Mounjaro vs Zepbound: Same Drug, Different Names

If you've been researching weight loss medications, you may have come across the name "Zepbound" and wondered how it relates to Mounjaro. The short answer: they're the same drug with different brand names, sold in different markets for different licensed uses.

Why two names for the same drug?

This is a common practice in the pharmaceutical industry. When a drug is approved for multiple conditions, manufacturers sometimes market it under different brand names to avoid confusion among prescribers and patients. It's the same approach Novo Nordisk takes with semaglutide — sold as Ozempic for diabetes and Wegovy for weight loss.

Eli Lilly followed the same playbook with tirzepatide:

Mounjaro — the brand name for tirzepatide used for Type 2 diabetes (and, in the UK, also for weight management)
Zepbound — the brand name for tirzepatide used specifically for weight management in the US (FDA-approved in November 2023)

The active ingredient, the doses, the pre-filled pen device, and the manufacturing process are all identical. The only differences are the brand name, the packaging, and the regulatory licence.¹

What does this mean in the UK?

In the UK, Mounjaro (tirzepatide) is licensed by the MHRA for both Type 2 diabetes and weight management. Because a single brand covers both indications, there's no need for a separate "Zepbound" product in the UK market. When your UK prescriber prescribes tirzepatide for weight loss, it will be dispensed as Mounjaro.²

You may see Zepbound mentioned in US-focused articles, clinical trial reports, or social media discussions. Just know that any data or experience relating to Zepbound applies equally to Mounjaro, since they're the same medication.

Clinical trial data

The key clinical trials for tirzepatide in weight management include:

SURMOUNT-1: 22.5% average weight loss at 15mg over 72 weeks (this is the data that supported both the Zepbound US approval and the Mounjaro UK weight management licence)³
SURMOUNT-5: 20.2% weight loss vs 13.7% for semaglutide 2.4mg in a head-to-head trial⁴

These trials are often reported under the "Zepbound" name in US media, but the results apply to Mounjaro in the UK since the drug is identical.

Why this matters for your research

When you're reading about tirzepatide online, you'll encounter both brand names. US sources tend to refer to "Zepbound" for weight loss discussions, while UK sources use "Mounjaro." Don't let this create confusion — they're interchangeable in terms of the drug itself. The clinical evidence, side effects, dosing, and expected results are exactly the same.

For a full overview of tirzepatide — how it works, dosing, side effects, and UK availability — see our Mounjaro medication guide.

Comparison