Mysimba is a tablet made by a company called Orexigen. It has two active ingredients in it: naltrexone hydrochloride and bupropion hydrochloride. When you take Mysimba to lose weight, the ingredients are released slowly and work on receptors in the brain that affect how much you want to eat.
Mysimba can be a suitable treatment for your weight loss if you’ve got a BMI of 30 or more, or if you’ve got a BMI of 27 or more and have other health risks, like type 2 diabetes.
It isn’t fully understood how Mysimba works for weight loss, but it’s thought that its active ingredients work on the receptors in the brain which affect food cravings.
By reducing your feelings of craving food, you’re more likely to eat less, and as a result maintain a calorie-deficit – making you lose weight.
What makes Mysimba different from other weight loss treatments?
Unlike other tablets, such as Orlistat or Alli, Mysimba doesn’t affect your digestion of fat. With Orlistat and Alli you’ll have to follow a low fat diet in order for either tablet to work. With Mysimba your diet doesn’t need to be specific, you’ll just want to eat less. This will mean that you’ll find it easier to actively reduce the amount of calories that you eat.
There are also other treatments for weight loss, like Saxenda, which you inject. This treatment also needs to be taken alongside a calorie controlled diet and exercise for it to work.
Mysimba tablets are marketed as ‘Contrave’ in the USA. Whilst you can’t get Contrave in Europe, Contrave and Mysimba contain exactly the same ingredients and will work in the exact same way to help you lose weight.
Many studies have shown positive weight loss results with Mysimba.
In a study of 1742 participants, it was found that Mysimba worked very well as an obesity treatment, with those who took Mysimba losing 6.1% body fat, compared with 1.3% in the placebo group.
In patients who were overweight and showing signs of type 2 diabetes, Mysimba was also successful in reducing the symptoms of prediabetes, too.
Mysimba is a longer-term treatment, which you’ll need to take for around 16 weeks. During this time you should start to see some weight-loss results. After the 16 weeks, your clinician will check on your progress to see how you’re getting on with it. If it’s having the desired effect, and you’re losing the weight that you want to, you’ll be able to carry on taking it for as long as it’s helpful and safe for you to.
Mysimba works best with a low-calorie diet. If you feel like Mysimba isn’t working for you, then you can have a chat with your clinician and see if there are any further tweaks you can make to your diet.
You’ll also notice greater benefits from Mysimba if you take it alongside regular exercise. The government recommends getting at least 150 minutes of moderate exercise per week (such as a brisk walk or a light swim) or 75 minutes of vigorous activity, such as running or playing high-intensity sport.
Taking Mysimba usually involves starting off with a small dose every day and increasing the number of tablets you take over a four-week period. Typically, you’ll follow these guidelines:
Your maximum dose is two tablets, twice a day – which equals 32mg of naltrexone hydrochloride and 360mg bupropion hydrochloride.
After you’ve been taking Mysimba for 16 weeks, your progress should be evaluated. Mysimba can be taken for as long as it’s needed, as long as it’s still giving results and it’s safe for you to take it. If you’re still taking it after a year then you’ll need another review, and then a further one for every year that you’re prescribed it for.
If you miss a dose then you shouldn’t take an additional one to make up for it. Simply take your next prescribed dose at the right time and carry on as normal.
Your Mysimba dose will start off with one tablet a day, then increase steadily over a period of four weeks until you’re taking the right amount of tablets.
After four weeks you’ll likely be taking two tablets, twice a day – this will be your maintenance dose. You’ll stick with this dose until your review with your clinician, which is held 16 weeks after you started taking the tablets.
Always try to take Mysimba at the same time every day, with food. If you’re taking one tablet, have it with your breakfast in the morning. If you’re at the stage when you’re taking three tablets a day, take two of those with breakfast and one with your evening meal.
You’ll need to avoid drinking where possible when taking Mysimba, as if you consume too much it can increase your risk of developing some serious side effects.
Mysimba is a weight loss medication that can help you if you’ve got a BMI of over 30. It works best when it’s taken with a calorie-controlled diet, and you should avoid drinking alcohol whilst you’re taking it.
It works by slowing down the receptors in your brain that control your food intake and energy. As a result, it makes you feel like eating less. It’s as simple as that.
It’s different from a lot of other weight loss treatments. With these other treatments, you’ll need to follow a strict low-fat eating plan, otherwise you might not lose weight at all. They can also sometimes have side-effects, like stomach issues, whilst you’re adjusting to taking the tablets every day.
If you think Mysimba could be right for you, talk to a clinician about your health. They'll be able to help you to determine the right treatment, diet and exercise plan for your life.
Naltrexone–bupropion (Mysimba) in management of obesity: A systematic review and meta‐analysis of unpublished clinical study reports. British Journal of Clinical Pharmacology, 86(4), pp.646–667.
Effect of naltrexone plus bupropion on weight loss in overweight and obese adults (COR-I): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet, 376(9741), pp.595–605. [Accessed 25-10-21].
Mysimba 8 mg/90 mg prolonged-release tablets - Summary of Product Characteristics (SmPC) - (emc). [Accessed 25-10-21].
Physical activity guidelines for adults aged 19 to 64.
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Unlike other tablets, such as 
Mysimba is a weight loss medication that can help you if you’ve got a BMI of over 30. It works best when it’s taken with a calorie-controlled diet, and you should avoid drinking alcohol whilst you’re taking it.
