Mysimba Prolonged Release Tablets

What is Mysimba?

Mysimba is a prescription weight-loss tablet containing naltrexone and bupropion. These prolonged-release tablets work on areas of the brain involved in appetite and food cravings, helping support weight loss when combined with a reduced-calorie diet and increased physical activity. Together, they affect brain pathways involved in hunger, cravings and reward.

Weight-loss medicines like Mysimba are typically prescribed when lifestyle changes alone have not produced sufficient results.

Start your Mysimba consultation

What is Mysimba used for?

Mysimba is used to support weight loss and long-term weight management in adults with obesity or overweight individuals who have weight-related health risks like high blood pressure, type 2 diabetes or high cholesterol.

Weight-loss medications may be considered when a person has:

• a BMI of 30 or above (obesity)
• a BMI of 27 or above with weight-related conditions

Mysimba is normally prescribed when lifestyle like changes like diet and exercise have not achieved the right level of weight loss.

What are the benefits of using Mysimba?

Potential benefits of Mysimba when used appropriately include:

• reduced appetite and food cravings
• improved portion control
• support for gradual, sustained weight loss
• potential improvements in weight-related health risks

Even modest weight loss can improve health outcomes. NICE guidance notes that losing 5–10% of body weight can significantly reduce cardiovascular and metabolic risk factors.

How does Mysimba work for weight loss?

Mysimba works by affecting appetite regulation and reward pathways in the brain. It targets two key systems involved in hunger and food cravings.

Bupropion stimulates neurons in the hypothalamus that help control appetite, while naltrexone blocks opioid receptors linked to the brain’s reward system. Together, they help reduce cravings and emotional eating patterns.

Unlike medications that affect digestion or blood sugar levels, Mysimba primarily works on your brain’s appetite control systems. This can help you maintain healthier eating habits over time.

How effective is Mysimba for weight loss?

Clinical studies show Mysimba can support meaningful weight loss when combined with lifestyle changes. Many patients lose around 5–10% of their starting body weight over one year of treatment.

According to research assessed by the European Medicines Agency, patients taking Mysimba lost more weight on average than those following lifestyle changes alone.

NICE also highlights that losing even a small percentage of body weight can improve your blood pressure, blood sugar levels and cholesterol levels. This helps reduce the risk of health complications later in life, like cardiovascular disease and type 2 diabetes.

Who can use Mysimba?

Mysimba is intended for adults with obesity or overweight individuals with weight-related health conditions. A healthcare professional must assess whether it's suitable for you.

It may be considered if:

• your BMI is 30 or above
• your BMI is 27 or above with weight-related conditions

Mysimba may not be suitable for people who:

are pregnant or breastfeeding

• have uncontrolled high blood pressure
• have a seizure disorder or epilepsy
• have severe liver disease

Your doctor or pharmacist will assess your medical history, as well as contributing lifestyle factors, to discuss your options and determine with you what weight loss management treatment is best for you to ensure long-term health.

Mysimba dosages

Mysimba tablets are taken daily, with the dose gradually increased over four weeks to reduce the risk of side effects.

The tablets are prolonged-release, meaning they release medication slowly throughout the day.

How many Mysimba tablets per day?

Typical dosing schedule:

• Week 1: one tablet once daily
• Week 2: one tablet twice daily
• Week 3: two tablets in the morning, one tablet in the evening
• Week 4 onwards: two tablets twice daily (maximum dose of four tablets per day)

Your healthcare provider may adjust the dose based on your response to treatment.

Is Mysimba safe?

Mysimba is generally considered safe when prescribed appropriately and taken as directed by a healthcare professional. It has been approved for weight management in adults within Europe and the UK.

Medicines used in the UK are regulated by the Medicines and Healthcare products Regulatory Agency(MHRA), which monitors safety, quality and effectiveness.

However, Mysimba may not be suitable for everyone and can cause side effects. Medical assessment is required before starting treatment.

How to take Mysimba for the best weight loss results

Like most weight management medications, if you want to maximise the benefits of taking Mysimba, it should be combined with healthy lifestyle changes.

This can include:

following a reduced-calorie, balanced diet

• increasing physical activity
• monitoring food intake and portion sizes
• maintaining regular medical follow-ups

The NHS recommends adults aim for at least 150 minutes of moderate physical activity per week to support overall health and weight management.

Is Mysimba available online in the UK?

Mysimba is a prescription-only medicine in the UK. This means it can only be accessed following an assessment by a qualified healthcare professional.

