Both mazdutide and retatrutide are weight-loss medications. Mazdutide was approved in China in 2025, while retatrutide is still in development and not yet licensed anywhere.
While neither is available in the UK, trials assessing their safety and effectiveness are currently underway, so they may become available soon. Here’s everything we know so far.
Mazdutide vs retatrutide: What’s the difference?
Both mazdutide and retatrutide are weekly injections that can help people lose weight. Here’s how they compare to each other, at a glance:
What are the benefits of mazdutide and retatrutide?
Research suggests that both mazdutide and retatrutide can help people to lose weight. They can also help people with diabetes to control their blood sugar.
Trials for both drugs are also looking at other possible benefits. We don’t have all the results yet, but it seems both mazdutide and retatrutide might also be good for improving blood fat levels, improving heart health, and reducing liver fat.
How do mazdutide and retatrutide work?
All weight-loss injections work by mimicking certain natural hormones, but the combinations in each medicine can differ.
Both mazdutide and retatrutide target:
- GLP-1, a hormone that regulates your blood sugar, reduces your appetite, and slows down your digestion.
- Glucagon, a hormone that helps your body burn stored fat and use more energy
In addition, retatrutide targets GIP, a hormone that also regulates blood sugar and reduces appetite. This makes retatrutide a "triple-G" agonist (GLP-1, GIP, and glucagon), while mazdutide is a dual agonist (GLP-1 and glucagon).
Mazdutide vs retatrutide: Weight loss results
We don’t have all the trial results for mazdutide or retatrutide yet. But from the data we do have, it seems people taking 6mg of mazdutide lost about 14% of their body weight after 48 weeks. In the same timeframe, people taking 12mg of retatrutide lost an average of 24.2%.
However, these results come from separate trials with different patient populations, making direct comparison difficult.
It's also worth noting that mazdutide is being studied at higher doses (up to 16mg), which may produce greater weight loss and potentially narrow the gap with retatrutide.
Side effects and safety
Like all medicines, both retatrutide and mazdutide can cause side effects. The side effects appear to be fairly similar to other weight-loss injections.
The most common side effects of both medicines are feeling sick, being sick, and diarrhoea. In the early trials of mazdutide, some people have also experienced respiratory tract infections while taking it.
Overall, both medications appear safe based on current trial data, with side effects typically mild and manageable through dose adjustment.
Side effects support at Voy
"If you're using Voy and you experience any side effects, rest assured that our expert clinicians are just a message or phone call away. They can adjust your dose, prescribe medication to ease your symptoms, or simply offer reassurance.
Everyone responds differently to weight loss treatment and we'll help you find what feels right for you."
Dosage and how they’re taken
Both retatrutide and mazdutide are given as once-weekly subcutaneous injections (under the skin).
Because neither medication is yet approved in the UK, we don't know for sure what the recommended dosages will be here. However, based on current approvals and trials:
Mazdutide: Approved doses in China are 2mg, 4mg, and 6mg weekly. Treatment starts at a lower dose and gradually increases over several weeks. Clinical trials are testing higher doses up to 16mg weekly.
Retatrutide: Still in development with no approved dosing schedule yet. In trials, doses have ranged from 1mg to 12mg weekly, with treatment starting low and gradually increasing.
Availability of retatrutide and mazdutide
Mazdutide is approved in China but not available in the UK yet. Retatrutide is not yet licensed anywhere. This means both are not available privately or through the NHS in the UK.
It’s likely that both medicines will be available in the UK in the future, but this will probably happen in late 2026 at the earliest.
Until trials are complete and these medications are licensed in the UK, you should only take approved weight-loss medications that have been prescribed to you by a licensed healthcare provider.
Taking anything that claims to be retatrutide or mazdutide at the moment is dangerous and could cause serious harm.
Mazdutide vs retatrutide vs other GLP-1s
When comparing weight loss medications, it's important to know that mazdutide hasn't been directly tested against most other options yet. The exception is semaglutide (Wegovy), where there has been one head-to-head trial.
From the research we have so far, it seems that after 48 weeks at the highest dose, people lost:
- 14% of their body weight on mazdutide
- 15% of their body weight on Wegovy
- 20.5% of their body weight on Mounjaro
- 24.2% of their body weight is retatrutide.
Keep in mind: These results come from separate studies with different groups of people, so it's hard to make exact comparisons. Mazdutide has mainly been studied in Chinese populations so far, while Wegovy, Mounjaro and retatrutide have been tested across more diverse groups worldwide.
Mazdutide vs semaglutide (Wegovy):
In a head-to-head trial with Chinese adults who had type 2 diabetes and obesity, mazdutide showed better results after 32 weeks:
- Mazdutide group achieved 10.29% weight loss compared to 6.00% in the semaglutide group.
- 48% of people on mazdutide hit both healthy blood sugar (HbA1c below 7%) and at least 10% weight loss, compared to 21% on semaglutide
However, this is just one study in Chinese patients with diabetes. More trials in different populations are needed to see if these results hold up.
Your weight loss journey
Mazdutide and retatrutide aren’t yet available. But there are other really effective weight loss medications that could help you reach your goals, such as Wegovy and Mounjaro. Get started today by taking Voy’s quiz to see if our science-backed weight loss programme could be a good fit for you.
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