Is Wegovy the Same as Mounjaro? What the Differences Actually Mean for You

You've looked up both names and still aren't sure which one is which

That's a genuinely common place to land. The names are used interchangeably in a lot of online conversations, sometimes by people who don't know they're referring to different medicines. You might have seen "Mounjaro" spelled as "Monjaro" in search results, that's a phonetic misspelling of the brand; the correct name is Mounjaro, and the same goes for the various ways people write "Monjaro" when looking for comparisons.

Wegovy has been available in the UK for longer. It was the first injectable GLP-1 medicine to receive a UK licence specifically for weight management. Mounjaro arrived later but with a different mechanism and, in trials, larger average weight reductions. Both require a prescription following a full clinical assessment, the medicine is only part of the picture.

The NHS medicines pages for tirzepatide and semaglutide set out what each one is, how it works and what side effects to expect. Both pages are worth reading before your consultation, not after.

The science behind why these two medicines behave differently

Wegovy works by mimicking GLP-1, a gut hormone released after eating. GLP-1 signals to the brain that you're full, slows the rate at which food leaves the stomach, and reduces appetite. Activating this single receptor is enough to produce meaningful weight loss for many people, semaglutide at its 2.4 mg maintenance dose led to around 15% average body weight reduction in the STEP 1 trial over 68 weeks.

Mounjaro does the same thing, but it also activates a second receptor: GIP. GIP is another gut hormone that works alongside GLP-1, and the combination appears to amplify the effect on appetite, energy use and blood-sugar regulation. In the SURMOUNT-1 trial, people taking tirzepatide 15 mg lost around 20–21% of their body weight on average over 72 weeks. It is the only dual GIP and GLP-1 receptor agonist licensed for weight management in the UK.

The head-to-head comparison of Wegovy and Mounjaro becomes clearest in SURMOUNT-5, a 72-week open-label trial published in the New England Journal of Medicine in 2025, which compared tirzepatide directly with semaglutide 2.4 mg in 751 adults with obesity who did not have diabetes. Tirzepatide produced greater average weight reduction. Worth noting: Wegovy now has a 7.2 mg dose option, and trials of that higher dose reported around 20.7% average weight loss, which narrows the gap considerably.

If you want to look more closely at how the two medicines compare across efficacy, mechanism and tolerability, the detailed Wegovy vs Mounjaro comparison covers that in full.

Same side-effect profile? Mostly, but not exactly

Because both medicines slow gastric emptying and act on appetite centres in the brain, their side-effect profiles are broadly similar. Nausea is the most commonly reported effect for both, especially in the first few weeks of treatment or after a dose increase. Vomiting, loose stools, constipation, indigestion and fatigue also appear in both lists.

There are some differences in the detail. The absorption of oral contraceptive pills may be reduced during tirzepatide treatment, UK guidance recommends adding a non-oral method of contraception for the first four weeks of Mounjaro and for four weeks after each dose increase. The same precaution isn't required for Wegovy based on current evidence. If HRT is part of your routine, NHS England suggests discussing transdermal forms with your doctor while taking tirzepatide.

Both medicines carry a Black Triangle (▼) symbol, meaning they are subject to additional monitoring by the MHRA. If you notice anything unexpected, you can report it directly via the Yellow Card scheme. Neither medicine is recommended during pregnancy, while breastfeeding, or if you are actively trying to conceive.

Which one might suit you, and how that question gets answered

Deciding between Wegovy and Mounjaro isn't a choice you make from a comparison article, however thorough. It's a clinical conversation. Your prescriber will look at your medical history, any other medicines you take, your BMI, any weight-related conditions, and how your body has responded to previous treatments if relevant.

Some people are better candidates for one than the other based on specific health factors. Some have a preference for a longer-established medicine; others are drawn to tirzepatide's dual mechanism after reading the trial data. A few are considering the newer oral Wegovy tablet, approved by the MHRA in June 2026, which removes the injection element entirely.

On the cost question: private prices for both medicines vary by dose and provider, and it's worth understanding what a quoted price actually includes before committing. Our page on weight-loss treatment options sets out what's covered and how the process works at nume. The needle you'd use on a Monday morning before the kettle's even boiled is the same size either way, fine, short, and much less intimidating than most people expect.

If you'd like to understand the full picture before deciding, our Wegovy overview and the information on weight loss treatment more broadly are good starting points. When you're ready, our prescribers are available to review your consultation the same day, a real clinician reads your answers, not a bot.