A guide to Retatrutide

Retratrutide is an experimental weight loss medication that’s gained a lot of media attention recently. Although clinical trials are still in progress, results so far are promising.

In this guide, we’ll go into detail on what retatrutide is, how it works, why it’s different to other weight loss medications that are already on the market, and when it’s likely to be available to purchase in the UK.

What is retatrutide? 

Retatrutide is a new drug that’s been developed by the pharmaceutical company Eli Lilly to treat obesity and type 2 diabetes.

It’s known as a triple agonist drug, which means it works by targeting 3 different hormone pathways involving glucagon-like peptide 1 (GLP-1), glucagon, and glucose-dependent insulinotropic polypeptide (GIP). 

It’s the first medication that targets all 3 pathways and will be given as a once-weekly injection.

Retatrutide is still going through clinical trials and is not yet available to buy or use, whether that’s privately or on the NHS.

How does retatrutide work?

This medication works by activating the body’s receptors for 3 hormones that control blood sugar and hunger levels: GLP-1, GIP, and glucagon. 

GLP-1 is a hormone released after eating that increases insulin secretion, slows down how fast the stomach empties, and reduces hunger cues.

After a meal, GIP is usually released from the small intestine to stimulate insulin release. It also helps to regulate hunger, although researchers are still trying to understand exactly how it does this.

Unlike the other 2 hormones, glucagon is usually released when blood sugar levels are low. It helps to break down glucose stores in the liver and the body’s fat stores which can help with weight loss.

Retatrutide makes the body think levels of all three of these hormones are high. This causes:

• Reduced feelings of hunger

• Improved blood sugar regulation

• Longer lasting feelings of fullness

• Increased fat metabolism

Together, these changes in the body make it easier to eat less and lose weight. To work effectively, retatrutide will need to be taken alongside eating a healthy balanced diet and exercising regularly. 

Targeting all three hormone pathways may lead to better weight loss and blood sugar improvements than focusing on just one or two of these hormones. 

Retatrutide is currently the only medication that targets all three.

What will retatrutide be used for?

Clinical trials are currently researching retatrutide as a treatment for obesity and type 2 diabetes. It’s likely that the medication will be prescribed as a treatment for one or both of these conditions.

As part of this research, some studies are also investigating whether retatrutide can improve other health problems related to being overweight. They’re testing whether the medication can help overweight people with:

• Lower back pain

• Knee arthritis

• Type 2 diabetes and sleep apnoea

• Cardiovascular or kidney disease

• Fatty liver disease

Depending on the results of these trials, retatrutide may also be prescribed in the future for overweight individuals suffering with some of these health conditions.

Clinical trials evidence about retatrutide

Although retatrutide phase 3 clinical trials are still ongoing, phase 1 and 2 clinical trials have already been completed. 

These studies tested the medication first in animals, then in humans with type 2 diabetes and/or obesity. 

Although results were promising, it’s worth remembering these were only short-term studies testing whether the medication is safe to take, side effects are manageable, and which doses could be effective.

Long term studies are still needed to check whether retatrutide is safe to take for longer periods. Larger phase 3 clinical trials are also ongoing to test the medication on bigger groups of people and see how it compares to other weight loss and diabetes treatments.

Potential benefits of retatrutide

Studies have mainly focused on the weight loss and blood sugar improving benefits of retatrutide, but one phase 2 trial has also looked into retatrutide’s ability to reduce liver fat.

Weight loss

Current evidence suggests retatrutide could be an effective weight loss drug.

In phase 1b trials, 72 people with type 2 diabetes took either retatrutide, another diabetes medication called dulaglutide, or a placebo (non-active) medication. 

This study mainly focused on whether retatrutide was safe and effective to take once a week. However, people taking the medication experienced better improvements in their blood sugar levels and lost more weight than those taking the placebo.

In phase 2 trials, retatrutide helped people lose significant amounts of weight. 

One trial of 338 overweight adults found that 83% of people taking 12mg retatrutide lost at least 15% of their starting weight in 48 weeks. This is significantly more than the group taking a placebo where only 2% lost a similar amount. Even at the lowest dose of 4mg, 60% of people taking retatrutide still managed to lose 15% or more of their body weight. 

Another study of 275 overweight people with type 2 diabetes compared retatrutide to dulaglutide or a placebo. Although the study mainly investigated blood sugar levels, they also looked at body weight.

Body weight was reduced by 16.94% in the group taking 12mg retatrutide after 26 weeks (compared to a 3% loss in the placebo group and 2.02% loss in the 1.5mg dulaglutide group). Groups taking doses of retatrutide higher than 0.5mg also lost more weight than the placebo group. 

Improved blood sugar control

Retatrutide also seems to be effective at improving blood sugar levels in people with type 2 diabetes.

