The short answer is that Mysimba and orlistat are not a licensed combination, and there is limited evidence on using them together. If someone is considering both, a prescriber needs to assess whether this is appropriate for them. The decision depends on their health, other medicines, treatment goals and how they have responded to previous treatment.
The appeal is easy to understand. Mysimba works on brain pathways involved in appetite and food reward, while orlistat works in the digestive system by reducing the absorption of dietary fat. They work in different ways, so it can seem logical to think that using both might produce a stronger effect.
That is why people ask questions such as can you take orlistat with an appetite suppressant, Mysimba vs orlistat, or whether Contrave and orlistat can be used in the same treatment plan. Contrave is the name used for the same naltrexone and bupropion combination in some countries outside the UK.
This guide explains what each medicine does, what is known about using them together, the safety points that matter, and what to tell your prescriber if you are already taking one and considering the other. Both medicines are intended to be used alongside dietary and lifestyle changes, including a reduced calorie diet and increased physical activity.
Key things to know
- Mysimba contains naltrexone and bupropion and acts on brain pathways involved in appetite and food reward.
- Orlistat reduces the absorption of dietary fat by blocking digestive enzymes called lipases. It does not work by reducing appetite.
- Mysimba has a 16 week review point. Orlistat should be stopped after 12 weeks if at least 5 per cent of initial body weight has not been lost.
- Bupropion is also used in some stop smoking medicines, so it is important not to take more than one bupropion containing medicine.
- Neither medicine replaces healthy eating and physical activity. Both are licensed to be used alongside these measures.
Quick Answers
| The question | The answer |
|---|---|
| Can you take Mysimba and orlistat together? | They are not a licensed combination. A prescriber would need to decide whether using both is appropriate for an individual. |
| Would combining them work better? | There is not enough evidence to say that using both together provides additional weight loss. Using more than one medicine can also make side effects and monitoring more complicated. |
| Does orlistat reduce bupropion absorption? | There is no established interaction listed between orlistat and bupropion, but this does not mean the combination has been proven safe or effective. |
| Can you take them at the same time of day? | There is no specific published timing schedule for taking these two medicines together. Follow the instructions from your prescriber and the patient information leaflets. |
| Can you take orlistat with a GLP 1 medicine? | This is not an established licensed combination. If you are considering both, speak to the prescriber managing your weight treatment. |
| What should I tell my prescriber? | Tell them about every medicine, supplement and weight loss product you take, including anything bought online or abroad. |
What Each One Actually Does
Understanding the difference between the two medicines helps explain why people are interested in taking them together.
| Mysimba | Orlistat | |
|---|---|---|
| Contains | Naltrexone and bupropion | Orlistat |
| Acts on | Brain pathways involved in appetite and food reward | Lipase enzymes in the gut |
| Effect | Can reduce hunger and food cravings | Reduces the amount of dietary fat absorbed from food |
| Format | Prolonged release tablet, with the dose built up over four weeks | Capsule taken with fat containing meals |
| Main side effects | Nausea, constipation, headache, insomnia, dry mouth | Oily or loose stools, urgency, wind, oily spotting |
| Stopping rule | Treatment should be discontinued after 16 weeks if at least 5 per cent of initial body weight has not been lost | Treatment should be discontinued after 12 weeks if at least 5 per cent of initial body weight has not been lost |
| Trial weight loss | Clinical trials have reported average weight losses of around 5 to 9 per cent of starting body weight over 56 weeks, depending on the study | Clinical trials have shown modest additional weight loss compared with diet alone |
The numbers are averages from clinical studies, not a promise of what one person will lose. The studies also included diet and lifestyle changes, so the medicine was not being used on its own.
Why Doubling Up Is Not a Simple Answer
Questions such as is combining weight loss tablets more effective, do combination weight loss treatments work better in the UK, and is doubling up on weight loss tablets safe all come back to the same issue: there is limited evidence to guide this particular combination.
There are several practical points to consider.
- The combination has not been established as a standard treatment. The product information for Mysimba and orlistat does not recommend them as a routine combination.
- Side effects can become more difficult to manage. Mysimba can cause nausea and constipation, while orlistat can cause oily stools, loose stools and urgency. Taking both may make it harder to work out which medicine is causing a problem.
