Colin FosterBy Colin Foster

Updated November 2026

Naltrexone for weight loss is a prescription medication that is sometimes used, usually in combination with another drug, to help adults with obesity or overweight reduce their food intake and cravings. This guide explains how the medicine is thought to work, who may be a candidate, what to expect in the first few months, and which questions to bring to your doctor. It does not replace medical advice, and naltrexone is not an over-the-counter product.

What Naltrexone Is and How It Is Used for Weight

Naltrexone was first approved in the United States in 1984 to treat alcohol and opioid dependence. Its use for weight management comes from a different formulation: a fixed-dose combination of naltrexone and bupropion, an antidepressant that is also used for smoking cessation. Together, these two drugs are approved as an extended-release tablet for chronic weight management in adults with obesity or in adults who are overweight and have at least one weight-related condition, such as high blood pressure, type 2 diabetes, or high cholesterol.

Shopping for one? See our guide: 7 Best Weight Loss Exercises (2026): Beginner-Friendly Picks.

The working idea is that the two drugs act on brain pathways linked to appetite and reward. Bupropion influences dopamine and norepinephrine signaling, and naltrexone blocks opioid receptors that are involved in the pleasure response to eating. Researchers believe this combination may reduce the urge to overeat, although the exact mechanism is still being studied. Results vary from person to person, and the medication works best as part of a broader plan that includes diet and physical activity.

Who May and May Not Be a Good Candidate

Prescribing decisions depend on a full medical history, so a doctor needs to weigh the benefits against the risks for each patient. The following list gives a general picture of who is typically evaluated for this treatment.

  • Adults with a body mass index (BMI) of 30 or higher, or 27 or higher with at least one weight-related health condition
  • People who have already tried diet and exercise changes without reaching their goals
  • People who are willing to attend regular follow-up visits and track progress

Some people should not use this medication. Those with uncontrolled high blood pressure, a seizure disorder, a history of eating disorders, bipolar disorder, or who are currently taking opioid medications generally need to avoid it or be closely supervised. Pregnant or breastfeeding people should not take it. Always tell your doctor about every prescription, over-the-counter product, and supplement you use.

Steps to Take Before Starting Treatment

If you and your doctor decide this option is worth exploring, the process usually follows a clear sequence. Going through these steps carefully helps you set realistic expectations from the start.

  1. Schedule a visit and bring a list of all current medications, supplements, and past weight-loss attempts.
  2. Get baseline measurements, including weight, waist circumference, blood pressure, and relevant lab work.
  3. Ask about your mental health history, since bupropion can affect mood and sleep.
  4. Review how the medicine is taken, which is typically a daily tablet with a gradually increasing dose over several weeks.
  5. Agree on a target, such as a percentage of body weight to lose over a set period, and a schedule for check-ins.

What Your Doctor May Check

Before prescribing, a clinician may review your blood pressure, heart rate, kidney and liver function, and screen for depression or suicidal thoughts. Follow-up visits often happen at about four weeks and then every few months. Your provider may adjust the dose or stop treatment if you are not making progress or if side effects are difficult to manage.

Common Side Effects and What to Expect

Most side effects are mild and tend to appear early. Nausea, constipation, headache, dry mouth, dizziness, and trouble sleeping are the most frequently reported. Taking the medication with food and following the dose schedule closely can help reduce some of these effects. Serious side effects are less common but important to recognize, including high blood pressure, seizures, and changes in mood or thoughts of self-harm. If any of these occur, contact your doctor right away or seek emergency care.

Combining Medication With Lifestyle Habits

Medication is not a substitute for healthy habits. Many people who lose weight successfully pair treatment with a consistent eating pattern and regular movement. Simple, sustainable changes tend to matter more than dramatic short-term rules.

Start with food portions and protein at each meal, and keep a basic food log for the first few weeks so you can see patterns. For movement, a daily walk is an accessible place to begin. Our guide to walking for weight loss explains how to build up distance safely, and our overview of weight loss tips for beginners covers habits that support steady progress.

Habit Starting Point Why It Helps
Daily walking 10 to 15 minutes at a comfortable pace Builds activity without much recovery time
Protein at meals A palm-sized portion at each meal Supports fullness and muscle maintenance
Food log Record meals for two weeks Reveals triggers and habits
Sleep routine Same bedtime most nights Helps regulate appetite hormones

Common Mistakes to Avoid

  • Expecting rapid results in the first few weeks, when weight changes can be slow or uneven.
  • Skipping follow-up appointments because you feel fine.
  • Stopping the medication suddenly without discussing it with your doctor.
  • Taking other weight-loss pills or supplements without checking for interactions.
  • Drinking alcohol heavily while on the medication, which can increase side effects.
  • Ignoring changes in mood, sleep, or blood pressure readings.

Tips for Getting the Most From Treatment

  1. Keep a simple weekly log of weight, waist size, and how you feel.
  2. Set process goals, such as walking four days a week, alongside outcome goals.
  3. Bring a written list of questions to every appointment.
  4. Plan meals ahead so you are not relying on impulse choices when cravings appear.
  5. Tell a trusted friend or family member about your goals so they can offer support.

Tools that support tracking and daily movement can make the lifestyle side of treatment easier to manage. Choose items based on what you will actually use.

  • Digital kitchen scale: Helps you measure portions accurately during the first few months, which makes food logs more reliable. View on Amazon
  • Body weight scale with smart app: Records weight trends over time so you can share accurate data with your doctor. View on Amazon
  • Comfortable walking shoes: Supports regular daily walks, which are an easy way to add activity. View on Amazon
  • Tape measure for waist tracking: A flexible measure gives a helpful second progress marker beyond the scale. View on Amazon

FAQ

Is naltrexone for weight loss the same as the alcohol or opioid version?

The weight-management product combines naltrexone with bupropion in an extended-release tablet at different doses than the single-ingredient forms used for addiction. Do not assume dosing or safety information carries over between them.

How much weight can people lose with this treatment?

Clinical trial results show average losses that vary by study and by how closely people followed the program. Your doctor can give you a realistic estimate based on your starting weight and health profile.

How long does treatment last?

Duration is individualized. Your doctor will reassess benefits and side effects regularly and decide whether to continue, adjust, or stop.

Can I drink alcohol while taking it?

Alcohol can increase side effects such as dizziness and nausea, and it adds calories that can slow progress. Ask your doctor how much, if any, is safe for you.

What happens if I miss a dose?

Follow the instructions your prescriber or pharmacist gave you. Do not double up on doses to make up for a missed one unless specifically told to.

Will I regain weight if I stop taking it?

Weight regain is common after stopping weight-management medication, which is why long-term habits matter. Discuss a maintenance plan with your doctor before stopping.

Is it safe to take with other medications?

Interactions are possible, especially with opioids, certain antidepressants, and blood pressure drugs. Always provide a complete medication list to your doctor and pharmacist before starting.

Conclusion

Naltrexone for weight loss, used as a combination tablet under medical supervision, is one option for adults with obesity or excess weight and related health conditions. Success depends on a careful medical evaluation, realistic expectations, regular follow-up, and steady changes to eating and activity. Talk with your doctor to decide whether it fits your health needs and goals. This article is for general education and is not a substitute for professional medical advice.

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Colin Foster

About Colin Foster

Colin Foster is part of our editorial team and reviews and edits our beginner fitness & weight-loss exercise guides, checking product details against manufacturer specifications and owner feedback.