Naltrexone

What naltrexone is and who takes it

Naltrexone is a prescription tablet that helps people who are trying to stop drinking or stay off opioids. It is not a painkiller, not a sedative and not a controlled substance. It does not cause a high, and it is not a replacement opioid the way methadone or buprenorphine are. The oral form carries US Food and Drug Administration labeling for alcohol dependence and for blocking the effects of opioids taken from outside the body. A long-acting injectable version, given monthly by a clinician, is also approved in the United States for both alcohol use disorder and opioid use disorder, as summarized in federal guidance on medications used in addiction treatment.

Two names come up often. ReVia is a brand name historically used for the oral tablet, and most oral prescriptions in the United States are filled with a generic version of the same active ingredient, naltrexone hydrochloride. Vivitrol is the brand name of the extended-release injection. Generic and brand tablets contain the same molecule and must meet the same federal standards, so the practical differences are usually price, pharmacy stock and the inactive ingredients in the pill.

The label is blunt about one thing: this medicine is not a cure on its own. It says the drug has not been shown to help except as part of a broader plan for treating addiction. In real life that means counseling, peer support, medical follow-up or a structured program alongside the prescription. People also search for low-dose naltrexone for pain and autoimmune conditions, which is a different and largely off-label story covered further down this page.

How the medicine works in the body

Naltrexone is an opioid antagonist. In plain terms, it sits on the same receptors in the brain that opioids and some of alcohol’s rewarding effects rely on, and it blocks them. It does not activate those receptors itself, so there is no euphoria and no sedation.

For opioids, the effect is a blockade. While the medicine is active, a usual dose of heroin, oxycodone or another opioid will produce little or no effect. That is the point: it removes the payoff, which can make a return to use less likely during early recovery.

For alcohol, the picture is less absolute. Drinking releases natural opioid-like chemicals that contribute to the pleasant rush of the first few drinks. Blocking those receptors appears to dull that reward and to reduce craving. Clinical reviews describe a modest but real effect, mainly on heavy drinking days rather than on total abstinence, and note that results are best when the medicine is paired with support, as discussed in a published review of naltrexone in alcohol dependence. It is not a drug that punishes you for drinking. Disulfiram does that; this one does not.

Because it blocks rather than replaces, timing matters enormously. Anyone with opioids still in their system can be thrown into sudden, severe withdrawal by the first dose. Labeling requires an opioid-free interval before starting, confirmed by history, urine testing or a naloxone challenge, and the exact waiting period is set out in the official prescribing information rather than by rule of thumb.

Approved uses, and what counts as off-label

The oral tablet label covers two purposes. The first is treatment of alcohol dependence. The second is blocking the effects of opioids given from outside the body, which in practice means supporting people who have completed detox and want to stay off opioids. Patient-facing summaries from the National Library of Medicine drug information service describe the same two roles.

Plenty of other uses circulate online. Low doses for fibromyalgia, Crohn’s disease, multiple sclerosis and long COVID are studied but not approved. Use for stimulant cravings, gambling or self-harm behaviors is experimental. A clinician can legally prescribe off-label, and many do, but off-label means the FDA has not reviewed the evidence for that purpose. It is fair to ask a prescriber what evidence they are relying on and what they expect to see if it works.

One combination is approved for something else entirely. Naltrexone paired with bupropion in an extended-release tablet, sold as Contrave, is approved for chronic weight management in adults with obesity, or with excess weight plus a weight-related health problem, alongside diet and activity changes. Naltrexone on its own is not a weight-loss drug.

Side effects people actually report

Most side effects show up early and fade. The ones described most often in labeling and patient resources such as Mayo Clinic’s oral naltrexone monograph include:

• Nausea, sometimes with vomiting, especially in the first days
• Headache and dizziness
• Tiredness, low energy or trouble sleeping
• Anxiety, restlessness or feeling on edge
• Joint and muscle aches
• Reduced appetite and stomach cramps

The monthly injection adds injection-site reactions, which range from soreness and a lump to, rarely, tissue damage that needs medical attention.

Less common but more serious issues deserve a plain warning. Liver problems have long been linked to naltrexone, particularly at doses above those recommended, which is why prescribers often check liver blood tests before starting and sometimes during treatment. Yellowing of the eyes or skin, dark urine, pain over the upper right side of the abdomen or unusual tiredness are reasons to contact a clinician promptly. Depressed mood and, rarely, suicidal thoughts have been reported in people taking this medicine, and anyone with a history of depression should raise that at intake. Allergic reactions with rash, swelling or breathing difficulty are a medical emergency.

