Tesamorelin and retatrutide both come up in searches about losing abdominal fat, and comparisons place them side by side as if they competed. They answer different questions. Tesamorelin is a labelled drug that releases growth hormone and shrinks the fat inside the abdomen of people with HIV-associated lipodystrophy without changing body weight; it is injected every day. Retatrutide is an investigational weekly injection acting on three appetite and metabolic receptors, tested for total body weight, with large trial results and no approval yet. This page sets the two records side by side (sources opened 2026-10-26) and converts the figures into syringe units. It reports figures; it suggests none.
The single-compound pages carry the full record: tesamorelin dosage and retatrutide dosage. Vial arithmetic for any volume is in the calculators for tesamorelin and retatrutide.
Side by side
| Tesamorelin | Retatrutide | |
|---|---|---|
| What it is | GHRH(1-44) analogue with an N-terminal hexenoyl group | Single peptide agonist at GIP, GLP-1 and glucagon receptors |
| Status | FDA-approved 2010 (EGRIFTA); SV and WR labels effective 2026-07-29 | Investigational; Lilly stated a planned submission in the first quarter of 2027 (2026-07-23) |
| Labelled or trial dose | 1.4 mg daily (SV), 1.28 mg daily (WR); 2 mg daily in the pivotal trial | 1–12 mg weekly (phase 2); 4, 9 and 12 mg weekly (TRIUMPH-1) |
| Frequency | Once daily | Once weekly |
| Half-life | 8 min (SV), 11 min (WR) | About 6 days (phase 1b) |
| What the trials measured | Visceral fat: −15.2% vs +5.0% at 26 weeks | Body weight: up to −24.2% at 48 weeks (phase 2), −28.3% at 80 weeks (TRIUMPH-1) |
| Effect on weight | "Weight neutral" per the WR label | The primary outcome |
| ClinicalTrials.gov, 2026-10-26 | 24 studies | 34 studies |
The rows that separate them are the target and the outcome. Tesamorelin was approved for one kind of fat in one population and does not move the scale; retatrutide is being developed to move the scale.
What each record holds
Tesamorelin. The EGRIFTA SV label states 1.4 mg, drawn as 0.35 mL after a 2 mg vial is reconstituted, injected into the abdomen once daily with rotated sites; the WR label states 1.28 mg from an 11.6 mg vial lasting seven days, and says the two products are not substitutable. Both read on openFDA on 2026-10-26. The pivotal trial, 412 adults with HIV and excess abdominal fat, gave 2 mg daily for 26 weeks and measured visceral fat by CT. The label's warnings include elevated IGF-1, fluid retention and glucose intolerance; this site's tesamorelin cycle page sets out what happened to the fat when treatment stopped.
Retatrutide. The phase 2 trial, read tonight in its abstract, randomised 338 adults with obesity or overweight plus a weight-related condition to six dose arms or placebo, once weekly for 48 weeks; at 12 mg, 83% lost 15% or more of body weight against 2% on placebo. Lilly's phase 3 releases, recorded on this site's retatrutide page, report −28.3% at 80 weeks on 12 mg in TRIUMPH-1 and results in type 2 diabetes and cardiovascular disease in TRIUMPH-2 and -3. The escalation ladder used in the trials is on the retatrutide dose schedule page.
The arithmetic of a week
| Tesamorelin | Retatrutide | |
|---|---|---|
| Labelled or trial week | 9.8 mg (SV) · 8.96 mg (WR) · 14 mg (pivotal) | 1 to 12 mg (one injection) |
| Injections per week | 7 | 1 |
| Typical research vials | 5 mg, 10 mg | 5 mg, 10 mg, 20 mg |
| Vials per labelled or 9 mg week | about one 10 mg vial (7 × 1.4 mg = 9.8 mg) | about one 10 mg vial |
The weekly milligrams land in the same place, but nothing else does: tesamorelin is cleared within the hour after each injection and is given seven times, retatrutide stays in the blood for days after one. Equal weekly mass does not mean equal exposure or equal effect, and the two act on unrelated receptors.
Units per draw
Units on a U-100 syringe = milligrams ÷ concentration in mg/mL × 100.
| Amount | 10 mg/mL | 5 mg/mL | 2.5 mg/mL |
|---|---|---|---|
| 1.28 mg (tesamorelin, WR figure) | 12.8 units | 25.6 | 51.2 |
| 1.4 mg (tesamorelin, SV figure) | 14 | 28 | 56 |
| 2 mg (tesamorelin pivotal; retatrutide first step) | 20 | 40 | 80 |
| 4 mg (retatrutide) | 40 | 80 | 160 (more than one syringe) |
| 8 mg (retatrutide) | 80 | 160 | 320 |
| 12 mg (retatrutide) | 120 (more than one syringe) | 240 | 480 |
Where the concentrations come from: 10 mg/mL is a 10 mg vial with 1 mL of water or a 20 mg vial with 2 mL; 5 mg/mL a 5 mg vial with 1 mL or a 10 mg vial with 2 mL; 2.5 mg/mL a 5 mg vial with 2 mL. The labelled tesamorelin products use their own concentrations (4 mg/mL for SV, 8 mg/mL for WR), which is why the labels give the dose in millilitres. The larger retatrutide trial doses do not fit one U-100 syringe below 10 mg/mL; per-dose tables are on retatrutide units.
What is not established
No study has compared tesamorelin with retatrutide or given them together. Tesamorelin's dosage was set for HIV-associated abdominal fat and has no labelled use outside it; retatrutide has no approved dose for anything. Nothing is known about what a weight-loss agonist does to tesamorelin's glucose warning, or the reverse. The research-vial figures that circulate for both come from vendor and forum pages, not from these trials. Medibact's tesamorelin guide and retatrutide guide cover the compounds. Decisions about administering anything belong with a clinician.
Sources and dates
Opened 2026-10-26: the EGRIFTA SV and EGRIFTA WR labels on openFDA (effective 2026-07-29), sections 2, 5 and 6; the abstract of Jastreboff et al. 2023 (PMID 37366315) and the PubMed record of Falutz et al. 2007 (PMID 18057338); ClinicalTrials.gov v2 API searches for tesamorelin (24), retatrutide (34) and both (0); PubMed counts for tesamorelin (122), retatrutide (207) and both (0). From this site's pages with their read dates: the Falutz visceral-fat result and tesamorelin half-lives (2026-09-18 and 2026-10-03), Lilly's TRIUMPH releases and submission plan (2026-09-18), the retatrutide half-life (2026-09-25). Unit arithmetic by this site. Corrections go to the contact page.