Retatrutide dose range
The amounts people commonly use, from the low end to the high end, with syringe units, schedule and half-life. The 7 published studies are one click away.
Human trials Metabolic Also called LY3437943
Common use ranges
Mostly from the official drug label or its main trials, plus clinic protocols. Trial sources agree on a 2 mg start and 4 week steps. The 1 mg start is community practice only.
- Half-life
- about 6 days
- How it is taken
- subcutaneous injection
- How long people use it
- Ongoing weekly use. The phase 2 trial ran 48 weeks. Phase 3 trials ran longer with a blinded extension.
- Mixing used for the units
- 15 mg vial + 1 mL water. 1 unit on a U-100 insulin syringe = 150 mcg.
Pick your vial size and how much water you add. The units below change to match.
15 mg vial + 1 mL water: 1 unit = 150 mcg
| Tier | Each dose | Syringe units15 mg vial + 1 mL water | How often | Schedule | Vial lastsat this tier |
|---|---|---|---|---|---|
| Lower start (community) [1] | 1 mg | 6.7 units 0.07 mL | once a week | Some people start at 1 mg once a week before the 2 mg step. 1 mg was a fixed arm in phase 2, not a trial start dose. | 6+ weeks |
| Step 1 [2] | 2 mg | 13.3 units 0.13 mL | once a week | Weeks 1 to 4, once a week | 6+ weeks |
| Step 2 [3] | 4 mg | 26.7 units 0.27 mL | once a week | Weeks 5 to 8, once a week. Also a maintenance dose in trials. | about 4 weeks |
| Step 3 [4] | 6 mg | 40 units 0.40 mL | once a week | Weeks 9 to 12, once a week. A step only, not a studied maintenance dose. | 17 days |
| Step 4 [5] | 9 mg | 60 units 0.60 mL | once a week | Weeks 13 to 16, once a week. Also a maintenance dose in trials. | 11 days |
| Max [6] | 12 mg | 80 units 0.80 mL | once a week | Week 17 on, once a week. Highest dose studied. | 8 days |
Good to know
- Not approved anywhere. The ladder is the phase 3 trial schedule.
- Step up every 4 weeks.
- Phase 3 kept people at 4, 9 or 12 mg as their final dose.
- Stomach side effects came mostly during step-ups. Starting at 2 mg instead of 4 mg cut them in phase 2.
- Phase 2 went 2, 4, 8, 12 mg. Phase 3 swapped 8 mg for 6 and 9 mg steps.
Sources for these amounts
- Lower start (community): Peptide Dossier, retatrutide starting dose · Jastreboff et al., NEJM 2023 phase 2 (PDF copy)
- Step 1: HCPLive, TRIUMPH-1 phase 3 results (May 2026) · Ro, retatrutide dosing
- Step 2: Ro, retatrutide dosing · HCPLive, TRIUMPH-1 phase 3 results (May 2026)
- Step 3: Ro, retatrutide dosing
- Step 4: Ro, retatrutide dosing · HCPLive, TRIUMPH-1 phase 3 results (May 2026)
- Max: Ro, retatrutide dosing · HCPLive, TRIUMPH-1 phase 3 results (May 2026)
How long people use it: Jastreboff et al., NEJM 2023 phase 2 (PDF copy) · HCPLive, TRIUMPH-1 phase 3 results (May 2026)
Half-life: Urva et al 2022, Lancet, phase 1b trial of LY3437943 (retatrutide)
Take the Retatrutide chart with you
Get a one-page printable chart for Retatrutide, with the syringe units for each vial and water mix. We can also email you when a new Retatrutide study is published.
This page shows what labels, clinics and users report, and what studies gave. It is not medical advice and not a recommendation for anyone. Many of these compounds are not approved for human use. Check your own medicines and lab work with a licensed clinician before using anything.
See the science: 7 published studies
Amounts given to people in studies
How it was given: Under the skin (SC)
Phase 2 and phase 3 trials started low and stepped up over weeks.
