Is Mounjaro 5 mg Equivalent to a Wegovy Dose?

Picture this: you've just moved from one pen to the other and you want to know where you actually are

Say you've been on Mounjaro 5 mg for four weeks and your prescriber is discussing a switch to Wegovy, or vice versa. The first thing worth knowing is that 5 mg is the second rung on Mounjaro's ladder. Treatment starts at 2.5 mg (a tolerability step designed to settle your system) and 5 mg is the first dose that begins to work therapeutically, typically reached after the first month. On the Wegovy side, the comparable position in the titration sequence is roughly 0.5 mg or 1.0 mg: doses you pass through during the first eight to twelve weeks before reaching the 1.7 mg and 2.4 mg maintenance levels, and if you're curious whether Wegovy 1 mg has a meaningful equivalent on the Mounjaro scale, that question has its own dedicated page.

So when people ask about a Mounjaro 5 mg equivalent to Wegovy, they're often really asking: are these two medicines at roughly similar points in their respective journeys? In broad terms, yes, both are early-titration doses, below the maintenance level where most of the weight-loss evidence sits. But the mechanisms differ. Mounjaro activates both the GIP and GLP-1 receptors; Wegovy targets GLP-1 alone. That dual action is why tirzepatide's results at peak doses tend to exceed semaglutide's in head-to-head data, though a tidy "5 mg equals X mg" conversion table doesn't exist in the clinical literature. You can read more about the broader equivalence question on our Mounjaro equivalent dose to Wegovy page.

What the trial evidence actually says at these dose levels

Most published data reports outcomes at maintenance doses, which makes early-titration comparisons tricky. In the SURMOUNT-1 trial, published in the New England Journal of Medicine, participants on 15 mg tirzepatide lost around 20–21% of body weight on average over 72 weeks. At 5 mg, the same trial reported roughly 15% average weight loss, a meaningful figure, though participants continued titrating upward in real-world use unless 5 mg was their highest tolerated dose.

For semaglutide, the STEP 1 trial (also published in the NEJM) showed approximately 15% average weight loss at the 2.4 mg maintenance dose over 68 weeks. Early titration doses in that trial contributed less individually. In the SURMOUNT-5 head-to-head trial (2025), tirzepatide produced greater average weight reduction than semaglutide 2.4 mg across a 72-week period, though Wegovy's newer 7.2 mg dose narrows that gap.

The table below summarises where each dose sits in its schedule and the headline trial outcome at that approximate level.

For a fuller look at how the top doses stack up, the Mounjaro 15 mg comparison page covers that territory in detail.

Why a straight conversion doesn't settle the question, and what does

Prescribers don't use a conversion chart when switching between these medicines, because no validated equivalence ratio exists. What they do instead is assess tolerability, response and the clinical rationale for switching. If someone has been on Mounjaro 5 mg for one month with good tolerability, a switch to Wegovy typically starts from Wegovy's own beginning (the 0.25 mg starting dose) rather than jumping to a mid-point. The reverse journey follows the same logic. Our dose conversion overview explains how prescribers approach that decision.

A quick check you can do in under a minute: pull up the NICE appraisal for tirzepatide (TA1026) and compare the eligibility criteria against TA875 for semaglutide. The criteria aren't identical, and knowing which one you meet shapes which medicine is the realistic starting point. Eligibility aside, both medicines require a clinical assessment, the prescriber weighs your medical history, current conditions, and which titration path suits you.

Neither Mounjaro nor Wegovy is universally the right choice. Mounjaro's dual-receptor action gives it a different profile; Wegovy has a longer post-market track record in the UK and the new 7.2 mg option. Which suits you is a clinical decision our prescribers make with you, it's not something a comparison table can resolve. Our Wegovy vs Mounjaro overview sets out the broader picture, and the cost comparison page covers what each typically costs privately in the UK. If you're ready to talk it through, our free consultation is the place to start, your answers go to a prescriber the same day.