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What Is Naltrexone/Bupropion?

What Is Naltrexone/Bupropion?

Obesity is a widespread and serious chronic disease. It affects about 42% of U.S. adults, according to a 2017 survey. While a low-calorie diet and exercise will always remain the foundation of any weight-management program, clinical guidelines recommend offering weight-loss medications to anyone who meets the criteria for obesity or is overweight with a weight-related medical condition.

Obesity is defined as having a BMI of over 30, and overweight is a BMI between 25 and 29.9. Examples of weight-related medical conditions include high blood pressure, type 2 diabetes, or abnormal blood cholesterol.1

There are currently six FDA-approved weight-loss medications. One of these is naltrexone/bupropion, which is marketed under the brand name Contrave. Naltrexone and bupropion work together to help with weight loss, along with a low-calorie diet and exercise plan.

What Is Naltrexone? 

Naltrexone is an opioid antagonist. It binds to opioid receptors in the brain. Opioid receptors mediate pleasure and reinforce enjoyment when eating, drinking alcohol, or using drugs, such as opioids.

Naltrexone is used to treat alcohol use disorder (AUD) and opioid use disorder (OUD). At higher doses, naltrexone reduces your cravings and desire to drink alcohol or use opioids.

At lower doses, naltrexone binds to opioid receptors but for a much shorter time. When naltrexone binds and then releases from opioid receptors, your brain responds by increasing endorphin production.

Low-dose naltrexone is used to treat chronic pain and reduce inflammation. Low-dose naltrexone is being tested for many other potential uses.

What Is Bupropion? 

Bupropion is an antidepressant. It increases the brain chemicals, norepinephrine, and dopamine in the brain. Bupropion is FDA-approved to treat major depressive disorder and seasonal affective disorder and to help people stop smoking.

While the mechanism is not fully understood, bupropion seems to suppress hunger signals in the brain. It is also a mild stimulant that may increase calories burned throughout the day.

How Naltrexone and Bupropion Work Together 

Naltrexone, when combined with bupropion, reduces cravings and decreases hunger. Naltrexone/bupropion acts in two areas of the brain: the hypothalamus and the reward pathway.

The hypothalamus is a part of the brain that controls hunger. The reward pathway in the brain mediates the pleasure you get from rewarding experiences. Eating delicious food, especially salty or sweet food, can cause intense cravings.

Naltrexone/bupropion work together in both areas of the brain. By reducing your hunger and food cravings, naltrexone/bupropion can help you lose weight.

Naltrexone/bupropion seems to promote weight loss by:

  • Suppressing hunger in the hypothalamus
  • Increasing satiety in the hypothalamus
  • Suppressing appetite
  • Increasing dopamine in your brain’s reward pathway
  • Reducing cravings

As researchers learn more about weight loss and the underlying causes of obesity, it has become clear that obesity is a complex disease. It is not simply a matter of calories consumed and calories burned. When you lose weight, your body works hard to help you regain that weight.

Weight loss medications act in the brain to help you overcome some of the metabolic changes in your body that may make it difficult to lose weight.

side effects

Side Effects of Naltrexone/Bupropion

All medications, including weight loss medications, cause side effects. It is important to work with your doctor to determine which weight-loss medication might work best to help you reach your weight-loss goals.

In clinical trials, bupropion increased suicidal thoughts and behaviors in children, adolescents, and young adults. It is important to monitor yourself for any signs of depression or suicidal thoughts, especially in the first few months after starting Contrave. If you have depression or suicidal thoughts, Contrave can make this worse.

Bupropion can also cause seizures. The risk of seizures increases as the bupropion dose increases. If you have a history of seizures or any other medical history that may increase your risk for seizures, ask your doctor if Contrave is a good choice for you.

Allergic reactions to Contrave may also occur. Symptoms of an allergic reaction include rash, blistering or peeling skin, hives, chest pain, swelling of the lips, tongue, or face, and shortness of breath. Allergic reactions can be very serious. If you have these symptoms, seek immediate help.

Other more serious side effects associated with Contrave use include:

  • An increase in blood pressure or heart rate: racing heartbeat. Don’t take Contrave if you have uncontrolled high blood pressure
  • Liver injury: nausea, pain in your upper abdomen, light-colored stool, dark-colored urine, yellow tinge to eyes or skin, unusual weakness, or fatigue
  • Mood changes: anxiety, nervousness, irritability, hostility, confusion, hallucinations, depression
  • Angle-closure glaucoma: sudden change in vision, eye pain, blurry vision, halos around lights, vision loss
  • Hypoglycemia: low blood sugar in people with type 2 diabetes

Most Common Side Effects

Milder or more common side effects reported by people taking Contrave include the following:

  • Altered taste
  • Constipation
  • Diarrhea
  • Dizziness
  • Dry mouth
  • Excessive sweating
  • Headache
  • Heart palpitations
  • Insomnia
  • Irritability
  • Muscle strain
  • Nausea
  • Rash
  • Stomach virus
  • Tremor
  • Trouble sleeping
  • Urinary tract infection
  • Vomiting

This is not a complete list of potential side effects. For more information, see the Contrave Medication Guide or ask your pharmacist.

Other Side Effects

Other side effects associated with naltrexone/bupropion include:

  • Abdominal pain or stomachache
  • Anxiety
  • Excessive sweating
  • Fatigue
  • Flu-like symptoms
  • Hot flush
  • Increase in blood pressure
  • Increase in heart rate
  • Ringing in your ears
  • Shakiness
  • Urinary tract infections

Naltrexone/bupropion work together to reduce hunger and appetite, increase satiety, and increase energy expenditure throughout the day. These two medications work together in the brain to induce weight loss. Like all medications, naltrexone/bupropion has potential side effects, and the risk may be higher for some people than others.

If you have obesity or are overweight with a weight-related medical condition and are interested in medical treatment options to help you manage your weight, contact an Invigor Medical treatment specialist.

While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

What Is Naltrexone/Bupropion?

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.


  • Sherman MM, Ungureanu S, Rey JA. Naltrexone/Bupropion ER (Contrave): Newly Approved Treatment Option for Chronic Weight Management in Obese Adults. P T. 2016 Mar;41(3):164-72. PMID: 26957883; PMCID: PMC4771085.
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Published: Nov 1, 2023


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