What's the name of the injection for weight loss?

Why are there so many different names for weight-loss injections?

It's a fair question, and the confusion is genuine. Every injectable medicine in this space has at least two names: the generic (the active ingredient, lowercase) and the brand (the commercial product, capitalised). Tirzepatide is the ingredient; Mounjaro is the pen you inject. Semaglutide is the ingredient; Wegovy is one brand of it for weight loss, while Ozempic is another brand of semaglutide that happens to be licensed only for type 2 diabetes.

That last distinction matters. Weight-loss injections must be licensed specifically for weight management, Ozempic is not, despite containing the same active molecule as Wegovy. The MHRA is clear on this point, and prescribers cannot lawfully issue Ozempic for weight loss as a routine first choice. If someone's offering it to you for that purpose without explaining the licence difference, that's worth querying.

Saxenda (liraglutide) is a third name you may have encountered, and if you're trying to get a handle on all the names used for weight-loss injection drugs, it's a useful one to know. It does hold a UK weight-management licence, but it works differently and requires daily rather than weekly injections. It's worth knowing the name exists; fewer clinicians are now reaching for it since the weekly options became available.

What exactly is Mounjaro, and why does it keep coming up?

Mounjaro is tirzepatide, a dual GIP and GLP-1 receptor agonist. That 'dual' part is what makes it distinct: it activates two gut-hormone pathways simultaneously, reducing appetite and slowing how quickly the stomach empties. It's the only weight-loss injection in the UK that works on both pathways at once.

The clinical trial evidence is substantial. In the SURMOUNT-1 trial, involving 2,539 adults with obesity, participants on the 15 mg dose lost an average of around 20–21% of their body weight over 72 weeks, as reported in the New England Journal of Medicine. NICE subsequently recommended tirzepatide for NHS use (TA1026, published December 2024), though with specific eligibility criteria for the NHS route.

Privately, the eligibility thresholds differ slightly from the NHS ones. Adults with a BMI of 30 or above, or 27 or above with a weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea or type 2 diabetes, may be suitable candidates, though a prescriber assesses the full picture, not just a single number. If you want to understand how to compare the available injections, eligibility is one of the first things to work through with a clinician.

What is Wegovy and how does it differ from Mounjaro?

Wegovy is semaglutide at a dose designed specifically for weight management, and understanding the weight loss injection name that applies to your treatment is genuinely useful when you're navigating prescriptions, pharmacy queries or insurance paperwork. It targets one receptor (GLP-1) rather than two, slowing gastric emptying and dampening appetite signals in a similar way. The standard maintenance dose was 2.4 mg weekly; the MHRA approved a higher 7.2 mg dose in early 2026, and a dedicated single-dose 7.2 mg pen followed in April 2026.

Trial results across 68 weeks in STEP 1 showed an average body-weight reduction of around 15% at the 2.4 mg dose, as published in the NEJM. The 7.2 mg data narrows the gap with Mounjaro's top-end figures considerably. Which performs better for a particular person depends on individual response, tolerability and the clinical picture, that's not a decision a webpage can make.

NICE also recommends Wegovy (TA875), but only within specialist weight management services and for a maximum of two years. The NHS waiting lists for those services are, in many parts of England, considerable. For people exploring their options now, the weight-loss treatment overview on this site sets out both the NHS and private paths clearly. Cost is often the next question people have, and a look at what a private consultation actually involves gives a clearer sense of what you're paying for beyond the medicine itself.

Are the names you hear on social media the same medicines?

Sometimes, sometimes not. 'Skinny jab' is a colloquial label that gets attached to any injectable weight-loss medicine, it doesn't refer to one specific product. If you've seen posts referencing a new pen or formulation and wondered what the new weight-loss injection is actually called, a regulated prescriber or pharmacist is the most reliable place to get a straight answer. Posts promoting unnamed or unbranded 'weight-loss pens' are a different matter: the MHRA has warned repeatedly about counterfeit injectable medicines sold online and through social media, and has seized large quantities of fake pens. Some have contained insulin rather than the stated ingredient, which can be dangerous.

The safe approach is straightforward: any legitimate weight-loss injection in the UK is a prescription-only medicine, supplied by a pharmacy you can verify on the GPhC register, following a clinical assessment. Sellers offering these medicines without a prescription, at prices far below the market, or via a social-media DM are red flags worth taking seriously. You can report suspicious sellers directly through the MHRA's Yellow Card scheme.

If you're at the stage of working out which injection might suit you, safety is a sensible starting point alongside efficacy. A clinician weighs both. Our prescribers at nume review every consultation personally before anything is dispensed, a useful reassurance if you're weighing up where to start. You can check your eligibility at any point; there's no obligation.