Semaglutide and tirzepatide are both FDA-approved medicines built around the GLP-1 receptor, sold as Ozempic and Mounjaro for type 2 diabetes and as Wegovy and Zepbound for weight management. Semaglutide activates only the GLP-1 receptor. Tirzepatide activates both the GLP-1 and GIP receptors together.
At a glance
| Semaglutide | Tirzepatide | |
|---|---|---|
| What it is | GLP-1 receptor agonist sold as Ozempic for type 2 diabetes and Wegovy for chronic weight management | Dual GLP-1/GIP receptor agonist sold as Mounjaro for type 2 diabetes and Zepbound for weight loss |
| How it's thought to work | Activates GLP-1 receptors, studied for suppressing appetite, slowing gastric emptying, and enhancing the body's own insulin secretion | Activates both GLP-1 and GIP receptors together, studied for appetite suppression, insulin signaling, and fat metabolism |
| Regulatory status | FDA-approved as Wegovy for chronic weight management and Ozempic for type 2 diabetes | FDA-approved as Mounjaro for type 2 diabetes and Zepbound for weight loss |
| Strength of evidence | Human trials (the STEP program) and FDA approval | Human trials (the SURMOUNT program) and FDA approval |
| Reported side effects | Nausea, vomiting, diarrhea, constipation, abdominal pain; rare pancreatitis; thyroid C-cell tumors seen in rodent studies | GI profile similar to semaglutide; injection site reactions; higher hypoglycemia risk when combined with insulin |
| Common vial sizes | 2mg, 5mg (lyophilized) | 5mg, 10mg, 15mg, 30mg |
| Mixing math example | 5 mg + 2 mL BAC water = 2,500 mcg/mL, 25 mcg per unit | 10 mg + 2 mL BAC water = 5,000 mcg/mL, 50 mcg per unit |
Key differences
The core mechanism difference is receptor count. Semaglutide is a single-receptor GLP-1 agonist, studied for suppressing appetite, slowing gastric emptying, and enhancing insulin secretion. Tirzepatide adds GIP receptor activation on top of that, which research links to insulin signaling and fat metabolism effects beyond what a GLP-1-only agonist provides. GIP, like GLP-1, is an incretin hormone the gut releases after eating that influences both insulin release and appetite.
Both are FDA-approved: semaglutide as Wegovy and Ozempic, tirzepatide as Zepbound and Mounjaro. Neither is investigational. Their evidence bases are both built on large human trial programs, the STEP trials for semaglutide and the SURMOUNT trials for tirzepatide, each reporting body weight reduction figures for study participants. Both are also available as compounded, lyophilized powder in vials, separate from the branded, pre-filled pens.
Side effect profiles overlap heavily: both are associated with nausea, vomiting, diarrhea, constipation, and abdominal pain. For semaglutide, rodent studies found thyroid C-cell tumors of uncertain human relevance, and pancreatitis has been reported as a rare risk. For tirzepatide, reports add a hypoglycemia risk specifically when combined with insulin, on top of the shared gastrointestinal profile.
What the research covers
The STEP trial program tested semaglutide in humans and reported body weight reduction of up to 16%. The SURMOUNT trial program tested tirzepatide and reported body weight reduction of up to 22.5%. Both programs supported the respective FDA approvals.
Frequently asked questions
What is the difference between semaglutide and tirzepatide?
Semaglutide activates only the GLP-1 receptor. Tirzepatide activates both the GLP-1 and GIP receptors. Both are FDA-approved incretin-based medicines for type 2 diabetes and weight management.
Is semaglutide or tirzepatide FDA-approved?
Both are FDA-approved. Semaglutide is sold as Ozempic and Wegovy; tirzepatide is sold as Mounjaro and Zepbound.
Which has more human research, semaglutide or tirzepatide?
Both have large human trial programs behind their approvals: the STEP trials for semaglutide and the SURMOUNT trials for tirzepatide.
Are semaglutide and tirzepatide the same thing?
No. They are related but distinct molecules. Semaglutide is a single-receptor GLP-1 agonist; tirzepatide is a dual GLP-1/GIP agonist.
Both entries, plus the calculator
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