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Mysimba

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Mysimba

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Medically reviewed

Marina Burgos

Last updated on 10/01/2026

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Mysimba

Property Description
Active Ingredients Bupropion and Naltrexone
Form Prolonged-release tablets
Pharmacological Class Anti-obesity agent
Common Use Chronic weight management in adults
Origin Synthetic compounds

What is Mysimba and What Type of Medication is It?

Mysimba is a prescription-only medicine specifically classified as an anti-obesity agent and a fixed-dose combination product for chronic weight management. This medicinal entity is composed of two distinct synthetic compounds, Bupropion and Naltrexone, co-formulated to deliver a dual therapeutic action. As a centrally acting agent, it influences neurological pathways in adults who require assistance with long-term weight control.

The unique profile of Mysimba arises from its combination therapy approach, a strategy clinically recognized for enhancing the effect of weight loss mechanisms compared to either component used alone. This product provides a systemic tool for supporting adherence to a reduced-calorie diet and incorporating exercise by leveraging two established pharmacological components simultaneously. The drug's classification as a fixed-dose combination product means both active ingredients are contained within a single oral formulation, a key factor in ensuring sustained release.

Composition, Form, and General Purpose

The active composition consists of Bupropion hydrochloride and Naltrexone hydrochloride. Mysimba is supplied as prolonged-release tablets, a specific oral formulation designed to release the active ingredients slowly and consistently into the system. The overarching therapeutic use of this dual-compound medicine is to facilitate long-term weight loss and support chronic weight management in appropriate adult patient groups.

The combination provides established support for patients seeking sustained control over their weight. The presence of Naltrexone and Bupropion is intended to influence two critical areas: the suppression of appetite and the mitigation of cravings. By modulating these aspects of food intake, the product's general purpose is to provide pharmacological assistance to patients striving to achieve a sustained reduction in overall energy consumption.

Regulatory References

  1. EMA Public Assessment Report (EPAR) for Mysimba

What side effects are possible with Mysimba?

Possible side effects and safety information

The safety profile of Mysimba is formally characterized by adverse reactions categorized by frequency and the body system affected, according to official regulatory documentation.

Frequency and System-Organ Classifications

Adverse effects are grouped into classifications based on incidence reported in clinical trials. Very Common side effects (ge 1/10), frequently noted at the start of treatment, primarily involve the Gastrointestinal and Nervous Systems, including nausea, constipation, vomiting, and headache. Common side effects (ge 1/100 to < 1/10) include anxiety, insomnia, dizziness, and increases in blood pressure (hypertension) and heart rate.

Serious Adverse Reactions and Safety Constraints

The official labeling documents rare but clinically significant risks. Serious adverse reactions documented include Seizures, which necessitates permanent discontinuation of the medicine, and the potential for severe Allergic Reactions, such as angioedema. Risk of Suicidal Thoughts and Behavior and the emergence of new or worsening psychiatric symptoms require monitoring. Furthermore, the label notes a risk of Hepatotoxicity (liver dysfunction) and specific Cardiovascular Effects.

Population-Specific and Time-Related Safety Notes

Official constraints restrict use in specific patient groups. The medicine is contraindicated in patients with severe hepatic impairment and is not recommended for those with end-stage renal disease or advanced age (ge 75 years). The risk of developing elevations in blood pressure and heart rate may be greater during the initial three months of treatment, requiring regular monitoring. Use is also contraindicated for patients with a current seizure disorder, uncontrolled hypertension, or current opioid dependence.

Overdose and Emergency Response

The official regulatory documents state that an overdose of Mysimba may present with severe neurological and cardiovascular manifestations. Documented clinical signs include seizure, hallucinations (seeing or hearing voices that do not exist), loss of consciousness, and rapid or pounding heartbeat (tachycardia). Other documented manifestations may include confusion or decreased awareness.

