Tirzepatide: what it is, what the studies show and where it stands
Tirzepatide is a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist, sold as a once-weekly injection under the skin.
At a glance
US Approved, prescription
Canada Authorized, prescription
Group Weight loss and metabolic
Sources 12
Checked 10 Oct 2026What is Tirzepatide?
Tirzepatide is a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist, sold as a once-weekly injection under the skin. [1]
Other names: LY3298176, Mounjaro, Zepbound.
How it has been given to people: subcutaneous injection, once weekly.
Looking for doses? Tirzepatide dosage chart and vial math
Is Tirzepatide approved in the US and Canada?
United States: FDA approved as Mounjaro (13 May 2022) and Zepbound (8 November 2023). [8]
Canada: Authorized by Health Canada as Mounjaro and Zepbound, both listed as marketed in the Drug Product Database. [9]
Both were checked on 10 Oct 2026 against the regulators' own product databases.
Which approved products contain Tirzepatide?
| Product | Country | Approved for | Label |
|---|---|---|---|
| Mounjaro | US | With diet and exercise, glycemic control in adults and children 10 years and older with type 2 diabetes. Also to lower the risk of major cardiovascular events in adults with type 2 diabetes at high risk. | Label |
| Zepbound | US | With a reduced-calorie diet and more physical activity: to reduce excess body weight and keep it off in adults with obesity, or with overweight and at least one weight-related condition. Also moderate to severe obstructive sleep apnea in adults with obesity. | Label |
| Mounjaro | CA | With diet and exercise, glycemic control in adults with type 2 diabetes, and in patients aged 10 to under 18 with type 2 diabetes in combination with metformin or basal insulin. | Label |
| Zepbound | CA | With a reduced-calorie diet and more physical activity: chronic weight management in adults with BMI 30 or greater, or 27 to under 30 with at least one weight-related condition. Also moderate to severe obstructive sleep apnea in adults with obesity. | Label |
What human studies of Tirzepatide exist?
The 6 findings listed here: 6 from randomized human trials.
In adults with obesity or overweight and no diabetes, mean weight change at 72 weeks was -15.0% on 5 mg and -19.5% on 10 mg. [3]
In the same trial mean weight change was -20.9% on 15 mg, against -3.1% on placebo. [3]
Head to head in adults with obesity and no type 2 diabetes, weight fell 20.2% on tirzepatide and 13.7% on semaglutide at 72 weeks. [4]
In type 2 diabetes, glycated hemoglobin fell 2.01, 2.24 and 2.30 percentage points on 5 mg, 10 mg and 15 mg at 40 weeks, against 1.86 on semaglutide 1 mg. [5]
In adults with obstructive sleep apnea and obesity not using positive airway pressure, the apnea-hypopnea index fell by 25.3 events per hour on tirzepatide and 5.3 on placebo at 52 weeks. [6]
In type 2 diabetes with cardiovascular disease, tirzepatide was noninferior to dulaglutide for cardiovascular death, heart attack or stroke. [7]
What are the side effects of Tirzepatide?
Reported in human studies or on a label:
- Zepbound label, reactions reported in 5% or more of patients: nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection site reactions, fatigue, hypersensitivity reactions, belching, hair loss and reflux. [2]
- Mounjaro label, reactions reported in 5% or more of patients: nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and abdominal pain. [1]
- In SURMOUNT-1 the most common adverse events were gastrointestinal, mostly mild to moderate, and came mainly while the dose was being raised. [3]
- In SURMOUNT-1, adverse events led to stopping treatment in 4.3% on 5 mg, 7.1% on 10 mg and 6.2% on 15 mg, against 2.6% on placebo. [3]
Warnings on the label
- Boxed warning on both US labels: tirzepatide caused thyroid C-cell tumors in rats. [2]
- Whether it causes these tumors, including medullary thyroid carcinoma, in people is not known. [2]
- Not for anyone with a personal or family history of medullary thyroid carcinoma (MTC), or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). [2]
- Not for anyone with a known serious hypersensitivity to tirzepatide or to an ingredient in the product. [2]
- Not recommended together with another tirzepatide product or any GLP-1 receptor agonist. [2]
- The 2.5 mg dose is for starting treatment and is not an approved maintenance dose. [2]
- It slows stomach emptying, which can change how other medicines taken by mouth are absorbed. [2]
- Oral birth control: the label advises switching to a non-oral method or adding a barrier method for 4 weeks after starting and for 4 weeks after each dose increase. [2]
- With insulin or a sulfonylurea the risk of low blood sugar goes up; the label says to consider lowering the dose of those medicines. [2]
- Missed dose (both US labels): take it as soon as possible within 4 days (96 hours). After 4 days, skip it and take the next dose on the usual day. [2]
What is the half-life of Tirzepatide?
