Wegovy mg doses vs Mounjaro: how do they actually compare?

Do the milligram numbers between Wegovy and Mounjaro even mean the same thing?

A common assumption is that a higher mg number signals a stronger or better medicine. It is worth letting that idea go gently, because the two medicines work on different receptors and are measured on entirely different scales.

Wegovy contains semaglutide, a GLP-1 receptor agonist. Its standard UK maintenance dose is 2.4 mg once weekly, reached after a titration that starts at 0.25 mg and moves up roughly every four weeks. In January 2026 the MHRA also approved a 7.2 mg dose, and a dedicated single-dose 7.2 mg pen was approved on 14 April 2026 for adults with a BMI of 30 or above. So Wegovy's dose ladder now spans 0.25 mg to 7.2 mg. A broader Wegovy vs Mounjaro overview covers the two medicines side by side if you want the full picture before reading on.

Mounjaro contains tirzepatide, which activates both GLP-1 and GIP receptors — the only dual-agonist weight-loss medicine licensed in the UK. Its titration begins at 2.5 mg and can reach 15 mg, again in roughly four-week steps set by the prescriber. The starting 2.5 mg exists to let the body adjust rather than to produce weight loss; the therapeutic work happens at higher doses.

Because the two active ingredients are structurally unrelated, a dose comparison in milligrams has no clinical meaning on its own. What matters is what each dose achieves in trials and whether it suits your medical profile.

What do the trial results say at each medicine's highest dose?

The clearest evidence comes from the phase 3 trials. In the SURMOUNT-1 study (2,539 adults with obesity, 72 weeks), Mounjaro 15 mg produced an average body-weight reduction of around 20–21%, with some analyses reaching roughly 22.5%, all alongside lifestyle changes. If you are currently on Mounjaro 15 mg and wondering what an equivalent Wegovy dose might look like, that comparison deserves its own careful reading.

Wegovy 2.4 mg in the STEP 1 trial (68 weeks) produced an average reduction of around 15%, as reported in the New England Journal of Medicine. The newer 7.2 mg dose, trialled over 72 weeks, reported approximately 20.7% average weight loss, which narrows the gap considerably.

The SURMOUNT-5 trial, published in the New England Journal of Medicine in 2025, put the two medicines head-to-head directly: tirzepatide produced greater average weight reduction than semaglutide 2.4 mg over 72 weeks in adults with obesity but without diabetes. NICE's appraisal of tirzepatide (TA1026) acknowledged indirect comparisons that favour tirzepatide, while noting that the 7.2 mg semaglutide data narrows the difference.

Does the dose each person reaches depend on the medicine or on the individual?

Both medicines follow a gradual titration, and not everyone reaches the maximum dose in the schedule. Side effects, tolerance and clinical judgement all influence how far up the ladder a prescriber takes someone.

The side-effect profiles of the two medicines overlap considerably. Nausea, loose stools, constipation and indigestion are the most frequently reported effects for both, typically at their worst after a dose increase and settling within a week or two for most people. How doses are chosen and adjusted across both medicines is explored in more detail if that is your main concern.

There are some practical differences too. Mounjaro is a dual-agonist, and for people with type 2 diabetes it is also licensed to treat their diabetes alongside managing weight. For women using oral contraceptives, UK guidance notes that the absorption of the pill may be reduced during the first four weeks of Mounjaro treatment and for four weeks after each dose increase, adding a non-oral method during those windows is advised. No equivalent concern has been raised for semaglutide. The NHS England guidance on weight-management injections covers both medicines' practical considerations in full.

If you are moving between the two medicines, the dose you were on does not map cleanly to a starting point on the other, switching from Mounjaro to Wegovy is a clinical decision, not an arithmetic one.

Which medicine is right at which dose, and who decides?

The evidence shows that both medicines produce clinically meaningful weight loss, and that tirzepatide holds a modest average advantage at currently equivalent doses, though the 7.2 mg semaglutide data suggests that gap is narrowing. Neither number makes the decision for you.

Factors a prescriber weighs include your BMI, any weight-related conditions, your medication history, whether you have type 2 diabetes, how you've responded to treatment before, and practical preferences like injection frequency or whether an oral option might suit you better. The dose-specific comparison between the two ladders goes deeper if you want to understand what each titration step involves, and if you are weighing up how Wegovy 1 mg compares to Mounjaro 5 mg at those earlier titration points, that page covers the detail you need.

Some people switch medicines after not achieving the results they hoped for; others tolerate one better than the other. Neither scenario is unusual. Our prescribers review the full picture (not just your BMI and a tick-box) before recommending anything. Speak to our prescribers and get a same-day clinical review at no cost to start. Which medicine suits you at which dose is exactly the kind of question that belongs in a proper consultation.