A critical, life-threatening risk is uniquely associated with the naltrexone opioid blockade. Attempting to overcome this blockade with large doses of exogenous opioids can result in life-endangering opioid intoxication, which is documented to carry the risk of fatal overdose, respiratory arrest, or circulatory collapse.

Regulators mandate that individuals seek immediate medical attention or contact emergency services right away if an overdose is suspected or if severe symptoms are observed. Urgent care is required immediately upon the onset of a seizure, loss of consciousness, or signs of severe opioid toxicity.

Management is symptomatic and supportive, as no specific antidote is known for the combination product. Due to the cardiotoxicity risk from the bupropion component, continuous cardiac monitoring and monitoring of vital signs are required as part of the official management protocol.

Therapeutic Uses of Mysimba

What Mysimba Treats: Main Uses and Benefits

Mysimba is a pharmacological tool used to support chronic weight management in appropriate adult patients by addressing symptoms related to systemic imbalance. It is prescribed as an adjunct to a reduced-calorie diet and increased physical activity.

The medication is applied across therapeutic domains involving heightened systemic burden.

Managing Clinically Defined Obesity and Overweight Status

This block covers the primary clinical indications and the patient health context for use. Mysimba is commonly used in patients defined as obesity or overweight when weight-related conditions are present, such as Type 2 diabetes, dyslipidaemia, or controlled hypertension. The core benefit is supporting patients' efforts toward a sustained reduction in body weight, which may assist in managing related metabolic symptoms.

Curbing Excessive Appetite and Intense Food Cravings

This is used for managing behavioral and symptomatic challenges that can affect successful weight loss. The medication may assist in addressing persistent excessive appetite and supports the patient in managing intense food cravings. This supportive function can assist patients coping with the distress of hunger and cravings, supporting adherence to dietary changes, and contributes to easing the overall symptom load related to eating behavior.

Quick Fact: Support for Appetite and Cravings

Mysimba is commonly used to help with symptom clusters that interfere with daily functioning, primarily by supporting patients during periods of noticeable hunger.

Eligibility and Restrictions for Use

Who Can and Cannot Use Mysimba?

Mysimba eligibility is strictly defined by regulatory documents, specifying the patient populations for whom the medicine is indicated and those for whom its use is absolutely contraindicated.

Populations Allowed

Use is approved for adult patients (aged 18 years and older) who meet specific Body Mass Index (BMI) criteria: patients with obesity (BMI ge 30 kg/m^2), or patients who are overweight (BMI ge 27 kg/m^2 to < 30 kg/m^2) and have one or more weight-related comorbidities, such as Type 2 diabetes or controlled hypertension.

Absolute Contraindications

Mysimba must not be used if a patient has any of the following conditions:

  • A current seizure disorder or a history of seizures.
  • A current or previous diagnosis of bulimia nervosa or anorexia nervosa.
  • Uncontrolled hypertension.
  • Dependency on chronic opioids or acute withdrawal from alcohol or benzodiazepines.
  • Severe hepatic or severe renal impairment.
  • Current treatment with Monoamine Oxidase Inhibitors (MAOI) or any other products containing bupropion or naltrexone.

