Naltrexone for Weight Loss: What the FDA Labels Actually Say

Quick answer

As of September 2026, naltrexone by itself is not FDA-approved for weight management. Its label, naltrexone hydrochloride tablets, USP, lists two indications: treatment of alcohol dependence and blockade of the effects of exogenously administered opioids. Exactly one FDA-approved weight-management product contains naltrexone, and it is a combination: CONTRAVE, an extended-release tablet of naltrexone and bupropion, indicated with a reduced-calorie diet and increased physical activity for adults with obesity, or overweight with at least one weight-related condition. Prescribing naltrexone alone for weight is an off-label decision that belongs to a licensed prescriber; FDA has not reviewed the drug's benefits and risks for that use.

What is naltrexone approved for?

The cleanest way to answer a question about any prescription medicine is to read its FDA prescribing information, often called the label. The current label for naltrexone hydrochloride tablets, USP (SpecGx LLC, version effective September 2026, published on DailyMed) describes naltrexone as an opioid antagonist and states that the tablets "are indicated in the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids."

That section adds a limit that is easy to skip past: the tablets "have not been shown to provide any therapeutic benefit except as part of an appropriate plan of management for the addictions." The manufacturer's own document frames naltrexone as one component of addiction care.

There is no weight-management indication on the naltrexone label. Its adverse reactions section does list loss of appetite among the events reported in trials for opioid addiction, but an adverse reaction is a safety observation the manufacturer must disclose, not evidence of benefit and not an approved use. If reading labels is new to you, how to read a prescription label walks through the sections in order.

Is naltrexone and bupropion (Contrave) approved for weight loss?

CONTRAVE (Nalpropion Pharmaceuticals LLC, label version effective November 2025) is an extended-release tablet that combines two active ingredients for weight management: naltrexone, the opioid antagonist above, and bupropion, which the label describes as an aminoketone antidepressant. A search for "naltrexone bupropion weight loss" is, in practice, a search for this product. Its indication reads: "CONTRAVE is indicated in combination with a reduced-calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in adults with obesity or overweight in the presence of at least one weight-related comorbid condition."

Three details in that sentence matter for anyone searching "naltrexone weight loss": the approval belongs to the combination product, not to either ingredient on its own; the indication is conditional on a reduced-calorie diet and increased physical activity; and the population is defined as adults with obesity, or adults with overweight who also have at least one weight-related condition.

The label also lists Limitations of Use. The effect of Contrave on cardiovascular morbidity and mortality has not been established. Coadministration with other naltrexone-containing products is not recommended, and coadministration with other bupropion-containing products is contraindicated. In plain words, the manufacturer says not to layer plain naltrexone, or a separate bupropion prescription, on top of Contrave. What bupropion by itself is approved for sits in a separate label, and our read of the Wellbutrin XL label shows it names major depressive disorder and prevention of seasonal affective disorder, not weight.

What does "off-label" mean, and who decides?

FDA maintains a consumer page titled "Understanding Unapproved Use of Approved Drugs 'Off Label'". It explains that before approval a company must demonstrate to FDA that a drug's benefits outweigh its risks for its intended uses, and that "safe" in that sense means the benefits outweigh the potential risks, not that the drug has no side effects. On prescribing, the page states: "From the FDA perspective, once the FDA approves a drug, healthcare providers generally may prescribe the drug for an unapproved use when they judge that it is medically appropriate for their patient." FDA gives three shapes an off-label use can take: a disease or condition the drug is not approved to treat, a drug given in a different way than its approved form, or a different dose than the label specifies. And it draws the line this article follows: for an unapproved use, FDA has not reviewed whether the benefits outweigh the risks.

Applied here: naltrexone for alcohol dependence or opioid blockade is on-label. Naltrexone alone for weight is off-label; FDA has not evaluated it for that purpose, and the decision, if it is ever made, rests with a licensed physician who has examined the individual patient. The same reading applies to prescriptions in other classes, including the SGLT2 inhibitor reviewed in Jardiance and what its label is actually approved for. This article does not recommend, encourage or explain how to obtain naltrexone for weight loss. It reports what the labels say so that a conversation with a physician starts from the primary documents.

The Contrave boxed warning, in plain words

The Contrave label opens with a boxed warning, titled "WARNING: SUICIDAL THOUGHTS AND BEHAVIORS", because it contains bupropion, an active ingredient also found in several antidepressant medications, and antidepressants as a class increased the risk of suicidal thoughts and behavior in children, adolescents and young adults in short-term trials. For an antidepressant on its own and the opposite question, weight gain, see what the Cymbalta label says about weight.

The instruction is not limited to young people: "In patients of all ages who are started on CONTRAVE, monitor closely for worsening, and for the emergence of suicidal thoughts and behaviors." The label asks prescribers to involve families and caregivers, and states that Contrave is not approved for pediatric patients or for treating major depressive disorder or other psychiatric disorders.

Plain naltrexone has no boxed warning. Its Warnings section does note that depression, suicide, attempted suicide and suicidal ideation have been reported in postmarketing experience with naltrexone used for opioid dependence, with no causal relationship demonstrated.

Who should not take Contrave, according to its label?

The Contrave Contraindications section names these situations:

• Uncontrolled hypertension.
• Seizure disorder or a history of seizures.
• Use of other bupropion-containing products, including certain antidepressants and a smoking-cessation product.
• Bulimia or anorexia nervosa, which the label says increase the risk of seizure.
• Chronic opioid or opiate agonist use (methadone is the label's example), partial agonist use (buprenorphine), or acute opiate withdrawal.
• Abrupt discontinuation of alcohol, benzodiazepines, barbiturates or antiepileptic drugs.
• Concomitant use of monoamine oxidase inhibitors (MAOIs), with a washout interval the label specifies; reversible MAOIs such as linezolid are included.
• Known allergy to bupropion, naltrexone or any other component.

