What is the same
Both are injected under the skin once a week, both labels are for type 2 diabetes alongside diet and exercise, and both carry a boxed warning about thyroid C-cell tumors [1][2].
What differs
- Active ingredient: tirzepatide (GIP and GLP-1 receptor agonist) versus semaglutide (GLP-1 receptor agonist).
- Approved uses: Mounjaro® also covers children 10 and older; Ozempic® also covers kidney risk reduction in chronic kidney disease [1][2].
- Forms: Mounjaro® comes in single-dose pens and vials, multi-dose vials and a four-dose KwikPen®; Ozempic® in multi-dose pens and single-dose syringes.
- Birth-control pills: in the first four weeks, and again for four weeks after every step up, the US Mounjaro® label points pill users to a contraceptive that is not swallowed, or to a barrier such as a condom on top of the pill [1]. The EU Mounjaro® label sees no need to change the pill [3].
Side by side, from the labels
| Label item | Mounjaro® | Ozempic® (injection) |
|---|---|---|
| Active ingredient | Tirzepatide, a GIP and GLP-1 receptor agonist | Semaglutide, a GLP-1 receptor agonist |
| Maker | Eli Lilly and Company | Novo Nordisk |
| 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] | Adults with type 2 diabetes: blood sugar control alongside diet and exercise; lowering the risk of major cardiovascular events in those with established cardiovascular disease; lowering the risk of kidney decline, kidney failure and cardiovascular death in those with chronic kidney disease. [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, thigh or upper arm, on the same day each week. |
| Forms in the US | Single-dose pens, single-dose vials, multi-dose vials and the KwikPen® (four doses per pen) (section 3). | Multi-dose pens and single-dose prefilled syringes, in several strengths (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] | Section 2.2 of the label: a low starting dose, raised in steps. Not repeated here; your prescriber sets your steps. [2] |
| Half-life (section 12.3) | About 5 days [1] | About 1 week [2] |
| Most common side effects (label) | Nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion, abdominal pain. | Nausea, vomiting, diarrhea, abdominal pain, constipation. |
| 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) before first use. After first use a pen can be kept for up to 56 days at 15–30 °C or in the fridge. Not to be frozen. |
| 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] | Authorised since 2018 for adults with type 2 diabetes that is not controlled well enough. [4] |
Timing facts from the labels
| Label item | Mounjaro® | Ozempic® (injection) |
|---|---|---|
| Half-life (section 12.3) | About 5 days [1] | About 1 week [2] |
| Time to peak level (section 12.3) | 8 to 72 hours after a dose [1] | 1 to 3 days after a dose [2] |
| Steady state (section 12.3) | After 4 weeks of weekly doses [1] | After 4 to 5 weeks of weekly doses [2] |
| After the last dose (section 12.3) | Not stated in the label [1] | About 5 weeks in the circulation after the last dose [2] |
| Missed dose (section 2) | Taken within 4 days (96 hours); after that, skipped (section 2.1) [1] | Taken within 5 days of the missed dose (section 2.1) [2] |
| Section on switching | None [1] | None in the injection label [2] |
Moving between them, in either direction
Neither the Ozempic® (injection) label nor the Mounjaro® label sets out a schedule for moving from one to the other [2][1]. 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.