You can start an online consultation for Mysimba with Chemist4U, and one of our expert clinicians will provide a prescription if the treatment is suitable.

Can you get Mysimba on the NHS?

In some cases, Mysimba may be available through specialist weight-management services within the NHS if eligibility criteria are met. Access may vary depending on local healthcare policies.

Standard Mysimba prices

The price of Mysimba may vary depending on the pharmacy, pack size and whether it's obtained privately or through NHS services.

Private prescriptions often involve the cost of both the consultation and the medication itself.

At Chemist4U, the price of Mysimba starts from £99.99.

How long does Mysimba take to work?

Mysimba begins affecting appetite signals soon after starting treatment, but noticeable weight loss usually develops gradually over several weeks.

Your healthcare provider will typically review your treatment progress after 16 weeks. If you’ve not lost at least 5% of your starting body weight, your treatment may be stopped.

How long does Mysimba stay in your system?

The active ingredients in Mysimba have half-lives that mean they remain in your body for several hours after each dose. However, most of the medication is eliminated within a few days after stopping treatment.

Because Mysimba tablets are prolonged release, the medication is released gradually throughout the day.

Potential Mysimba side effects

Like all medicines, Mysimba may cause side effects. Many are mild and improve as the body adjusts to treatment.

Common side effects include:

• nausea
• headache
• constipation
• dry mouth
• insomnia
• dizziness

Seek urgent medical help if you experience:

• seizures
• severe allergic reactions (swelling of face, throat or difficulty breathing)
• severe mood changes or suicidal thoughts
• signs of high blood pressure like severe headaches or chest pain

Contact a healthcare professional immediately if severe symptoms occur.

How long do the side effects last?

Most side effects appear during the early weeks of treatment and improve as the body adapts to the medication. Gradually increasing your dose helps reduce the likelihood of side effects.

How Mysimba interacts with other medicines

Mysimba may interact with certain medications and medical conditions. Always inform your healthcare provider about any medicines you are taking.

Important interactions include:

• oral contraceptives (severe vomiting or diarrhoea may reduce effectiveness)
• antidepressants or psychiatric medicines
• opioid medicines (due to naltrexone’s opioid-blocking effects)
• medicines that increase seizure risk

Mysimba is not recommended during pregnancy or breastfeeding, as weight-loss medicines are generally not considered safe during these periods.

Mysimba alternatives

Other weight-management medicines may be available depending on your health needs and eligibility.

Examples include:

• orlistat (generic Xenical) – reduces fat absorption
• Wegovy – appetite regulation
• Mounjaro – hormone-based treatment

Your healthcare professional can help determine the most suitable option for your circumstances.

Mysimba vs Mounjaro vs Ozempic

Storage information

Store Mysimba tablets below 30°C in their original packaging to protect from moisture.

Keep medicines out of sight and reach of children. Do not use after the expiry date printed on the packaging.

Always follow the storage instructions included in the patient information leaflet.

Frequently asked questions about Mysimba

Why is Mysimba considered dangerous?

Some people may consider Mysimba dangerous due to potential side effects like increased blood pressure or seizure risk. However, when prescribed appropriately and monitored by a healthcare professional, it can be a safe and effective weight-management treatment.

Can I take Mounjaro and Mysimba together?

While Mounjaro and Mysimba work differently, combining them isn’t usually recommended and should only be done under medical supervision. Always consult your doctor before using multiple weight-loss medications together.

Can I take Mysimba and orlistat together?

Using both medications together may increase side effects and should only be done if recommended by a healthcare professional.

Can you drink alcohol on Mysimba?

Alcohol may increase certain side effects, like dizziness or mood changes, while excessive alcohol consumption may increase the risk of seizures (fits). Your prescriber may suggest you don't drink alcohol, or drink as little as possible, while on Mysimba.

Does Mysimba increase metabolism?

Mysimba does not directly increase metabolism. Instead, it works by reducing appetite and cravings through its effects on the brain.

Is Contrave the same as Mysimba?

Yes. Contrave is the brand name used in some countries for the same combination of naltrexone and bupropion found in Mysimba.

Sources

• Obesity. (2023) NHS [Accessed 12 March 2026]
• Physical activity guidelines for adults. (2023). NHS. [Accessed 12 March 2026]
• Obesity: identification, assessment and management. (2014). NICE. [Accessed 12 March 2026]
• Mysimba, INN-naltrexone/bupropion. EMA. [Accessed 12 March 2026]