Retatrutide Weight Loss Injections

What is retatrutide?

Retatrutide is a new weight loss medication currently in clinical trials. It belongs to a group of medicines called peptides. These are tiny proteins that send signals in your body to control things like hunger, energy, and metabolism.

It works in a similar way to treatments like Mounjaro and Wegovy, but it goes a step further. It targets three hormones, GLP-1, GIP, and glucagon, instead of just one or two. Because of this triple effect, it’s been nicknamed “Triple G.”

By working on three hormones, retatrutide can help reduce appetite, control blood sugar, and promote fat loss, helping patients lose more weight when taken alongside healthy lifestyle changes.

While it’s mainly designed to support people living with obesity, early research shows it could also help manage conditions like type 2 diabetes and fatty liver disease.

Is retatrutide available in the UK yet?

Not yet. Retatrutide is still being studied in clinical trials and has not been approved for use in the UK. That means it is not currently available to buy through private prescriptions or on the NHS.

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When will retatrutide be available to buy?

Retatrutide is expected it to be available some time during 2026 or 2027, if it passes clinical trials.

Here’s what a typical timeline for this could like:

Why is it called the ‘Triple G’ weight loss drug?

Retatrutide is known as the ‘Triple G’ weight loss treatment because it targets 3 hormones, GLP-1, GIP, and glucagon. Up until now, other weight loss treatments have only targeted either one or two hormones.

How does retatrutide work?

Retatrutide works by controlling your appetite, managing blood sugar, and helping your body burn fat. It does this by targeting three key hormones in your body: GLP-1, GIP, and glucagon.

By working on all three at once, retatrutide helps you:

• Eat less by reducing hunger and cravings.
• Feel fuller for longer by slowing down how quickly your stomach empties.
• Burn more energy by increasing your body’s natural calorie use.
• Control blood sugar by supporting healthy insulin and glucagon levels.

What happens when you take retatrutide?

Once you inject retatrutide, it travels through your bloodstream and attaches to special receptors in your:

• Brain: reduces appetite and cravings.
• Gut: slows down digestion and helps you feel full.
• Pancreas: improves insulin release and helps control blood sugar.
• Fat cells: encourages your body to burn stored energy.

This approach means retatrutide doesn’t just help you eat less; it also helps your body burn more fat.

How retatrutide compares to Wegovy and Mounjaro

While retatrutide works in a similar way to Mounjaro and Wegovy, there are some key differences:

Different active ingredients
Retatrutide is the name of the active ingredient it contains, while Mounjaro’s active ingredient is tirzepatide and Wegovy’s is semaglutide.

UK approval

Out of the three, retatrutide is the only one not approved for use in the UK yet.

Weight loss results

In trials, retatrutide has been shown to be the most affective over a shorter period of time. However, each treatment is very effective in supporting long-term weight loss.

Hormones targeted

All of these treatments work at GLP-1receptors but Mounjaro also stimulates GIP receptors and retatrutide additionally works on a third type of receptors known as Glucagon receptors.

Is retatrutide better for weight loss than Wegovy and Mounjaro?

So far in trials, retatrutide is achieving better weight loss results than Mounjaro and Wegovy. However, it’s still in trial phases, and will need more testing to say for certain.

We’ve put together this table to show how effective the different weight loss injections available are compared to retatrutide in similar trials. Remember: these results may change as it goes through further testing.

Our Head of Pharmacy, Jason Murphy, says: “It’s important to remember that just because a treatment has shown better results in trials, it doesn’t mean it’s the best option for you. Different people respond in different ways to different treatments, and a good weight loss journey is built on finding the treatment that suits your needs. We’ll help make sure you’re on a treatment that helps you get results you can maintain and is safe and suitable for your health and lifestyle.”

Retatrutide clinical trials, weight loss results and benefits

Retatrutide is showing very promising results in clinical trials with people taking it losing up to 24% of their weight. Let’s take a deeper look at these trials to get a better understanding of the treatment.

Weight loss achieved in stage 2 clinical trials

This clinical trial took place over 48 weeks.

In 24 weeks:

• Participants lost an average of 5% of their starting weight on the highest dose.
• Participants on the 2 highest does of retatrutide lost as much as weight as patients on Wegovy typically lose after 72 weeks.
• Participants on the placebo lost an average of 6% of their weight.

In 48 weeks:

• Patients lost up to 24% of their weight on the highest dose.
• Patients lost more weight than patients usually lose on Mounjaro over a 72-week period.
• Patients on the placebo lost an average of 1% of their starting weight.

Response rate seen in stage 2 clinical trials

This table shows how well participants responded to retatrutide in the trial by showing how many of them lost a percentage of weight at each dose.

• Nearly 92% of people taking retatrutide at the 4mg dose lost at least 5% of their body weight
• 100% of people in the trial lost at least 5% of their weight on 8mg and above.
• Only 27% of participants on the placebo lost at least 5% of their weight

Side effects reported in stage 2 clinical trials

The most common side effects reported so far were mild to moderate gastrointestinal (digestive) issues, like constipation, nausea, vomiting and diarrhoea. These increased with higher doses, but starting at a lower dose (2 mg instead of 4 mg) helped reduce these side effects.

Stage 2 trials summary:

• Participants lost up to 24% of their body weight on the highest dose over 48 weeks.
• Nearly 100% of participants lost at least 5% of their body weight regardless of dose.
• Even at lower doses, retatrutide showed significant weight loss compared to the placebo.
• Improvements were also seen in blood sugar control, cholesterol levels, and other health markers.
• Most common side effects were similar to other GLP-1- treatments, including nausea, diarrhoea, and constipation, which usually improved over time or reduced with titration (gradually increasing the dose over time).

