Mounjaro or Wegovy: which is best for weight loss?

The biggest myth: one of these medicines is objectively "the best"

The framing most people arrive with is that Mounjaro and Wegovy exist on a simple ranking, and the job is to identify the winner. The reality is messier and more useful. These two medicines work on different hormonal pathways, carry somewhat different side-effect profiles, and suit different people for reasons that only surface during a proper clinical review.

Mounjaro (tirzepatide, made by Eli Lilly) activates two gut-hormone receptors simultaneously (GIP and GLP-1) making it the only dual-agonist weight-loss medicine currently licensed in the UK. Wegovy (semaglutide, made by Novo Nordisk) targets the GLP-1 receptor alone. That mechanistic difference is part of why their average outcomes diverge in trials. But average outcomes describe populations, not individuals. Somebody who responds strongly to GLP-1 stimulation alone may find Wegovy entirely adequate; somebody who tolerates one medicine poorly may do better on the other. If you are trying to work out what is best, Mounjaro or Wegovy, for your situation, the comparison table below sets out the factual differences, and the section after it explains what those numbers actually mean for you.

One thing worth saying plainly: Ozempic is also semaglutide, but it is licensed for type 2 diabetes, not weight loss. If you have seen it mentioned alongside Mounjaro and Wegovy and are wondering which is best, Ozempic or Mounjaro, given how often the two are compared, that page explains the licensing distinction and what it means in practice. Our comparison of Mounjaro and Ozempic also explains the licensing distinction clearly.

Mounjaro vs Wegovy: the facts side by side

The table below draws from the published trial programmes and the respective NICE technology appraisals. Where figures are trial averages, they are presented as such, individual results vary.

The SURMOUNT-5 trial is the clearest direct comparison available: in a 72-week open-label study of adults with obesity but no diabetes, tirzepatide produced meaningfully greater average weight reduction than semaglutide 2.4mg. People asking what's better, Mounjaro or Wegovy, on average will find that trial's findings put the numbers in context.

What the comparison doesn't tell you: side effects and individual fit

Both medicines share a GI-led side-effect profile, nausea, loose stools, constipation, reflux and fatigue are the most commonly reported, particularly when starting or stepping up. For most people they are mild and settle within a couple of weeks. They are not identical, though. The intensity and mix of symptoms can differ between medicines, and some people find one far more tolerable than the other.

There are also practical clinical differences worth knowing. Women taking oral contraceptives alongside Mounjaro are advised to use an additional non-oral method for the first four weeks of treatment and for four weeks after each dose increase, because tirzepatide may reduce pill absorption. NHS England's weight-management-injections guidance covers this, and also notes that transdermal HRT forms such as patches or gels are worth considering over oral HRT for the same reason. These are conversations for a prescriber, not a comparison table.

For anyone already on treatment and thinking about switching, or for a broader look at how to choose between the weight-loss options available, the right starting point is a consultation rather than a forum thread.

How a clinical decision is actually made, and what comes next

A comparison page can lay out the evidence. What it cannot do is account for your medication history, any conditions that might make one of these medicines unsuitable, or the dose trajectory that fits your situation. That is what the consultation is for.

At nume, a GPhC-registered Independent Prescriber reads your consultation responses personally (a real clinician, not a routing algorithm) and considers the full picture before making a recommendation. If you order before 12pm on a weekday and the prescriber approves your treatment, it goes out the same day. The pen arrives with a DPD tracking notification, in a plain box that gives nothing away, the next working day. There are no subscription commitments; every repeat order is reviewed again from scratch.

If you want to see how the prescribing process works in practice, our clinical team page gives you a sense of who is doing the reviewing. And if the cost question is part of what you're weighing up, the price comparison between the two sets out what private treatment typically costs and what legitimate pricing includes. For answers to common questions before you start, our FAQs page covers the ones our prescribers hear most often.

Which medicine suits you is a clinical decision our prescribers make with you, and for a detailed look at which is best, Mounjaro or Wegovy, for different clinical profiles, that page goes further than a comparison table can. Check your eligibility and start a free consultation to get a proper answer.