The UK weight loss injection medication names you'll actually encounter

Which injection drug names are actually licensed for weight loss in the UK?

The short answer: two. Mounjaro, the brand name for tirzepatide made by Eli Lilly, and Wegovy, the brand name for semaglutide made by Novo Nordisk. Both are once-weekly subcutaneous injections (self-administered at home via a pre-filled pen) and both carry a UK marketing authorisation for weight management alongside a reduced-calorie diet and increased physical activity.

You may have come across other names in the same conversation. The fuller picture of injectable weight loss options includes medicines sometimes mentioned online, but the licensing position in the UK is quite specific. Ozempic is also semaglutide, the same active ingredient as Wegovy, but its UK licence covers type 2 diabetes management, not weight loss. Prescribing it for weight management would be off-label, which is a clinical decision with a different legal and safety framework. Similarly, Saxenda (liraglutide) holds a UK weight management licence but is an older GLP-1 medicine not dispensed by all private providers. The names matter because the licence determines the clinical evidence base your prescriber is working from.

The NHS tirzepatide page on the NHS medicines section and the equivalent semaglutide entry both summarise what these medicines are approved to treat, which is a useful cross-reference if you want to verify what you've read elsewhere.

What is the pharmacological difference between these two weight loss injection medicines?

Both tirzepatide and semaglutide are GLP-1 receptor agonists, meaning they mimic the gut hormone GLP-1, which signals satiety to the brain and slows gastric emptying. That shared mechanism explains the overlapping side-effect profiles and the broadly similar approach to treatment, a low starting dose that is stepped up gradually by your prescriber over several months.

The difference is what tirzepatide does additionally. It also activates GIP receptors, a second gut-hormone pathway involved in appetite regulation and metabolic function. This dual action is why Mounjaro is described as a dual GIP and GLP-1 receptor agonist and is, as of mid-2026, the only medicine of its kind licensed in the UK. Whether that translates into a meaningful difference in outcomes for any individual person is a clinical question, but the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, found that tirzepatide produced greater average weight reduction than semaglutide 2.4mg over 72 weeks in a head-to-head study. NICE's appraisal notes that indirect comparisons also favour tirzepatide, though both medicines remain clinically significant options. Our clinical team has more on how prescribers weigh up these differences during a consultation.

A practical note worth knowing: many people researching these medications find the injection aspect the biggest hesitation. If that applies to you, our guide to weight loss injections covers how the pens work, what to expect from each step-up dose, and how the technique is simpler than it sounds.

Are there any other injection names that come up, and should they?

Quite a few names circulate on social media and in forum threads that are worth addressing directly. Zepbound is tirzepatide under its US brand name; it does not exist as a UK product and cannot be obtained from any UK pharmacy. Anyone selling Zepbound-branded pens in the UK is not operating through the licensed UK supply chain. Ozempic, as mentioned above, is a real and widely prescribed medicine but for diabetes, its appearance in weight-loss discussions stems from its shared active ingredient with Wegovy, not from a weight management licence. Rybelsus is oral semaglutide, approved for type 2 diabetes at doses of 3, 7 and 14mg; the oral semaglutide approved for weight management is Wegovy tablets, at a different dosing schedule entirely.

The MHRA has issued clear public guidance on reporting suspect medicines and side effects, any supply of these prescription medicines without a valid prescription is both illegal and genuinely risky. Counterfeit pens have been seized in significant quantities across the UK, and some have contained substances other than what was stated on the label. If you're comparing options and would prefer to avoid injections altogether, our guide to the best non-injection weight loss medications sets out which licensed oral alternatives may be suitable and how they compare on evidence.

Who can be prescribed these injection medicines in the UK?

Eligibility is set by the medicines' UK licences, not by the provider. For both Mounjaro and Wegovy, the licensed population is adults with a BMI of 30 or above, or a BMI of 27 or above alongside at least one weight-related health condition, for example, high blood pressure, raised cholesterol, obstructive sleep apnoea, type 2 diabetes, or prediabetes. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance.

Those criteria define the outer boundary. A prescriber then assesses whether treatment is appropriate for you specifically: your full medication list, your health history, your weight trend, and any contraindications. Pregnancy, breastfeeding, and trying to conceive are situations where these medicines are not recommended. People under 18 are outside the licensed population for either injection. A history of certain thyroid conditions or pancreatitis requires careful prescriber judgement.

On the NHS, access follows a phased rollout under NICE technology appraisal guidance (tirzepatide under NICE TA1026 and Wegovy under a specialist service pathway) with strict thresholds and waiting lists in most areas. Private prescribing through a regulated online pharmacy follows the licensed eligibility criteria without the NHS queue, subject to the same clinical gatekeeping. Once you know you're eligible, our step-by-step guide on how to inject weight loss medication walks you through the technique so you feel confident before your first dose. If you'd like to find out whether you meet the clinical criteria, starting a free consultation with our prescribers is the next step, and if you want a broader overview before then, our page on weight loss medication injections explains how these treatments work, what to expect, and how to get started. It's assessed the same day, by a real clinician.