Naltrexone's own contraindications: opioids first

The naltrexone label's list is shorter and centers on one theme. Naltrexone is contraindicated in patients receiving opioid analgesics, in patients currently dependent on opioids (including those maintained on methadone or buprenorphine), in patients in acute opioid withdrawal, in anyone who has failed a naloxone challenge test or has a positive urine screen for opioids, and in anyone with a history of sensitivity to naltrexone or the product's other components.

The Warnings section explains why. Naltrexone blocks opioid receptors, so it can precipitate withdrawal in anyone who is not completely free of opioids. After treatment stops, tolerance may be lower than before, so a previously tolerated opioid dose can cause life-threatening intoxication; the label reports fatal overdoses after discontinuation and directs prescribers to discuss overdose reversal agents such as naloxone. A separate Hepatotoxicity warning reports cases of hepatitis and clinically significant liver dysfunction in association with naltrexone exposure.

Adverse reactions the labels name

The Contrave label names nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth and diarrhea as its most common adverse reactions, and refers readers to the boxed warning and the warning categories above for the serious ones.

The naltrexone label, in its alcoholism safety study, names nausea, headache, dizziness, nervousness, fatigue, insomnia, vomiting, anxiety and somnolence. In its opioid-addiction trials it lists difficulty sleeping, anxiety, nervousness, abdominal pain or cramps, nausea or vomiting, low energy, joint and muscle pain and headache, followed by a longer list that includes loss of appetite, diarrhea, constipation, irritability, skin rash and chills.

Drug interactions the labels name

Naltrexone. The label says studies of interactions with drugs other than opiates have not been performed, so caution is advised with any concomitant medicine. It specifically states: "Patients taking naltrexone hydrochloride may not benefit from opioid containing medicines, such as cough and cold preparations, antidiarrheal preparations, and opioid analgesics." It also flags disulfiram, another potentially hepatotoxic medicine, and thioridazine.

Contrave. The label's interaction section is longer because bupropion is metabolized by, and inhibits, liver enzymes. It names: MAOIs (contraindicated); drugs metabolized by CYP2D6, including many antidepressants, some antipsychotics, beta-blockers such as metoprolol and certain antiarrhythmics; digoxin; CYP2B6 inhibitors such as clopidogrel and CYP2B6 inducers such as ritonavir, carbamazepine and phenytoin; drugs that lower the seizure threshold; dopaminergic drugs such as levodopa; and opioid analgesics, with a warning matching naltrexone's that opioid-containing medicines may not fully work. The label also states Contrave can cause a false-positive urine test for amphetamines.

What the labels ask a physician to check

The labels describe what must be checked, whether the question is about the combination product or naltrexone alone.

• Confirm the indication. For Contrave, does the patient fit the labeled population, with a reduced-calorie diet and increased physical activity as part of the plan? For naltrexone alone, weight management is not on the label, so the request is an off-label question that FDA has not evaluated.
• Screen for contraindications. Opioid use of any kind, including opioid-containing cough or antidiarrheal products, is the first question for both products. For Contrave the physician adds blood pressure control, seizure history, eating-disorder history, other bupropion products, MAOIs and recent discontinuation of alcohol or sedatives.
• Review the medication list against the interaction sections.
• Consider the boxed warning, including monitoring for suicidal thoughts and behaviors and family or caregiver involvement.
• Plan follow-up. Both labels warn about opioid overdose vulnerability after stopping and carry hepatotoxicity warnings, so the physician decides what monitoring is needed and which symptoms call for urgent care.

None of this includes a promise about outcomes. The labels describe indications, risks and monitoring; the physician decides whether any of it fits the person in front of them.

How do GLP-1 medicines differ from naltrexone for weight loss?

Many readers are comparing naltrexone with medicines in a different class. FDA-approved GLP-1 receptor agonist products for weight management include WEGOVY (semaglutide), whose current label covers both an injection and tablets and states that "WEGOVY injection is indicated in combination with a reduced calorie diet and increased physical activity" to reduce excess body weight and maintain weight reduction long term in the populations the label names, and ZEPBOUND (tirzepatide), an injection the label describes as a GIP and GLP-1 receptor agonist "indicated in combination with a reduced-calorie diet and increased physical activity" for that purpose in adults.

Those products have their own boxed warnings, contraindications and interaction sections, and this article does not compare their effect with Contrave or naltrexone; the labels do not make that comparison. Compounded versions of GLP-1 medicines also exist. Compounded medications are not FDA-approved as final products. See whether compounded semaglutide is FDA-approved, what a GLP-1 medication is and Wegovy alternatives. Two other single-ingredient medicines that draw similar off-label questions are covered in topiramate for weight loss and Trulicity for weight loss.

Questions to bring to a physician

FDA's off-label page suggests asking what a drug is approved for and whether approved alternatives exist. Building on that:

• Is the use being discussed on-label or off-label?
• If Contrave is being considered, do I fit the population its label describes?
• Do I take any opioid-containing product, including cough, cold or antidiarrheal medicines?
• Which of my current medicines appear in the interaction sections?
• What does the boxed warning mean for me, and what should my family watch for?
• What monitoring will you do, and which symptoms mean I should call right away?

This article is for informational purposes only and does not constitute medical advice. Medication is prescribed only if a licensed physician determines it is appropriate. Label text reflects the versions current on DailyMed as of September 19, 2026.