Zepbound vs Mounjaro: the question that keeps reaching our prescribers

You've seen Zepbound all over American health content, here's why it doesn't transfer

If you've landed on this page after watching US wellness videos or reading American news coverage of tirzepatide, you're not alone. A question our prescribers hear most weeks runs roughly like this: "I keep seeing Zepbound mentioned, is it the same as Mounjaro, and can I get it here?"

The honest answer: yes, and no. Zepbound and Mounjaro are both tirzepatide. Eli Lilly filed separate regulatory applications in different markets and chose different brand names. The FDA approved Zepbound for weight loss in the United States in late 2023. The MHRA licensed Mounjaro for the same indication in the UK. The pens look similar; the dosing schedule runs through the same strengths (starting at 2.5 mg, titrated upward by the prescriber). But UK law governs what can be prescribed and dispensed here, and Zepbound sits entirely outside that framework.

The MHRA has been explicit: GLP-1 medicines sourced through unregulated channels carry real risks, including counterfeit products that have been seized in large numbers across the UK. Buying anything labelled Zepbound from a UK seller is a warning sign, not a shortcut. You can verify any online pharmacy on the GPhC pharmacy register before handing over any personal or payment details.

For a fuller look at how tirzepatide compares under its correct UK identity, our page on how tirzepatide relates to Mounjaro covers the naming history and mechanism in more depth, and if you want to understand exactly where tirzepatide and Zepbound differ as products, that page sets out the regulatory and practical distinctions clearly.

What Mounjaro actually does, and how its results compare to semaglutide

Since zepbound vs mounjaro questions often arrive alongside curiosity about whether tirzepatide is genuinely more effective than other weight-loss medicines, the evidence is worth setting out cleanly.

Tirzepatide works on two receptors simultaneously (GIP and GLP-1) making it the only dual-agonist weight-loss medicine licensed in the UK. Most other injectable options (including Wegovy) act on GLP-1 alone, and our page explaining how GLP-1 receptor agonists differ from Mounjaro is a useful starting point if you want to understand why that distinction matters clinically. In the SURMOUNT-1 trial, published in the New England Journal of Medicine, participants on the 15 mg dose lost an average of around 20–21% of body weight over 72 weeks. The SURMOUNT-5 trial, also published in the NEJM (2025), ran tirzepatide head-to-head against semaglutide 2.4 mg in adults with obesity and no diabetes; tirzepatide produced greater average weight reduction across the 72-week trial period.

The Wegovy 7.2 mg dose, approved by the MHRA in April 2026, narrows the gap with tirzepatide's highest-dose results, something worth discussing with a prescriber if you're weighing the two. For a closer read on how the two medicines compare across the evidence base, see our overview of how GLP-1 receptor agonists differ from Mounjaro.

What is actually licensed for weight loss in the UK, and how do you access it?

Two injectable medicines hold UK MHRA licences specifically for weight management in adults: Mounjaro (tirzepatide) and Wegovy (semaglutide). Both are prescription-only medicines. Neither can be legally supplied without a prescription issued following a genuine clinical assessment, which means a prescriber reviewing your health history, weight, medications and suitability, not an automated questionnaire.

Zepbound does not appear on that list. If a seller in the UK is offering it, they are not working within the licensed supply chain. The MHRA has warned consistently that fake and unlicensed weight-loss pens have caused harm, including hospitalisations.

The private route to Mounjaro in the UK involves a consultation, clinical review, and prescription from a GPhC-registered Independent Prescriber. At nume, that review happens the same day by a named prescriber. Medicines travel through the authorised Eli Lilly supply chain. You can read about our approach on the about us page, or explore the treatment options available at our weight-loss treatments page.

For context on how Mounjaro sits alongside newer agents still in development, our page comparing retatrutide and Mounjaro looks at the next wave of pipeline candidates. Which medicine suits you is a clinical decision made with a prescriber who knows your full picture, not one a comparison article can make for you.