- Each medicine has its own review point. Mysimba has a 16 week stopping rule, while orlistat has a 12 week stopping rule. A prescriber would need to consider the response to each treatment rather than simply adding another medicine.
- The cost and treatment burden may increase. There is no clear evidence that taking both provides enough additional benefit to justify this for most people.
The broader point is simple. Using two weight loss medicines is not something to put together yourself. If your current treatment is not working well enough, your prescriber can review your progress and decide whether to continue, change or stop treatment.
Do They Interact?
Does orlistat affect how Mysimba is absorbed, and does orlistat reduce bupropion absorption? These are sensible questions because orlistat changes the way some substances are absorbed from the gut.
There is no established pharmacokinetic interaction listed between orlistat and the active ingredients in Mysimba, naltrexone and bupropion. However, there is also no good clinical evidence showing that taking the two weight loss medicines together is safe and effective as a routine treatment.
Orlistat mainly acts inside the digestive system. Its effect on absorption is particularly important for fat soluble vitamins such as vitamins A, D, E and K. It can also interact with some prescription medicines, so your full medication list should always be checked before starting it.
This is an important difference: not having a known direct interaction does not automatically mean that a combination is suitable for you.
Before starting either medicine, a healthcare professional should assess your BMI, medical history, current medicines and any conditions that could affect treatment. This can include high blood pressure, diabetes, seizure history, certain mental health conditions, liver problems and opioid use.
The fat question, which matters for both
High fat meals are relevant when taking both medicines, although for different reasons.
Mysimba product information advises avoiding high fat meals because they can increase the amount of bupropion absorbed. Higher exposure to bupropion can increase the risk of seizures.
Orlistat also works best with a reduced calorie diet in which around 30 per cent of calories come from fat. If a meal contains no fat, the orlistat dose can be missed. Eating a lot of fat in one meal can also make orlistat side effects such as oily stools and urgency more noticeable.
So, the general dietary advice for the two medicines points in a similar direction. A lower fat, balanced diet can help with tolerability when using orlistat and also avoids the high fat meals that can affect bupropion exposure.
Timing and Missed Doses
Can you take Mysimba and orlistat at the same time of day? There is no specific published timing schedule for using these two medicines together.
What is known is how each medicine should be taken on its own.
The Mysimba dose is increased gradually over the first four weeks. The tablets should be swallowed whole and are preferably taken with food.
Orlistat 120 mg is normally taken with water immediately before, during or up to one hour after each main meal that contains fat. If a meal is missed or contains no fat, the orlistat dose should be missed.
If you are prescribed both, follow the instructions given by your prescriber rather than trying to create your own schedule. If you miss a Mysimba dose, do not take an extra dose. Take the next dose at the usual time.
The Smoking Cessation Overlap
This is an important safety point and it is separate from orlistat.
Bupropion is also used in stop smoking treatment. The same active ingredient is present in Mysimba, although the products and their dosing are different.
If you are using a stop smoking medicine containing bupropion, tell your prescriber before starting Mysimba. Taking two bupropion containing products could increase your total exposure to bupropion and may increase the risk of seizures.
The same applies to medicines bought privately or online. Always check the active ingredients rather than relying only on the brand name.
Alcohol and Caffeine
Mysimba and alcohol need particular care. The Mysimba product information advises that alcohol consumption should be minimised or avoided. Bupropion can increase the risk of seizures, and sudden alcohol withdrawal can also increase seizure risk.
If you regularly drink a lot of alcohol, tell your prescriber before starting Mysimba. Do not suddenly stop heavy alcohol use without appropriate medical advice.
Orlistat and alcohol are different. There is no specific alcohol interaction listed in the orlistat product information. However, alcohol contains calories and can also be consumed with high fat foods, which may make it harder to follow the diet recommended with orlistat.
Mysimba and caffeine do not have a specific restriction in the product information. However, Mysimba can be associated with effects such as insomnia, anxiety and increased blood pressure or heart rate. If you notice problems with sleep or feel unusually restless, reducing caffeine may be worth discussing with your healthcare professional.
Vitamins and Absorption
Mysimba and orlistat vitamin absorption is mainly an orlistat issue.
Because orlistat reduces the absorption of dietary fat, it can also reduce the absorption of fat soluble vitamins A, D, E and K, as well as beta carotene.
