Retatrutide: dosage in studies
Not a recommendation, not treatment guidance. This page shows only what published human studies used, with sources. This site does not say how much anyone should use of any substance. Fimea warns against using injectable peptides bought online: Fimea warning.
Retatrutide is an investigational drug acting on the GIP, GLP-1 and glucagon receptors, still in clinical development [3, 4]A.
In published human studies it has been given under the skin once a week at doses of 0.5-12 mg: in two phase 2 trials (results over 36 and 48 weeks) and three phase 3 trials (40-80 weeks) [1, 2, 3, 4, 5]A.
Doses used in studies
| Study | Participants | Dose | Frequency | Duration | Source and level |
|---|---|---|---|---|---|
| Jastreboff 2023 (phase 2) | 338 adults with obesity, or overweight with a weight-related condition | 1, 4, 8 or 12 mg under the skin; 4 and 8 mg started from 2 or 4 mg, 12 mg from 2 mg | Once a week | 48 weeks | [1]A |
| Rosenstock 2023 (phase 2) | 281 adults with type 2 diabetes | 0.5, 4, 8 or 12 mg under the skin; 4 mg started from 2 mg or directly, 8 mg from 2 or 4 mg, 12 mg from 2 mg | Once a week | Results at 24 and 36 weeks | [2]A |
| TRANSCEND-T2D-1, Bajaj 2026 (phase 3) | 537 adults with type 2 diabetes not on diabetes medicines | 4, 9 or 12 mg under the skin | Once a week | 40 weeks | [3]A |
| TRIUMPH-2, Bellido 2026 (phase 3) | 1,152 adults with a BMI of 27 or more and type 2 diabetes | 4, 9 or 12 mg under the skin | Once a week | 80 weeks | [4]A |
| TRIUMPH-1, Jastreboff 2026 (phase 3) | 2,339 adults with obesity without diabetes | 4, 9 or 12 mg under the skin | Once a week | 80 weeks | [5]A |
Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed
Notes
The phase 3 abstracts do not give the starting dose or the escalation schedule, so the table shows only their maintenance doses [3, 4, 5]A.
All five trials were funded by the manufacturer (Eli Lilly) [1, 2, 3, 4, 5]A.
What points the other way or is uncertain
In the phase 2 obesity trial gastrointestinal effects rose with the dose and heart rate increased in a dose-dependent way [1]A. In TRIUMPH-2, 12% (9 mg) and 8% (12 mg) stopped treatment because of adverse events or death, versus 4% on 4 mg and 5% on placebo; low blood pressure and skin sensation disturbances were more common on retatrutide [4]A.
Products sold online as retatrutide do not match the trial drug: in Australia, three products labelled as 10 mg contained 5.13, 16.5 and 19.0 mg of retatrutide [7]D.
A young woman in Switzerland was admitted to hospital with nausea that did not respond to treatment after four weekly injections of a product said to contain retatrutide (case report) [6]B.
- Retatrutide: the full substance page
- Retatrutide: reconstitution and unit calculator
- Are peptides legal in Finland?
- All dose pages and calculators
Read the research yourself: sources
- Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. PMID 37366315
- Rosenstock J, et al. Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA. Lancet. 2023;402(10401):529-544. PMID 37385280
- Bajaj HS, et al. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial. Lancet. 2026;407(10546):2402-2413. PMID 42250575
- Bellido V, et al. Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial. Lancet. 2026;408(10563):1455-1472. PMID 42810372
- Jastreboff AM, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. 2026 (online ahead of print 29 Sep 2026). PMID 42814954
- Buzzi RM, Huber LC. Emerging risks of health optimisation: refractory nausea associated with peptide injections reported to contain retatrutide. BMJ Case Rep. 2026;19(10):e276106. PMID 42843917
- Piatkowski T, et al. Composition and Labelling Accuracy of Products Sold as Retatrutide in Australia. Drug Alcohol Rev. 2026;45(6):e70231. PMID 42559975
Sources checked in PubMed on 12 Oct 2026. Piatkowski 2026 is a letter without an abstract, so its figures are from the full text.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.