Semaglutide and retatrutide both act on the GLP-1 receptor but differ sharply in regulatory status and mechanism. Semaglutide, sold as Ozempic and Wegovy, is a single-receptor GLP-1 agonist and is FDA-approved. Retatrutide is a triple GLP-1/GIP/glucagon receptor agonist that remains an investigational compound, studied in clinical trials rather than sold as an approved medicine.
At a glance
| Semaglutide | Retatrutide | |
|---|---|---|
| What it is | GLP-1 receptor agonist sold as Ozempic for type 2 diabetes and Wegovy for chronic weight management | Investigational triple GLP-1/GIP/glucagon receptor agonist studied in clinical trials 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 GLP-1, GIP, and glucagon receptors together, studied for appetite suppression, insulin signaling, and energy expenditure |
| Regulatory status | FDA-approved as Wegovy for chronic weight management and Ozempic for type 2 diabetes | Not FDA-approved; investigational, sold outside trials only by unregulated research-chemical suppliers |
| Strength of evidence | Human trials (the STEP program) and FDA approval | Human trials: a Phase 2 study (Jastreboff et al., NEJM 2023); not yet approved |
| Reported side effects | Nausea, vomiting, diarrhea, constipation, abdominal pain; rare pancreatitis; thyroid C-cell tumors seen in rodent studies | Nausea (most common), diarrhea, vomiting, constipation, decreased appetite; generally mild to moderate |
| Common vial sizes | 2mg, 5mg (lyophilized) | 5mg, 10mg |
| Mixing math example | 5 mg + 2 mL BAC water = 2,500 mcg/mL, 25 mcg per unit | 5 mg + 1 mL BAC water = 5,000 mcg/mL, 50 mcg per unit |
Key differences
Semaglutide selectively activates the GLP-1 receptor, studied for appetite suppression, slowed gastric emptying, and enhanced insulin secretion. Retatrutide activates the GLP-1, GIP, and glucagon receptors together, with the added glucagon activity associated in research with increased energy expenditure and fat oxidation on top of the GLP-1 effects. GIP is a second incretin hormone the gut also releases after eating, distinct from the appetite and gastric-emptying pathway semaglutide alone works through.
Semaglutide is FDA-approved as Ozempic for type 2 diabetes and Wegovy for chronic weight management, sold as branded, pre-filled pens. Retatrutide is not FDA-approved and remains investigational. Outside clinical trials it is sold only by unregulated research-chemical suppliers, with no comparable branded product of its own.
Both are associated with gastrointestinal side effects: nausea, vomiting, diarrhea, and constipation. For semaglutide, reported risks also include rodent thyroid C-cell tumor findings of uncertain human relevance, plus a rare reported risk of pancreatitis. Retatrutide's reported effects also include decreased appetite, generally described as mild to moderate.
What the research covers
Semaglutide's evidence base comes from the STEP trial program, which reported body weight reduction of up to 16% and supported its FDA approval. Retatrutide's evidence comes from a Phase 2 trial (Jastreboff et al., NEJM 2023), reporting body weight reduction of up to 24.2% at 48 weeks and, in a MASLD substudy, average liver fat reductions of up to 82% at 24 weeks. Retatrutide's program has not yet reached FDA approval.
Frequently asked questions
What is the difference between semaglutide and retatrutide?
Semaglutide activates only the GLP-1 receptor and is FDA-approved. Retatrutide activates the GLP-1, GIP, and glucagon receptors and remains an investigational compound.
Is semaglutide or retatrutide FDA-approved?
Semaglutide is FDA-approved as Ozempic and Wegovy. Retatrutide is not FDA-approved; it is still an investigational compound.
Which has more human research, semaglutide or retatrutide?
Semaglutide has a completed, FDA-reviewed trial program (STEP). Retatrutide has Phase 2 human trial data (Jastreboff et al., NEJM 2023) but has not completed the approval process.
Are semaglutide and retatrutide the same thing?
No. Semaglutide is a single-receptor GLP-1 agonist. Retatrutide is a triple GLP-1/GIP/glucagon receptor agonist and a separate, investigational molecule.
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