Mounjaro®
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Start journey Learn moreHow tirzepatide compares with its closest rivals, and what the evidence actually shows
Is semaglutide (Wegovy) a realistic alternative, or does tirzepatide always win?
This is the comparison most people mean when they ask what is better than tirzepatide, and the honest answer is: it depends on the dose. At 2.4mg weekly, Wegovy produced around 15% average weight loss over 68 weeks in the STEP 1 trial, published in the New England Journal of Medicine. That is meaningful. But in SURMOUNT-5, a direct head-to-head trial published in the NEJM in 2025, tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks in adults with obesity and without diabetes.
Where it gets more interesting is Wegovy 7.2mg, approved by the MHRA in January 2026. Trials at that dose reported average weight loss of around 20.7% over 72 weeks, close enough to tirzepatide's 15mg results that the gap narrows considerably. A dedicated single-dose 7.2mg pen was approved on 14 April 2026 for adults with a BMI of 30 or above. So for some patients, higher-dose semaglutide is now a legitimate near-equivalent, not a consolation option.
The full comparison of what outperforms Mounjaro covers the evidence in more depth. The short version: tirzepatide holds a results advantage on published evidence at equivalent licensed doses, but the margin at the top of each medicine's range is smaller than the headlines suggest. Side-effect profiles overlap too, both are GI-led, with nausea, diarrhoea and constipation the most commonly reported effects, typically peaking around dose increases then settling.
| Medicine | Mechanism | Avg. weight loss (highest licensed dose) | UK licence (weight management) |
|---|---|---|---|
| Tirzepatide (Mounjaro) | Dual GIP + GLP-1 agonist | ~20–21% (15mg, 72 wks (SURMOUNT-1) | Yes) BMI ≥30 or ≥27 + comorbidity |
| Semaglutide 2.4mg (Wegovy) | GLP-1 agonist | ~15% (2.4mg, 68 wks (STEP 1) | Yes) BMI ≥30 or ≥27 + comorbidity |
| Semaglutide 7.2mg (Wegovy) | GLP-1 agonist | ~20.7% (72 wks (phase 3 data) | Yes) BMI ≥30 only (MHRA Apr 2026) |
| Semaglutide (Ozempic) | GLP-1 agonist | Not assessed for weight loss | No (licensed for type 2 diabetes only |
| Retatrutide | Triple GIP + GLP-1 + glucagon agonist | Phase 3 trials ongoing; not yet licensed | No) not yet approved in the UK |
One misconception worth letting go gently: Ozempic is not a weight-loss medicine that doctors have quietly approved. It contains semaglutide, yes, but it is licensed in the UK for type 2 diabetes, not weight management, and prescribing it for weight loss is outside its authorisation. Understanding which GLP-1 medicines are actually licensed for weight loss in the UK clears up most of the confusion around this.
What about next-generation agents, is retatrutide better than tirzepatide?
Retatrutide is a triple agonist that activates GIP, GLP-1 and glucagon receptors simultaneously. Phase 2 data published in the NEJM reported average weight loss of around 24% over 48 weeks at the highest dose, figures that attracted considerable attention. Phase 3 trials are ongoing. It is not licensed anywhere in the world as of summer 2026, and what retatrutide's trial data means compared with Mounjaro is worth reading carefully before drawing conclusions from early-phase numbers.
Early-phase weight-loss figures routinely look better than they do in larger, longer trials with more diverse populations. Whether retatrutide will outperform tirzepatide in a licensed setting (and whether it reaches UK approval) remains genuinely uncertain. The evidence on retatrutide against Mounjaro is promising but preliminary; it cannot be prescribed in the UK today.
The same applies to cagrilintide combined with semaglutide (CagriSema), another candidate generating trial interest. Whether CagriSema outperforms tirzepatide is a question the data are still answering. Both sit firmly in the 'watch this space' category rather than the 'available now' one.
Does 'better' sometimes mean something other than total weight lost?
For many people, yes. Total weight loss is the headline, but it is not always the most relevant number. Tolerability matters, some people find semaglutide's GI side effects easier to manage than tirzepatide's, or vice versa. Injection frequency is the same for both (once weekly). Cost varies across providers and doses. And for people who have a reason to avoid injections altogether, the oral Wegovy tablet (approved by the MHRA on 11 June 2026 as the first oral GLP-1 licensed for weight management in the UK) is now a real option, reporting around 13.6% average weight loss in the OASIS 4 trial.
Then there are individual clinical factors: existing conditions, other medicines, BMI, and how someone has responded to treatment before. Liraglutide (Saxenda) versus tirzepatide is a comparison that comes up for people already on liraglutide, the evidence generally favours tirzepatide on weight outcomes, but switching is always a prescriber decision. NICE's appraisal of tirzepatide under TA1026 sets out the UK evidence base and eligibility framework in full. Which medicine suits you is a clinical decision our prescribers make with you, not a verdict that fits every reader of this page.
If you want to explore your options with a prescriber rather than a comparison table, starting a free consultation at nume is the practical next step.
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