The Next Generation Weight Loss Injection?

As interest in weight loss injections grows across the UK, a new medication is making headlines: Retatrutide. Early clinical trials show even greater results than its predecessors—semaglutide (Wegovy) and tirzepatide (Mounjaro). But what is Retatrutide? How does it compare to what’s already available in the UK? And when can we expect to see it here?

In this blog, we break down what you need to know if you’re considering GLP-1 or GIP-based weight management treatments.

What is Retatrutide?

Retatrutide is an experimental triple-hormone receptor agonist that targets:

• GLP-1 (Glucagon-like peptide-1)

• GIP (Glucose-dependent insulinotropic polypeptide)

• Glucagon receptors

This triple-action approach sets it apart from current medications. Semaglutide (Ozempic/Wegovy) activates GLP-1 only, while tirzepatide (Mounjaro/Zepbound) acts on both GLP-1 and GIP. By also targeting the glucagon receptor, Retatrutide may promote even greater fat loss and energy expenditure.

How Does Retatrutide Compare?

What Does the Evidence Say?

The SURMOUNT-3 and SURMOUNT-4 trials (tirzepatide) showed:

• 22.5% mean weight loss in some groups over 72 weeks

The TRIUMPH-1 trial (Retatrutide) reported:

• Up to 24.2% body weight reduction over 48 weeks

• Even those with severe obesity (BMI > 35) saw substantial and sustained results

• Improvements in insulin sensitivity, blood pressure, and lipid profiles

It’s important to note these are trial results, and real-world data will take time to gather.

When Will Retatrutide Be Available in the UK?

Retatrutide is currently in Phase 3 trials and not yet licensed anywhere globally. The manufacturer (Eli Lilly) has hinted at a possible US launch by 2026, with UK availability expected post-MHRA approval—likely between 2026–2027.

For now, tirzepatide is expected to be the next GLP-1/GIP dual agonist approved in the UK, potentially by late 2025, followed by Retatrutide a year or two later.

Side Effects and Risks

As with all GLP-1–based treatments, common side effects include:

• Nausea

• Vomiting

• Constipation or diarrhoea

• Fatigue or headache

Retatrutide may carry additional risks due to its glucagon receptor activity, including:

• Raised heart rate

• Risk of lean muscle loss if weight loss is too rapid

• Potential thyroid or gallbladder issues (similar to semaglutide)

All of these will be closely monitored in UK MHRA evaluations.

Who Might Be Eligible in the Future?

Pending MHRA approval and NICE guidance, Retatrutide could eventually be recommended for:

• Adults with BMI ≥ 30, or BMI ≥ 27 with obesity-related conditions

• Patients struggling with Type 2 diabetes, PCOS, or metabolic syndrome

• Those who have not responded adequately to other weight loss interventions

Will It Be Available on the NHS?

Unlikely initially. Like Wegovy, Retatrutide may:

• Launch privately first via specialist clinics like ours

• Be subject to strict NHS prescribing criteria based on cost-effectiveness and NICE guidance

• Require monthly reviews, lifestyle interventions, and monitoring

Final Thoughts

Retatrutide offers a new frontier in weight loss pharmacology, with impressive early results and a triple-action mechanism. But it’s not a silver bullet. It must be used as part of a comprehensive plan, including:

• Nutritional advice

• Physical activity

• Ongoing clinical support

At our clinic, we already offer GLP-1 therapies like Wegovy and Mounjaro with face-to-face consultations, monthly reviews, and individualised plans—not just a one-size-fits-all approach.

Want to Learn More?

We keep up to date with emerging obesity treatments like Retatrutide, and we’re happy to guide you through current safe, licensed options available right now.