Naltrexone and Wegovy Together: the Facts

The misconception: Mysimba means naltrexone and Wegovy can be combined

The confusion here is understandable, and our prescribers hear this question most weeks. Mysimba is a UK-licensed weight-loss tablet that contains naltrexone and bupropion together in fixed doses. It works through entirely different mechanisms to semaglutide, acting on opioid and dopamine pathways involved in appetite and food reward. Because naltrexone is an ingredient of a licensed weight-loss medicine, some people assume it can be freely added to Wegovy treatment for extra effect. That is not how either medicine works, and it is not a combination that has been evaluated in robust UK clinical trials or approved by the MHRA for weight management.

Wegovy on its own targets the GLP-1 pathway, slowing gastric emptying, reducing appetite signals and improving satiety. Adding naltrexone on top would not simply double those effects; the pharmacological targets are different, and potential interactions with other medicines a person takes, or with underlying conditions, require individual assessment. You can read more about how Wegovy works and who it is licensed for in the UK on our dedicated page.

The short version: Mysimba is one thing. Wegovy is another. Combining them, or adding plain naltrexone to semaglutide treatment, is not a standard practice and is not something any responsible prescriber would do without a compelling, evidence-based reason specific to that patient.

What naltrexone actually does, and the UK licensing picture

Naltrexone is an opioid receptor antagonist, meaning it blocks the activity of opioid receptors in the brain. In the UK it is licensed for maintaining abstinence from alcohol and opioids, typically at doses of 50 mg daily. It has no standalone licence for weight management in this country. The only context in which naltrexone carries a UK weight-management authorisation is inside the Mysimba combination tablet (8 mg naltrexone / 90 mg bupropion, extended-release), which the MHRA has approved for use alongside a reduced-calorie diet and increased physical activity in adults with a BMI of 30 or above, or 27 or above with a weight-related condition. That approval is specific to the fixed combination and the clinical evidence generated for it, not for naltrexone given separately.

Semaglutide (Wegovy) has a separate and distinct UK licence. The NHS medicines page for semaglutide sets out its approved use, common side effects and the clinical monitoring it requires. Nothing in either product's licensed indication contemplates them being taken together, and the NHS does not recommend or commission that combination for weight management.

People who are currently prescribed naltrexone for dependence treatment and who want to explore weight-management options should bring both medicines to the conversation with their prescriber, so that any clinical implications are properly considered before a decision is made.

Interaction and safety considerations a prescriber weighs up

Taking two medicines that act on overlapping or intersecting systems always raises questions that belong with a clinician. A few specific points are worth knowing. Bupropion, which accompanies naltrexone in Mysimba, lowers the seizure threshold and carries its own contraindications, so the Mysimba combination is not appropriate for everyone. Semaglutide slows gastric emptying, which affects how quickly oral medicines are absorbed, this is one reason that oral medicines taken alongside Wegovy sometimes need a clinical review. Adding any additional oral medicine to semaglutide treatment, including naltrexone, means that absorption timing may be altered in ways that matter clinically.

There is also the question of opioid analgesia. Naltrexone blocks opioid receptors, which means it can reduce or eliminate the effect of opioid painkillers. Anyone who might need opioid-based pain relief (including for planned surgery) needs their prescribing team to be aware. The MHRA's Yellow Card scheme is the route to report any unexpected side effects from any licensed medicine, including suspected interactions.

None of this means the question is unreasonable. It means the answer depends on a person's full medical picture, current medicines and the reason they are asking, which is exactly what a clinical consultation is for.

The private route for semaglutide, and how combination questions are handled

At nume, every treatment decision goes through a GPhC-registered Independent Prescriber who reads your consultation personally. If your answers mention current naltrexone use or a query about combining medicines, that information shapes the clinical assessment, it is not screened out by software. Treatment is only approved where it is clinically appropriate for the individual.

Wegovy is a prescription-only medicine requiring that individual assessment, and it is one of two weight-management treatments currently available through our consultation service. If you want to understand how private semaglutide treatment is priced alongside what is included, the Wegovy price comparison page covers that honestly. For a broader look at weight-loss treatment options in the UK, including how the different licensed medicines compare, our overview sets it out plainly.

If your specific question is about another combination (for instance, Saxenda and Wegovy together, or other medicines in the 'Wego Together' conversation) those pages address the distinct clinical questions each pairing raises. The answer to most of them follows similar logic: two medicines targeting weight loss at the same time is a specialist decision, not something to arrange independently.