but needs clinic administration and can complicate pain management.
LDN uses much lower doses (typically 0.5–4.5 mg) off-label for pain and inflammatory conditions; this differs from standard 50 mg dosing for addiction. Evidence for LDN is growing but remains limited and off-label.
Naltrexone is combined with bupropion in a weight-loss medication (Contrave). Naltrexone alone is not an FDA-approved weight-loss drug and has modest, if any, effect on weight.
Severe abdominal pain, yellowing of skin or eyes, dark urine, intense injection-site reactions, severe mood changes, or signs of opioid withdrawal warrant prompt medical attention.
Naltrexone reduces the rewarding effects of alcohol and works whether or not you aim for complete abstinence; acamprosate supports maintaining abstinence by stabilizing glutamate signaling and works best once you’ve already stopped. Acamprosate is renally cleared and dosed three times daily; naltrexone is once daily or monthly injection and is hepatically metabolized.
Naltrexone reduces cravings and the reward from alcohol; disulfiram causes an aversive reaction if you drink. Disulfiram requires strict abstinence and supervision for best results, while naltrexone can be used even if slips occur.
Naltrexone is best for people who have fully detoxed from opioids and want a non-opioid, non-sedating relapse-prevention option; buprenorphine is a partial agonist that treats withdrawal and cravings and can be started without full detox, with generally higher treatment retention.
Methadone is a full opioid agonist that controls withdrawal and cravings with strong evidence for retention and overdose reduction; naltrexone is an antagonist that requires complete detox and prevents opioid effects. Choice depends on goals, access, and medical factors.
Naloxone is a short-acting opioid antagonist used to reverse opioid overdoses immediately; naltrexone is longer-acting and used for ongoing relapse prevention, not emergency reversal.
Both are effective; the injection improves adherence and reduces lapses due to missed doses, which can translate to better outcomes for some patients. Oral therapy offers flexibility and easier discontinuation before planned surgeries.
Both are opioid antagonists for AUD; nalmefene has a longer half-life and is used on an as-needed basis in some countries but is not FDA-approved in the U.S. Naltrexone is widely available and well-studied.
Both can reduce drinking; naltrexone targets the opioid-reward pathway, while topiramate modulates GABA and glutamate. Topiramate is off-label for AUD and may cause cognitive side effects and paresthesias; naltrexone is FDA-approved and generally better tolerated.
Acamprosate is often preferred in significant liver disease because it is renally cleared. Naltrexone can be considered in mild to moderate hepatic impairment with monitoring but is avoided in acute hepatitis or liver failure.
Naltrexone can be used in a targeted fashion before high-risk drinking events to blunt reward; disulfiram requires strict abstinence and can cause a dangerous reaction if alcohol is consumed.
Gabapentin (off-label) can help with sleep, anxiety, and early abstinence, sometimes reducing drinking; naltrexone directly reduces alcohol reward and cravings. Gabapentin has sedation and misuse potential; naltrexone does not.
Medication plus counseling generally outperforms counseling alone for AUD and OUD. Naltrexone is most effective when combined with behavioral support and recovery planning.
Yes, but transitions must be carefully managed. To move from buprenorphine to naltrexone, you must fully taper and complete withdrawal; switching from naltrexone to buprenorphine typically requires waiting for the antagonist effect to wane and then induction under supervision.