Age and Physiological Restrictions

Use is contraindicated during pregnancy and breastfeeding. Safety and efficacy have not been established for children and adolescents under 18 years of age. For geriatric patients over 75 years, use is not recommended.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Property Description
Medicinal product categories with documented interactions Monoamine Oxidase Inhibitors (MAOIs), Opioid Agonists, CYP2D6 Substrates, CYP2B6 Inhibitors/Inducers, Seizure Threshold-Lowering Agents, Dopaminergic Drugs.
Specific interacting medicines (if explicitly listed) Methadone, Buprenorphine, Levodopa, Amantadine, Pimozide, Eliglustat, Ticlopidine, Clopidogrel, Ritonavir, Efavirenz.
Mechanistic basis of interactions (only if stated in label) Bupropion is an inhibitor of CYP2D6. Naltrexone is an opioid receptor antagonist. Additive dopamine agonistic effects.
Timing-based interaction rules (if applicable) A 14-day washout period is mandatory between discontinuing an MAOI and initiating treatment, and vice-versa.
Population-specific interaction notes (if applicable) Severe hepatic impairment is a contraindication. Moderate renal impairment requires a dose restriction.
Classification Description
Interaction severity classification (as defined in official documents) Contraindicated Combinations (e.g., MAOIs, Opioids). Significant Pharmacokinetic Alterations (e.g., CYP2D6 substrates). Increased Risk of Seizure.
Regulatory basis (EMA / FDA / etc.) Based on EMA Summary of Product Characteristics (SmPC) and FDA Prescribing Information.
Interaction-context constraints (as defined in official documents) Must not be co-administered with other bupropion-containing products. Co-administration with CYP2B6 inhibitors requires a dose restriction. Must not be administered following a high-fat meal.

Official Interaction Statements

  • Co-administration with Monoamine Oxidase Inhibitors (MAOIs) is formally contraindicated due to the risk of hypertensive reactions.
  • Use with Opioid Agonists or Partial Agonists is contraindicated; the Naltrexone component may precipitate acute opioid withdrawal.
  • Bupropion is a documented strong inhibitor of the CYP2D6 enzyme, which can increase the systemic exposure of co-administered medicines metabolized by CYP2D6.
  • Co-administration with agents that lower the seizure threshold increases the overall risk of seizure.
  • Administration is officially not recommended following a high-fat meal due to increased systemic exposure of Naltrexone.

Connection to the Overall Interaction Profile

Regulatory documents define this product's interaction structure primarily through two essential components: the Naltrexone component necessitates formal contraindications with opioids, while the Bupropion component establishes constraints based on CYP2D6 inhibition and the cumulative risk of seizures. This structure requires mandatory timing separation from MAOIs and specific dose restrictions when co-administered with CYP2B6 inhibitors, as explicitly stated in the regulatory labels.

Mechanism of Action

Targeting Hypothalamic Appetite Control

The primary mechanism involves naltrexone and bupropion acting synergistically on the hypothalamic melanocortin system, the central system governing energy balance and appetite signaling. Bupropion stimulates POMC neurons, while naltrexone acts as a mu-opioid receptor antagonist to block the natural beta-endorphin self-inhibition, thereby amplifying and sustaining the release of the alphaMSH mediator. This cascade ultimately activates the MC4 receptor, producing a sustained physiological signal for anorexigenic signaling and increased energy expenditure.

Modulating the Hedonic Food Reward System

The combination also engages the brain's mesolimbic reward pathway, which links pleasure and motivation to feeding behavior. Bupropion's activity as a weak dopamine reuptake inhibitor, combined with naltrexone's opioid receptor antagonism, helps adjust signaling dynamics within this pathway. This focused modulation of the reward system leads to a physiological attenuation of hedonic signaling associated with food cues, which influences the central regulation of feeding behaviors.

Dosage and Administration Information

Mysimba is an oral medication, provided as a prolonged-release tablet containing a fixed-dose combination of 8 mg naltrexone hydrochloride and 90 mg bupropion hydrochloride. Adherence to a strict, structured dosing schedule is mandatory for this medicine, beginning with a gradual dose titration over the first four weeks of treatment.

Official Administration Guidelines

The full maintenance dose of this medicine is reached by the start of Week 4, where the total daily intake is four tablets, taken as two tablets twice daily (morning and evening). This corresponds to the Maximum Recommended Daily Dose (MRDD) of 32 mg naltrexone HCl and 360 mg bupropion HCl.

Feature Detail
Route of administration Oral use.
Timing in relation to meals Must be taken with food, but not with a high-fat meal.
Preparation requirements Tablets must be swallowed whole; they must not be cut, crushed, or chewed.
Missed-dose rules If a dose is missed, patients should not take an additional dose; the prescribed next dose should be taken at the usual time.

