What medicine is the same as Mounjaro?

Step 1: understanding the name you keep seeing, tirzepatide

When a medicine is approved, it gets two names: a brand name chosen by the manufacturer and a generic chemical name (the INN) set by the World Health Organisation. For Mounjaro, the INN is tirzepatide. They refer to exactly the same thing. If an article says tirzepatide produced around 20% average weight reduction in a 72-week trial, it is talking about Mounjaro. If a prescriber writes tirzepatide on your prescription, the pharmacy dispenses Mounjaro. The relationship between tirzepatide and Mounjaro is simply brand versus chemical name, nothing more complicated than that.

A question our prescribers hear most weeks is whether "tirzepatide" is a newer or stronger version of Mounjaro, or a cheaper generic. It is neither. There is currently only one licensed form of tirzepatide in the UK for weight management, and it is manufactured and sold as Mounjaro by Eli Lilly. No generic tirzepatide exists on the UK market at present.

The distinction matters practically because some online sources, particularly those selling outside the licensed supply chain, list products labelled "tirzepatide" or "tirzepatide peptide" without the Mounjaro branding. That is a significant red flag. The MHRA has warned about counterfeit weight-loss pens sold online, some containing harmful substances. If it is not sourced through a GPhC-registered pharmacy with a valid prescription, it is not guaranteed to be the real medicine.

Step 2: how tirzepatide's mechanism sets it apart from other GLP-1 medicines

Semaglutide (the active ingredient in Wegovy and Ozempic) works on a single receptor: the GLP-1 receptor. Tirzepatide activates two: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). That dual action is why it is often described as a dual agonist, and it is the key biological difference between Mounjaro and the semaglutide-based options. Both pathways are involved in appetite regulation and blood-glucose management, and activating them together appears to produce a stronger average effect on body weight.

For context on how GLP-1 relates to Mounjaro specifically, tirzepatide is partly a GLP-1 receptor agonist (so it shares that mechanism with semaglutide) but the added GIP action makes it pharmacologically distinct. The NHS describes this dual mechanism in its patient-level information on tirzepatide, and it is summarised in NICE's appraisal of the medicine (TA1026).

In clinical trials the results reflected this difference. SURMOUNT-1, a 72-week study involving 2,539 adults with obesity, reported an average body-weight reduction of around 20–21% at the 15 mg dose. The subsequent comparison between GLP-1 medicines became clearer in SURMOUNT-5, a head-to-head trial published in the New England Journal of Medicine (2025), which found that tirzepatide produced greater average weight loss than semaglutide 2.4 mg over 72 weeks.

Step 3: what is not the same as Mounjaro, and why it matters

Several names come up regularly in searches that sound similar but refer to different medicines or different licences. Clarifying each one keeps you safe.

Ozempic contains semaglutide, like Wegovy, but it is licensed in the UK for type 2 diabetes, not weight management. Using it off-label for weight loss is not within its UK authorisation. You can read more about the difference between GLP-1 medicines if you want a fuller comparison.

Zepbound is the brand name Eli Lilly uses for tirzepatide in the United States. It does not exist as a UK product. Any UK seller referring to Zepbound is either confused about which market they are operating in or is not operating within the licensed supply chain.

Tirzepatide peptide is a phrase that circulates in bodybuilding and research communities. The distinction between tirzepatide peptide and Mounjaro is worth understanding clearly: while the underlying molecule is related, products sold as research peptides are not licensed medicines, have no clinical quality oversight and carry real safety risks.

For a full overview of tirzepatide as a licensed treatment, our tirzepatide information page covers how the medicine works, eligibility, and what the clinical evidence shows. If you are thinking about cost alongside clinical options, the Mounjaro pricing page explains what a legitimate private prescription typically includes.