Orforglipron vs tirzepatide
Foundayo vs Zepbound, side by side
Foundayo vs Zepbound compares two different Eli Lilly medicines for weight management. Foundayo (orforglipron) is a tablet taken once a day; Zepbound (tirzepatide) is an injection taken once a week. They work differently, were tested in separate trials and have never been compared head to head. Here is what each label says, and how to read their numbers fairly.
On this page
- Foundayo vs Zepbound at a glance
- A daily tablet vs a weekly injection: what the labels say
- Orforglipron vs tirzepatide: how each works
- Foundayo vs Zepbound weight loss: the trial results
- Foundayo vs Zepbound side effects
- Foundayo and Zepbound strengths and dosing format
- Foundayo vs Mounjaro in the UK
- Foundayo vs Zepbound cost and coverage
- Switching between Zepbound and Foundayo
- Questions to bring to your prescriber
- Questions people ask
- Sources
In short
- Foundayo and Zepbound are both Eli Lilly medicines approved in the US for weight management, but they are different molecules: Foundayo (orforglipron) is a once-daily tablet acting on the GLP-1 receptor, and Zepbound (tirzepatide) is a once-weekly injection acting on GIP and GLP-1 receptors.1,2
- Foundayo can be taken at any time of day, with or without food, and is stored at room temperature; Zepbound is injected under the skin once a week and kept in the fridge.1,2,7
- In separate 72-week trials in adults without diabetes (ATTAIN-1 and SURMOUNT-1), average weight change was −11.1% on Foundayo 17.2 mg (placebo −2.1%) and −20.9% on Zepbound 15 mg (placebo −3.1%); both count everyone randomized, but with no head-to-head trial they cannot be compared directly.1,2
- Stomach side effects lead both labels: nausea affected 26–35% of people on Foundayo (10% on placebo) and 25–29% on Zepbound (8% on placebo) in their trials.1,2
- Which suits you is a decision for you and your prescriber, and Handle records either one, or both across a switch.
Foundayo vs Zepbound at a glance
Label facts, side by side. The trial figures come from separate trials; the sections below explain how to read them. For every GLP-1 medicine in one place, see GLP-1 medications compared.
| Foundayo | Zepbound | |
|---|---|---|
| Made by | Eli Lilly and Company; discovered by Chugai Pharmaceutical4 | Eli Lilly and Company2 |
| Active ingredient | Orforglipron, a small-molecule GLP-1 receptor agonist1,5 | Tirzepatide, a GIP and GLP-1 receptor agonist2 |
| First US approval | April 1, 2026, under the FDA's national priority voucher pilot3 | November 8, 202310 |
| Approved in the US for | Weight reduction and long-term maintenance in adults with obesity, or overweight plus a weight-related condition1 | The same, plus moderate to severe obstructive sleep apnea in adults with obesity2 |
| Type 2 diabetes | Not a US approval; included in the UK authorization1,7 | Not a US approval; tirzepatide for type 2 diabetes is sold as Mounjaro10 |
| How it's taken | One tablet by mouth a day, any time, with or without food1,7 | One injection under the skin a week, any time of day, with or without meals2 |
| Strengths | 0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg1 | 2.5, 5, 7.5, 10, 12.5 and 15 mg2 |
| Half-life | About 29 to 49 hours1 | About 5 to 6 days2 |
| Storage | Room temperature, 20–25 °C (68–77 °F)1 | Fridge, 2–8 °C (36–46 °F); a single-dose pen or vial may be kept up to 30 °C (86 °F) for a total of 21 days2 |
| Weight change, 72-week trial without diabetes (everyone randomized) | −11.1% on 17.2 mg; placebo −2.1% (ATTAIN-1)1 | −20.9% on 15 mg; placebo −3.1% (SURMOUNT-1)2 |
| Nausea in the label trials | 26–35%; placebo 10%1 | 25–29%; placebo 8%2 |
| Boxed warning | Risk of thyroid C-cell tumors1 | Risk of thyroid C-cell tumors2 |
| UK | Authorized August 10, 2026; not currently on the NHS7 | Not sold under this name; tirzepatide is sold as Mounjaro8 |
A daily tablet vs a weekly injection: what the labels say
How each label says the medicine is taken and stored. This is label text, not advice about your own routine.
