Is Retatrutide Better Than Semaglutide for Weight Loss?

The misconception worth correcting first: 'retatrutide is the new Wegovy, just stronger'

This framing appears constantly, and it deserves a gentle correction. Retatrutide is not a next-generation version of semaglutide. They are structurally distinct drugs. Semaglutide targets the GLP-1 receptor only. Retatrutide is a triple agonist, activating GLP-1, GIP and glucagon receptors simultaneously, a mechanism that tirzepatide (Mounjaro) partly shares but does not replicate in full. The glucagon component is what makes retatrutide genuinely novel: it increases energy expenditure alongside reducing appetite, rather than acting primarily through satiety alone.

So when people ask whether retatrutide is better than semaglutide, the more precise question is whether that triple mechanism produces meaningfully greater weight loss, and at what cost in side effects. Phase-2 data, published in the New England Journal of Medicine, suggest the answer to the first part may be yes, but the evidence base is narrow compared with the thousands of trial participants behind semaglutide's licence. Retatrutide has not completed phase-3 trials. Semaglutide has, repeatedly, and the MHRA has reviewed that body of evidence in full.

That gap matters. Phase-2 trials are designed to establish dose ranges and early signals, not to prove safety and efficacy at population scale. They run for shorter periods with smaller cohorts. The headline figures are striking, but they carry more uncertainty than the STEP 1 trial evidence underpinning Wegovy's licence.

What the numbers look like side by side

The table below draws on published trial data. Figures are from separate trials in different populations, they are not a direct head-to-head comparison and should not be read as one.

The retatrutide phase-2 weight-loss figures are among the largest reported for any injectable medicine. But the 48-week duration is shorter than Wegovy's 68-week STEP 1 study, and phase-2 cohorts are considerably smaller. Comparing percentages across different timelines and populations overstates the precision of any conclusion. Our page on how retatrutide and semaglutide compare across more factors goes deeper into the mechanistic differences.

The licensing gap and what it means in practice

In the UK right now, retatrutide cannot be prescribed for weight loss. There is no MHRA authorisation, no licensed dose, and no supply through the regulated UK pharmacy chain. A prescriber cannot lawfully write a routine private prescription for it as a weight-loss medicine. This is the single most important practical distinction between the two drugs at this moment.

Semaglutide as Wegovy is different. It holds a full MHRA licence. NICE has appraised it (TA875) and recommended it under specific criteria within specialist weight management services. Private prescribers can prescribe it for eligible adults outside the NHS route. Wegovy is also available in a higher 7.2mg dose following MHRA approval in 2026, which narrows the efficacy gap with tirzepatide in trials. For anyone asking whether retatrutide is better than Wegovy right now, the honest answer is that the comparison cannot yet be made on equal terms: one is a licensed, dispensable medicine; the other is not.

If retatrutide completes phase-3 trials and gains MHRA authorisation, the conversation changes. Our page on switching from semaglutide to retatrutide tracks what that regulatory path might look like for people already on treatment.

How Wegovy fits into a clinically supervised weight-loss plan today

For adults considering a licensed injectable weight-loss medicine now, the realistic options in the UK are semaglutide (Wegovy) and tirzepatide (Mounjaro). Semaglutide is a once-weekly GLP-1 injection with a well-established safety profile across a large evidence base. The STEP 1 trial recorded roughly 15% average weight loss over 68 weeks at the 2.4mg maintenance dose, and the newer 7.2mg formulation pushes those figures further still. That is not a small effect.

Whether semaglutide is the right choice for any individual depends on their BMI, health history, other medicines they take and what their prescriber concludes from a full assessment. A different licensed option, like tirzepatide, may suit some patients better, our comparison of the two licensed injectable options sets that out clearly. It is also worth reading about how orforglipron compares with semaglutide if you are weighing up the broader landscape of emerging treatments. Cost is also a real factor for many people; what Wegovy actually costs privately is worth reading before starting any consultation.

At nume, a real prescriber reads your consultation answers the same day, the same clinician who decides whether Wegovy, Mounjaro or neither is clinically appropriate for you. There is no algorithm making that call. If you want to explore what is available and licensed right now, speak to our prescribers through a free consultation.