What is the same
Both are from Eli Lilly, both are labelled for long-term weight reduction with diet and physical activity in adults with obesity or overweight plus a weight-related condition, neither is established in children, and both carry a boxed warning about thyroid C-cell tumors [1][2].
What differs
- Form and rhythm: a tablet once a day (Foundayo™) versus an injection once a week (Zepbound®).
- Food: Foundayo™ is taken with or without food, swallowed whole, no more than one tablet a day [1]. It has no empty-stomach rule like the oral semaglutide tablets.
- Storage: Foundayo™ stays at room temperature; Zepbound® is refrigerated, with a limited time allowed outside the fridge [1][2].
- Other uses: Zepbound® is also labelled for moderate to severe obstructive sleep apnea in adults with obesity [2].
- Interactions: the Foundayo™ label changes its use alongside certain other medicines that affect the liver enzyme CYP3A4 (sections 2.2 and 7) [1].
- Birth-control pills: both US labels point pill users to a method that is not swallowed, or an added barrier, after starting and after each step up — for 30 days with Foundayo™ and 4 weeks with Zepbound® [1][2].
Side by side, from the labels
| Label item | Foundayo™ (tablet) | Zepbound® |
|---|---|---|
| Active ingredient | Orforglipron, a GLP-1 receptor agonist, by mouth | Tirzepatide, a GIP and GLP-1 receptor agonist |
| Maker | Eli Lilly and Company | Eli Lilly and Company |
| FDA-approved uses | With diet and physical activity: long-term weight reduction in adults with obesity, or overweight plus a weight-related condition. Not established in children. [1] | With diet and physical activity: long-term weight reduction in adults with obesity, or overweight plus a weight-related condition; moderate to severe obstructive sleep apnea in adults with obesity. Not established in children. [2] |
| How it is taken | Once a day by mouth, with or without food, swallowed whole; no more than one tablet a day. | Once a week, under the skin of the abdomen or thigh, or the back of the upper arm, at any time of day. |
| Forms in the US | Tablets in six strengths, bottles of 30 with a desiccant (section 3). First US approval: 2026. | Single-dose pens, single-dose vials, multi-dose vials and the KwikPen® (four doses per pen) (section 3). |
| Dose steps | Section 2.1 of the label: a low starting dose raised after at least 30 days at each step. Section 2.2 changes the steps when certain other medicines are used. Not repeated here; your prescriber sets your steps. [1] | Sections 2.1–2.2 of the label: a starting dose that is not a maintenance dose, raised in steps of at least 4 weeks, then a maintenance dose that depends on the use. Not repeated here; your prescriber sets your steps. [2] |
| Half-life (section 12.3) | About 29 to 49 hours [1] | About 5 days (5 to 6 days in people with overweight or obesity) [2] |
| Most common side effects (label) | Nausea, constipation, diarrhea, vomiting, indigestion, abdominal pain, headache, bloating, fatigue, burping, reflux, gas, hair loss. | Nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection-site reactions, fatigue, allergic reactions, burping, hair loss, reflux. |
| Storage (label) | Room temperature (20–25 °C), in the supplied bottle. | Refrigerated (2–8 °C). Single-dose pens and vials may be kept unrefrigerated up to 30 °C for a total of 21 days. Multi-dose vials and KwikPens® are discarded 30 days after first use or after 4 doses. |
| Boxed warning | Yes: risk of thyroid C-cell tumors. The label explains the rodent findings come from other GLP-1 products, because orforglipron is not active in rats or mice. | Yes: risk of thyroid C-cell tumors. |
| In the EU (EMA) | Not yet authorised: EMA’s committee gave a positive opinion on 15 October 2026 for obesity and type 2 diabetes in adults (EMA list checked 20 October 2026). [3] | Not a separate EU product: in the EU, tirzepatide for weight management is authorised under the Mounjaro® name. [4] |
Timing facts from the labels
| Label item | Foundayo™ (tablet) | Zepbound® |
|---|---|---|
| Half-life (section 12.3) | About 29 to 49 hours [1] | About 5 days (5 to 6 days in people with overweight or obesity) [2] |
| Time to peak level (section 12.3) | 4 to 8 hours after a tablet [1] | About 24 hours (8 to 72) after a dose [2] |
| Steady state (section 12.3) | After about 1 week of daily tablets [1] | After 4 weeks of weekly doses [2] |
| After the last dose (section 12.3) | Not stated in the label [1] | Not stated in the label [2] |
| Missed dose (section 2) | Taken as soon as possible without doubling the next one; after 7 or more missed in a row, the label restarts the steps lower (section 2.3) [1] | Taken within 4 days (96 hours); after that, skipped (section 2.3) [2] |
| Section on switching | None [1] | None [2] |
Using them together
The Foundayo™ label says use with another GLP-1 receptor agonist is not recommended [1]. The Zepbound® label says the same about other tirzepatide products and any GLP-1 receptor agonist [2].
Moving between them, in either direction
Neither the Foundayo™ (tablet) label nor the Zepbound® label sets out a schedule for moving from one to the other [1][2]. The timing facts above describe each medicine on its own; they are not a plan for a change. If a switch comes up, in whichever direction, the gap, the first dose of the new medicine and its steps are set by your prescriber.
Ozempic®, Wegovy®, Rybelsus®, Saxenda®, Victoza® and FlexTouch® are registered trademarks of Novo Nordisk A/S. Mounjaro®, Zepbound® and KwikPen® are registered trademarks owned or licensed by Eli Lilly and Company; Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by these companies.
