What is the same
Same active ingredient, same maker, same four forms (single-dose pen, single-dose vial, multi-dose vial, KwikPen®), same storage rules and the same boxed warning [1][2].
What differs
- Approved uses: type 2 diabetes for Mounjaro®; weight reduction and obstructive sleep apnea for Zepbound® [1][2].
- Age: Mounjaro® is labelled for children 10 and older with type 2 diabetes; Zepbound® is not established in children.
- Dose steps: the Zepbound® label separates a starting dose from maintenance doses; the Mounjaro® label describes increases for blood sugar control. Both are in section 2.
- Using with other medicines: the Zepbound® label says combining it with other tirzepatide products or any GLP-1 receptor agonist is not recommended [2].
Side by side, from the labels
| Label item | Mounjaro® | Zepbound® |
|---|---|---|
| Active ingredient | Tirzepatide, a GIP and GLP-1 receptor agonist | Tirzepatide, a GIP and GLP-1 receptor agonist |
| Maker | Eli Lilly and Company | Eli Lilly and Company |
| FDA-approved uses | Blood sugar control in adults and children 10 and older with type 2 diabetes, alongside diet and exercise; lowering the risk of major cardiovascular events in adults with type 2 diabetes who are at high risk. [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 week, under the skin of the abdomen or thigh, or the back of the upper arm, at any time of 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 | Single-dose pens, single-dose vials, multi-dose vials and the KwikPen® (four doses per pen) (section 3). | 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 in steps of at least 4 weeks if more blood sugar control is needed. 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 5 days [1] | About 5 days (5 to 6 days in people with overweight or obesity) [2] |
| Most common side effects (label) | Nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion, abdominal pain. | Nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection-site reactions, fatigue, allergic reactions, burping, hair loss, reflux. |
| Storage (label) | 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. | 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. | Yes: risk of thyroid C-cell tumors. |
| In the EU (EMA) | Authorised since 2022 for type 2 diabetes (age 10 and older) and for weight management in adults. Zepbound® is not a separate EU product. [3] | Not a separate EU product: in the EU, tirzepatide for weight management is authorised under the Mounjaro® name. [3] |
Timing facts from the labels
| Label item | Mounjaro® | Zepbound® |
|---|---|---|
| Half-life (section 12.3) | About 5 days [1] | About 5 days (5 to 6 days in people with overweight or obesity) [2] |
| Time to peak level (section 12.3) | 8 to 72 hours after a dose [1] | About 24 hours (8 to 72) after a dose [2] |
| Steady state (section 12.3) | After 4 weeks of weekly doses [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 within 4 days (96 hours); after that, skipped (section 2.1) [1] | Taken within 4 days (96 hours); after that, skipped (section 2.3) [2] |
| Section on switching | None [1] | None [2] |
Moving between them, in either direction
Neither the Mounjaro® 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.
