Mounjaro to Wegovy dose conversion, explained honestly

Why isn't there a straight Mounjaro to Wegovy dose conversion chart?

People search for a tidy chart that says "5mg Mounjaro equals X mg Wegovy", and it is a fair thing to want. The honest answer is that no such official chart exists, and any table claiming a one-to-one swap is inventing a precision the science doesn't support.

The reason is mechanical. Mounjaro's active ingredient, tirzepatide, is a dual agonist: it activates both the GIP and GLP-1 receptors, the two gut-hormone pathways involved in appetite and blood sugar. Wegovy's semaglutide acts on the GLP-1 receptor alone. Because one medicine pulls two levers and the other pulls one, the milligram numbers on their packaging measure different things. A 15mg dose of tirzepatide simply is not the same kind of unit as a 2.4mg dose of semaglutide.

The dose ladders reflect that. Mounjaro runs 2.5, 5, 7.5, 10, 12.5 and 15mg. Wegovy climbs 0.25, 0.5, 1.0, 1.7 and 2.4mg, with a higher 7.2mg maintenance dose now approved by the MHRA. The step sizes, the starting points and the maximums all differ. So a switch is never arithmetic. It is a fresh clinical decision about where to begin the second medicine and how quickly to move up. That is exactly why our prescribers treat a Mounjaro to Wegovy dose conversion as a new titration plan, not a lookup.

• See our fuller comparison of Wegovy versus Mounjaro.
• How the two dose ladders line up.

What Wegovy dose would I start on if I'm switching from Mounjaro?

Whatever Mounjaro strength you were taking, the safest default when moving to Wegovy is to begin at 0.25mg, the lowest rung. That feels counter-intuitive if you have already worked up to, say, 10mg Mounjaro and tolerate it well. Surely you should slot in higher? The problem is that your body's tolerance to tirzepatide doesn't reliably carry across to semaglutide, because they aren't the same molecule acting the same way.

Starting low again is about the stomach, not caution for its own sake. Both medicines slow gastric emptying and can cause nausea, particularly when a dose jumps. Beginning Wegovy at 0.25mg gives your system time to settle before the strength climbs, usually in roughly four-week steps as the prescriber judges tolerance. That first dose isn't really treating your weight; its job is to let you adjust.

This is a question our prescribers hear most weeks: "can't I just carry my dose over?" The honest reply is that some people do move up the Wegovy ladder faster than someone starting from scratch, if their history supports it, but that is a judgement made with your records in front of us, not a rule you can read off a chart. Individual factors matter more than the number on your old pen.

The practical detail of switching from Mounjaro to Wegovy is worth reading before you assume where you'll land. The NHS medicines guidance on semaglutide also explains how the dose builds gradually.

Is there a rough way to line the doses up at all?

Yes, but only as an illustration of the ballpark, never as a prescribing instruction. Because the maximum doses of both medicines produced broadly comparable weight loss in trials, people sometimes think of the top of each ladder as loosely analogous. That is the most a Mounjaro to Wegovy dose conversion chart can honestly claim.

Here is a factual comparison of the two ladders and their trial evidence. The percentages are averages from separate trials, not head-to-head equivalents at each step:

Read that table as "these are two different systems", not "row three of Mounjaro equals row three of Wegovy". The step numbers don't correspond. The trial figures come from the SURMOUNT-1 study of tirzepatide and the STEP 1 study of semaglutide, both published in NEJM, and they measured different groups over different lengths of time.

For a closer look at how a specific rung maps, our page on the Mounjaro dose equivalent to Wegovy works through the thinking without pretending the numbers are exact.

Does Wegovy 2.4mg match any particular Mounjaro dose?

This is the single most common version of the conversion question, so it deserves a direct answer. Wegovy 2.4mg was for a long time the standard maintenance dose, and people naturally want to know its Mounjaro counterpart. There isn't a defined one.

What we can say is that in the SURMOUNT-5 trial, an open-label head-to-head over 72 weeks in 751 adults with obesity and no diabetes, tirzepatide produced greater average weight reduction than semaglutide 2.4mg. That doesn't tell you which Mounjaro milligram "equals" 2.4mg Wegovy; it tells you the top of the tirzepatide ladder outperformed 2.4mg semaglutide on average across a whole trial population. Individual results vary widely around any average.

