Contrave works by targeting two areas of the brain simultaneously: the hypothalamus, which regulates appetite, and the mesolimbic dopamine circuit, which controls reward and cravings. It combines two existing medications, naltrexone (an opioid blocker) and bupropion (commonly used for depression and smoking cessation), that act on different pathways to reduce hunger and make food less rewarding. Neither drug produces much weight loss on its own, but together they amplify each other’s effects in a way that helps people eat less.
Two Brain Pathways, Two Drugs
Your brain controls eating through two distinct systems. The first is a hunger-regulation center in the hypothalamus that tells you when you’re hungry and when you’ve had enough. The second is your reward system, the same circuitry involved in addiction, which makes certain foods (especially high-calorie, high-sugar ones) feel intensely pleasurable and hard to resist. Contrave’s two ingredients each address one of these systems.
Bupropion activates neurons in the hypothalamus called POMC neurons. When these cells fire, they release signals that suppress appetite and increase energy expenditure. The problem is that POMC neurons also release the body’s own opioids, which act as a brake, shutting down the very signal bupropion just activated. That’s where naltrexone comes in. By blocking opioid receptors, naltrexone removes that brake. The result: POMC neurons fire more and keep firing, producing a stronger and longer-lasting appetite-suppressing effect than bupropion could achieve alone.
How It Reduces Cravings
Beyond simple hunger, many people struggle with cravings triggered by the sight, smell, or even the thought of certain foods. This is driven by the brain’s reward system. Naltrexone blocks opioid receptors throughout this circuit, which changes how the brain responds to food cues. Research suggests this isn’t just about making food less pleasurable. Naltrexone appears to strengthen the brain’s ability to resist distraction by attractive food cues, essentially making it easier to ignore a plate of cookies on the counter or say no to a drive-through. This “top-down control” effect may explain why people on Contrave report feeling less preoccupied with food, not just less hungry.
Bupropion contributes to this as well by increasing dopamine and norepinephrine activity in the brain. These chemicals affect mood, motivation, and energy levels. For people whose overeating is partly driven by low mood or emotional eating, this boost can break the cycle of eating for comfort.
Who Can Take It
Contrave is FDA-approved for adults with a BMI of 30 or greater, or a BMI of 27 or greater if they also have at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol. It’s meant to be used alongside a reduced-calorie diet and increased physical activity, not as a standalone solution.
How the Dose Builds Up
Contrave isn’t started at full strength. The dose builds gradually over four weeks to help your body adjust and reduce side effects. In the first week, you take one tablet in the morning only. The second week adds a second tablet in the evening. The third week increases the morning dose to two tablets while keeping one in the evening. By week four, you reach the full maintenance dose of two tablets twice daily, totaling 32 mg of naltrexone and 360 mg of bupropion per day. This slow ramp-up is particularly important for managing nausea, which is the most common reason people stop taking the medication early.
The 16-Week Checkpoint
Contrave doesn’t work for everyone, and there’s a built-in rule for figuring out whether it’s working for you. By week 16, you should have lost at least 5% of your starting body weight. If you haven’t hit that threshold, the medication is unlikely to produce meaningful results with continued use, and the recommendation is to discontinue it. This checkpoint matters because it prevents you from staying on a medication for months without benefit. If you weighed 220 pounds when you started, for example, you’d want to see at least an 11-pound loss by the four-month mark.
What to Expect With Side Effects
Nausea is by far the most commonly reported side effect, and it tends to be worst during the first few weeks while the dose is still being increased. This is one reason for the gradual titration schedule. Other frequently reported effects include constipation, headache, dizziness, trouble sleeping, dry mouth, and vomiting. Most of these improve as your body adjusts over the first month or two.
Bupropion, one of Contrave’s two ingredients, lowers the seizure threshold. This means people with a history of seizures, eating disorders like bulimia or anorexia (which can alter electrolytes and increase seizure risk), or those who are abruptly stopping alcohol or sedatives should not take it. Because naltrexone blocks opioid receptors, Contrave is also off-limits if you’re currently taking opioid pain medications or are in opioid withdrawal. Taking naltrexone while opioids are in your system can trigger sudden and severe withdrawal symptoms.
How It Compares to Newer Weight Loss Drugs
Contrave works through a completely different mechanism than the newer injectable weight loss medications like semaglutide and tirzepatide, which mimic gut hormones called incretins. Those drugs tend to produce larger average weight losses (15% or more of body weight in clinical trials, compared to more modest results with Contrave). However, Contrave is taken as a pill rather than an injection, is often more affordable, and may be a better fit for people whose weight struggles involve strong food cravings, emotional eating, or reward-driven eating patterns rather than purely physical hunger. It also has a longer track record, having been on the market since 2014.
The two approaches aren’t mutually exclusive. Some prescribers combine Contrave’s craving-reduction effects with other strategies, though this depends on individual circumstances and medical history. What makes Contrave distinct is its direct action on the brain’s reward circuitry, something the injectable medications don’t specifically target.