Mysimba: What It Is, How It Works, and Who It’s For

Mysimba isn’t another fad diet or miracle supplement. It’s a prescription medication approved for long-term weight management in adults with obesity or overweight who also have weight-related health issues like high blood pressure, type 2 diabetes, or high cholesterol. Unlike quick-fix pills, Mysimba works by targeting the brain’s control centers for appetite and cravings, helping people eat less and stick to healthier habits over time.

How Mysimba Actually Works

Mysimba is a combination of two active ingredients: naltrexone and bupropion. Each one has a different job, but together they create a stronger effect than either alone.

Naltrexone, originally used to treat opioid addiction, blocks certain receptors in the brain that trigger reward-seeking behavior. When you eat high-calorie foods, your brain releases dopamine - a chemical that makes you feel good. Naltrexone dulls that reward signal, so those cravings for chips, cookies, or ice cream lose their punch.

Bupropion, commonly known as an antidepressant (sold as Wellbutrin), also helps reduce appetite. It increases levels of dopamine and norepinephrine in the brain, which can make you feel fuller longer and less driven to snack between meals. It also helps with mood, which matters because stress and low mood often lead to emotional eating.

These two drugs don’t speed up your metabolism or block fat absorption. They don’t make you sick if you eat sugar. Instead, they change how your brain responds to food. That’s why people on Mysimba often report feeling less obsessed with food, not because they’re starving, but because the urge to overeat just isn’t as strong.

Who Is Mysimba For?

Mysimba isn’t for everyone. It’s only approved for adults with a BMI of 30 or higher (obesity), or a BMI of 27 or higher with at least one weight-related condition like prediabetes, sleep apnea, or hypertension.

It’s not meant for people trying to lose 5 or 10 pounds for a wedding or vacation. It’s designed for those who’ve tried diet and exercise but still struggle to keep weight off - often because their body fights back by increasing hunger and slowing metabolism. In clinical trials, people using Mysimba lost an average of 5% to 10% of their body weight over a year, compared to just 1% to 2% with placebo.

It’s also not for people with uncontrolled high blood pressure, a history of seizures, eating disorders like bulimia or anorexia, or those taking certain antidepressants or opioid painkillers. Your doctor will check your full medical history before prescribing it.

How to Take Mysimba

You don’t start on the full dose. Mysimba comes in tablets, and you begin with one tablet daily for the first week. Each week, you increase the dose until you reach the full dose of two tablets twice a day - that’s four tablets total per day.

This slow ramp-up helps your body adjust and reduces side effects like nausea, headaches, or dizziness. Most people feel better after the first two weeks. You should take it with food, never on an empty stomach, to avoid stomach upset.

It takes time to work. Many people don’t notice major changes until after 4 to 8 weeks. If you haven’t lost at least 5% of your body weight after 16 weeks, your doctor may stop the treatment. That’s because if it’s not helping by then, it’s unlikely to work later.

Side Effects and Risks

Like all medications, Mysimba has possible side effects. The most common ones include nausea, constipation, headaches, dry mouth, dizziness, and trouble sleeping. These usually fade within a few weeks.

Less common but more serious risks include increased blood pressure, seizures (especially if you have a history), and mood changes. There’s a small chance of suicidal thoughts, particularly in people with a history of depression. That’s why doctors monitor patients closely in the first few months.

Alcohol should be avoided while taking Mysimba. Combining it with alcohol can raise the risk of seizures. Also, never take it with other medications that contain bupropion or naltrexone - you could overdose on one or both components.

What Happens When You Stop?

Weight loss with Mysimba doesn’t last if you stop taking it. In studies, most people regained about two-thirds of the weight they lost within a year after stopping the medication.

This doesn’t mean Mysimba failed. It means weight management is a long-term process. The drug helps you build healthier habits by reducing cravings, but you still need to eat well and stay active. Think of it like a training wheel - it helps you ride longer until you learn how to balance on your own.

Some people stay on Mysimba for years. Others use it for 12 to 18 months, then slowly taper off while continuing lifestyle changes. The goal isn’t lifelong dependency - it’s to give you the mental space and physical control to make lasting changes.

Mysimba vs. Other Weight Loss Drugs

There are other prescription weight loss medications like Saxenda (liraglutide), Wegovy (semaglutide), and Contrave (which is actually the same as Mysimba - just a different brand name in the U.S.).

Wegovy and Saxenda are GLP-1 agonists. They work by slowing digestion and making you feel full faster. They’re injected weekly and tend to cause more weight loss on average - around 15% of body weight. But they’re also more expensive and can cause more nausea.

Mysimba is taken as a daily pill and is generally cheaper than the GLP-1 drugs. It doesn’t cause as much nausea, but it also doesn’t lead to as much weight loss. For people who prefer pills over injections and want a moderate but steady result, Mysimba is a solid middle-ground option.

Real-World Results

One patient, a 48-year-old teacher with type 2 diabetes and a BMI of 36, started Mysimba after losing 30 pounds through diet and exercise - only to gain it all back within a year. She began Mysimba at the lowest dose and increased slowly. After six months, she lost 22 pounds. Her blood sugar improved. She stopped needing one of her diabetes meds.

"It didn’t make me lose my appetite," she said. "It just made me not care as much about snacks. I still ate three meals a day, but I didn’t crave the candy bar at 3 p.m. anymore. That’s what changed everything."

Another man, a 55-year-old truck driver with high blood pressure, lost 18 pounds over nine months. He didn’t join a gym, but he started walking after dinner and swapped soda for water. Mysimba helped him stick to those changes.

Getting a Prescription

You can’t buy Mysimba over the counter. You need a doctor’s prescription. Many primary care doctors now treat obesity as a medical condition, not just a lifestyle issue. If your doctor doesn’t offer it, ask for a referral to an endocrinologist or obesity specialist.

Insurance coverage varies. In some countries, it’s covered if you have a qualifying BMI and health condition. In others, it’s out-of-pocket. The monthly cost can range from $80 to $200 depending on your location and pharmacy.

Is Mysimba Right for You?

If you’ve struggled with weight for years, tried multiple diets, and feel like your body is working against you - Mysimba might help. It’s not magic. It won’t fix poor eating habits overnight. But if you’re ready to make real changes and want a tool that reduces the mental battle around food, it’s one of the most evidence-backed options available.

It’s not about being "thin." It’s about being healthier, more energetic, and less burdened by weight-related illness. For many, Mysimba isn’t the end of the journey - it’s the first real step forward.

If you’re considering Mysimba, talk to your doctor about your goals, your health history, and what you’re willing to change in your daily routine. The medication can help, but it works best when you’re ready to work with it - not against it.