In the same study of 275 overweight people with type 2 diabetes, HbA1c levels (a measure of long-term blood sugar levels) were measured over 24 weeks. 

After 24 weeks, the group taking the highest dose of retatrutide reduced their HbA1c levels by 2.02% compared to 0.01% in the placebo and 1.51% in the dulaglutide groups. 

Fat loss from the liver

Retatrutide can help normalise fat levels in the liver in certain people.

In some overweight people, fat can accumulate in the liver causing a condition known as metabolic dysfunction-associated steatotic liver disease (previously nonalcoholic fatty liver disease).

One phase 2 clinical trial has tested whether retatrutide can help reduce liver fat levels in people with this problem.

Of the 76 people included, 86% achieved normal liver fat levels after taking 12mg of retatrutide for 24 weeks. In the group who received placebo medication, 0% achieved normal liver fat levels.

Possible side effects and risks 

In phase 1 clinical trials, the most common side effects of retatrutide were nausea/vomiting (feeling or being sick) or bloating. These side effects were mostly mild.

Findings in other studies were similar, with mild gastrointestinal side effects mentioned as the most common side effect in the liver fat trial, the type 2 diabetes trial, and the obesity trial.

More serious side effects were much rarer. These included raised liver enzyme levels, increased heart rate, abnormal heart rhythm, and increased skin sensitivity.

Generally, side effects seemed to be more common where people took a high retatrutide dose. They also seem similar to the side effects associated with other weight loss injections.

More studies that include larger groups of people will be needed to investigate rarer and long-term side effects.

When will retatrutide be approved? 

According to the pharmaceutical company that has developed retatrutide, Eli Lilly, the launch of retatrutide will depend on the results of ongoing phase 3 clinical trials. 

Results from some of these trials are set to be announced in 2026, so it’s unlikely that retatrutide will be available in the UK before 2027. It may even take longer.

After retatrutide is launched, it will likely take some time for it to be assessed by the national institute of health and care excellence (NICE). Once NICE has reviewed the medication, they will then make a decision about NHS funding.

Retatrutide will likely be available to buy privately in the UK before it becomes available on the NHS.

Comparing retatrutide to other GLP-1 agonist medications

Popular weight loss medications like Wegovy, and Mounjaro all belong to the GLP-1 agonist medication category. 

This means they work by activating the GLP-1 receptor, tricking the body into thinking GLP-1 hormone levels are high. The body reacts with decreased hunger cues, slowed stomach emptying, and improved blood sugar regulation. This helps you to feel less hungry and eat less, helping you to lose weight.

Wegovy and Ozempic contain the ingredient semaglutide that just acts on this GLP-1 receptor. Mounjaro contains tirzepatide that also targets the GIP receptor. Retatrutide not only targets GIP and GLP-1 receptors, but the glucagon receptor too.

Semaglutide and tirzepatide are both effective weight loss medications, although how much weight each person can lose varies. 

Based on the information we have so far, retatrutide may lead to more weight loss than semaglutide (Wegovy) or tirzepatide (Mounjaro). 

One review of the current available studies found that retatrutide helped people to lose more weight than tirzepatide, but that it’s more likely to cause side effects. Previous studies have found tirzepatide to be more effective for weight loss than semaglutide, so it makes sense that retatrutide could also help people to lose more weight than with semaglutide.

Clinical trials into retatrutide are still ongoing. This means the information we have about the drug is limited, and we don’t have any information about it being used in a real-life setting. 

There has also not yet been a study that directly compares retatrutide with tirzepatide and/or semaglutide. Until there is, it’s difficult to say for sure whether one is better than the others. 

People respond differently to medications too, meaning not everyone will get the same weight loss results or experience the same side effects. The best weight loss medication for one person may not be the same for another. 

To be effective, all medications need to be taken alongside making lifestyle changes, like eating less and exercising more.

Final thoughts

Retatrutide is an exciting new weight loss drug that’s the first to target 3 different hormone receptors involved in hunger and metabolism.

It’s still going through clinical trials and is not yet available to purchase in the UK or elsewhere. We expect retatrutide to be available in the UK from 2027 at the earliest and it will probably be available from private providers before you can get it on the NHS.

If you see retatrutide currently advertised online or through social media, this is illegal. Do not buy this medication as it is likely to be counterfeit and dangerous for you to take.

It’s important to buy weight loss medication from a reputable online provider. That way, you know the medicine you’re buying is legitimate and a healthcare professional will review your medical history to check that it’s safe for you to take.

Quick Meds is a UK-based GPhC-accredited online pharmacy that offers a genuine and professional online weight loss service. Although retatrutide is not yet available, we offer a variety of other weight loss injections and tablets. Learn more about the treatments we offer by starting an online weight loss consultation.