Retatrutide in Glasgow: Why I Advised a Patient to Pause Using This Unapproved Weight-Loss Injection

Written by 

Lalit Matai, Pharmacist Prescriber (GPhC 2086556) & Clinical Director, MediGlow Aesthetics & Health

The demand for weight-loss injections in Glasgow has never been higher.

Recently, a patient attended my clinic and informed me that she had been receiving Retatrutide injections from an aesthetic practitioner.

I advised the patient to pause treatment until the source, quality, and regulatory status of the product could be independently verified.

What Is Retatrutide?

Retatrutide is an investigational weight-loss medication currently being developed by Eli Lilly. Early clinical trial data have demonstrated weight loss approaching 25–30% of body weight in some patients, making it one of the most promising obesity treatments currently under investigation.

Unlike existing medications, Retatrutide targets three separate metabolic pathways:
• GLP-1 receptors
• GIP receptors
• Glucagon receptors

Is Retatrutide Legal or Approved in the UK in 2026?

No.

At the time of writing, Retatrutide is not approved by the MHRA in the United Kingdom and remains an investigational medicine undergoing clinical trials.

Retatrutide vs Mounjaro vs Wegovy – What’s the Difference?

Retatrutide’s trial results are impressive – which is exactly why interest is so high, and exactly why people are being offered it before it has completed the regulatory process that Mounjaro and Wegovy have already been through. The numbers above are real. The medicine behind them is not yet legally available.

When Will Retatrutide Be Approved in the UK?

As of mid-2026, Retatrutide has completed its first successful Phase 3 trial (TRIUMPH-1, reported May 2026), with seven further Phase 3 trials expected to report throughout 2026 covering different patient groups and outcomes. Based on typical regulatory timelines, an FDA submission is not expected before late 2026 or early 2027.

UK approval through the MHRA typically follows FDA approval by 6 to 12 months. Realistically, this places potential UK availability in 2027 to 2028 at the earliest – and that is before any NHS appraisal process, which could add further time.

 Questions to Ask Before Any Weight-Loss Injection in Glasgow

• Is the practitioner medically qualified?
• Are they a registered prescriber?
• Where has the medication been sourced from?
• Can evidence of the supply chain be provided?
• Is it supplied through a regulated pharmaceutical wholesaler?

The Risks of Unregulated Weight-Loss Injections in Glasgow

Patients may have no guarantee regarding:
• Product purity
• Sterility
• Correct dosing
• Storage conditions
• Product authenticity

Why Clinical Trials Matter

Clinical trials establish:
• Whether a medicine is effective
• Which side effects may occur
• Long-term safety outcomes
• Appropriate patient selection
• Monitoring requirements

My Advice –  What to Do If You’ve Been Offered Retatrutide

If somebody offers you Retatrutide today, ask questions. A legitimate healthcare professional should be able to explain the source of the medication, its regulatory status, and the rationale for treatment.

No amount of potential weight loss is worth compromising your safety.

FAQ

• What is Retatrutide and how is it different from Mounjaro?

Retatrutide is an investigational medication that targets three hormone pathways – GLP-1, GIP, and glucagon receptors – compared to Mounjaro (tirzepatide), which targets two (GLP-1 and GIP). Early trial data suggests Retatrutide may produce greater weight loss than Mounjaro, but it has not completed clinical trials and is not approved for use anywhere in the world.

• Is it legal to be given Retatrutide in the UK?

Retatrutide is not approved by the MHRA and cannot be legally prescribed or dispensed in the UK outside of a registered clinical trial. If you have been offered Retatrutide by a practitioner in Glasgow or anywhere else in the UK, this medication has not gone through the safety and quality checks required for legal use.

• When will Retatrutide be available in the UK?

Based on the current Phase 3 trial timeline, Retatrutide is not expected to be approved by the MHRA before 2027 at the earliest, with wider NHS availability potentially following in 2028. This timeline depends entirely on the outcome of ongoing trials.

• What weight-loss injections are legally available in Glasgow right now?

Mounjaro (tirzepatide) and Wegovy (semaglutide) are both MHRA-approved and can be legally prescribed following a clinical assessment by a registered prescriber. At MediGlow, every weight management consultation includes a full medical history review, baseline measurements, and ongoing monitoring by a GPhC-registered pharmacist independent prescriber.

About the Author

Lalit Matai
Pharmacist Prescriber (GPhC 2086556)
Clinical Director
MediGlow Aesthetics & Health
The Glen Clinic, Thornliebank, Glasgow G46 8NG

REFERENCES

1. Jastreboff AM, Kaplan LM, Frías JP, et al. Retatrutide, a Triple-Hormone Receptor Agonist, for Obesity. New England Journal of Medicine. 2023;389:514-526.

2. Medicines and Healthcare products Regulatory Agency (MHRA). Guidance and enforcement actions relating to unlicensed and illegal medicines in the United Kingdom.

3. Eli Lilly and Company. Retatrutide Phase 3 Clinical Trial Programme (TRIUMPH Studies) and Investor Updates.

4. Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021;384:989-1002.

5. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022;387:205-216.