Ozempic vs Wegovy vs Mounjaro: A Plain Guide to the Three Medications
Three brand names dominate the metabolic-medicine conversation: Ozempic, Wegovy, and Mounjaro. People often treat them as three separate drugs, or lump all three together as interchangeable. Both readings are wrong. The plain truth is simpler and more interesting: two of these brands are the very same molecule, and the third is a different molecule entirely. This guide sorts out which is which, in ordinary language, and then notes where the underlying compounds appear as research peptides.
The brand names here are trademarks of their makers, cited only to identify and compare the products. Ozempic and Wegovy are trademarks of Novo Nordisk; Mounjaro is a trademark of Eli Lilly. Naming them implies no affiliation. All three are approved by Health Canada.
| Brand | Molecule | Maker | Approved use |
|---|---|---|---|
| Ozempic | Semaglutide | Novo Nordisk | Type 2 diabetes glycemic control |
| Wegovy | Semaglutide | Novo Nordisk | Chronic weight management |
| Mounjaro | Tirzepatide | Eli Lilly | Type 2 diabetes glycemic control |
The key insight: Ozempic and Wegovy are the same molecule
Read the middle column of that table slowly. Ozempic and Wegovy both contain semaglutide. Same molecule, same maker, two brands. The reason there are two names is that Novo Nordisk brought semaglutide to market under separate brands for separate approved indications: Ozempic for glycemic control in type 2 diabetes, and Wegovy for chronic weight management. The molecule is identical; the branding, the labelling, and the approved use differ.
This is the single most useful thing to understand about the trio. When someone says Ozempic and Wegovy, they are talking about one 31-amino-acid GLP-1 receptor agonist wearing two different labels. It is not two chemistries. It is one chemistry, two indications, two boxes.
Mounjaro is a different molecule
Mounjaro breaks the pattern because it is not semaglutide at all. It contains tirzepatide, a 39-amino-acid peptide made by a different company, Eli Lilly. More importantly, it works differently. Semaglutide is a mono-agonist that targets the GLP-1 receptor alone. Tirzepatide is a dual-agonist that targets the GLP-1 receptor and the GIP receptor together. So Mounjaro is not a rebranded Ozempic and not a Lilly copy of Wegovy. It is a distinct molecule with a distinct, two-receptor mechanism.
That means the mental model to carry away is a two-plus-one grouping. Ozempic and Wegovy are the semaglutide pair. Mounjaro stands on its own as the tirzepatide entry. Same broad research theme - incretin biology and metabolism - but two different molecules across the three brands.
Why the confusion is so common
The mix-up is easy to fall into. All three are given as weekly injections in their branded forms. All three surface in the same news coverage. And two of them share a molecule while the third shares a mechanism family, so everything feels adjacent. But adjacency is not identity. Novo Nordisk owns the semaglutide brands; Eli Lilly owns the tirzepatide brand. One molecule spans two of the boxes; a second molecule fills the third.
Where the research peptides come in
Separate from the branded medicines, the underlying molecules are also produced as research peptides supplied research-use-only. These are laboratory reference materials - lyophilised powder in a vial, characterised by a certificate of analysis, reconstituted at the bench - and they are a different category from any approved medicine. A group studying GLP-1 mono-agonism at the bench can source research-grade semaglutide, and a group studying the dual GIP and GLP-1 mechanism can source research-grade tirzepatide. The full catalogue is on the store page.
To be explicit about the boundary: a branded medicine and a research peptide are different categories and are not interchangeable. Nothing here suggests using research material in place of a prescribed medicine, and nothing here is a dosing schedule or protocol for any human or veterinary use. Research peptides are for laboratory investigation only. Any treatment decision belongs with a licensed healthcare professional.
Reading further
If you want to see exactly how each molecule differs from its branded counterpart, two comparisons go deeper: semaglutide versus Ozempic walks the semaglutide side, and tirzepatide versus Mounjaro walks the tirzepatide side. Both reinforce the same lesson this guide sets up: keep the molecule separate from the brand, and keep the medicine separate from the research material.
The short version
Ozempic and Wegovy are both semaglutide from Novo Nordisk, branded for two different approved uses. Mounjaro is tirzepatide from Eli Lilly, a different molecule with a dual-receptor mechanism. Two brands, one molecule; a third brand, a second molecule. The compounds also exist as research peptides, which are a separate laboratory category altogether.
Research use only. This article is educational and is not medical, legal, or financial advice. The compounds discussed are not approved for human or veterinary use, consumption, or therapeutic application.