Mysimba: Weight treatment in tablet form

What is Mysimba and how do naltrexone and bupropion work?

Mysimba is administered as tablets and contains the two active substances bupropion and naltrexone. Together, they affect the central nervous system and the mechanisms that regulate appetite and energy intake.

Bupropion affects the neurotransmitters dopamine and norepinephrine, which are involved in the brain's reward and appetite regulation. It can help curb rapid impulses and be a valuable tool in emotional eating. Naltrexone works by blocking opioid receptors, which modulates the reward system's response to food. It can be helpful for cravings or snacking between meals.

The combination of these effects can contribute to reduced appetite and decreased cravings for energy-dense food, which in turn can facilitate a reduced energy intake.

For the best effect, the treatment is combined with lifestyle measures, such as dietary changes and physical activity.

Who can get Mysimba prescribed for overweight?

Medications for weight treatment, such as Mysimba, can be considered for adults with a Body Mass Index (BMI) ≥30, or at a BMI ≥27 in combination with at least one weight-related complication.

Examples of such conditions include prediabetes, type 2 diabetes, dyslipidemia, or high blood pressure.

The assessment is based on established medical guidelines, where pharmacological treatment is intended as a complement to lifestyle measures.

Prescription is always preceded by an individual medical assessment. The doctor takes into account your medical history, ongoing medication, and previous attempts at weight loss to determine if the treatment is appropriate.

Read more about how obesity is defined and treated in our article on the subject.

Contraindications and caution

Risks with high blood pressure and other conditions

Mysimba should not be used in certain medical conditions where the treatment may involve an increased risk.

The medication is contraindicated in case of:

• uncontrolled high blood pressure
• epilepsy or history of seizures
• bipolar disorder
• ongoing or historical eating disorders (e.g., anorexia or bulimia)
• concomitant treatment with monoamine oxidase inhibitors (MAO inhibitors) or recently discontinued such treatment
• concomitant use of opioids or opioid dependence

Mysimba should also not be used during pregnancy or breastfeeding. Naltrexone/bupropion should be used with caution in patients over 65 years of age and is not recommended for patients over 75 years of age.

Bupropion, one of the active substances, can affect blood pressure and lower the seizure threshold. Therefore, it is important that blood pressure is well-controlled before treatment is initiated and that a thorough medical assessment is performed.

Caution should be exercised in certain conditions, such as impaired liver or kidney function as well as concomitant treatment with medications that can increase the risk of seizures. Prior to treatment, an individual assessment must be made, where the doctor reviews medical history, current medications, and any risk factors to ensure that the treatment is appropriate and safe.

Side effects

Like other medical treatments, Mysimba can cause side effects. Common side effects are nausea, vomiting, headache, dry mouth, sleep disturbances, dizziness, and constipation. These usually appear at the beginning of the treatment period and tend to subside as the body adjusts. The risk of side effects varies between different individuals.

Since the medication affects the central nervous system, patients should be attentive to changes in mood, anxiety, or depression. New or worsening psychological symptoms should be reported to healthcare professionals.

Certain medications can interact with Mysimba, especially those affecting the nervous system or lowering the seizure threshold. Therefore, it is important that a doctor reviews current and past medications before treatment begins.

In case of severe or prolonged side effects, the dose should be adjusted or the treatment reconsidered in consultation with healthcare professionals. Side effects are often dose-dependent and can in many cases be alleviated through a gradual dose escalation.

Mysimba should be combined with dietary changes and regular physical activity

To promote a healthy body composition during weight loss, it is important to combine the treatment with an adequate protein intake and regular strength training. The goal is to preserve muscle mass to the greatest extent possible while fat mass decreases.

Medical treatment can contribute to a reduced energy intake. During an energy deficit, the body uses both fat and muscle tissue as an energy source. Without adequate protein intake and muscle-stimulating activity, part of the weight loss may therefore consist of loss of muscle mass.

Strength training acts as a signal to the body to preserve musculature, while protein provides the building blocks required to maintain and repair muscle tissue.

Preserved muscle mass is also important for basal energy expenditure, which can facilitate weight stability over time.

Frequently asked questions about Mysimba

How much weight do you lose with Mysimba?

Clinical studies show that treatment with Mysimba can lead to an average weight loss of approximately 5–8 percent of body weight after about 12 months, provided that the medication is combined with lifestyle measures such as dietary changes and physical activity.

The effect varies between individuals, and some patients achieve greater weight loss while others have a more limited response. Mysimba can work well for people where appetite and cravings are the main driving forces behind overeating. Factors such as adherence to treatment and the degree of lifestyle changes affect the outcome. Treatment with Mysimba must be discontinued after 16 weeks if the patient has not lost at least 5% of their initial body weight.

What happens if I forget a tablet?

If you forget to take a dose of Mysimba, you should skip the missed dose and take the next dose at the regular time.

You should not take a double dose to compensate for a missed tablet.

Can I drink alcohol when taking Mysimba?

Alcohol consumption should be limited or avoided during treatment with Mysimba.

Although no clear pharmacokinetic interactions have been seen between the medication's content and alcohol, there have been occasional reports of neuropsychiatric side effects and altered alcohol tolerance during treatment with bupropion.

How you react to alcohol can therefore vary, and it is important to be attentive to the body's signals.

In case of uncertainty regarding alcohol intake during treatment, it is recommended that you consult your doctor.

Do I need a prescription to buy Mysimba?

Mysimba is a prescription medication within the EU and may only be prescribed by licensed healthcare professionals after a medical assessment.

The assessment aims to ensure that the treatment is appropriate and safe, and is based on, among other things, your BMI, your health status, and any other illnesses.

Sources

European Medicines Agency (EMA). Mysimba. https://www.ema.europa.eu/en/medicines/human/EPAR/mysimba

Koskinas KC et al. Obesity and cardiovascular disease: an ESC clinical consensus statement. European Heart Journal. https://pubmed.ncbi.nlm.nih.gov/39210706/