Switching from Wegovy to Mounjaro is common and usually straightforward, but it is not a like-for-like swap: you restart Mounjaro at its 2.5 mg starter dose regardless of how high you climbed on Wegovy, leave a week between your last Wegovy dose and your first Mounjaro dose, and expect the early side effects to return briefly while your body adjusts. A prescriber makes the call — this guide is the map, not the medicine.
Plenty of people start on one weekly jab and move to the other — because Wegovy stalled, the side effects were rough, or they want the extra weight loss Mounjaro tends to deliver (or they're going the other way, on cost or supply grounds). Because both are once-weekly GLP-1 medicines, the mechanics are well understood; the important part is doing it in the right order, at the right doses, with a prescriber signing off.
This guide covers how to switch from Wegovy to Mounjaro (and back), what the dose reset means, how to time it, what to expect, and what it costs — with real UK prices checked on 4 July 2026.
Why people switch from Wegovy to Mounjaro
The most common reason is results. Wegovy (semaglutide) is a GLP-1 receptor agonist; Mounjaro (tirzepatide) hits two gut hormones at once — GIP and GLP-1 — and in the head-to-head SURMOUNT-5 trial tirzepatide produced roughly 20% average weight loss versus about 14% for semaglutide over 72 weeks. If Wegovy has plateaued at the top of the ladder, Mounjaro is the obvious next question.
Other common triggers:
- Side effects. Some people tolerate one molecule better than the other. Nausea, reflux or fatigue that never settled on Wegovy sometimes eases on Mounjaro — though it can also go the other way.
- Supply. When one medicine is short at your pharmacy, switching to the other keeps treatment going rather than pausing.
- Cost. At matched maintenance doses the two are closer than people assume, so price alone rarely forces a switch — but it can tip a finely balanced decision. Our Mounjaro vs Wegovy price breakdown lays out the numbers dose by dose.
Whatever the reason, the switch is a clinical decision. A prescriber will check it's appropriate for you before changing anything.
The one rule that catches everyone out: you reset the dose
This is the part people get wrong. Wegovy and Mounjaro are dosed in different units and on different ladders, so a "high" dose on one tells you nothing about where you start on the other. You do not carry your dose across. You start Mounjaro at 2.5 mg weekly — the starter dose — even coming off Wegovy's top 2.4 mg dose. The 2.5 mg dose isn't a treatment dose; it lets your body get used to tirzepatide and limits early nausea. From there you climb in the usual steps.
| Stage | Wegovy (semaglutide) ladder | Mounjaro (tirzepatide) ladder |
|---|---|---|
| Starter | 0.25 mg (weeks 1–4) | 2.5 mg (weeks 1–4) |
| Step up | 0.5 → 1 → 1.7 mg (~4 weeks each) | 5 → 7.5 → 10 → 12.5 mg (≥4 weeks each) |
| Usual maintenance | 2.4 mg (from ~week 17) | 5, 10 or 15 mg (tailored to you) |
| Higher option | 7.2 mg (obesity only, MHRA-approved Jan 2026) | 15 mg maximum |
Because you restart at the bottom, expect a few months of stepping up before you reach a full Mounjaro maintenance dose. That climb is deliberate — rushing it causes the worst nausea. There's more on how each ladder feels in our side-effects comparison.
Timing: when to take your first Mounjaro dose
Both jabs are once weekly, so the switch slots into your existing rhythm. The standard approach is:
- Take your last Wegovy dose as normal.
- Wait a week — take your first Mounjaro 2.5 mg dose on the day your next Wegovy dose would have been due. One weekly gap, no double-dosing, no long washout.
- Pick your new "jab day" and keep it. Rotate injection sites (tummy, thigh, upper arm); take it with or without food, any time of day, same day each week.
Your prescriber may adjust this if you're switching mid-ladder or managing side effects, so follow their instruction over any general rule. For most people, "last Wegovy, wait a week, first Mounjaro at 2.5 mg" is the shape of it.
A switch needs a prescriber's sign-off and a fresh assessment. The Weight Clinic is our recommended provider for it: free consultation, monthly video reviews with a clinician while you re-titrate, needles included, and a refund if you're declined — so an assessment that ends in "not right for you" doesn't cost you. New patients get £35 off with code NEWME.
What to expect in the first few weeks
A bit of a reset. Because you're starting a new medicine at its lowest dose, two things tend to happen at once.