Special Procedural Conditions

Certain dose limitations are specified for certain patient populations. For individuals with moderate or severe renal impairment or mild hepatic impairment, the maximum recommended daily dose is restricted to two tablets per day (one in the morning, one in the evening). Use of the medicine is advised with caution in older adults over 65 years of age and is not recommended for those over 75 years. The protocol requires that the need for continued treatment must be evaluated after 16 weeks or 12 weeks at the full maintenance dose, and treatment should be discontinued if the patient has not achieved at least a 5% loss of initial body weight.

Recent Clinical Evidence

Research evidence / Overview of studies for Mysimba

Evidence for Chronic Weight Management in Obese and Overweight Adults

The core research for Mysimba (naltrexone/bupropion) was studied for chronic weight management and was conducted using large, controlled Randomized Controlled Trials (RCTs). This design is widely used in medicine because it is helpful for observing responses related to a specific measured outcome. These trials involved non-diabetic adults presenting with either obesity or who were overweight with related health conditions.

In these studies, researchers was studied for several outcomes related to systemic or functional imbalance. The primary measurement was change in overall body weight and the proportion of participants who reached specific weight reduction thresholds. Trials also explored how the medicine was associated with changes in metabolic markers like blood lipids and examined patient-reported outcomes describing perceived discomfort and control over eating.

Research Focus in Adults with Type 2 Diabetes Mellitus

A dedicated controlled trial was evaluated in adults who were overweight or obese and also had an established diagnosis of Type 2 Diabetes Mellitus (T2DM). Studies monitored standard weight loss outcomes but also specifically examined outcomes related to systemic or functional imbalance associated with diabetes, including measuring changes in long-term blood sugar markers, like glycated haemoglobin (HbA1c).

Long-Term Studies and Durability of Research Outcomes

While the main effectiveness studies for Mysimba was observed in an intermediate follow-up duration of about one year, research has also explored outcomes over longer periods. Studies report how symptoms evolved for weight outcomes after the first year of treatment, but the overall evidence for sustained weight maintenance over several years appears to have an inherently lower certainty than the intermediate-term trial data. Limited information for long-term outcomes is available, and research is ongoing.

Key Limitations and Areas of Research Uncertainty

Regulatory reviews have highlighted areas where the evidence base for Mysimba is limited. The long-term cardiovascular profile is being addressed by a large, dedicated Phase 4 trial that research is ongoing to complete. Until these definitive results are reported, certainty remains low regarding the medicine's long-term cardiovascular safety in real-world use over extended periods. Furthermore, follow-up durations were limited for sustained weight loss in core trials.

Key Studies & References

  1. Requirement for long-term cardiovascular safety study (Phase 4 CVOT)

Frequently Asked Questions (FAQ)

Common questions about Mysimba (FAQ)

Q: Is Mysimba only used for weight loss, or does it have other purposes?

Mysimba is officially indicated for chronic weight management in adults. While the individual components (naltrexone and bupropion) are approved for other conditions when used separately, the fixed-dose combination product of Mysimba is specifically approved for weight management only, in conjunction with diet and exercise.

Q: Can Mysimba be used by people with a history of depression?

Official product information includes warnings regarding the potential risk of suicidal thoughts and behavior and the emergence of new or worsening psychiatric symptoms. Regulatory documents indicate that individuals with a history of depression are a population for whom close monitoring and professional consideration are advised due to this risk.

Q: Is it safe to use Mysimba during pregnancy or while breastfeeding?

According to official regulatory documents, its use is formally contraindicated during both pregnancy and breastfeeding. Healthcare professionals are advised against its use in these circumstances.

Q: What is the general guidance on stopping Mysimba treatment?