Other benefits seen in trials:

This trial also showed that retatrutide may help people with fatty liver disease.

Fatty liver disease means there’s too much fat in the liver, leading to health conditions like liver disease.

• Most people who took higher doses (8 or 12 milligrams) had much less fat in their liver after 48 weeks.
• Their liver fat went down to a healthy level (less than 5%.)

This means that, while more tests still need to be carried out, retatrutide could be a good way to treat fatty liver disease in the future.

Retatrutide dosage and dosing schedule

Retatrutide dosage in clinical trials has been very similar to other weight loss injections, with a dosing schedule that slowly increases, so your body gets used to the medication.

In trials, participants were given retatrutide in the following schedule:

Starting dose: 1mg or 2mg weekly

Dose increase: every 4 weeks (if tolerating current dose)

Maximum dose: Up to 12mg weekly

Maintenance dose: Varies depending on person, ranging from 4mg-12mg

Every participant taking a dose of 4mg or higher started on a lower strength before gradually increasing. This has been shown to reduce side effects while still leading to solid weight loss results.

This schedule may change with more testing, but right now we expect retatrutide to be taken in the same way if it’s approved.

Retatrutide side effects and safety

Retatrutide has been shown to cause some side effects during trials. Much like other weight loss injections, these side effects were more common at higher doses and when increasing the dose.

Most common reported side effects:

• nausea
• vomiting
• diarrhoea
• constipation
• bloating
• abdominal pain

These side effects were shown to reduce over time as people got used to treatment.

Other less common side effects reported include:

Skin sensitivity: Sensitivity or hypersensitivity, including tenderness or pain when touched were reported in around 7% of participants versus 1% on the placebo.

Injection site reactions: Mild redness, swelling, or itching.

Cardiovascular effects: Slight increases in resting heart rate and occasional irregular heartbeats (usually mild and temporary).

Liver enzyme changes: Small, temporary increases in liver enzymes were seen in about 1% of participants, but these levels usually returned to normal.

Serious side effects reported:

Rare cases of acute pancreatitis (inflammation of the pancreas) were also reported, but they occurred at similar rates to the placebo group so we can’t say for sure if retatrutide was the direct cause.

Some also reported developing kidney stones, but this can be caused by rapid weight loss, so it can’t be confirmed if this was because of retatrutide.

Jason Murphy, Head of Pharmacy: “Serious side effects with any medication are very rare. That’s why new treatments go through rigorous testing through multiple trials to ensure they’re safe to use, both short- and long-term. We’ll keep a close eye on the retatrutide studies and any reported side effects to ensure we’re always prescribing safely for our patients.”

Safety warnings and precautions

Some people will not be able to take retatrutide due to certain health conditions, and there will be medications that may interact with it, making it unsafe. At the moment, this information is not fully confirmed, but more details will be available as trials continue. Sincer retatrutide works similarly to other weight loss injections, it’s likely the lists of restrictions and interactions will be similar.

Black market sellers

There are already websites claiming to sell retatrutide, but it’s unlikely to be genuine or safe. Retatrutide is not approved in the UK yet, so no one should be selling it. If you see offers like “Retatrutide 20mg” online, it’s most likely unregulated and could be dangerous. Always request your medication from trusted, licensed providers like us and watch out for fake sellers.

Retatrutide beyond weight loss

Early research shows retatrutide could have other important health benefits too:

May reduce liver fat by up to 40% (based on phase 2 clinical data)

Too much fat in the liver can lead to long-term problems like fatty liver disease. By helping reduce liver fat, retatrutide may improve liver health.

Improves insulin sensitivity and helps control blood sugar

Retatrutide may make your body respond better to insulin, which helps keep blood sugar levels stable. This is especially important for people at risk of type 2 diabetes or those already managing the condition.

Potential heart health benefits (currently being studied)

Early studies suggest retatrutide could have a positive effect on heart health, but more research is necessary. By supporting healthy weight loss and possibly improving blood sugar and cholesterol, it may help reduce the risk of heart disease over time.

Could lower triglycerides and inflammation markers

High levels of triglycerides (a type of fat in your blood) and ongoing inflammation can increase the risk of heart disease and other health issues. retatrutide may help bring these levels down, supporting overall heart and metabolic health.

Research is still ongoing, and these findings come from early trials. Learn more about how other weight loss injections are helping people beyond weight loss.

Retatrutide prices: what to expect

There’s no official pricing available for retatrutide yet because it still has not been approved for use. However, we can get an idea of what to expect by looking at early estimates and similar weight loss treatments.

Based on current trends:

• Prices are expected to be similar to other GLP-1 medications like Wegovy and Mounjaro.
• Likely to be between £150–£350 per month depending on the dose and provider.
• Final pricing will depend on MHRA approval, UK availability, and whether it’s offered on the NHS in the future.

How to buy retatrutide once it’s approved

You’ll most likely buy retatrutide in the same way as other weight loss injections like Mounjaro and Wegovy. You’ll need to meet certain criteria, such as having a high BMI or a weight-related health condition.

If you’re ordering from Chemist4U, you’ll need to complete an online consultation form. One of our clinicians will review it, and if retatrutide is suitable for you, they’ll issue a prescription and we’ll deliver it straight to your door.

Sources:

• Retatrutide: What is it and is it FDA approved? (2024) Drugs.com [accessed 1 September 2025]
• Retatrutide clears fatty liver disease in patients with obesity (2024) HCPLive [accessed 1 September 2025]
• What is Retatrutide Peptide and How Does it Work? (2024) Peptide Sciences [accessed 1 September 2025]
• Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial (2023). The New England Journal of Medicine [accessed 1 September 2025]
• Retatrutide melts fat fast but at a cost, warn experts (2025) Diabetes.co.uk [accessed 1 September 2025]