Early side effects can come back. Nausea, mild stomach upset, reflux and tiredness are most common when you begin any GLP-1 jab or step up a dose. You had this on Wegovy at the start; you may get a milder version again on Mounjaro. It usually settles within a week or two of each dose. Small, low-fat meals, eating slowly and stopping when full all help.
Appetite control may dip briefly. Dropping from a full Wegovy dose to Mounjaro 2.5 mg means you're on a smaller effective dose for a few weeks, so some people notice a little more hunger or "food noise" before they climb. This is temporary and expected — the price of a safe titration, not a sign the switch is failing.
Severe or persistent vomiting, signs of dehydration, or severe stomach pain that spreads to your back are not part of a normal adjustment — contact your prescriber or seek urgent care. And report any suspected side effect through the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.
Switching the other way: Mounjaro back to Wegovy
The same logic runs in reverse. Moving from Mounjaro to Wegovy — usually on cost, tolerability or supply grounds — you restart Wegovy at its 0.25 mg starter dose, not at a dose that "matches" your Mounjaro level. Take your last Mounjaro dose, wait a week, then begin Wegovy 0.25 mg and titrate up over roughly 16 weeks to 2.4 mg.
Be realistic if you're stepping down: on the trial evidence, average weight loss on semaglutide is lower than on tirzepatide, so some people who switch back see progress slow. That doesn't make it the wrong call — tolerability and price are real reasons — but go in with eyes open. Our results comparison sets out what the numbers say.
What the switch costs
Because you restart at the starter dose, your first month on the new medicine is a starter-month price, then you climb. Here's where our recommended provider sits, alongside the wider market across the 24 regulated UK pharmacies we track (checked 4 July 2026).
| Dose stage | The Weight Clinic | Typical UK range |
|---|---|---|
| Mounjaro 2.5 mg starter month | £160 (£125 with NEWME) | £145.99 – £229.00 |
| Mounjaro 5 mg | £185 | £173.99 – £259.00 |
| Mounjaro 10 mg | £260 | £249.99 – £324.00 |
| Mounjaro 15 mg | £295 | £288.99 – £359.00 |
| Wegovy 2.4 mg maintenance | £230 | £174.99 – £249.00 |
Two things worth noting when budgeting a switch. First, watch the first-month promos — a starter month is often discounted (The Weight Clinic drops the Mounjaro 2.5 mg month to £125 with code NEWME), so the switch month can look cheaper than your steady state. Second, a refund-if-declined policy matters more when switching, because you're being reassessed for a different medicine and the answer might be no. For the full dose-by-dose picture, see the homepage price table and our full Mounjaro vs Wegovy comparison.
Frequently asked questions
Can I switch from Wegovy straight to a matching Mounjaro dose?
No. The two use different units and ladders, and there is no equivalent "high" dose to carry across. You start Mounjaro at 2.5 mg even coming off Wegovy's top 2.4 mg dose, then titrate up. This is a safety step, not a formality.
How long should I leave between my last Wegovy jab and first Mounjaro jab?
Usually one week — take your first Mounjaro dose on the day your next Wegovy dose would have been due. Both are once weekly, so there's no long washout. Follow your prescriber's specific instruction, especially if you're switching mid-ladder.
Will I put weight back on during the switch?
You may see progress slow briefly, because you drop to a low starter dose while your body adjusts and appetite control can dip for a few weeks. Most people keep losing once they climb the ladder. Talk to your prescriber if progress stalls for longer than expected.
Is switching to Mounjaro guaranteed to work better than Wegovy?
Nothing is guaranteed. On the trial evidence Mounjaro produces more average weight loss (about 20% vs 14% head-to-head), but individual results vary and tolerability differs from person to person. Some people do better on Wegovy. A switch is worth discussing with a prescriber, not treating as a certainty.
Do I need a new consultation to switch?
Yes. Switching medicine means a fresh assessment and a new prescription — a prescriber has to agree it's appropriate. With our recommended provider that consultation is free and refunded if declined, so being reassessed for a different jab doesn't cost you if the answer is no.
If you and a clinician have decided Mounjaro is the next step, The Weight Clinic is our recommended provider: competitive everyday pricing, a free consultation, monthly clinician video reviews while you re-titrate, needles included, and a full refund if you're declined. New patients get £35 off their first order with code NEWME.