Foundayo
A tablet, once a day
- By mouth once a day, with or without food1
- No fasting, water limit or waiting time in the label; Lilly and the MHRA describe it as taken at any time of day, with no food or water restrictions1,4,7
- Swallowed whole, not broken, crushed or chewed, and no more than one tablet a day1
- Stored at room temperature, in bottles of 301
Zepbound
An injection, once a week
- Under the skin once a week, at any time of day, with or without meals2
- In the abdomen or thigh, or the back of the upper arm if someone else injects, rotating sites with each dose2
- A single-dose pen or vial, a four-dose vial or a four-dose KwikPen, which is never shared, even with a new needle2
- Stored in the fridge and never frozen; single-dose pens and vials may spend up to 21 days in total at up to 30 °C2
Both labels advise people who use an oral contraceptive pill to switch to a non-oral method, or add a barrier method, after starting and after each dose increase: for 30 days with Foundayo and for 4 weeks with Zepbound.1,2
Orforglipron vs tirzepatide: how each works
Both act on the GLP-1 receptor, the target of a gut hormone that helps regulate appetite and how much we eat.1,2 Tirzepatide also activates a second receptor, GIP. Zepbound's label says nonclinical studies suggest GIP "may further contribute" to regulating food intake, which is laboratory evidence rather than proof of an extra effect in people.2
Orforglipron is a small molecule rather than a peptide,5 so it needs no absorption enhancer, and Foundayo's label sets no food or water rules; it describes no clinically relevant food effect.1 Both medicines slow stomach emptying, most of all after the first dose.1,2
Another difference is time in the body. Orforglipron's half-life is about 29 to 49 hours, with a steady level after about a week of daily tablets; tirzepatide's is about 5 to 6 days, steady after about 4 weeks of weekly injections.1,2
Foundayo vs Zepbound weight loss: the trial results
Each label reports a 72-week, placebo-controlled trial in adults without diabetes and another in adults with type 2 diabetes. Every figure counts everyone who was randomly assigned, whether or not they kept taking the medicine (a treatment-regimen estimate).
| Foundayo: ATTAIN trials | Zepbound: SURMOUNT trials | |
|---|---|---|
| Adults without diabetes | −7.4% on 5.5 mg, −8.3% on 9 mg, −11.1% on 17.2 mg; placebo −2.1% (ATTAIN-1, 3,127 people)1,5 | −15.0% on 5 mg, −19.5% on 10 mg, −20.9% on 15 mg; placebo −3.1% (SURMOUNT-1, 2,539 people)2,6 |
| Adults with type 2 diabetes | −5.1% on 5.5 mg, −7% on 9 mg, −9.6% on 17.2 mg; placebo −2.5% (ATTAIN-2)1 | −12.8% on 10 mg, −14.7% on 15 mg; placebo −3.2% (SURMOUNT-2)2 |
| Stopped the study medicine early (trial without diabetes) | 22–24%; placebo 30%1 | 14.3–16.4%; placebo 26.4%2 |
The ATTAIN trials used an investigational formulation of orforglipron. The label shows the results under Foundayo's own strengths, while the journal paper reports the investigational doses as 6, 12 and 36 mg.1,5 These are averages from trials, not a prediction for any one person.
Reading the numbers fairly
No trial has compared Foundayo with Zepbound directly, so every comparison crosses two separate trials. The designs are unusually alike (72 weeks, placebo-controlled, the same kind of analysis), but the people and the years differed, the placebo groups lost different amounts, and more people stopped the study medicine early in ATTAIN-1, which a treatment-regimen figure counts.1,2,5,6
Watch for mismatched figures. Lilly's launch announcement gives 12.4% for Foundayo's highest dose, an efficacy estimate of what would have happened had everyone stayed on treatment, alongside 11.1% regardless of whether people finished the trial.4 The Zepbound figures above are treatment-regimen figures like the 11.1%, so setting 12.4% against 20.9% mixes two kinds of number.
