Semaglutide vs Retatrutide
Verdict: Semaglutide is the proven incumbent: approved, widely prescribed, with years of real-world data and roughly 15% average body-weight reduction in trials. Retatrutide is the challenger with the most dramatic phase-2 numbers published to date — around 24% at the top dose — but it remains an investigational compound with no approval anywhere. If the question is 'what has the evidence and the supply chain today', it's semaglutide. Retatrutide's triple-agonist mechanism is why the research community watches it so closely.
Side by side
| Semaglutide | Retatrutide | |
|---|---|---|
| Typical dose | 250 mcg–2.4 mg | 1 mg–12 mg |
| Frequency | 1x weekly, titrated up over months | 1x weekly, titrated up |
| Administration | subcutaneous injection | subcutaneous injection |
| Common vials | 2 mg, 5 mg, 10 mg | 5 mg, 10 mg |
| Typical mix | 5 mg + 2 ml water | 10 mg + 2 ml water |
| Units for typical dose | 20 units (500 mcg) | 40 units (2 mg) |
Mechanism: one receptor vs three
Semaglutide is a pure GLP-1 receptor agonist — appetite suppression and delayed gastric emptying do most of the work. Retatrutide adds GIP and glucagon receptor agonism on top; the glucagon component in particular appears to raise energy expenditure rather than only cutting intake. That's the theoretical reason its phase-2 weight-loss curve kept falling where single-agonist curves start to flatten.
The numbers, honestly framed
In STEP trials semaglutide 2.4 mg averaged ~15% body-weight loss over 68 weeks. Retatrutide's phase-2 (NEJM 2023) reported ~24% at 12 mg over 48 weeks — the largest reduction published for any single agent at that time. Cross-trial comparisons are imperfect: different populations, durations and titrations. Phase-3 retatrutide data will be the real test.
Practical differences
Both are weekly subcutaneous injections with nausea-led GI side effects managed by slow titration. Semaglutide has established dose ladders (0.25 → 2.4 mg). Retatrutide protocols in research settings typically titrate from 2 mg toward 8–12 mg. Heart-rate increase was noted in retatrutide's phase 2 — one of the things phase 3 is watching.
Can you stack them?
These are not stacked together — they compete for the same job on overlapping receptors. Choosing between them is a matter of evidence maturity versus trial ceiling, not combination.
More comparisons
Educational comparison based on commonly published research protocols — not medical advice or an endorsement of any compound.