Mounjaro and Wegovy Are Not the Same — Here Is What Actually Differs

The myth: Mounjaro and Wegovy do the same thing in the same way

It is easy to see why people assume Mounjaro and Wegovy are the same. Both are once-weekly injections. Both are used for weight management. Both slow gastric emptying, reduce appetite and are given by a similar pre-filled pen. But that surface similarity is where the overlap largely ends.

Wegovy's active ingredient, semaglutide, is a GLP-1 receptor agonist, it mimics one gut hormone, GLP-1, which signals fullness and regulates blood sugar. Mounjaro's active ingredient, tirzepatide, does something structurally different: it is a dual GIP and GLP-1 receptor agonist, activating two separate receptor pathways involved in appetite regulation and metabolism. No other weight-loss medicine licensed in the UK works this way. If you want to understand the GLP-1 mechanism shared by both treatments, this page on semaglutide and GLP-1 covers it clearly.

In practice, this dual action appears to produce greater average weight reduction at the highest doses. The SURMOUNT-5 head-to-head trial, published in the New England Journal of Medicine in 2025, found that tirzepatide produced greater average weight loss than semaglutide 2.4mg over 72 weeks in adults with obesity and without diabetes. That said, Wegovy's newer 7.2mg dose narrows the gap considerably, average weight loss of around 20.7% was reported at 72 weeks, approaching tirzepatide's top-dose results. Which medicine suits a given person is a clinical decision, not a marketing one.

What the licensing actually says, and how they differ

Both medicines carry a UK licence for weight management in adults with a BMI of 30 or above, or 27 or above alongside at least one weight-related condition such as high blood pressure, high cholesterol or obstructive sleep apnoea. Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance. But their NICE recommendations differ, and that matters for NHS access.

NICE recommended tirzepatide (TA1026, published December 2024) for use in adults with a BMI of 35 or above plus at least one weight-related comorbidity, with a phased NHS rollout currently underway. NICE recommended semaglutide as Wegovy (TA875) only within specialist weight management services, for a maximum of two years, a restriction that does not apply to tirzepatide. You can read the full NICE recommendation for tirzepatide at NICE TA1026.

Privately, both are available through a regulated online pharmacy following clinical assessment. If you are weighing one against the other, this comparison of Wegovy and Mounjaro sets out the clinical factors side by side.

One thing worth keeping straight: Mounjaro is also Mounjaro. It is sometimes misspelled "Manjaro" in searches, but the brand name is Mounjaro in the UK. Wegovy is never Zepbound, that is the US brand name for tirzepatide and is not a UK product.

Is Mounjaro the same as semaglutide? No, and Ozempic is a separate matter too

Mounjaro is not the same as semaglutide. Mounjaro is tirzepatide. Semaglutide is the molecule inside both Wegovy and Ozempic, but those two products are licensed for completely different conditions. Wegovy is licensed for weight management. Ozempic is licensed for type 2 diabetes. Prescribing Ozempic for weight loss is off-label, it is not what the product is authorised for, and the MHRA has been clear on this point.

Similarly, Rybelsus is oral semaglutide (3mg, 7mg and 14mg tablets) licensed for type 2 diabetes, it is not the same as the Wegovy tablet, which follows an entirely different dose schedule (1.5mg up to 25mg) and was approved by the MHRA specifically for weight management in June 2026. The relationship between Wegovy and semaglutide is worth reading if this distinction matters to your decision.

If you are curious whether the two injectable treatments differ in more everyday terms, this page looks specifically at that. Both injections are stored in the fridge, the pen sits there between doses, taken out a few minutes before your weekly injection to reach room temperature. That part of the routine is the same. The medicine inside is not.

How to decide, and what comes next

Neither tirzepatide nor semaglutide is a universal answer. A prescriber will consider your medical history, any existing conditions, current medicines (including oral contraceptives, since tirzepatide can temporarily reduce their absorption during the first weeks of treatment and after dose increases), and your preferences before recommending either treatment. The side-effect profiles are similar (nausea, constipation and digestive changes are the most commonly reported with both) though individual responses vary. Some people tolerate one better than the other. That is precisely what a clinical consultation exists to work out.

For a fuller picture of both treatment options and what the consultation process involves, our weight-loss treatment overview is a good next step. If you already know you want to understand more about cost and what a private prescription includes, the Mounjaro and Wegovy pricing page covers that clearly. Both treatments are prescription-only medicines, a regulated prescriber must review your case before any treatment is issued. That remains true whichever medicine you are considering.

If you are ready to find out which treatment a prescriber thinks suits you, start your free consultation with our clinical team today.