Mounjaro®
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Start journey Learn moreComparing Wegovy 1.7mg and Mounjaro: what the evidence actually tells us
The myth worth clearing up: these doses do not convert directly
A common assumption is that because Wegovy and Mounjaro are both injectable weight-loss medicines given once weekly, their doses must map onto each other — that there is some tidy equivalence where, say, 1.7mg of Wegovy matches a specific Mounjaro strength, a question we explore in detail on its own page. That is not how either medicine works.
Wegovy (semaglutide) activates a single receptor involved in appetite regulation: the GLP-1 receptor. Mounjaro (tirzepatide) activates two, the GLP-1 receptor and, additionally, the GIP receptor. Because the underlying pharmacology differs, the dose scales were developed entirely separately, each calibrated against its own receptor system. A milligram of one drug is not interchangeable with a milligram of the other.
There is also a practical reason the comparison is imprecise: 1.7mg is not a maintenance dose for Wegovy. It is a step in the titration schedule (as the full Wegovy versus Mounjaro comparison explains) sitting between the 1.0mg step and the 2.4mg maintenance dose. Most clinical trial data for Wegovy was gathered at the 2.4mg level, not at 1.7mg, which limits direct comparison at this specific strength.
Where 1.7mg of Wegovy sits, and what Mounjaro looks like at a similar stage
The standard Wegovy titration runs: 0.25mg, 0.5mg, 1.0mg, 1.7mg, and then 2.4mg as the usual maintenance dose, and if you are curious how that very first 0.25mg starting dose compares to Mounjaro, we cover that comparison separately. Patients typically reach 1.7mg around week 12 to 16 of treatment, shortly before stepping up. It is a transitional dose, not a long-term one.
Mounjaro's schedule spans six strengths from 2.5mg to 15mg, titrated roughly every four weeks by the prescriber. By the time a Wegovy patient is at 1.7mg, a Mounjaro patient would likely be somewhere in the early-to-middle part of their own schedule (perhaps at 5mg or 7.5mg) though the exact point depends on individual tolerability and clinical decisions, not a formula.
The numbers look very different on paper (1.7 versus 7.5), but that reflects the different dose units and receptor systems, not a meaningful clinical gap. For a closer look at one specific comparison point, this page explores what Wegovy dose aligns broadly with Mounjaro 7.5mg. What matters clinically is where a patient is in their titration relative to their maintenance target, not the number printed on the pen.
It is worth noting that the question of cross-medicine equivalence is one our prescribers hear most weeks, particularly from patients who are switching or being transferred from one treatment to the other. The consistent answer is that switching is a clinical decision, not an arithmetic one.
How trial results compare at the doses that were actually studied
Since 1.7mg was not studied as a standalone maintenance dose in the major trials, comparison is most meaningful at the maintenance levels where the evidence was gathered.
In SURMOUNT-1, published in the New England Journal of Medicine, participants on tirzepatide 15mg lost an average of around 20 to 21% of body weight over 72 weeks. The STEP 1 trial, also published in the NEJM, showed semaglutide 2.4mg producing an average reduction of around 15% over 68 weeks. In the more recent SURMOUNT-5 head-to-head trial (2025), tirzepatide produced greater average weight loss than semaglutide 2.4mg over 72 weeks in adults with obesity who did not have diabetes, though the difference narrowed as semaglutide's higher 7.2mg dose becomes more widely used.
These figures are averages from large trials; individual results vary, and neither medicine guarantees a specific outcome. NICE's appraisal of tirzepatide (TA1026) notes the indirect comparisons between the two medicines, acknowledging tirzepatide's stronger average trial performance while recognising both as effective options. You can read the NICE tirzepatide appraisal in full on their website.
| Factor | Wegovy (semaglutide) | Mounjaro (tirzepatide) |
|---|---|---|
| Receptor targets | GLP-1 only | GLP-1 and GIP (dual) |
| Titration steps (weight management) | 0.25 → 0.5 → 1.0 → 1.7 → 2.4mg | 2.5 → 5 → 7.5 → 10 → 12.5 → 15mg |
| Standard maintenance dose | 2.4mg (7.2mg also approved) | Up to 15mg |
| Average weight loss at maintenance (major trial) | ~15% at 2.4mg (STEP 1, 68 weeks) | ~20–21% at 15mg (SURMOUNT-1, 72 weeks) |
| Head-to-head evidence | SURMOUNT-5 (2025): tirzepatide produced greater average loss; gap narrows at semaglutide 7.2mg | |
| UK licensed for weight management | Yes | Yes |
What this means if you are considering switching or starting treatment
If you are already on Wegovy at 1.7mg and wondering whether Mounjaro might suit you better, or you are starting fresh and trying to work out which medicine fits your situation, the dose number is genuinely the wrong place to start. What matters is your medical history, current weight, any relevant conditions, and how your body has responded to treatment so far.
Patients transferring from one medicine to the other need a clinical assessment, not a conversion calculation, our prescribers review evidence of your current dose and treatment history before recommending where to begin. There is also a cost dimension worth understanding: the price difference between Mounjaro and Wegovy can be meaningful at certain dose levels, and that is a fair thing to factor into the conversation.
Both are prescription-only medicines assessed by the NHS and well-documented on NHS guidance pages. Neither is suitable for everyone, and a prescriber makes that call, not a comparison article. Which suits you is a clinical decision our prescribers make with you. Start your free consultation and a GPhC-registered prescriber will review your case the same day.
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