The orlistat product information recommends a balanced diet that includes fruit and vegetables, and a multivitamin may be advised. If a multivitamin is used, it should be taken at least 2 hours after orlistat or at bedtime.
Mysimba does not have the same effect on fat soluble vitamin absorption. So, the vitamin advice comes from the orlistat side of treatment.
If you take other medicines as well, ask your pharmacist about the best time to take your multivitamin and other medicines.
Monitoring on Mysimba
Mysimba treatment involves ongoing checks rather than a single assessment at the start.
Blood pressure and pulse: Mysimba can increase blood pressure and heart rate in some people. Blood pressure and pulse should be checked before treatment and regularly during treatment. Uncontrolled high blood pressure is a reason not to use Mysimba.
Mood and mental health: Mysimba contains bupropion, and the product information includes warnings about suicidal thoughts and behaviour. If your mood changes significantly, or you develop thoughts of harming yourself, seek medical advice promptly.
It is also important to tell your prescriber if you have a history of seizures, bipolar disorder, an eating disorder, a significant head injury or other conditions that could affect whether Mysimba is suitable.
Combining With Injections
Questions such as can you take Mysimba with Mounjaro, can you take orlistat with Mounjaro, can you take orlistat with Wegovy, GLP 1 and orlistat together, and Mysimba with a GLP 1 injection all need an individual assessment.
These medicines have different licences, dosing schedules and safety considerations. Some combinations have been studied in research settings, but that does not mean that combining medicines is automatically suitable or routinely recommended for individual patients.
For example, Mysimba and a GLP 1 medicine can both affect appetite and food intake, while orlistat works mainly in the digestive system. The different ways they work do not, by themselves, prove that taking them together will provide additional benefit.
If your current treatment is not giving you the result you expected, tell your prescriber. They can look at your progress, side effects, diet, other medicines and health conditions before deciding whether a different treatment would be more suitable.
You can also compare weight loss treatment options and read more about the injectable treatment on the Mounjaro injection for weight loss page.
What To Tell Your Prescriber
If you are considering combination weight loss treatment, start by giving your prescriber the full picture.
- Every weight loss medicine or product you are taking or have recently taken, including supplements and anything bought online or abroad.
- Any stop smoking treatment, especially if it contains bupropion.
- Your mental health history, including any history of bipolar disorder or an eating disorder.
- Any history of seizures or significant head injury.
- Any medicines that may increase the risk of seizures.
- Your blood pressure readings, if you have them.
- Any heart, liver or kidney problems.
- How much alcohol you normally drink.
- Any opioid medicines, including some prescription painkillers and medicines for coughs or diarrhoea.
These details help your prescriber decide whether Mysimba, orlistat or another treatment is suitable for you. They can also help identify medicines that should not be taken together.
A weight loss consultation gives you an opportunity to discuss your current treatment, concerns and options before making a change.
Realistic Expectations
How much weight can you lose on Mysimba, how much weight can you lose on orlistat and realistic weight loss on tablets in the UK are better answered with clinical trial figures than promises.
In clinical trials, Mysimba produced average weight losses in the region of 5 to 9 per cent of starting body weight over 56 weeks, depending on the study and analysis. Participants were also following dietary and lifestyle programmes.
Orlistat has also been shown to produce additional weight loss compared with diet alone. In longer term clinical studies, the average difference compared with placebo was a few kilograms, although individual results varied.
Some newer injectable weight management medicines have produced larger average weight losses in clinical trials. However, the results depend on the medicine, dose, length of treatment and study population, so these figures should not be treated as a prediction for one person.
The useful question is not simply which medicine produces the biggest number. It is which treatment is appropriate for your health, can be taken safely, and can be used alongside changes you can maintain.
Reviews and Ongoing Support
Weight loss medicine reviews can vary between providers, so it is worth knowing what follow up you will receive before starting treatment.
A review should look at your weight and progress, check blood pressure where the medicine requires it, ask about side effects and discuss whether treatment should continue. With Mysimba, mood and other safety concerns also need attention.
If something is not working or is difficult to tolerate, tell your prescriber or pharmacist rather than changing the dose yourself. Sometimes a side effect can be managed with practical advice. Other times, the medicine may need to be changed or stopped.
