Is Wegovy Just as Good as Mounjaro for Weight Loss?

What did the head-to-head trial find?

A question our prescribers hear most weeks is whether the two medicines are essentially the same thing with different names. They are not. SURMOUNT-5, published in the New England Journal of Medicine (2025), was an open-label trial of 751 adults with obesity and no diabetes, comparing tirzepatide with semaglutide 2.4mg over 72 weeks. Tirzepatide produced greater average weight reduction. The mechanistic reason matters here: Mounjaro activates two gut-hormone receptors (GIP and GLP-1), while Wegovy acts on GLP-1 alone. Stimulating both pathways appears to produce a stronger appetite-suppressing and metabolic effect in most people.

It is worth noting that SURMOUNT-5 was open-label, meaning participants knew which drug they were on, a design limitation. And averages mask individual variation. Some people do exceptionally well on semaglutide; others plateau on tirzepatide. The trial establishes a population-level difference, not a certainty for any single patient.

Wegovy does have a newer development that narrows the gap: a 7.2mg maintenance dose was approved by the MHRA in January 2026 and a dedicated single-dose pen followed in April 2026, with trials reporting around 20.7% average weight loss at that higher dose, approaching tirzepatide 15mg results. Whether that dose is appropriate for you is a separate clinical question entirely. If you want to understand whether Wegovy is as good as Mounjaro when you factor in this newer dose, we cover that question in detail alongside the trial evidence. You can read more about how Wegovy performs relative to Mounjaro in greater depth if you want the longer version.

How do the two medicines compare side by side?

Both are once-weekly subcutaneous injections, both are Black Triangle medicines under additional MHRA monitoring, and both carry broadly similar side-effect profiles dominated by gastrointestinal symptoms. The practical differences come out most clearly in a structured comparison.

One practical difference that catches people out: tirzepatide's interaction with oral contraceptives. Because Mounjaro slows gastric emptying more markedly, the pill's absorption can be reduced in the early weeks of treatment and after dose increases, so an additional barrier method is recommended during those windows. Semaglutide does not carry the same documented evidence for this. If you are on the pill, that difference matters. A broader look at semaglutide versus tirzepatide covers this and other safety considerations in detail.

Does the NICE guidance treat them the same way?

No, and the differences are clinically significant. NICE recommends Wegovy (TA875) only within a specialist weight management service and for a maximum of two years. Mounjaro (TA1026, December 2024, updated September 2025) carries no equivalent two-year cap and can be initiated in primary care from April 2026 under the new GP contract. Both have BMI thresholds (≥35 with a weight-related comorbidity as a general rule, with lower thresholds for some ethnic backgrounds under UK guidance) but the service requirements and duration limits differ. That distinction shapes access on the NHS considerably.

For private prescribing, both medicines are available through regulated online pharmacies to eligible adults with a BMI of ≥30, or ≥27 with a relevant weight-related condition, following a full clinical assessment. Neither is available without one. You can check whether you are likely to meet the criteria through our free consultation, which is reviewed the same day by a real prescriber. If you want context on NHS waiting times versus private routes, the treatment overview sets out the landscape clearly.

So which one should you choose?

On average, across a population, the trial data favours tirzepatide. But averages do not choose medicines, prescribers do, with you. Factors that can shift the decision include your current medications, any history of GI conditions, whether you take an oral contraceptive, your BMI and comorbidities, and how you tolerated a previous GLP-1 if you have switched from one. Cost is another consideration; a direct cost comparison breaks down what private prices look like across both medicines and what drives the differences.

If you are coming to this having read something about Ozempic, it is worth being clear: Ozempic is also semaglutide but it holds a licence for type 2 diabetes, not weight management. It is not the same product as Wegovy and is not prescribed for weight loss. The comparison that matters for weight management is Wegovy versus Mounjaro. Which suits you is a clinical decision our prescribers make with you, with your full history in front of them.