The newer Wegovy 7.2mg dose, approved by the MHRA in 2026, narrowed that gap, with trials reporting around 20.7% average loss over 72 weeks, approaching tirzepatide's 15mg figures. So the "equivalent" a prescriber has in mind depends partly on which Wegovy dose you're heading for.

If your question is really "what Mounjaro dose is like Wegovy 2.4mg", our dedicated page on Wegovy 2.4mg equivalence to Mounjaro handles it in detail. And if you're moving in the other direction entirely, the Wegovy 1.7mg to Mounjaro conversion covers a different common switch point. The core message holds both ways: any wegovy to mounjaro dose conversion chart is a starting point for a conversation, not a substitute for one.

What about side effects when I change over?

Changing from one GLP-1 medicine to another can bring the early side effects back, even if your original treatment had settled. That surprises people, and it's worth expecting so it doesn't throw you.

Both medicines share a gastrointestinal-led profile. The common ones include feeling sick, being sick, loose or hard stools, indigestion, burping, tiredness, headache and reactions where you inject. These tend to show up most when you start a medicine or step up a dose, and for many people they ease within days to a couple of weeks as the body adjusts. Because a switch means restarting the Wegovy ladder, you may feel that settling-in period again.

There is a rarer but serious signal to know about. In January 2026 the MHRA issued a Drug Safety Update flagging acute pancreatitis as an uncommon side effect of GLP-1 medicines that can be serious. Severe, persistent stomach pain that may spread through to your back, with or without vomiting, needs urgent medical attention. That guidance applies to both Mounjaro and Wegovy.

If you're weighing the day-to-day tolerability of each, our comparison of Wegovy dose against Mounjaro is useful, and the NHS overview of tirzepatide lists what to watch for. You can report any suspected side effect through the MHRA Yellow Card scheme. Tell any healthcare team, including an anaesthetist before surgery, that you take one of these medicines.

Who can be prescribed either medicine in the first place?

Before dose conversion even comes up, both medicines have the same broad licensed eligibility, so it's worth checking you'd qualify for either. In UK private practice, that means 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, prediabetes or obstructive sleep apnoea.

Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance, reflecting different health risks at a given weight. And meeting the number never guarantees a prescription on its own; a prescriber looks at your full history, your other medicines and your goals before deciding anything is suitable.

Some people aren't suitable for either medicine. Neither is recommended in pregnancy, while breastfeeding, or if you're trying for a baby, and they aren't licensed for under-18s. A history of medullary thyroid cancer, MEN2 or pancreatitis needs a proper discussion first. One extra point on tirzepatide specifically: it may reduce how well an oral contraceptive pill is absorbed, so the NHS advises adding a barrier method for the first four weeks and after each dose increase. There's no equivalent evidence of that for semaglutide.

The NHS England guidance on weight-management injections sets out these points, and our page on weight-loss treatment options walks through what's available. If you're not sure which side of the threshold you sit on, the simplest move is to check your eligibility with our prescribers.

How does the switch work at nume, step by step?

If you're already on one medicine and considering the other, the process with us is built around a real clinician, not a form that spits out a dose. Here's how a switch runs in practice.

You complete a free online consultation covering your health history, your current treatment and how you've got on with it. That goes to a GPhC-registered Independent Prescriber, who reads it the same day. For anyone transferring between medicines, we ask for evidence of your current treatment and dose, so the switch is planned from fact rather than guesswork. The prescriber then decides whether a switch is appropriate and, if so, where to start you on the new ladder and how to build up.

Order before 12pm on a weekday and, once you're clinically approved, treatment is dispatched the same day and arrives free the next working day by DPD, tracked, in plain unbranded packaging. Picture it landing before the school run. There's no subscription and no auto-renewal; every repeat order is clinically re-reviewed, which matters when your dose is still moving.

You can verify us on the GPhC register (premises number 9012878) before you trust anyone with a prescription, and our clinical team is happy to talk through a switch. Which medicine and which dose suits you is a clinical decision our prescribers make with you, never one you should read off a chart alone.

Related questions we've answered

• Semaglutide to tirzepatide dose conversion
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