Withdrawal-like symptoms in the first hours are a signal in their own right. They usually mean opioids were still in the body when the first dose went in.

Warnings, interactions and what to avoid

The single most important safety point has nothing to do with side effects. After a period on this medicine, tolerance to opioids drops. When the blockade wears off, or if a dose is skipped or treatment stops, a previously ordinary amount of an opioid can cause life-threatening breathing problems or death. Federal labeling states this directly, and it is reinforced by National Institute on Drug Abuse material on overdose reversal. Trying to override the blockade with a large opioid dose is especially dangerous. Households often keep naloxone on hand for this reason.

Other warnings and interactions worth knowing:

• Prescription opioid painkillers, cough syrups with codeine and some anti-diarrhea medicines will not work normally while the blockade is active. Tell every clinician, dentist and pharmacist that you take it.
• Emergency and surgical care needs advance notice. Carry a card or wear identification so that pain control can be planned safely if you are unable to speak for yourself.
• Active liver failure or acute hepatitis is a reason not to start, according to the prescribing information.
• Current opioid use, opioid withdrawal or a positive opioid screen rules out starting until the opioid-free interval has passed.
• Alcohol still impairs judgment and still damages the liver. Blocking craving does not make drinking safe.
• Pregnancy, breastfeeding, kidney problems and bleeding disorders should all be discussed before the first prescription.

People sometimes ask what to avoid day to day. The short answer is opioid-containing products of any kind unless a clinician has planned for them, plus heavy drinking, plus stopping the medicine quietly without telling anyone on your care team.

Low-dose naltrexone: what the label does not cover

Low-dose naltrexone, often shortened to LDN, uses a fraction of the strength found in standard tablets. It is usually made by a compounding pharmacy as a capsule or liquid, because that low strength is not sold as an FDA-approved product. Compounded preparations are not reviewed by the FDA for safety, effectiveness or quality before they are sold, even when the active ingredient in them is approved at other strengths. That is a genuine difference in oversight, not a technicality.

Interest centers on chronic pain, fibromyalgia, inflammatory bowel disease and autoimmune conditions, with the theory that brief receptor blockade nudges the body’s own pain-signaling systems. Published studies are mostly small, short and preliminary. No FDA-approved indication exists at these doses, so anyone taking it is relying on a clinician’s judgment and early research rather than on a reviewed label.

Reported low-dose naltrexone side effects tend to be milder than at full strength: vivid dreams, disrupted sleep, headache, nausea and short-lived fatigue come up most often. The opioid interaction concern does not disappear at low doses, so the same disclosure rules apply before surgery or urgent care. Ask which pharmacy compounds the product, whether it is a 503A or 503B facility, how the strength is verified, and what the plan is if it does not help.

Drinking, cravings and realistic expectations

Two questions dominate searches about naltrexone and alcohol. Do you have to quit before you start, and what happens if you drink anyway?

Abstinence before the first dose is not required for the alcohol indication in the way an opioid-free window is for opioid treatment. Some treatment approaches start the medicine while a person is still drinking, with a goal of cutting back rather than stopping outright. That decision belongs to a clinician who knows the full history, including liver health and any withdrawal risk. Alcohol withdrawal itself can be dangerous and sometimes needs supervised care first.

If someone drinks while taking it, there is no violent reaction. Alcohol still causes intoxication, still impairs driving and still carries every other risk it normally does. What many people describe is a quieter pull: the first drink feels less rewarding, and the urge to keep going is weaker. That effect is modest and it is not universal. Research from the national institute that studies alcohol and health consistently frames medication as one tool among several, most useful when combined with behavioral support and honest tracking of drinking days.

Weight loss, naltrexone-bupropion and how it differs from Ozempic

A steady stream of searches asks whether this drug is like Ozempic. It is not. The mechanisms, the approvals and the risk profiles are different, and only the combination product has a weight-management indication.

