Skip to content
RetaRadar
Menu

Advertising disclosure:LeoLab pays for the #1 position in our ratings. Every vendor, including LeoLab, is scored with the same published formula.How we make money

Fake and unlicensed weight-loss jabs in the UK: what the MHRA has found

Demand for GLP-1 medicines has created a large illegal market in the UK. Here is what the regulator has seized and warned about since 2023, and how to tell a legitimate supplier from an illegal one.

By the RetaRadar team · Updated 30 September 2026

The Medicines and Healthcare products Regulatory Agency (MHRA) regulates medicines in the UK and investigates illegal supply. Since 2023 its warnings have moved from individual fake pens to organised production. This page sets out the main public findings in date order, with links to the MHRA's own announcements.

2023: fake pens and hospital admissions

In October 2023 the MHRA warned the public about fake weight-loss pens bought online. Some people who used them were admitted to hospital, possibly because the pens contained insulin rather than the medicine on the label (MHRA, October 2023). Unexpected insulin can cause dangerously low blood sugar.

Falsified Mounjaro KwikPens

The MHRA has also issued an alert about falsified Mounjaro (tirzepatide) KwikPens, which copy the packaging of the licensed product (MHRA alert). Licensed Mounjaro is only supplied on prescription, and genuine pens come from a pharmacy with a prescriber's involvement.

October 2025: the first illicit production facility

In October 2025 the MHRA said it had found the first illicit weight-loss medicine production facility in the UK, at an industrial unit near Northampton. Officers seized more than 2,000 unlicensed retatrutide and tirzepatide pens (MHRA, 24 October 2025).

May 2026: the largest seizure so far

In May 2026 the MHRA reported its largest ever seizure of unlicensed weight-loss medicines: about 12,000 doses, including retatrutide, found at a country estate near Northampton. Two people were arrested (MHRA, 29 May 2026).

July 2026: "no summer shortcut"

Ahead of the summer, the MHRA repeated that retatrutide "has not been authorised for use in the UK, meaning anyone selling this product is doing so illegally", and urged people to get weight-loss medicines only through legitimate routes (MHRA, 24 July 2026).

Why unlicensed jabs are risky

  • You cannot know what is inside. The 2023 cases show the contents may not match the label.
  • No quality control. Licensed medicines are made to Good Manufacturing Practice and checked for sterility, dose and contamination. Illegal products are not.
  • No medical oversight. GLP-1 medicines carry warnings about pancreatitis, dehydration and interactions with contraception, which a prescriber is meant to check. See our guide to Mounjaro and Wegovy on the NHS.
  • Retatrutide is still experimental. Even the manufacturer's own product is only available inside clinical trials. See retatrutide explained.

How to check a supplier of licensed medicines

  1. A prescription is required. Wegovy and Mounjaro are prescription-only medicines. A seller who does not ask about your medical history is not operating legally.
  2. Check the pharmacy is registered. Every pharmacy in Great Britain must be registered with the General Pharmaceutical Council. You can search the GPhC registers; in Northern Ireland, pharmacies are registered with the Pharmaceutical Society of Northern Ireland.
  3. Be wary of social media and messaging apps. Legitimate pharmacies do not sell prescription medicines through WhatsApp, Telegram or Instagram direct messages.
  4. Report problems. Suspected side effects and suspected fake products can be reported through the MHRA's Yellow Card scheme.

Where this site fits in

RetaRadar rates sellers of research-grade retatrutide, which is sold for laboratory research, not as a medicine. We exclude shops that sell pre-filled pens, supply syringes or publish dosing advice, because those signs point to products intended for people. Nothing on this site is a recommendation to use retatrutide. If you are looking for weight-loss treatment, speak to your GP or a registered pharmacy.

Sources

  • MHRA press releases, October 2023, October 2025, May 2026 and July 2026, and the falsified Mounjaro alert, all linked above.
  • General Pharmaceutical Council, online registers.
  • MHRA Yellow Card scheme.