Drugs Like Semaglutide and How They Compare

How the GLP-1 class produces weight loss, and where tirzepatide fits in

Official NICE guidance on both semaglutide and tirzepatide describes GLP-1 receptor agonists as medicines that slow the rate at which food leaves the stomach and reduce appetite by acting on receptors in the gut and brain. Semaglutide binds selectively to the GLP-1 receptor; that single mechanism is the basis of Wegovy's licensed action for weight management. Tirzepatide (sold as Mounjaro) activates the GLP-1 receptor and the GIP receptor simultaneously, making it the only dual-agonist weight-loss medicine with a UK licence. Whether that second pathway explains tirzepatide's larger average trial results is still being studied, but the clinical outcome data is consistent: activating GIP alongside GLP-1 does something additive to weight reduction in most people.

If you want a deeper look at the pharmacology behind semaglutide specifically, our semaglutide overview covers the mechanism, the licensed indications and what the STEP trial programme found. The short version: the GLP-1 class works by changing appetite physiology, not willpower, which is why the results in carefully conducted trials are large enough to matter clinically.

Liraglutide (Saxenda) is another GLP-1 agonist licensed for weight management in the UK, though it is injected daily rather than weekly and its average trial weight loss is lower than either semaglutide or tirzepatide at their maintenance doses. Exenatide and dulaglutide are in the same drug class but hold licences only for type 2 diabetes in the UK. The GLP-1 class overview sets out which medicines sit in this category and what each is authorised to treat.

What the head-to-head evidence actually showed between drugs like Wegovy and Mounjaro

The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, is the most relevant piece of evidence for anyone comparing semaglutide-like drugs. It randomised 751 adults with obesity but without diabetes to either tirzepatide or semaglutide 2.4 mg over 72 weeks. Tirzepatide produced the larger average weight reduction. NICE's appraisal of tirzepatide (TA1026) noted indirect comparisons across trial programmes also favoured tirzepatide over semaglutide 2.4 mg, and SURMOUNT-5 confirmed that finding directly.

It is worth being precise about what that means in practice. A larger average does not mean every person loses more on tirzepatide; individual responses vary considerably in both directions. Semaglutide 2.4 mg produced around 15% average body-weight reduction in the STEP 1 trial over 68 weeks, a clinically meaningful result that genuinely changed outcomes for most participants. The newer Wegovy 7.2 mg dose, approved by the MHRA in early 2026, pushes the average further, narrowing the gap with tirzepatide's highest dose. Both remain prescription-only, and a prescriber will consider your full clinical picture rather than simply prescribing the drug with the largest published average.

For a closer look at the Wegovy evidence base and dosing pathway, the Wegovy page covers what the MHRA licence covers and how the titration schedule works. If you are specifically curious about cost differences between these options, the Wegovy cost page provides honest context on UK private pricing without glossing over the variation between providers.

Which semaglutide-like drugs are available through a UK private prescription, and which are not

This is the question that gets muddled most often, and it is an easy muddle to fall into. Ozempic is semaglutide, but it is licensed for type 2 diabetes, not weight management. The NHS semaglutide page makes this distinction clearly: the weight-management licence belongs to Wegovy, not Ozempic. Prescribing Ozempic for weight loss in people without diabetes would be off-label, which is outside the scope of what a responsible online prescriber should do routinely. Rybelsus is also semaglutide (oral tablets) but again licensed only for type 2 diabetes. Wegovy tablets (the newly approved oral semaglutide for weight management) are a separate product with a separate licence; if that distinction matters to you, the semaglutide analogues page unpicks the different formulations.

In practice, the two medicines a UK-licensed private prescriber can offer for weight management are Wegovy (semaglutide, injection or tablet) and Mounjaro (tirzepatide). That is it. If a seller is offering something described as a semaglutide drug for weight loss that falls outside those two options, check whether it holds a UK licence and verify the pharmacy on the GPhC register before proceeding. We hear from people who feel embarrassed they ever considered an unlicensed source, there is no need to feel that way; the marketing is deliberately confusing. Worth knowing, not judging.

Eligibility for either medicine requires a clinical assessment. The licensed thresholds are a BMI of 30 or above, or 27 or above alongside a weight-related condition such as high blood pressure or type 2 diabetes. A prescriber reviews the complete picture. If you are ready to find out whether either option suits you, checking your eligibility with our clinical team is the next sensible step.