This is one of the most confusing corners of modern medicine, but the confusion is entirely on the label, not in the chemistry. Four famous brand names — Ozempic, Wegovy, Mounjaro, Zepbound — are really only two medicines.
In plain terms: two molecules wearing four different name tags.
The map
| Brand | Active compound | Approved for |
|---|---|---|
| Ozempic | Semaglutide | Type 2 diabetes |
| Wegovy | Semaglutide | Chronic weight management |
| Mounjaro | Tirzepatide | Type 2 diabetes |
| Zepbound | Tirzepatide | Chronic weight management |
- Ozempic and Wegovy are both semaglutide — a GLP-1 receptor agonist. Wegovy is the version the FDA approved specifically for weight management in 20211.
- Mounjaro and Zepbound are both tirzepatide — a dual GIP/GLP-1 agonist. Zepbound is the weight-management approval, granted in 20232.
Why one molecule gets two brands
It looks like marketing trickery, but there's a real regulatory reason. A drug is approved for a specific use (an "indication"), and a company will often launch the same molecule under a separate brand for a separate approved use — frequently with its own dose range and packaging. So semaglutide-for-diabetes (Ozempic) and semaglutide-for-weight (Wegovy) are the same chemical, cleared and sold as two distinct products.
That's why "which is better, Ozempic or Wegovy?" is a question about products and approvals, not chemistry — they contain the identical active ingredient.
So there are really two compounds
Strip away the four brands and you're left with exactly two active ingredients, and the only comparison that's actually about pharmacology is between those two:
- Semaglutide switches on one gut-hormone receptor (GLP-1).
- Tirzepatide switches on two (GIP *and* GLP-1) — the "twincretin."
They're dosed weekly, with half-lives of roughly 7 and 5 days. The full head-to-head is in semaglutide vs tirzepatide.
The short version
Ozempic and Wegovy are semaglutide; Mounjaro and Zepbound are tirzepatide. Within each pair the difference is the approved use (diabetes vs weight), not the drug. The one genuine pharmacological distinction across all four is single-receptor (semaglutide) versus dual-receptor (tirzepatide). All are FDA-approved, weekly injections. This is an educational overview, not medical advice.