Semaglutide is the GLP-1 drug sold as Wegovy and Ozempic; retatrutide is Eli Lilly's investigational molecule that adds the GIP and glucagon receptors. One has labels with a fixed dose ladder; the other has a set of trial arms and no approval. Both are injected once weekly and both climb for sixteen weeks before reaching their top dose, but the milligram figures on their ladders are an order of magnitude apart at the start. This page sets the two records side by side (read 2026-10-05) and does the syringe arithmetic. It compares; it recommends neither.
The single-compound records are on the semaglutide and retatrutide dosage pages; the same comparison against tirzepatide is on retatrutide vs tirzepatide.
Status first
| Semaglutide | Retatrutide | |
|---|---|---|
| Developer | Novo Nordisk | Eli Lilly |
| Receptors | GLP-1 | GIP + GLP-1 + glucagon |
| Approval | Wegovy and Ozempic labels (Wegovy version published 2026-06-30) | None; Lilly plans to file in Q1 2027 (release of 2026-07-23, as recorded on the retatrutide page) |
| Form | Solutions of stated strength in pens; a tablet | Trial supply; research-market powders labelled 5, 10 and 20 mg |
| Half-life | About 1 week (label) | About 6 days (Urva et al. 2022) |
| Direct comparison | TRANSCEND-T2D-2, HbA1c at week 80, no results posted | same trial |
The Wegovy label states the half-life and its consequence in one sentence: semaglutide "will be present in the circulation for about 5 to 7 weeks after the last injectable dose of 2.4 mg". Retatrutide's figure comes from a 12-week phase 1b study in 72 people with type 2 diabetes, which reported a half-life of approximately 6 days. What that tail means for anyone moving between the two, and the one head-to-head trial still to report, is on switching from semaglutide to retatrutide.
The two ladders side by side
| Weeks | Semaglutide (Wegovy injection label) | Retatrutide 12 mg arm (TRIUMPH, as described by Lilly) |
|---|---|---|
| 1–4 | 0.25 mg | 2 mg |
| 5–8 | 0.5 mg | 4 mg |
| 9–12 | 1 mg | 6 mg |
| 13–16 | 1.7 mg | 9 mg |
| 17 onward | 2.4 mg (usual maintenance); 1.7 mg; 7.2 mg after tolerating 2.4 mg | 12 mg |
The shapes match and the numbers do not. Each ladder takes four four-week steps to reach its maintenance dose, but semaglutide's steps are 0.25 to 0.7 mg and retatrutide's 2 to 3 mg. The retatrutide 4 mg arm in TRIUMPH-1 needed one escalation step (Lilly release of 2026-05-21, as recorded). In the phase 2 trial the 4 and 8 mg arms started at either 2 or 4 mg; the authors report that gastrointestinal events "were partially mitigated with a lower starting dose (2 mg vs. 4 mg)".
The milligram scales are not interchangeable. Retatrutide's 2 mg first step is close to semaglutide's 2.4 mg maintenance dosage; semaglutide's highest labelled dosage, 7.2 mg, falls between retatrutide's 6 and 9 mg steps. A milligram figure only means something inside its own molecule's ladder.
What each ladder produced, in its own trial
| Trial and dose | Weight change | Placebo | Duration | Source |
|---|---|---|---|---|
| STEP 1, semaglutide 2.4 mg | −14.9% | −2.4% | 68 weeks | PMID 33567185 |
| STEP UP, semaglutide 7.2 mg | −18.7% | −3.9% | 72 weeks | as recorded on the semaglutide page |
| Retatrutide phase 2, 4 mg | −17.1% | −2.1% | 48 weeks | PMID 37366315 |
| Retatrutide phase 2, 12 mg | −24.2% | −2.1% | 48 weeks | PMID 37366315 |
| TRIUMPH-1, retatrutide 12 mg | −28.3% | −2.2% | 80 weeks | Lilly release, 2026-05-21, as recorded |
These come from different programmes with different durations, populations and analyses; the STEP 1 figure counts everyone randomised whether or not they stayed on treatment. They describe each drug against its own placebo, not one drug against the other. STEP 1 reported that 4.5% of participants on semaglutide stopped treatment because of gastrointestinal events, against 0.8% on placebo; Lilly reports TRIUMPH-1 discontinuations for any adverse event of 4.1% on 4 mg to 11.3% on 12 mg against 4.9% on placebo (as recorded). The categories differ, so the two figures do not line up.
