What are the new weight loss injections called?

You’ve heard about “the new weight loss jab” — here’s what you’re actually looking at

Picture this: a friend mentions they are on “the new injection” and you search to find out what the weight loss injection is called, only to land in a tangle of brand names, generic names and American terms that do not apply here. That confusion is entirely understandable. In the UK there are two distinct medicines licensed for weight management by injection, and the name you see depends entirely on who is writing about them.

Mounjaro is the brand name for tirzepatide, made by Eli Lilly. It was approved in the UK for weight management in late 2023 and is the newer arrival, and if you are curious about what the newest weight loss injection is called, tirzepatide under the Mounjaro brand is the answer. Wegovy is the brand name for semaglutide at the 2.4 mg weekly dose, made by Novo Nordisk; it gained its UK weight-loss licence in 2021. The generic names (tirzepatide, semaglutide) are what prescribers and pharmacists use; the brand names are what most people encounter first. A quick way to check whether a product you have read about is UK-licensed: search for it on the NHS medicines page for tirzepatide or the equivalent semaglutide entry — if it is there, the MHRA has licensed it; if it is not, treat it with real caution.

You may also encounter the name “Ozempic”. That is also semaglutide, but it is licensed for type 2 diabetes, not weight management, and should not be confused with Wegovy. Similarly, “Zepbound” is the US brand of tirzepatide; it does not exist as a UK product.

How the two injections differ, and why the distinction matters for your consultation

Wegovy works on one receptor: GLP-1, which is released after eating and signals fullness to the brain. Mounjaro activates two: GLP-1 and GIP. GIP is a separate gut hormone that also plays a role in appetite and energy balance. That dual action is why Mounjaro is sometimes described as a next-generation medicine in this class, and it is reflected in the clinical data.

In the SURMOUNT-1 trial, tirzepatide produced average body-weight reductions of around 20–21% at the 15 mg dose over 72 weeks. The STEP 1 trial for semaglutide 2.4 mg reported around 15% over 68 weeks. A direct comparison in the SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, confirmed that tirzepatide produced greater average weight reduction than semaglutide 2.4 mg in adults with obesity who did not have diabetes. These are population averages from controlled trials; individual results vary, and your prescriber weighs up far more than a headline percentage.

Both medicines share a broadly similar side-effect profile, nausea, digestive discomfort, and fatigue are most commonly reported, often most noticeable after starting or after a dose increase, and usually settling within a couple of weeks. For a fuller picture of which injection carries the lower risk profile for your circumstances, a clinical assessment is the only reliable route. Exploring the overview of licensed UK weight loss injections is a useful starting point.

What “licensed for weight loss” actually means, and who can get these injections

A UK licence from the MHRA means the medicine has been assessed for quality, safety and effectiveness for a defined use in a defined population. Both Mounjaro and Wegovy are licensed for adults with a BMI of 30 or above, or a BMI of 27 or above alongside at least one weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea. Neither is licensed for under-18s. Neither is recommended during pregnancy, while breastfeeding, or when actively trying to conceive.

NICE has appraised both medicines. Its guidance on tirzepatide (TA1026) recommends it for NHS use in adults with a BMI of 35 or above plus at least one weight-related comorbidity, with thresholds 2.5 kg/m² lower for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds. NHS access is being phased in gradually, and waiting times through specialist services can be long. Private treatment through a regulated pharmacy, following a proper clinical assessment, is how many people access these medicines in the meantime.

If you are weighing up your options, the treatment comparison page sets out what each involves. And if the cost question is front of mind, the realities of pricing for weight loss injections are worth reading before you make any decisions. Understanding which injection is considered most effective for different profiles can also help frame the right questions to bring to a prescriber.

A note on names you might have seen, and red flags worth knowing

The surge of interest in GLP-1 medicines has created a secondary market in unverified products. If you have seen an injection described as a “skinny jab” or offered for sale without any mention of a prescription, that is a sign to stop and check. The MHRA has warned repeatedly that fake pens have been seized in the UK, some containing harmful substances. Every legitimate supply of Mounjaro or Wegovy flows through a pharmacy registered with the GPhC. You can verify any online pharmacy in under a minute at the GPhC register, the search takes seconds and the result tells you whether the pharmacy is regulated and permitted to dispense prescription medicines.

At nume, prescriptions are issued only by a GPhC-registered Independent Prescriber who personally reviews every consultation. If you have questions about which of these medicines might suit your situation, speak to our prescribers through a free consultation, there is no obligation and no fee for the assessment itself.