Regulatory guidance requires that treatment should be discontinued if the patient has not achieved at least a 5% loss of initial body weight after 12 to 16 weeks at the full maintenance dose. Decisions regarding discontinuing treatment are made in consultation with a healthcare professional.

Q: How does the official guidance define a 'non-responder' to Mysimba?

Official guidance defines a non-responder as a patient who does not achieve a weight loss of at least 5% of their initial body weight after 12 to 16 weeks of treatment at the full maintenance dose. If this threshold is not met, official protocol indicates that discontinuation of the medicine should be considered.

Q: Does Mysimba work immediately, or does it take time to notice effects?

The medicine is started with a gradual dose titration over the first four weeks. Efficacy is evaluated in clinical trials after 12 to 16 weeks at the full dose, which indicates that the full therapeutic effect is observed over time.

Q: How is Mysimba different from other weight management medications?

Mysimba is a unique medicine because it is a fixed-dose combination product containing two active substances, naltrexone and bupropion. This combination is intended to influence two different central neurological pathways that are involved in controlling food intake and reward.

Q: Is Mysimba considered a stimulant?

Official documents classify the product as an anti-obesity agent. While one of its components, bupropion, is known to have central nervous system activating effects and can cause side effects like insomnia and anxiety, the product is not formally classified as a controlled stimulant.

Q: What happens if I forget to take a dose of Mysimba?

If a dose is missed, regulatory information advises that an additional dose is not taken to make up for the missed one. The prescribed next dose should be taken at the usual time.

Q: Can Mysimba be taken indefinitely, or is there a recommended time limit for use?

While there is no mandatory upper time limit stated in official guidance, treatment must be evaluated after 12 to 16 weeks at the full dose for efficacy. Continued long-term use is subject to the ongoing assessment of risk versus benefit by a healthcare professional.

Q: Is it common to feel nauseous when starting Mysimba?

Yes, nausea is listed in official documents as a Very Common side effect, meaning it may affect more than 1 in 10 people. It is frequently noted in clinical trials, particularly at the start of treatment.

Q: Do the common side effects of Mysimba usually go away over time?

The medicine utilizes a gradual dose titration schedule over the first four weeks, which is intended to help the body adjust to the medicine. Official data notes that Very Common side effects are frequently seen at the start of treatment.

Q: Are there any known severe side effects associated with Mysimba?

Yes, serious adverse reactions documented in official labeling include Seizures, severe Allergic Reactions (such as angioedema), and risks related to Suicidal Thoughts and Behavior, Hepatotoxicity (liver dysfunction), and Cardiovascular Effects.

Q: Can Mysimba affect my mood or energy levels?

Official documents report that Common side effects include anxiety, insomnia (trouble sleeping), and dizziness, which can influence mood and energy. Serious risks also include the potential for suicidal thoughts and the emergence of new or worsening psychiatric symptoms.

Q: Is it necessary to follow a specific diet while taking Mysimba?

Yes, according to official indications, Mysimba is intended to be used as an adjunct to a reduced-calorie diet and increased physical activity. It is not designed to be used on its own.

Q: Do I need to exercise while using Mysimba?

Yes, the medicine is officially indicated for use as an adjunct to a reduced-calorie diet and increased physical activity. The clinical studies and intended use rely on this combination of pharmacological support and lifestyle changes.

Q: What should I know about potential interactions between Mysimba and alcohol?

Official warnings advise against excessive alcohol intake while using this medicine, as it may increase the risk of seizures and other central nervous system events. Use is also formally contraindicated during acute alcohol withdrawal.

Q: Can Mysimba be taken alongside common over-the-counter pain relievers?

The Naltrexone component of the medicine is contraindicated with opioid analgesics (pain relievers containing opioids). Since the bupropion component interacts with certain medications, including those that lower the seizure threshold, consultation with a healthcare professional is generally required when considering co-administration.

Q: Does Mysimba interact with common prescription medications for high blood pressure?

