The Complete Guide to Mysimba Slimming Tablets

Mysimba has supported weight-loss journeys across the UK for over a decade. While it is regarded as a budget-friendly option, this daily tablet has been widely tested in clinical trials and is a safe, effective way to manage your weight.

So, are Mysimba slimming tablets the right weight loss treatment for you? This article provides a comprehensive guide to frequently asked questions and covers important factors such as side effects, costs, and dosages.
 

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What are Mysimba Tablets?

Mysimba is a prescription medication tablet taken to support and enhance weight loss journeys and to tackle obesity. It combines the two active ingredients, naltrexone and bupropion, to reduce total body weight by an average of 3.7-8.1%. As you progress through treatment, the number of tablets you take increases, up to a maximum of 4 per day. This allows your body time to adjust to the new medicine and reduces the severity and impact of side effects. A treatment plan usually spans one year, but can be continued for as long as needed under annual clinical review. It will continue as long as the user loses at least 5% body weight in the first 16 weeks of treatment, and follows yearly clinician check-ups to assess whether they should continue treatment.

Although originally created by Orexigen Therapeutics, commercialisation and distribution agreements have led to Mysimba now being manufactured by Siegfried Barberà S.L. It was approved as a weight loss treatment by the EMA (European Medicines Agency) in 2015, making it one of the earliest treatments of its kind.

What Does Mysimba Do?

Mysimba reduces appetite and suppresses positive emotions tied to food consumption to reduce overeating. This, when paired with other healthy practices like an improved diet and regular exercise, makes the process more effective and your weight loss journey more efficient.

How Do Mysimba Tablets Work?

To understand how Mysimba works, we must first understand the problem it solves.

After consuming high-fat or high-sugar foods, dopamine receptors in the brain are activated, which makes us feel good or rewarded. However, this can lead to an addiction or dependence on unhealthy foods, which creates a cycle of emotional cravings and frequent snacking. This is where Mysimba comes in.

The two main ingredients in Mysimba target two different parts of the brain. Independently, ‘bupropion’ is typically used in treatments that help people to quit smoking, while ‘naltrexone’ is used as an alcohol addiction treatment. When combined, however, they work together to suppress appetite and block opioid receptors, reducing the association of rewarding feelings with unhealthy foods. Less rewarding feelings mean less desire to overeat!

This leads to a lower food intake and makes sticking to a low-calorie diet much easier. Mysimba’s contemporaries on the UK market tend to target hormones in the digestive system rather than focusing purely on receptors in the brain, and this difference gives it a unique mechanism of action. You may find that a treatment focusing on the psychological aspects of weight loss works better for you.

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• Reduces cravings & emotional eating 
• Convenient, twice-daily oral treatment 
• Proven weight loss results

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• Online prescription - No doctor visit

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How Long Does it Take for Mysimba to Work?

After taking the first dose of Mysimba, many notice a drop in appetite within the first few weeks. Mysimba’s gradual dose escalation is necessary to give your body sufficient time to respond and acclimatise to the medication. It isn’t something that can be rushed; otherwise, the side effects may become more severe.

Visible changes in BMI (Body Mass Index) typically become noticeable around the 8-week mark, and the full extent of weight loss is usually seen after a year. Your clinician will closely monitor your progress. At the 16-week mark, they will assess your progress. If you have lost at least 5% of your starting body weight, you may continue with the treatment. If not, they may recommend a different treatment.

Who Can Use Mysimba?

Eligibility for Mysimba slimming tablets is largely based on BMI. If your initial BMI is ≥ 30, or ≥ 27 if you have at least one weight-related health issue, such as type 2 diabetes, high blood pressure or sleep apnoea, then you may be eligible. Above all, it is for those struggling with food cravings and emotional eating.

Who Cannot Take Mysimba? 

Taking Mysimba while on other medicines may have undesirable effects. Some opiate-containing medicines, painkillers and dependence medicines work in similar parts of the brain, and so could interact with Mysimba to make one or both less effective. They could also lead to more severe side effects. Opioid-containing medicines should not be used while on Mysimba.

Medications for depression, diabetes and blood pressure could all be impacted by Mysimba. Your clinician will tell you if you are taking something that could cause an issue.

