The names of weight loss injections licensed in the UK

Step 1, Know what you're looking at: the two names and what they mean

When people search for the name of a weight loss injection, they usually encounter a tangle of brand names, generic names and medicines that sound similar but serve different purposes. Here is the straightforward breakdown.

Mounjaro is the brand name; tirzepatide is the active ingredient. It is made by Eli Lilly and comes as a pre-filled KwikPen delivering one weekly dose. It is the only dual receptor agonist in this class, it activates both GIP and GLP-1 receptors, which are involved in appetite regulation and blood-sugar control. You can read more about how weight loss injections work in practice, including what to expect from your first pen.

Wegovy is the brand name; semaglutide is the active ingredient. Also a pre-filled, once-weekly pen, it is made by Novo Nordisk and acts on the GLP-1 receptor alone. Semaglutide also exists under a different brand name (Ozempic) but Ozempic is licensed for type 2 diabetes management, not weight loss. The two should never be confused. Similarly, Rybelsus is an oral semaglutide tablet licensed for diabetes, not weight management.

So if someone asks what the name of the weight loss injection is, the accurate answer is that there are two: Mounjaro and Wegovy. Both are detailed on the full list of licensed weight loss injections available in the UK.

Step 2, Understand the trial evidence behind each name

The names matter less than what the medicines actually do, and both have substantial clinical trial data behind them.

Mounjaro was studied in the SURMOUNT-1 trial (2,539 adults with obesity, 72 weeks). At the highest dose, participants saw an average body-weight reduction of around 20–21%, making it the most effective licensed option in this class to date. A later head-to-head study (the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025) compared tirzepatide directly with semaglutide 2.4mg and found tirzepatide produced greater average weight loss over 72 weeks. NICE's appraisal of tirzepatide (TA1026) drew on this evidence when recommending it for NHS use in eligible adults.

Wegovy was studied in the STEP 1 trial (68 weeks), where participants lost an average of around 15% of body weight at the 2.4mg maintenance dose. A higher dose (7.2mg) received MHRA approval in early 2026 and has shown results approaching those of tirzepatide in trials. The NHS medicines page for semaglutide covers the medicine's approved uses and side-effect profile in plain language.

Neither figure is a guarantee. Clinical trial averages describe populations; individual results vary based on starting weight, adherence, diet, activity and other factors. A prescriber will discuss realistic expectations with you.

Step 3, Check whether you're likely to be eligible

Both injections share broadly similar eligibility criteria, set by their UK licences. Adults with a BMI of 30 or above qualify, as do those with a BMI of 27 or above if at least one weight-related health condition is present, for example, prediabetes, high blood pressure, high cholesterol or obstructive sleep apnoea. For some ethnic backgrounds, UK guidance applies thresholds around 2.5 kg/m² lower; this is explained in detail on the branded weight loss injection guide.

Neither medicine is licensed for anyone under 18, and both are not recommended during pregnancy, breastfeeding or when actively trying to conceive. Certain conditions (including a personal or family history of medullary thyroid carcinoma) require careful prescriber review before any GLP-1 medicine is considered.

BMI alone is never the whole picture. A prescriber looks at your full medical history, current medicines, and any contraindications. If you want to check how the eligibility criteria apply to you specifically, this guide on finding the right injection for weight loss walks through the key questions in more detail.

The cost context for these medicines (which varies by dose, provider and what is included in the price) is covered on our weight loss injection cost page, where we look honestly at what drives the differences between providers.

Step 4, Understand how a legitimate prescription route works

Once you know the names of the injections, the natural next question is how to access one safely. In the UK, both Mounjaro and Wegovy are prescription-only medicines. A clinician must assess your medical history, confirm eligibility, and issue a prescription before any medicine is dispensed. There is no legal shortcut to that step.

With a regulated online pharmacy, the process can move quickly. At nume, you complete a free consultation, our prescribers are GPhC-registered Independent Prescribers, and a real clinician reads your answers the same day, not an automated system. If treatment is clinically appropriate, it is dispatched the same day for orders placed before 12pm, arriving the next working day by tracked DPD delivery in plain packaging. Plenty of people place their order during a morning coffee and have their pen by the following afternoon.

You can verify any online pharmacy on the GPhC's public pharmacy register before you hand over any personal or medical information. It takes about thirty seconds and tells you whether a pharmacy is genuinely regulated. Our own registration number is 9012878. The newest licensed injection in the UK page has more on recent approvals and what the regulatory process involves.

If you are still weighing up which injection might suit you, our comparison of weight loss injection names and options sets out the differences side by side. And for a broader look at how quickly results typically appear, the timeline guide for weight loss injections is worth reading before you decide.