# Retatrutide vs Mounjaro vs Wegovy: efficacy, safety and UK availability compared

> Comparison of retatrutide with tirzepatide (Mounjaro) and semaglutide (Wegovy), with cross-trial caveats and current UK availability.

Canonical: https://yezz.co.uk/retatrutide-vs-mounjaro-vs-wegovy · Last reviewed: 2026-09-11 · Author: Nick Johnson, Independent Prescription Pricing Analyst, Medstack Ltd

## Key facts
- Best trial averages: Wegovy ≈14.9% (STEP 1, 68 weeks), Mounjaro ≈20.9% (SURMOUNT-1, 72 weeks), retatrutide 28.3% (TRIUMPH-1, 80 weeks) — different trials, not head-to-head.
- “Retatrutide is a third more effective than Mounjaro” is arithmetic, not evidence; the TRIUMPH-5 head-to-head settles it in late 2026/2027.
- Mounjaro and Wegovy are MHRA-authorised now, roughly £94–£230 and £100–£170 per month privately through GPhC-registered pharmacies.
- Retatrutide has no approval, no price and no legal supply — a reason to check back in 2028, not to pay anyone today.
- Whichever medicine: prescription-only supply must go through a GPhC-registered pharmacy after a genuine clinical consultation.

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Cite as: Nick Johnson. "Retatrutide vs Mounjaro vs Wegovy: efficacy, safety and UK availability compared". Yezz, 2026-09-11. https://yezz.co.uk/retatrutide-vs-mounjaro-vs-wegovy