The trial that will compare them
Two registrations on ClinicalTrials.gov (searched 2026-10-05) name both drugs as interventions, both sponsored by Eli Lilly:
| Record | Phase | People | Comparison | Status |
|---|---|---|---|---|
| NCT06260722, TRANSCEND-T2D-2 | 3 | about 1,250, type 2 diabetes on metformin with or without an SGLT2 inhibitor | retatrutide dose level 1 and dose level 2 against semaglutide; primary end point HbA1c change at week 80 | active, not recruiting; primary completion 2026-08-27; no results |
| NCT06982859 | 1 | about 95, type 2 diabetes | retatrutide, semaglutide and placebo; insulin secretion and sensitivity at week 28 | active, not recruiting; primary completion December 2026 (estimated) |
Neither record states the doses in its arm descriptions, and neither has weight change as its primary end point. Until one reports, every retatrutide-versus-semaglutide figure is a comparison across trials.
Both ladders in syringe units
Units on a U-100 syringe = mg ÷ mg/mL × 100. Semaglutide's labelled products are pens of fixed strength and need no units; the table applies to research-market powder vials, for which no label exists.
| Dose | 2.5 mg/mL | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|---|
| Semaglutide 0.25 mg | 10 | 5 | 2.5 | 1.25 |
| Semaglutide 1 mg | 40 | 20 | 10 | 5 |
| Semaglutide 2.4 mg | 96 | 48 | 24 | 12 |
| Semaglutide 7.2 mg | 288 ✕ | 144 ✕ | 72 | 36 |
| Retatrutide 2 mg | 80 | 40 | 20 | 10 |
| Retatrutide 4 mg | 160 ✕ | 80 | 40 | 20 |
| Retatrutide 9 mg | 360 ✕ | 180 ✕ | 90 | 45 |
| Retatrutide 12 mg | 480 ✕ | 240 ✕ | 120 ✕ | 60 |
✕ = more than one 1 mL syringe holds. The two molecules use opposite ends of the barrel: semaglutide's first step at 10 mg/mL is 2.5 units, where one mark is 40% of the amount, while retatrutide's top dose overflows a syringe at anything under 12 mg/mL. The mg to units page sets out the formula; the calculator's semaglutide and retatrutide settings handle any vial and volume.
What is not established
No completed trial compares retatrutide with semaglutide, and the one running in type 2 diabetes measures blood sugar first. Retatrutide has no regulator-reviewed dose; its phase 3 results are known from Lilly's releases rather than peer-reviewed papers. No dose of one is equivalent to a dose of the other. Research-market vials under either name have no data of their own. The compounds are covered in Medibact's semaglutide guide and retatrutide guide. Nothing on this page is an instruction; dose and product belong with a clinician.
Sources and dates
Opened 2026-10-05: the Wegovy label on DailyMed (Novo Nordisk, version published 2026-06-30); PubMed abstracts 33567185 (Wilding et al., NEJM 2021), 37366315 (Jastreboff et al., NEJM 2023) and 36354040 (Urva et al., Lancet 2022); ClinicalTrials.gov intervention search for retatrutide AND semaglutide and records NCT06260722 and NCT06982859. The TRIUMPH figures, escalation description and filing plan are as recorded on this site's retatrutide page from Lilly's releases of 2026-05-21 and 2026-07-23; the STEP UP figures as recorded on its semaglutide page. Unit figures are arithmetic by this site. Corrections go to the contact page.