The combination tablet carries a boxed warning because bupropion can increase suicidal thoughts and behaviors in some people, and it also raises seizure risk in people with certain conditions. Those warnings do not transfer to the single-ingredient product, but they matter a lot if the combination is what a program is offering. Readers weighing appetite-focused options against GLP-1 medicines can compare the mechanisms in our Semaglutide Uses And Warnings reference and the antidepressant side of the combination in Bupropion Safety Basics, then look at how programs are structured in the Comparing GLP-1 Telehealth Programs guide.

What it costs when you are paying yourself

Cost is where the generic and brand distinction earns its keep. Generic oral tablets are an old, widely made medicine, and self-pay pharmacy prices are usually far below those of the branded combination tablet or the monthly injection, which is given in a clinic and often billed as a medical rather than pharmacy service. Tracked self-pay monthly pricing for telehealth programs that prescribe it starts at per month.

Four things move the number on a one-month self-pay basis:

1. Which product: generic tablet, branded combination, compounded low dose or long-acting injection.
2. Whether the monthly fee includes the medicine, or only the visit and prescribing.
3. Whether laboratory work, such as liver tests, is bundled or billed separately.
4. Whether an introductory month is discounted and renews at a higher rate.

Monthly figures are easier to judge once you see the twelve-month version of the same decision.

Insurance is a separate track. Many plans, including Medicaid programs in most states, cover medications used for alcohol and opioid use disorder, but formularies, prior authorization rules and copays vary by plan and by state. Nothing on this page can promise coverage; the only reliable answer comes from your own plan documents or member services. Coverage policy background is tracked by an independent health policy research organization. If you are deciding between running it through a plan and paying cash, compare the two totals side by side rather than the headline numbers.

Advertised self-pay prices change often, so treat any figure as a snapshot. You can scan what programs charge across conditions in the Telehealth Provider Directory, see the scoring approach on the How Scores Are Built page, and work through a worked example on the Free Savings Report.

How telehealth programs handle this prescription

Telemedicine prescribing rules differ by state, and so do the programs themselves. Some are addiction-focused practices with counseling built in. Others are general primary care platforms where this is one item on a long list. A few weight-focused services offer the combination tablet rather than the single ingredient. Those are very different products with different oversight.

Things worth comparing before you commit:

• Whether an actual clinician visit happens, by video or phone, and how long it lasts
• Whether liver testing is required, arranged and paid for
• How the opioid-free interval is confirmed before a first prescription
• Whether counseling, peer support or care coordination is included or sold separately
• Refill process, follow-up frequency and what happens if side effects appear
• Which pharmacy fills the prescription, and whether a compounded low-dose product is involved
• What the monthly charge actually buys, and what it excludes

Patient experiences on this site sit alongside the editorial reviews, and the two answer different questions: one describes how a program felt to use, the other describes what it charges and how it is structured. Program-level analysis lives in our Telehealth Cost Analysis archive, and every drug reference is indexed under Browse Medication References. Simple health math is collected in the Free Health Calculators section.

Questions worth asking before the first dose

Bring a short list to the appointment. Useful ones include: is the oral tablet or the monthly injection a better fit for my situation, and why? How long should I plan to stay on it? Will you check my liver first, and how often after that? What should I do about pain control if I need surgery or land in an emergency room? Do I need naloxone at home, and does my family know how to use it? What happens if I drink or use while taking this? If this is a compounded low-dose product, which pharmacy makes it and what is the evidence for my condition? And, practically, what will this cost me each month once any introductory rate ends?

Also mention every other medicine you take, including over-the-counter cough and diarrhea products, plus any history of depression, liver disease or kidney problems.

When to seek care right away

Call emergency services for slow or stopped breathing, blue lips, unresponsiveness after any opioid use, chest pain, or swelling of the face, lips or throat. Contact a clinician promptly for yellow eyes or skin, dark urine, persistent right-sided abdominal pain, vomiting that will not stop, severe injection-site pain or a spreading wound, or new thoughts of self-harm. Severe withdrawal symptoms after a first dose need same-day attention. If drinking has stopped abruptly and shaking, confusion, sweating or seizures appear, that is a medical emergency rather than something to wait out.

Where these facts come from

Prescribing details, contraindications and warnings on this page follow official US labeling, which you can search through the National Library of Medicine label database and the regulator’s own approved drug products lookup. Treatment context draws on federal addiction agencies and peer-reviewed reviews cited above. Labeling is updated periodically, so the current package insert always outranks any summary, including this one.

Educational content, not medical advice. Always consult a qualified clinician before starting, stopping or switching treatment.