What Works Better Than Wegovy for Weight Loss in the UK?

Does the trial data actually show one is better than the other?

Yes — with an important caveat about what 'better' means. The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, put tirzepatide (Mounjaro) directly against semaglutide 2.4mg (Wegovy) in 751 adults with obesity over 72 weeks. Tirzepatide produced meaningfully greater average weight loss. NICE's appraisal of tirzepatide (TA1026) notes that indirect comparisons also favour tirzepatide over semaglutide at the standard maintenance dose.

That said, the picture is shifting. Novo Nordisk's higher 7.2mg Wegovy dose (approved by the MHRA in January 2026 and available as a dedicated single-dose pen from April 2026) reported around 20.7% average weight loss over 72 weeks, which narrows the gap considerably with tirzepatide's highest dose. Whether that narrows it to nothing depends on the individual, and that's genuinely still being studied.

For context, here is how the headline figures compare across the main UK-licensed weight-loss injections:

All figures are from clinical trials in specific populations, your result will vary. Neither medicine is a guaranteed outcome; they work alongside a reduced-calorie diet and increased activity.

How do Mounjaro and Wegovy actually differ day-to-day?

Both are once-weekly injections into the abdomen, thigh or upper arm. The pens look similar. The meaningful practical differences come down to mechanism, starting dose, and the titration path your prescriber sets.

Tirzepatide activates two gut-hormone receptors (GIP and GLP-1) making it the only dual-agonist weight-loss medicine licensed in the UK. Wegovy activates GLP-1 alone. Whether that dual action translates into a meaningfully different experience for a given person is hard to predict in advance; some people tolerate one better than the other despite both sharing a GI-led side-effect profile (nausea, loose stools and constipation being the most common, typically settling as your body adjusts).

There is one practical difference worth flagging if you take the combined oral contraceptive pill: for tirzepatide specifically, NHS guidance recommends adding a barrier method for the first four weeks of treatment and for four weeks after each dose increase, because absorption of the pill may be reduced. There is no equivalent recommendation for semaglutide. NHS England's guidance on weight-management injections covers this clearly, worth a read before your consultation if it applies to you.

Storage is the same for both: refrigerated between 2–8°C, with a limited window at room temperature covered in the Patient Information Leaflet. The Wegovy tablet (oral semaglutide, approved June 2026) changes this (no fridge needed) but that's a separate conversation. You can read more about how Wegovy works if you want the full picture on the injection first.

What about Ozempic, isn't that semaglutide too?

It is, but it's a different licence entirely. Ozempic contains semaglutide and is licensed for type 2 diabetes management in the UK, not for weight loss. Using it off-licence for weight management is not what it's approved for, and no legitimate UK prescriber should offer it as a weight-loss treatment to someone without diabetes. If you are trying to understand whether Wegovy is actually better than Ozempic for weight loss, and why the two are not interchangeable in clinical practice, that page goes into this in detail, but the short version is: if someone is offering you Ozempic for weight loss and you don't have diabetes, that's a red flag worth taking seriously.

Similarly, Saxenda (liraglutide) is GLP-1-based and licensed for weight management in the UK, but the trial evidence puts it behind both Wegovy and Mounjaro on average weight loss. If you're weighing that up, the Wegovy vs Saxenda comparison covers the numbers. The same evidence-led logic applies: the best option is the one clinically appropriate for you, not the one with the biggest headline figure.

How does eligibility differ between Mounjaro and Wegovy on the NHS and privately?

Privately (which is how both medicines are dispensed through nume) the licensed eligibility for each follows the SmPC. For both, the baseline is a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, high cholesterol or prediabetes. Lower thresholds apply for some ethnic backgrounds under UK guidance. If you are unsure whether you meet the minimum weight requirement for Wegovy, the prescriber looks at your full health picture, not BMI alone.

On the NHS the situation is more complicated. Tirzepatide (TA1026) is rolling out in phases through GP practices, with strict BMI and comorbidity thresholds that are gradually widening. Wegovy (TA875) is available through specialist weight management services only, for a maximum of two years, and waiting lists are commonly long. If you don't currently meet NHS criteria or don't want to wait, a private regulated route is the practical alternative.

You can check your eligibility quickly right now: the NHS BMI calculator takes under a minute and gives you a starting figure to bring into your consultation. Worth doing before you book.

Our Mounjaro vs Wegovy comparison goes deeper on the eligibility side-by-side if that's the specific question on your mind. And if you'd like to explore all the treatment options in one place, speak to our prescribers through a free consultation, the clinical team, led by our clinical lead, will work through which medicine fits your situation. If the question of whether Wegovy is genuinely better than other forms of semaglutide is still on your mind, that page unpacks the distinction in full.