Every study used for this page
Proof grade: Human trials. Tested in randomized human trials. Amounts are quoted as each study reported them. Where the abstract does not state an amount, the row says so.
| Study | Who was studied | Amount given, as reported | Route | How often | How long | What the authors reported |
|---|---|---|---|---|---|---|
| PMID 363540402022 | Human, T2D, phase 1b (72 safety pop: 15 placebo, 5 dulaglutide, 9 at 0.5 mg, 9 at 1.5 mg, 11 at 3 mg, 11 at 3/6 mg, 12 at 3/6/9/12 mg) | 0.5, 1.5, 3, 3/6, 3/6/9/12 mg (LY3437943 = retatrutide; top doses by stepwise escalation) | SC | Once weekly | 12 weeks | Dose-proportional PK, half-life ~6 days; weight loss up to -8.96 kg vs placebo at 3/6/9/12 mg |
| PMID 359853402022 | Human phase 1 single ascending dose + obese mice | Not stated in the abstract | Not in abstract | Single dose (human SAD) | Weight reduction persisted to day 43 after one dose | Mouse weight loss and improved glycemia; human SAD safe, supports weekly dosing |
| PMID 373852802023 | Human, T2D, phase 2 (n=281 randomized) | 0.5, 4 (start 2), 4 (no escalation), 8 (start 2), 8 (start 4), 12 mg (start 2) | SC | Once weekly | 36 weeks (primary HbA1c at 24 wk) | HbA1c -2.02% at 12 mg (24 wk) vs -0.01% placebo; weight -16.94% at 12 mg (36 wk); 0.5 mg HbA1c -0.43% |
| PMID 373663152023 | Human, obesity, phase 2 (n=338) | 1 mg; 4 mg (start 2 mg or 4 mg); 8 mg (start 2 or 4 mg); 12 mg (start 2 mg) | SC | Once weekly | 48 weeks | Weight at 48 wk: -8.7% (1 mg), -17.1% (4 mg), -22.8% (8 mg), -24.2% (12 mg) vs -2.1% placebo |
| PMID 388585232024 | Human, obesity + MASLD, phase 2a substudy (n=98) | 1, 4, 8, 12 mg | SC | Once weekly | 48 weeks (liver fat read at 24 wk) | Liver fat -42.9% (1 mg) to -82.4% (12 mg) at 24 wk vs +0.3% placebo |
| PMID 428103722026 | Human, obesity + T2D, phase 3 TRIUMPH-2 (n=1152) | 4 mg (n=292), 9 mg (n=284), 12 mg (n=287) vs placebo (n=289) | SC | Once weekly | 80 weeks | Weight -11.9% (4 mg), -16.8% (9 mg), -18.8% (12 mg) vs -5.1% placebo |
| PMID 428149542026 | Human, obesity, phase 3 TRIUMPH-1 (n=2339) | 4, 9, 12 mg | SC | Once weekly | 80 weeks | Weight -17.6% (4 mg), -23.7% (9 mg), -25.0% (12 mg) vs -3.9% placebo; also knee OA pain and sleep apnea benefit |
How to read the study numbers
- One study, one group. Each figure is what one team chose for its own participants or animals.
- Route matters. An amount given into a vein (IV) is not the same as the same amount under the skin, in the nose or by mouth.
- Animals are not small people. An animal amount is shown as the study gave it. It is not a human amount.
- Short studies. Many studies ran days or weeks. They do not show what happens over longer use.
Common questions
What amounts of Retatrutide were used in human studies?
In the studies listed here, people were given from 0.5 mg weekly up to 12 mg weekly. The amount used most often was 4 to 12 mg weekly. These are what study teams chose for their participants under supervision.
Where do these Retatrutide numbers come from?
From 7 published studies, each linked to its PubMed or ClinicalTrials.gov record. Every figure was checked against the study abstract or its open full text. Proof grade: Human trials.
How long does Retatrutide stay in the body?
Its half-life is about 6 days in people. Half-life is how long it takes for half of a dose to leave the blood. The effect can last longer than that.
Is this a recommendation for how much Retatrutide to use?
No. This page shows the amounts reported by drug labels, clinics and users, next to what researchers gave in studies. It is not medical advice and not a recommendation for anyone. Talk to a licensed clinician before using any of it.