Wegovy vs the alternatives: how the comparison actually works

The decision you're really making: mechanism, licence, or fit?

Most people searching 'Wegovy vs…' have already decided they want a weight-loss injection. The real question is which licensed medicine suits their biology, health history and lifestyle best. That is a clinical question, not a marketing one, but understanding the landscape helps.

Wegovy works on a single pathway: it activates GLP-1 receptors in the gut and brain, slowing gastric emptying and reducing appetite. Mounjaro (tirzepatide) activates both GLP-1 and GIP receptors simultaneously, making it the only dual-agonist weight-loss medicine licensed in the UK. That biological difference is material, though it doesn't automatically make one medicine better for any individual person.

A misconception worth addressing gently: many people assume Ozempic is a weight-loss medicine available through the same route as Wegovy. It isn't. Ozempic is semaglutide licensed for type 2 diabetes, not weight management, you can read more about the differences between Wegovy and Ozempic, but the short version is that they're not interchangeable for this purpose. Saxenda (liraglutide) is UK-licensed for weight management, but the trial evidence for the newer medicines generally shows greater average reductions; how Saxenda compares to Wegovy is its own detailed question. And Rybelsus, oral semaglutide in 3/7/14mg tablets, is a diabetes medicine, distinct from the newly approved Wegovy tablets designed for weight management.

The Wegovy treatment overview covers the full licensed picture if you want to start there.

What the evidence shows, and what it can't tell you about your outcome

Trial data gives population averages. They're the best signal we have, but your result will depend on adherence, lifestyle changes alongside treatment, your starting weight and your physiology.

In the STEP 1 trial published in the New England Journal of Medicine, adults taking semaglutide 2.4mg lost around 15% of body weight on average over 68 weeks alongside lifestyle changes. Tirzepatide's SURMOUNT-1 trial produced average reductions of around 20–21% at the highest dose over 72 weeks. The SURMOUNT-5 head-to-head trial (72 weeks, 751 adults with obesity, published in NEJM 2025) found tirzepatide produced greater average weight loss than semaglutide 2.4mg, the most direct comparison available.

Wegovy 7.2mg, approved by the MHRA in January 2026 as a higher maintenance dose, reported approximately 20.7% average weight loss over 72 weeks in trials, closing the gap with tirzepatide 15mg considerably. A dedicated single-dose 7.2mg pen was approved in April 2026. Whether that higher dose is appropriate is a clinical decision reached through dose titration, not a starting point.

For a wider look at where Wegovy sits among GLP-1 medicines as a group, comparing Wegovy against the GLP-1 class covers that ground.

Eligibility, NICE, and what private prescribing changes

Both medicines carry NICE recommendations, but with different scope. NICE's appraisal of semaglutide (TA875) limits NHS use to a maximum of two years within a specialist weight management service. The NICE appraisal of tirzepatide (TA1026) applies to adults with a BMI of 35 or above plus at least one weight-related condition, with BMI thresholds 2.5 kg/m² lower for certain ethnic backgrounds. NHS access to both medicines involves waiting lists and phased eligibility criteria that continue to evolve.

Private prescribing follows the licensed indications directly: adults with a BMI of 30 or above, or 27 and above with a qualifying condition such as hypertension, type 2 diabetes or dyslipidaemia. Lower thresholds apply for some ethnic backgrounds under UK clinical guidance. BMI alone doesn't settle it, a prescriber reviews the whole picture, including current medicines, medical history and what's realistic for you.

If you've been prescribed semaglutide elsewhere and want to understand more about the medicine itself, semaglutide versus the Wegovy brand unpacks that distinction. And if Mounjaro is already on your radar, comparing Mounjaro and Wegovy side by side goes deeper on the head-to-head evidence.

Side effects, tolerability and the practical shape of each treatment

The side-effect profiles of Wegovy and Mounjaro overlap substantially because both slow gastric emptying. Nausea, loose stools, constipation, indigestion and fatigue are common to both, typically at their worst after starting treatment or after a dose increase, and for many people they ease within a couple of weeks. Neither medicine is easier on the stomach in a reliably consistent way across patients, tolerability is individual.

One practical difference: because tirzepatide can reduce absorption of oral medicines, women using the combined oral contraceptive pill should use an additional non-oral method for the first four weeks of treatment and for four weeks after each dose increase. NHS England's guidance on weight-management injections covers this and similar interactions, including HRT considerations, clearly. The equivalent caution for semaglutide does not currently carry the same evidence base.

Pancreatitis is a known but infrequent serious risk across the GLP-1 class, seek urgent help for severe stomach pain that radiates to the back. Both medicines also carry a Black Triangle (▼) designation, meaning they're subject to additional MHRA monitoring while post-market data accumulates.

Which treatment suits you is a clinical decision our prescribers make with you, not something a comparison table resolves. Check your eligibility through a free consultation and a prescriber will review your situation the same day.