What each trial does show is more weight loss on average with the medicine than with placebo, with wide variation between individuals.1,2 Which medicine suits you depends on your health, your other medicines, how you feel about injections or daily tablets, and coverage: a conversation for your prescriber. If the Wegovy pill is also on the table, see Foundayo vs Wegovy and Zepbound vs Wegovy.
Foundayo vs Zepbound side effects
Both labels' main tables pool their two 72-week trials. Each figure is the range across the three doses, with placebo alongside. Stomach and gut effects lead both lists.
| Side effect | Foundayo (ATTAIN-1 and ATTAIN-2) | Zepbound (SURMOUNT-1 and SURMOUNT-2) |
|---|---|---|
| Nausea | 26–35% (placebo 10%) | 25–29% (placebo 8%) |
| Constipation | 20–27% (placebo 9%) | 11–17% (placebo 5%) |
| Diarrhea | 21–25% (placebo 11%) | 19–23% (placebo 8%) |
| Vomiting | 13–24% (placebo 4%) | 8–13% (placebo 2%) |
| Indigestion | 12–16% (placebo 4%) | 9–10% (placebo 4%) |
| Stomach pain | 13–14% (placebo 7%) | 9–10% (placebo 5%) |
| Burping | 6–8% (placebo 1%) | 4–5% (placebo 1%) |
| Fatigue | 6–9% (placebo 4%) | 5–7% (placebo 3%) |
| Headache | 8–9% (placebo 7%) | Not listed in its table |
| Hair loss | 4–5% (placebo 2%) | 4–5% (placebo 1%) |
| Injection-site reactions | Not applicable (tablet) | 6–8% (placebo 2%) |
| Stopped because of side effects | 6–10% (placebo 3%) | 4.8–6.7% (placebo 3.4%) |
Sources: Foundayo label, Table 1 and section 6 (reactions in at least 5% of people and more common than placebo)1; Zepbound label, Table 1 and section 6 (at least 2%)2. Rates from separate trials cannot be directly compared.
Other differences in the safety sections
Heart rate: Foundayo raised average heart rate by 4 to 5 beats per minute (0.5 on placebo), and Zepbound's label reports rises of 1 to 3 (none on placebo). Hair loss was more common in women on both: 7% of women and 0.9% of men on Foundayo, and 7.1% of women and 0.5% of men on Zepbound.1,2
Both carry the boxed warning about thyroid C-cell tumors and are not for people with a personal or family history of medullary thyroid carcinoma or MEN 2. Foundayo's adds that orforglipron is not pharmacologically active in rats or mice and caused no tumors in rodents.1,2
On both, stomach side effects came early: Foundayo's label says nausea, vomiting and diarrhea were more frequent while the dose was being increased and decreased over time, and Zepbound's says most people who stopped because of side effects did so in the first few months.1,2 More detail: Foundayo side effects and Zepbound side effects.
In Handle
Notice the weeks after each change
Handle's daily check-in asks about nausea every day and about the symptoms you choose, such as constipation, vomiting or heartburn, on the same short card whatever you answer.
Some answers, such as severe nausea, come with a clear next step, like contacting your care team. Handle never diagnoses and is not a monitoring or emergency service.
- Switch symptoms on or off whenever you like
- Add up to six extra, such as fatigue or belching, or one in your own words
- A private note for the day that nothing reads
Foundayo and Zepbound strengths and dosing format
Manufacturing facts, not a dose to take. Both labels start low and step up gradually; your prescriber sets the steps and the amount.
- Foundayo. Six tablet strengths (0.8, 2.5, 5.5, 9, 14.5 and 17.2 mg), one tablet a day, in bottles of 30.1
- Zepbound. Six strengths (2.5, 5, 7.5, 10, 12.5 and 15 mg), one injection a week, as a single-dose pen or vial, a four-dose vial or a four-dose KwikPen.2
- Milligrams don't translate. Orforglipron and tirzepatide are different molecules, so the numbers on the two boxes are not comparable, and one cannot be converted into the other.
