Foundayo vs Mounjaro: daily tablet or weekly injection?
Both are made by Eli Lilly, both help with weight management, and they work differently enough that the choice genuinely matters. Here is the honest comparison, including the part where Mounjaro wins.
| Foundayo | Mounjaro | |
|---|---|---|
| Form | Tablet, once daily | Injection, once weekly |
| Active ingredient | Orforglipron, a small-molecule GLP-1 receptor agonist | Tirzepatide, a dual GIP and GLP-1 receptor agonist |
| Average weight loss in trials | 11.1% at 17.2 mg over 72 weeks (ATTAIN-1) | Higher averages reported in its own trial programme |
| Food and timing rules | None: any time of day, with or without food | None, but a fixed weekly injection day |
| Storage | Room temperature, no fridge | Refrigeration required, cold chain matters |
| UK approval | MHRA approved 10 August 2026 | Long established in UK private supply |
| UK prices | Compare on Dayo | Compare live prices on Monj |
Trial results across different medicines are not directly comparable: studies differ in design, duration and populations. Treat this as orientation for a prescriber conversation, not a league table.
Last reviewed: 23 August 2026
The honest headline: Mounjaro loses less weight for you, on average
Let's put the uncomfortable bit first, because most comparison pages bury it. In its trial programme, Mounjaro's tirzepatide produced larger average weight loss than orforglipron did in ATTAIN-1. If maximum average effect is your single priority, the injection is currently the stronger performer.
That is not the end of the argument, though, because the medicine you actually take consistently beats the medicine you theoretically should be on. Which brings us to why Foundayo exists.
Where Foundayo wins
- No needles. For people with genuine needle aversion, this is not a minor preference, it is the difference between treatment and no treatment.
- No fridge, no cold chain. Tablets store at room temperature, which makes travel, holidays, long working days and living without reliable fridge space dramatically simpler. Our travel guide covers how much easier this is in practice.
- No sharps disposal and none of the logistics that come with injections.
- Daily rhythm suits some people better than remembering a weekly injection day, and a missed daily tablet is a smaller event than a missed weekly dose.
- Likely cost advantage. Tablets are generally cheaper to manufacture and distribute than injectables, though UK pricing is not yet published, so we are flagging the expectation rather than claiming the fact.
Where Mounjaro wins
- Larger average weight loss in trials, as above.
- Dual mechanism. Tirzepatide targets both GIP and GLP-1 receptors, where orforglipron targets GLP-1 alone.
- A track record. Years of UK real-world use, established supply chains, and prescribers who know it inside out. Foundayo is days old in the UK.
- Once a week beats once a day for people who would rather think about treatment 52 times a year than 365.
Side effects: broadly similar territory
Both are GLP-1 medicines and both are dominated by gut side effects, particularly nausea, constipation and diarrhoea, clustering around starting treatment and each dose increase. Both carry the class warning about thyroid C-cell tumours seen in rodent studies, meaning neither is suitable for anyone with a personal or family history of medullary thyroid carcinoma or MEN 2. Our side effects map covers Foundayo's profile in full.
What differs is the rhythm. A weekly injection means side effects that ebb and flow across the week; a daily tablet spreads exposure more evenly. Neither pattern is universally better, and individuals genuinely differ.
Can you switch between them?
Yes, and this is where Foundayo has real evidence rather than theory. The ATTAIN-MAINTAIN trial studied people moving from injectable tirzepatide or semaglutide onto orforglipron and found they largely maintained their weight loss. That makes the tablet a credible maintenance option after injections. Any switch is prescriber-led, never overlapping the two medicines, and normally means rejoining the dose ladder rather than leaping to an equivalent dose. Full detail in our switching guide.
So which should you ask about?
The honest answer is that this is a prescriber's decision informed by your priorities, your history and what you will realistically stick to. A reasonable way to frame it: if maximum average effect matters most and injections do not bother you, Mounjaro has the stronger evidence today. If needles, fridges or travel are the thing standing between you and consistent treatment, Foundayo removes those obstacles at some cost in average effect. Neither answer is wrong, and neither is a website's to make.
Whichever way you lean, check eligibility first with our BMI and licence guide, and buy only from a pharmacy that passes verification.