Mysimba should also not be taken if you are pregnant, breastfeeding, or planning to conceive or breastfeed. If you have a history of seizures, bipolar disorder, eating disorders such as bulimia or anorexia, or if you are undergoing certain forms of withdrawal, you should not use Mysimba. A full list of those who cannot use Mysimba is in the Patient Information Leaflet. Always consult a clinician before starting treatment.

Mysimba Dose Information 

Mysimba slimming tablets are to be taken daily, swallowed whole with water, and preferably with food, to minimise the risk of side effects. You must not split, crush or chew them, as it can affect their effectiveness.

The starting dose of Mysimba will be prescribed as follows:

• Week 1 - One tablet every morning
• Week 2 - Two tablets daily, one in the morning, one in the evening
• Week 3 - Three tablets daily, two in the morning, one in the evening
• Week 4 - Four tablets daily, two in the morning, two in the evening

From then on, it is four tablets a day until the treatment has run its course. Remain consistent to maximise the treatment's effects. If you accidentally miss a dose, skip it and take the next one at your normal scheduled time. For your own safety, do not take a double dose.

How to Improve Weight Loss with Mysimba

A combination of regular exercise and healthy dietary changes is essential to getting the most out of Mysimba slimming tablets.

Exercise doesn't have to be strenuous. Cycling, walking, swimming and jogging are all forms of cardiovascular exercise that will aid the effectiveness of the treatment. About 2.5 hours per week of varied activity will greatly help reduce BMI, though you should generally avoid exercise straight after meals. Instead, a light walk is better to avoid disrupting digestion.

Your diet should include more lean protein, such as fish, eggs, chicken, and tofu. From there, pairing them with vegetables and bread will give you the kind of well-rounded diet that Mysimba thrives upon.

As stated, Mysimba is a supporting treatment, not a cure. It will make your weight loss efforts much more effective, but it will be ineffective on its own. To maximise your results, dedication and commitment are key.

Mysimba Tablets Side Effects

The most common Mysimba side effects are typically mild to moderate and improve as treatment continues and your body adjusts. You may also experience no side effects; everyone reacts differently. The most common ones include:

• Nausea
• Headaches
• Dizziness
• Dry mouth
• Fatigue
• Insomnia
• Anxiety
• Constipation

There are more serious and potentially dangerous side effects that Mysimba can cause, such as suicidal thoughts, seizures, and severe skin reactions. These are a cause to seek medical attention immediately. The full list of side effects, ranging from common to severe, is available in the Patient Information Leaflet.

To manage the effects as best as possible, take the tablets with food to reduce nausea. Drinking plenty of fluids will help with the dry mouth, and avoiding caffeine will help with the anxiety. Always seek a clinician's advice if the effects become severe or persistent.

How Does Mysimba Compare to Nevolat?

Mysimba and Nevolat work differently but aim for the same outcome. While Mysimba blocks opioid receptors in the brain to regulate hunger and reduce the pleasure associated with overeating, Nevolat works in both the brain and the stomach, slowing digestion and keeping you physically full longer.

Both are administered daily and regulate body weight, but the main difference is that Nevolat is an injection rather than a tablet. For some, daily tablets will be preferable to daily injections, especially if you would need assistance from another person when injecting.

When comparing the highest dosage after 56-week trials, Mysimba reduces total body weight by an average of 3.7-8.1%, while Nevolat sits around 8%.

When deciding which is right for you, you must also consider the ingredients, as one may contain something you are allergic to. While both work toward the same goal, their different makeup means they can affect people differently.

Both cost and availability are also factors to consider. Mysimba is typically the cheaper option, being around £109 per month, whereas Nevolat is £199 for one month's dosages.

Research is fundamental before starting either treatment, as it shouldn't be rushed. We offer a comprehensive breakdown of the differences between the two treatments, so you can easily find which one would work best for you.

Mysimba? Our pleasure!

Applying for Mysimba slimming tablets is both fast and secure when done through our website. After you complete a short form, one of our clinicians will assess whether it is the right treatment for you before passing the order on to our General Pharmaceutical Council-registered dispensing pharmacy. If your order is approved before 3pm on a weekday, Mysimba will be at your door the very next day, in discreet plain packaging.

Regardless of where you are in your weight loss journey, from the very beginning to midway through and needing a boost, Prescription Doctor is here to help. Our team of dedicated clinicians will be with you every step of the way, offering support and ensuring everything runs smoothly.

Start your consultation with Prescription Doctor today, and let’s move forward together.
 

Authored & Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 03/09/2026 Reviewed on: 03/09/2026