- Other medicines. Foundayo is broken down mainly by the enzyme CYP3A4, so its label restricts some medicines that affect that enzyme; in both labels' diabetes trials, low blood sugar was more common with a sulfonylurea. Your prescriber and pharmacist check these.1,2
- Missed doses. The two labels have different rules, as you would expect for a daily tablet and a weekly injection. Ask your prescriber or pharmacist rather than applying one medicine's rule to the other; Handle records what happened and never tells you to catch up.
Foundayo vs Mounjaro in the UK
There is no Zepbound in the UK: tirzepatide for weight management is sold as Mounjaro, which the MHRA authorized for that use in November 2023, so for UK readers this page is Foundayo vs Mounjaro.8 See Mounjaro vs Zepbound for how the two names relate.
The MHRA authorized Foundayo on August 10, 2026, the first approval in Europe. Unlike the US label, it covers type 2 diabetes as well as weight management, the latter for adults with a BMI of 30 or more, or 27 to 30 with at least one weight-related condition.7 It is not currently available on the NHS; the MHRA says decisions on NHS use will include an evaluation by NICE.7
NICE recommends tirzepatide for weight management on the NHS in England for people with a BMI of at least 35 and at least one weight-related condition, with a phased rollout.9 UK product information can be worded differently from US labels, so the leaflet that comes with your medicine is the one to follow.
Foundayo vs Zepbound cost and coverage
Both are prescription medicines approved in the US for the same weight-management use, so coverage depends on how your plan treats each brand. Lilly announced savings and self-pay options for Foundayo at launch; prices and programs change, so check current figures with your plan or pharmacy.4 Handle does not sell or source medicines.
Switching between Zepbound and Foundayo
Whether and when to switch, and the starting strength, are your prescriber's decisions. Neither label sets out a schedule for switching between these two, and both say using them with other GLP-1 medicines is not recommended.1,2 What you can do is keep a record that makes the change easy to review.
- 1Write down the plan
Which medicine you are stopping, the date of your last dose, and the strength and start date of the new one, as your prescriber gave them.
- 2Record the last injection
Its date, strength and injection site.
- 3Record the first tablet
Its date, strength and the time of day you settle on. If you use an oral contraceptive pill, the label's 30-day contraception advice starts here.1
- 4Watch the first weeks
Note nausea, constipation and vomiting, any medicine you start or stop (Foundayo's label lists several that affect it), and your weight as weekly averages.1
- 5Bring it to your review
So you and your prescriber can see how the change went.
In Handle
From a weekly pen to a daily tablet, one record
Zepbound is listed in Handle by name. Foundayo isn't on the list yet, so you add it under “Something else” with its name, amount and daily schedule. Dose logging, the check-in, weight, food, Journey and the consultation report (a Premium feature) all work the same way.
Your Zepbound history stays where it is, and Journey shows the switch; the consultation report lists it too. More in our Foundayo tracker and Zepbound tracker guides.
- Injections with their site; tablets with the time you took them
- Daily or weekly reminders in the iPhone app
- Add a forgotten dose, up to 30 days back
Questions to bring to your prescriber
Useful whether you are starting fresh or thinking about a change.
- Does a daily tablet or a weekly injection fit my health and routine better, and why?
- Given my other conditions, how might the side effects compare for someone like me?
- Do any of my medicines interact with Foundayo, such as ones that affect the enzyme CYP3A4?
- If I switch, how will we manage the change, and what should I watch for in the first weeks?
- What does my plan cover, and what would I pay for each?
- What should I do if I miss a dose of the one I'm prescribed?
More on getting ready: preparing for a GLP-1 doctor appointment.
Questions people ask
Is Foundayo the same as Zepbound?+
No. Both are Eli Lilly medicines approved in the US for weight management, but Foundayo is orforglipron, a once-daily tablet acting on the GLP-1 receptor, and Zepbound is tirzepatide, a once-weekly injection acting on GIP and GLP-1 receptors. They have separate trials, labels and storage rules.1,2
Is Foundayo tirzepatide?+
No. Foundayo's active ingredient is orforglipron, a small-molecule GLP-1 receptor agonist that Chugai Pharmaceutical discovered and Lilly licensed in 2018.1,4 Tirzepatide is the medicine in Zepbound and Mounjaro. All three are Eli Lilly products, which is why they are often mentioned together. Our guide to whether there is a Mounjaro pill sets out which GLP-1 pills are approved.
