Switching from Wegovy or Mounjaro to Foundayo: What to Expect
The honest answer to "what dose of Foundayo should I switch to" is: there isn't one yet. Not because nobody's looked, but because Foundayo (orforglipron) works differently enough from Wegovy (semaglutide) and Mounjaro (tirzepatide) that a simple milligram conversion doesn't currently exist. If you're already being treated with an injectable GLP-1 medicine and wondering about changing to Foundayo, this page sets out what a prescriber conversation about switching typically covers, what's genuinely known and unknown this early after Foundayo's UK launch, and what changes practically once you're no longer injecting. For general orientation on what Foundayo is and how it's licensed, see Medino's full Foundayo overview.
Key takeaways
- No milligram-for-milligram dose conversion exists yet between Foundayo and Wegovy or Mounjaro - genuinely unknown, not withheld.
- Switching to Foundayo means restarting at its own lowest dose, 0.8mg - the same starting point as someone who's never taken a GLP-1 medicine before, not a dose based on what you were previously taking.
- Switching between different active substances is a decision for your prescriber, not something to plan or begin on your own.
- The closest trial evidence, ATTAIN-MAINTAIN, only tested switching after a weight-loss goal had already been reached and held steady - it doesn't show what happens switching mid-treatment, and it isn't an effectiveness result.
- Expect practical changes too: no more injection pen or sharps disposal, and a shift from a weekly injection day to a once-daily tablet, taken any time.
Why switching isn't a simple swap
Wegovy and Mounjaro are both peptide medicines, injected because a peptide would be broken down by digestion before it could work as a tablet. Foundayo is a different kind of molecule entirely: a small, non-peptide compound that survives the stomach and reaches the bloodstream like most tablets do. It activates the same GLP-1 receptor as Wegovy, and shares that target with Mounjaro's GLP-1 component too, but it gets there by a genuinely different chemical route. For the full mechanism-by-mechanism comparison of all three, see Foundayo vs Wegovy vs Mounjaro.
That difference is exactly why no dose-equivalence table exists. Nobody has run the trial that would be needed to say a given Wegovy or Mounjaro dose corresponds to a specific Foundayo dose, and no UK regulator or NHS body has published switching guidance that states one. Foundayo's own UK-licensed schedule reflects this: everyone starts at 0.8mg once daily for the first 30 days, whatever they were taking before, including someone switching from the highest dose of either injectable. There's no partway entry point - see Foundayo's full titration schedule for exactly what the steps after that first month look like.
Pharmacist insight: people sometimes assume that being well-established on a high dose of one GLP-1 medicine should count for something when starting another. With Foundayo, it currently doesn't change the starting dose - the schedule is the same 0.8mg beginning that applies to anyone new to the medicine. -Alessandro Grenci, Superintendent Pharmacist at medino
What existing Medino guidance on switching between other GLP-1s can (and can't) tell you
Medino already covers switching between Mounjaro and Wegovy, the injectable-to-injectable case. That page describes a short washout period, generally around a week, and a new starting dose typically informed by the dose you were last tolerating on the previous medicine, rather than always restarting completely from scratch. It's a genuinely useful format precedent, and it's worth reading if you want a sense of how a switching conversation between two comparable medicines is usually structured.
It doesn't transfer directly to Foundayo, though, and it's worth being clear about why. Mounjaro and Wegovy are both peptide GLP-1 medicines with broadly comparable dose-response patterns, which is what makes reading across from one to the other a reasonable clinical approach, even without a formally published equivalence study behind it. Foundayo isn't in that position. It's chemically distinct enough that there's no comparable basis yet for informing a starting dose from a previous injectable dose - which is exactly why its own schedule simply starts everyone at the same point, rather than adjusting for where someone's coming from.
What to discuss with your prescriber before switching
A switching conversation works better with specifics than with a general "I want to try the tablet instead." Worth bringing:
- Your current dose, and roughly how long you've been on it.
- How you've responded so far - weight change, and whether it's felt like it's still working or has plateaued.
- Why you're considering a switch: needle aversion, routine, side effects, or curiosity about the newer option are all legitimate reasons to raise.
- Any side effects you've had, even mild ones, and how they've settled or not settled over time.
- Any recent gap in your treatment, or a change of dose, that's happened recently.
