The names of weight loss injectables licensed in the UK — and what sets them apart

You've seen the names everywhere. Here's what's actually in front of you.

Someone in your office mentioned Ozempic. A friend is on Wegovy. A social-media ad used a name you didn't recognise. It's genuinely confusing, because several brand names refer to the same molecule, some are for diabetes rather than weight loss, and at least one doesn't exist as a UK product at all.

Start here: in the UK, the injectable weight loss medicines with full MHRA authorisation for weight management are Mounjaro and Wegovy. Those are the names that matter if your goal is licensed, clinically supervised treatment.

Mounjaro contains tirzepatide, made by Eli Lilly. It's the only dual-agonist available, activating both the GIP and GLP-1 gut-hormone receptors to reduce appetite and slow gastric emptying. It comes as a pre-filled KwikPen (four doses per pen) in six strengths from 2.5mg to 15mg. Treatment begins at 2.5mg, a dose designed to help your system adjust gradually before the prescriber titrates upward.

Wegovy contains semaglutide, made by Novo Nordisk. It targets the GLP-1 receptor only. The standard maintenance dose is 2.4mg weekly, titrated from 0.25mg. In April 2026 the MHRA also approved a 7.2mg single-dose pen for adults with a BMI of 30 or above, making it the highest licensed semaglutide dose for weight management in the UK. For a full comparison of how the two stack up, our guide to weight loss injections sets the evidence side by side.

Both carry a Black Triangle (▼), meaning the MHRA collects ongoing safety data. The NHS medicines page for tirzepatide and the equivalent page for semaglutide are reliable plain-English summaries of what each medicine does and what side effects to watch for.

The names that don't mean what most people assume

This is where a lot of confusion lives. Ozempic is semaglutide (the same molecule as Wegovy) but it's licensed in the UK for type 2 diabetes management, not for weight loss. Prescribing it for weight loss when Wegovy exists for exactly that purpose is off-label, and the MHRA has been clear that Ozempic should not be sought as a weight-loss treatment. More on the Ozempic question is covered separately, because it comes up constantly.

Saxenda is liraglutide, a GLP-1 medicine by Novo Nordisk that does hold a UK licence for weight management. It requires a daily injection rather than weekly, and its average weight loss results in trials sit below those of both Mounjaro and Wegovy at their respective maintenance doses. Saxenda is not dispensed by nume, if it's the right option for your situation, your GP or a specialist service can advise.

Zepbound is the brand name Eli Lilly uses for tirzepatide in the United States. It does not exist as a UK product. If you've seen it advertised or offered from a UK seller, that's worth treating as a serious red flag, the MHRA has warned repeatedly about fake and illegally traded weight-loss pens sold online, including counterfeit tirzepatide. Report suspect sellers via the MHRA Yellow Card scheme.

The practical upshot: when you search for injectable names, you're mostly finding the same two molecules (tirzepatide and semaglutide) wearing different brand hats depending on the country or the indication. The licence matters. The indication matters. The name alone tells you less than it seems.

What these injectables share (and where they differ in practice

Both Mounjaro and Wegovy are once-weekly subcutaneous injections, meaning you inject into the fat under the skin) abdomen, thigh or upper arm, rotating sites. Both slow gastric emptying and reduce appetite through gut-hormone pathways. Both are taken alongside a reduced-calorie diet and increased physical activity; neither is a standalone fix.

In terms of how they fit into a routine, the pen goes in the fridge (2–8°C), and most people find a fixed day each week helps, Saturday morning, for instance, before anything else. The SmPC sets out a limited window for room-temperature storage if refrigeration isn't possible; always check the Patient Information Leaflet for the exact figure, since it differs between products.

Results differ too. In the SURMOUNT-1 trial, tirzepatide at 15mg produced an average body-weight reduction of around 20–21% over 72 weeks. The STEP 1 trial for semaglutide at 2.4mg showed approximately 15% average reduction over 68 weeks. The more recent SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, directly compared the two medicines in adults with obesity and found tirzepatide produced greater average weight loss. The higher 7.2mg Wegovy dose narrows that gap somewhat. Which is right for a given person is a clinical judgement, not a website decision. More on how these injections work in practice goes deeper on the mechanism.

Eligibility for private treatment broadly follows the licensed criteria: adults with a BMI of 30 or above, or 27 and above with at least one weight-related condition such as hypertension, high cholesterol, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. A prescriber considers the whole picture, not the BMI figure alone. For anyone thinking about what treatment might suit them, starting with a free consultation is the straightforward next step.

NHS versus private: what the names mean for access

Both Mounjaro and Wegovy are available on the NHS, but under strict criteria and phased eligibility that means most people currently don't qualify or face significant waiting lists. NICE's appraisal of tirzepatide (TA1026) sets out the NHS thresholds: from June 2025, adults with a BMI of 40 or above and four or more qualifying comorbidities became eligible in the first cohort; a second cohort (BMI 35–39.9 with four or more conditions) opened in June 2026. Further phases are expected from 2027.

Wegovy on the NHS is routed through specialist weight management services, which carry their own waiting times. Scotland, Wales and Northern Ireland operate different access criteria.

Private treatment through a GPhC-registered pharmacy is the alternative for people who meet the licensed criteria but don't qualify for NHS treatment yet, or prefer not to wait. The cost landscape for private treatment, including what a legitimate price includes and what to be wary of, is covered in detail on the weight loss injections cost page. The short version: a legitimate price covers the prescription, clinical oversight and dispensing, not just the pen.

A full list of injectable names and their indications pulls together the complete picture if you want to cross-reference before speaking to a prescriber. More on what to make of each name is also available.