About 5 days. [1]
How does Tirzepatide compare with others in its group?
These are the peptides filed under weight loss and metabolic. The last column says whether a randomized human trial is on record for each.
| Peptide | US | Canada | Half-life | Randomized human trial |
|---|---|---|---|---|
| Retatrutide | Not approved, in trials | Not authorized | About 6 days, from a 12-week phase 1b trial of once-weekly dosing in people with type 2 diabetes (72 enrolled). | Yes |
| Tirzepatide | Approved, prescription | Authorized, prescription | About 5 days. | Yes |
| Semaglutide | Approved, prescription | Authorized, prescription | About 1 week. | Yes |
| Cagrilintide | Not approved, in trials | Not authorized | 159 to 195 hours, about 6.6 to 8.1 days, measured in a phase 1b trial where it was given with semaglutide 2.4 mg. | Yes |
| AOD-9604 | Not approved | Not authorized | Not found | Yes |
| 5-Amino-1MQ | Not approved | Not authorized | Not found | No |
| SLU-PP-332 | Not approved | Not authorized | Not found | No |
| HGH Fragment 176-191 | Not approved | Not authorized | Not found | No |
What could not be found
These were searched for and did not turn up. They are listed so a missing number is not mistaken for a hidden one.
- Canadian product monographs were opened for the indications and the dose schedule only. Warnings, side effects, missed-dose and storage text in this file come from the US labels.
- Length of treatment in SURPASS-CVOT is not stated in the PubMed abstract.
Tirzepatide questions
Is Tirzepatide approved in the US?
FDA approved as Mounjaro (13 May 2022) and Zepbound (8 November 2023).
Is Tirzepatide authorized in Canada?
Authorized by Health Canada as Mounjaro and Zepbound, both listed as marketed in the Drug Product Database.
What is the half-life of Tirzepatide?
About 5 days.
Has Tirzepatide been tested in a randomized human trial?
Yes. At least one randomized human trial is listed on this page.
Sources
Each one was opened on 10 Oct 2026 and matched to the line it supports.
- Mounjaro (tirzepatide) injection, US prescribing information, Eli Lilly and Company, label version 40 2026-08-27. dailymed.nlm.nih.gov.
- Zepbound (tirzepatide) injection, US prescribing information, Eli Lilly and Company, label version 40 2026-08-28. dailymed.nlm.nih.gov.
- Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med 2022. PubMed 35658024. Trial NCT04184622.
- Aronne LJ et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. N Engl J Med 2025. PubMed 40353578. Trial NCT05822830.
- Frias JP et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med 2021. PubMed 34170647. Trial NCT03987919.
- Malhotra A et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. N Engl J Med 2024. PubMed 38912654. Trial NCT05412004.
- Nicholls SJ et al. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes. N Engl J Med 2025. PubMed 41406444. Trial NCT04255433.
- Drugs@FDA via openFDA: applications with generic name tirzepatide api.fda.gov.
- Health Canada Drug Product Database: products with active ingredient tirzepatide, with status lookups health-products.canada.ca.
- Mounjaro (tirzepatide injection) Canadian product monograph, Eli Lilly Canada Inc., date of authorization 2026-06-23 2026-06-23. pdf.hres.ca.
- Zepbound (tirzepatide injection) Canadian product monograph, Eli Lilly Canada Inc., date of authorization 2026-06-11 2026-06-11. pdf.hres.ca.
- FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (content current as of 10/01/2026) fda.gov.
Next
Tirzepatide dosage5 mg vial20 mg vial30 mg vialWeight loss and metabolicStatus in Canada
DosageFacts is an information site. It is not medical advice. Talk to a licensed professional before using any medication.