- Other medicines you're taking, including hormonal contraception - Foundayo can reduce the effectiveness of oral contraceptives, which is worth knowing about in advance if that applies to you.
Someone who's tolerated Mounjaro well for eight months but is simply tired of a weekly injection routine has a different starting point for that conversation to someone who's struggled with nausea on Wegovy from early on and is wondering whether a different medicine might suit them better. Both are reasonable reasons to raise a switch; neither one predicts how Foundayo specifically would go, since that hasn't been tested for either scenario.
Your prescriber will also want to confirm none of Foundayo's own precautions apply to you - a history of pancreatitis or gallbladder problems, for example. See Foundayo's full warnings and precautions list for what that covers. And once you're taking it, Foundayo's own side-effect profile is worth knowing, since it may not match what you're used to from an injectable.
What's not yet known this early after launch
It helps to be specific about which switching question has evidence behind it and which doesn't, because they're not the same question. There are broadly three situations someone might be in: switching while still actively titrating an injectable and not yet at a treatment goal; switching after already reaching and holding a stable weight loss; or switching mainly because of tolerability problems rather than a goal-related reason. Only the middle one has direct trial evidence.
That evidence comes from a trial called ATTAIN-MAINTAIN, which followed people who had already achieved a stable weight loss on tirzepatide or semaglutide and then switched them to either orforglipron or a placebo tablet for a further year. Those switched to orforglipron held on to 74.7% (prior tirzepatide) or 79.3% (prior semaglutide) of the weight they'd already lost, against 49.2% and 37.6% on placebo - group-average results that individual maintenance will vary around. Genuinely more weight regain happened on orforglipron than on nothing, just markedly less than stopping treatment altogether (around 5kg on average for the tirzepatide group, around 1kg for the semaglutide group, over the year).
It's worth being precise about what that trial does and doesn't show. It didn't include a group that simply continued their original injectable, so it can't tell you whether switching to Foundayo holds weight as well as staying on Wegovy or Mounjaro would have. And because everyone in it had already reached their goal before switching, it says nothing about how Foundayo performs as a fresh effectiveness question, or about switching earlier in treatment. If you're weighing a switch mid-titration, that's genuinely less-charted territory than the maintenance question ATTAIN-MAINTAIN answers.
Whatever situation you're in, don't stop your current medicine on your own initiative while you're deciding. If you have type 2 diabetes, stopping a GLP-1 medicine without a plan can let your blood sugar rise, and any switch is safer worked out as a managed handover than as a gap you fill in later.
Practical logistics of the switch
Past the clinical questions, switching to Foundayo changes some everyday things. There's no more injection pen to store, and no more sharps disposal to think about - Foundayo is a tablet, swallowed whole, so that whole side of a weekly routine simply stops applying. In its place is a once-daily habit: any time of day, with or without food, no water-volume rule, which some people find easier to build into an existing routine like breakfast, and others find takes longer to feel automatic than a once-a-week task did. For more on how taking a tablet instead of an injection changes day-to-day life more generally, see oral GLP-1 vs injections.
Frequently asked questions
Is there a Foundayo dose that roughly matches my current Wegovy or Mounjaro dose?
No - this isn't currently known, and any source that gives you a specific number here is going further than the evidence supports. Foundayo's own schedule starts everyone at 0.8mg, regardless of what dose of another medicine they were previously taking.
Do I need a gap between stopping my injection and starting Foundayo?
There's no published standard gap specific to this switch. Medino's existing guidance on switching between Mounjaro and Wegovy uses a roughly week-long washout for that pairing, but that's guidance for two comparable injectables, not evidence for the Foundayo case - this is exactly the kind of detail your prescriber will judge based on your specific situation.
If I switch to Foundayo and it doesn't suit me, can I go back to my injectable?
That's a decision for your prescriber to work through with you, based on your history and how the switch has gone, rather than something with a fixed rule. Don't restart or change any medicine yourself without that conversation first.
What if I feel unwell during the switch - is that something to worry about?
Mild digestive symptoms are common when starting or changing GLP-1 medicines and usually settle. But some symptoms need faster attention regardless of what you've recently switched from or to - see when to seek urgent medical help while taking Foundayo for what those are.