Is Foundayo as effective as Zepbound?+
No trial has compared them directly. In separate 72-week trials in adults without diabetes (ATTAIN-1 and SURMOUNT-1), average weight change was −11.1% on Foundayo 17.2 mg (placebo −2.1%) and −20.9% on Zepbound 15 mg (placebo −3.1%), both counting everyone randomized.1,2 Separate trials cannot show how the two would compare in the same people.
Does Foundayo have fewer side effects than Zepbound?+
Their labels list similar side effects, led by nausea, constipation, diarrhea and vomiting. Nausea affected 26–35% of people on Foundayo (10% on placebo) and 25–29% on Zepbound (8% on placebo), and 6–10% (3% on placebo) versus 4.8–6.7% (3.4% on placebo) stopped because of side effects.1,2 These come from separate trials, so they cannot be ranked.
Do you have to take Foundayo on an empty stomach?+
No. Foundayo's label says to take it once a day, with or without food, and sets no fasting, water or waiting-time rules; tablets are swallowed whole, one a day.1 That is different from the Wegovy pill, which has empty-stomach rules: see Foundayo vs Wegovy.
Is Foundayo available in the UK?+
It is authorized there. The MHRA approved Foundayo on August 10, 2026, for weight management and type 2 diabetes, the first approval in Europe. It is not currently available on the NHS; NHS use will depend on a NICE evaluation.7 In the UK, tirzepatide is sold as Mounjaro rather than Zepbound.8
Is Foundayo approved for type 2 diabetes?+
Not in the US, where its label covers weight reduction and long-term maintenance only.1 In the UK it is: the MHRA's August 2026 authorization includes type 2 diabetes.7 Zepbound is not a diabetes approval either; in the US, tirzepatide for type 2 diabetes is sold as Mounjaro.10
Can you switch from Zepbound to Foundayo?+
Your prescriber can move you from one to the other and decides the timing and starting strength. Neither label sets out a switching schedule, and both say using them with other GLP-1 medicines is not recommended.1,2 Handle keeps your Zepbound history and adds Foundayo, so the switch sits on one record.
Can I track Foundayo in Handle?+
Yes. Foundayo is not on Handle's list of named medicines yet, so add it under “Something else” with its name, amount and daily schedule. Logging doses, the daily check-in, weight, food, Journey and the consultation report (a Premium feature) then work the same way. See our Foundayo tracker page.
Sources
- Eli Lilly and Company, via DailyMed (U.S. National Library of Medicine). Foundayo (orforglipron) tablets — Prescribing Information, effective July 29, 2026.
- Eli Lilly and Company, via DailyMed (U.S. National Library of Medicine). Zepbound (tirzepatide) injection — Prescribing Information, effective August 28, 2026.
- U.S. Food and Drug Administration. FDA Approves First New Molecular Entity Under National Priority Voucher Program, April 1, 2026.
- Eli Lilly and Company, via PR Newswire. FDA approves Lilly's Foundayo (orforglipron), the only GLP-1 pill for weight loss that can be taken any time of day without food or water restrictions, April 1, 2026.
- The New England Journal of Medicine, via PubMed. Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment (ATTAIN-1), 2025.
- The New England Journal of Medicine, via PubMed. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), 2022.
- Medicines and Healthcare products Regulatory Agency (UK). UK first in Europe to authorise orforglipron for weight management and type 2 diabetes, August 10, 2026.
- Medicines and Healthcare products Regulatory Agency (UK). MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss, November 8, 2023.
- National Institute for Health and Care Excellence. Tirzepatide for managing overweight and obesity (TA1026), published December 23, 2024; updated September 1, 2025.
- U.S. Food and Drug Administration. FDA Approves New Medication for Chronic Weight Management, November 8, 2023.
Written by the Handle team from the sources above, last checked on September 23, 2026. How we write: our editorial policy. Spotted something out of date? Tell us at [email protected].
Handle supports recording and conversations with your care team. It does not diagnose, and it never tells you to start, change, skip or stop a dose. This page is general information, not medical advice. Always follow your prescriber and your medicine's instructions for use.