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Retatrutide vs Tirzepatide
The honest difference
Tirzepatide is a licensed UK medicine. Retatrutide showed even bigger weight loss in trials, but is not approved and is banned in sport.
Peptide
Retatrutide
Grade B: promising human evidence
Why people buy it
People buy it to lose weight. It is a new weight-loss injection still being tested by a drug company.
Bottom line
A strong weight-loss drug in real trials, but not approved yet. Online vials are not the drug that was tested.
- UK status
- Retatrutide is an investigational medicine with no MHRA marketing authorisation. It is not available on prescription or legally for sale in the UK.
- Sport / WADA
- Prohibited at all times under S0 (non-approved substances). The WADA 2026 Prohibited List bans any substance not covered by another section that has no current approval by any government health authority for human therapeutic use, explicitly including drugs in clinical development.
Peptide
Tirzepatide
Grade A: approved / strong human evidence
Why people buy it
This is the real medicine in Mounjaro. People take it to lose weight or to control type 2 diabetes.
Bottom line
A proven medicine that really works. Get it from a doctor or pharmacy, not a website.
- UK status
- Licensed UK medicine. Tirzepatide (brand Mounjaro, Eli Lilly) holds MHRA marketing authorisation for both type 2 diabetes and chronic weight management (broadly, a BMI of 30 or above, or 27 or above with a weight-related comorbidity).
- Sport / WADA
- Not specifically named on the WADA Prohibited List and not a recognised performance-enhancing agent in sport.
Grades are about evidence in humans, not about whether something is right for you. Nothing here is dosing advice. Talk to a qualified clinician before any health decision.
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