Mounjaro®
Starting from £179.99/mo
Start journey Learn moreWhat the evidence shows when you put Wegovy and Mounjaro side by side
Step 1: Understand why the two medicines produce different results on average
Wegovy (semaglutide) activates a single gut-hormone receptor (the GLP-1 receptor) which slows gastric emptying and reduces appetite. Mounjaro (tirzepatide) activates two receptors: GLP-1 and GIP. That dual action is thought to produce a stronger appetite-suppressing and metabolic effect in many people, which is reflected clearly in the trial data.
In the SURMOUNT-1 trial, participants taking tirzepatide at the highest dose lost around 20–21% of their body weight on average over 72 weeks. The STEP 1 trial for semaglutide 2.4mg, also 72 weeks, showed around 15% average weight loss. Those are population averages across thousands of participants, your own response depends on biology, lifestyle, adherence and the dose you can tolerate. But the gap in the population data is real, and it's the reason many clinicians now consider tirzepatide the stronger option for people without contraindications. A fuller comparison of Wegovy and Mounjaro covers the mechanism differences in more detail.
It's worth noting that Novo Nordisk's newer 7.2mg semaglutide dose has narrowed that gap, trials reported around 20.7% average weight loss over 72 weeks at 7.2mg, approaching tirzepatide's results. So the picture is evolving, and dose matters enormously.
Step 2: Read the head-to-head trial, not just the separate results
The clearest data point in this comparison is SURMOUNT-5, published in the New England Journal of Medicine in 2025. It was an open-label, head-to-head trial in 751 adults with obesity and no diabetes, running for 72 weeks. Tirzepatide produced greater average weight reduction than semaglutide 2.4mg. That's a direct comparison, not an extrapolation across two separate trials with different populations, and it's the kind of evidence that moves clinical opinion.
NICE discussed these indirect comparisons when appraising tirzepatide in TA1026, and their committee notes favoured tirzepatide on weight outcomes. That said, SURMOUNT-5 compared semaglutide at 2.4mg (not the newer 7.2mg dose) so future direct comparisons at the higher semaglutide dose may tell a different story.
The practical takeaway: if you've been on Wegovy for several months at maintenance dose and the results feel modest compared with what Mounjaro trials suggest, that's not just anecdote, the population-level data supports the pattern. The reverse question (Mounjaro not working, considering Wegovy) involves its own clinical reasoning, too.
Step 3: Check what the comparison looks like in a table
| Factor | Wegovy (semaglutide 2.4mg) | Mounjaro (tirzepatide 15mg) |
|---|---|---|
| Receptor targets | GLP-1 only | GLP-1 + GIP (dual agonist) |
| Average weight loss (72-week trials) | ~15% (STEP 1, NEJM) | ~20–21% (SURMOUNT-1, NEJM) |
| Head-to-head evidence | SURMOUNT-5 (NEJM 2025): tirzepatide showed greater average loss than semaglutide 2.4mg in 751 adults | |
| Higher-dose option | 7.2mg approved in UK (MHRA, Jan/Apr 2026); ~20.7% avg over 72 weeks | 15mg is the maximum licensed dose |
| UK licence (weight management) | BMI ≥30, or ≥27 with a weight-related condition | BMI ≥30, or ≥27 with a weight-related condition |
| Administration | Once-weekly injection | Once-weekly injection via KwikPen |
Numbers above are population averages from cited trials, individual responses vary. Cost context for private treatment is covered on this cost comparison page.
Step 4: What actually matters if you're considering a switch
Population averages explain the pattern you've noticed, but switching medicines isn't a DIY decision. A prescriber needs to look at your current dose, how long you've been on it, whether you've hit a genuine plateau or whether there's something else at play (a change in sleep, stress, or the medications you take alongside it). Some people on Wegovy haven't yet reached their optimal dose, the 7.2mg option is newer and not yet widely discussed. Others are genuinely better candidates for tirzepatide's dual mechanism, and if you've had good results on Mounjaro previously, there are recognised clinical patterns that explain why Wegovy may feel less effective by comparison.
If you've already switched and found the reverse problem, there are specific clinical patterns worth understanding, some people who moved back to Wegovy after Mounjaro have found that semaglutide feels less effective in that sequence. It's also worth knowing that stopping either medicine entirely carries its own risks; regain after stopping treatment is a well-documented pattern in the clinical data, not a personal failing.
At nume, a real clinician reads your consultation (not software) and that review happens the same day. If you order before 12pm on a weekday, your treatment is dispatched the same afternoon once approved, arriving the next working day. Our clinical team reviews the evidence, your history and your current dose before making any recommendation. Which medicine suits you is a clinical decision our prescribers make with you.
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