The weight loss injection brand names you'll actually encounter in the UK

The biggest myth: that 'brand name' means you have many options to browse

People searching for weight loss injection brand names often arrive expecting a comparison of five or six named products, the way you might compare brands of protein powder. That picture is wrong, and it matters practically.

In the UK, the Medicines and Healthcare products Regulatory Agency licenses medicines for specific indications. As of mid-2026, Mounjaro and Wegovy are the two injection brand names holding a UK licence for weight management in adults. That is the complete list for injections. You may read about Ozempic, Saxenda, or Zepbound in the press or on social media. Ozempic is semaglutide licensed for type 2 diabetes; prescribing it for weight loss is off-label and not how a properly governed weight-management service operates. Saxenda (liraglutide) held a weight-management licence but is not widely dispensed by regulated online pharmacies at present. Zepbound is simply the United States brand name for tirzepatide, it does not exist as a UK-authorised product. Any seller offering 'Zepbound' in Britain is not operating within the UK licensed supply chain.

This matters because counterfeit and illicitly traded pens have caused real harm. The MHRA has warned repeatedly about fake weight-loss injections sold online, and in October 2025 the first illicit UK manufacturing site producing counterfeit tirzepatide pens was raided. If you want a clear picture of which products are genuinely authorised here, our page covering weight loss injections brand names available in the UK explains the full landscape and helps you distinguish legitimate options from those that are not. The safe starting point is knowing which two brand names are actually legitimate here, and then verifying that the pharmacy supplying them appears on the GPhC pharmacy register.

Mounjaro and Wegovy: what makes each brand distinct

Both injections work by mimicking hormones involved in appetite regulation and blood-sugar control, but they work slightly differently and their trial results differ too.

Mounjaro activates two receptors: GIP and GLP-1. It is the only dual-agonist weight-loss medicine licensed in the UK. In the SURMOUNT-1 trial, participants lost an average of around 20–21% of body weight at the highest dose over 72 weeks. A later head-to-head trial, SURMOUNT-5, found tirzepatide produced greater average weight loss than semaglutide 2.4 mg over the same period. You can read about the names and mechanisms behind weight loss injections in more detail if you want to go deeper on the science.

Wegovy activates the GLP-1 receptor alone. The STEP 1 trial found an average weight reduction of around 15% at the 2.4 mg dose over 68 weeks. A higher 7.2 mg dose was subsequently approved by the MHRA, with trial data showing around 20.7% average loss at that level, approaching Mounjaro's results. Both medicines are taken once weekly via a pre-filled pen and are titrated gradually by the prescriber to help your system adjust. For a fuller look at how Wegovy's dosing compares across strengths, our page on the new weight loss injection options covers the recent approvals.

Neither brand is suitable for everyone. Pregnancy, breastfeeding, or trying to conceive rules both out. A history of medullary thyroid carcinoma, multiple endocrine neoplasia type 2, or certain gastrointestinal conditions requires careful prescriber review. Under-18s are not covered by either licence. The prescriber weighs all of this, which is why the consultation is the essential first step rather than a formality.

Who the licences actually cover, and what 'eligible' really means

Both brand names share broadly similar eligibility criteria under their UK licences: adults with a BMI of 30 or above, or 27 and above if at least one weight-related health condition is present, such as high blood pressure, high cholesterol, type 2 diabetes, or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance.

A BMI figure that clears the threshold does not guarantee a prescription. The prescriber looks at your full health picture: current medicines, relevant medical history, and whether either brand is appropriate given any contraindications. This is why legitimate providers ask detailed questions and, in the case of a well-run service like ours, verify your weight on a video call rather than taking a self-reported number on faith.

If you are wondering about cost alongside eligibility, our page on what weight loss injections actually cost in the UK lays out what private pricing typically covers and what to watch for when a price looks unusually low. Getting a branded medicine from a legitimate, regulated pharmacy is the thing that keeps supply safe, the brand name on the pen only matters if the pen is genuine. The NHS also provides access to both medicines under specific criteria, though waiting lists for specialist weight management services are commonly long; our guide to weight loss injections covers both routes side by side.

Side effects: what these brand names share and where they differ in practice

Because both Mounjaro and Wegovy slow gastric emptying and act on appetite-regulating pathways, their side-effect profiles overlap considerably. Nausea is the most commonly reported, especially after starting or moving up a dose. Diarrhoea, constipation, indigestion, and fatigue turn up in both brands' trial data. Injection-site reactions are usually mild. These effects tend to settle as your system adjusts, often within a week or two of a dose change, though the pace varies between people.

The NHS patient information for tirzepatide is a reliable first reference if you want a complete list, as is the patient leaflet inside the box, and if you are currently on either medicine and worried about a symptom, the first call is to your prescribing team rather than a search engine.

One area the NHS specifically flags for tirzepatide: women using oral contraceptives should add a non-oral method of contraception for the first four weeks of treatment and for four weeks after each dose increase, because absorption of the pill can be reduced. No equivalent effect has been established for semaglutide, but it is worth raising with your prescriber regardless. A question our prescribers hear most weeks is whether HRT is affected in a similar way, the NHS advises considering transdermal forms of HRT (patches or gels) while on tirzepatide, and this is worth discussing before you start rather than after. Our page on gastrointestinal side effects from weight loss injections goes into more detail on managing the most common complaint. Suspected side effects from either brand can be reported to the MHRA via the Yellow Card scheme, something many people don't realise they can do as a patient rather than a clinician.

If you'd like a real clinician to look at which of these brands suits your situation, the consultation is free and takes about ten minutes, most people find it straightforward, even if the pen-in-the-fridge step that follows feels novel at first. Check your eligibility with our prescribers and you'll have a same-day clinical review of your answers.