The medicine can cause increases in blood pressure and heart rate, which requires regular monitoring. Uncontrolled hypertension is a contraindication. The concurrent use of high blood pressure medicines may require monitoring or dosage adjustments.

Q: Is Mysimba a habit-forming or addictive medicine?

Regulatory guidance contraindicates the use of the medicine in individuals dependent on chronic opioids or those undergoing acute withdrawal. While the bupropion component has pharmacological activity, the combination product is not formally classified as habit-forming in the context of controlled substances.

Q: What is the average duration of treatment with Mysimba in clinical settings?

Core clinical trials for efficacy evaluated the medicine over an intermediate duration of about one year (up to 56 weeks). The duration of treatment for an individual patient is determined by a healthcare professional based on ongoing assessment of efficacy and tolerance.

Q: Is it normal to have trouble sleeping when first taking Mysimba?

Yes, insomnia (difficulty in sleeping) is listed in official product information as a Common side effect, meaning it may affect up to 1 in 10 people. It is a known effect of the medicine.

Q: Can Mysimba cause dry mouth?

Yes, dry mouth is listed in official regulatory documents as a Common side effect, meaning it may affect up to 1 in 10 people in clinical trials.

Q: Does Mysimba affect fertility?

Official documentation is limited on human fertility, but preclinical studies in animals showed no or limited effects on reproductive function at clinically relevant exposures. Use during pregnancy is strictly contraindicated.

Q: Does Mysimba require a special prescription?

Yes, Mysimba is classified as a prescription-only medicine and requires authorization from a licensed healthcare professional.

Q: Is Mysimba available in other forms besides a tablet?

No, according to official product information, Mysimba is supplied only as a prolonged-release tablet.

Q: Why is it sometimes combined with lifestyle changes?

The medicine is officially indicated for use as an adjunct to diet and exercise because the combination of pharmacological support and lifestyle changes has been the focus of clinical study for enhancing weight loss mechanisms.

Q: Are there common signs that Mysimba may not be working for someone?

The primary objective sign of non-response, based on official documents, is the patient not achieving at least a 5% loss of initial body weight after 12 to 16 weeks at the full maintenance dose.

Q: Is it true that Mysimba can help with cravings?

Studies and official information indicate that the combination of active ingredients is intended to influence the suppression of appetite and the mitigation of food cravings by modulating the brain's mesolimbic reward pathway.

Q: Does Mysimba have any effects on blood sugar levels?

Dedicated clinical trials evaluated the medicine in adults who also had Type 2 Diabetes Mellitus. These studies specifically examined changes in long-term blood sugar markers, such as glycated haemoglobin (HbA1c), in addition to weight outcomes.

Q: Are there restrictions on driving or operating machinery while taking Mysimba?

Official warnings advise that the medicine has been associated with side effects such as dizziness and somnolence (sleepiness). These reactions can affect a person's ability to drive, operate machinery, or perform other tasks that require full attention.

Q: Is it normal to experience dizziness when taking Mysimba?

Yes, dizziness is listed in official product information as a Common side effect, meaning it may affect up to 1 in 10 people.

Q: Does Mysimba require refrigerated storage?

Official instructions state that the medicine should be stored below 30 C. It does not require refrigerated storage.

How should Mysimba be stored and disposed of?

Official Storage and Disposal Requirements

Regulatory documentation outlines specific requirements for storing and disposing of Mysimba (naltrexone hydrochloride/bupropion hydrochloride) tablets to maintain product quality and protect the environment.

Requirement Area Official Instructions
Temperature & Stability Store below 30 C. Do not use past the expiration date on the box and blister.
Packaging Keep the medicine out of the sight and reach of children. Tablets must not be cut, crushed, or chewed.
Disposal Do not dispose of this medicine in household trash or by flushing it down a sink or toilet.
Environmental Rule Return unused or expired medicine to a pharmacist. This ensures responsible destruction and prevents the medicine from entering the environment.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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