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GIP/GLP-1/glucagon triple receptor agonist (investigational) · dosing

Retatrutide dosage chart: phase 2 and phase 3 trial regimens

Also called Reta or Reta peptide.

There is no approved dosing label for Retatrutide. This chart maps published and sponsor-disclosed trial regimens—it is not an approved or recommended schedule.

The published trial tested 1–12 mg once weekly. It enrolled 338 participants and ran as the 48-week phase 2 dose-finding trial. Retatrutide has no approved dosing label. 3 later readouts studied 4 mg, 9 mg, or 12 mg targets; each result shows its publication status, and missing dose steps stay unreported. Those are randomized study regimens, not a schedule for personal use.

Source: Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med 2023;389:514-26 (PMID 37366315)

What matters first

What trials tested
1–12 mg once weekly
Study size
338 participants
Approved schedule
No FDA-approved Retatrutide dosing label exists.

Medically reviewed by Jennifer Montecillo, MD · non-practicing medical reviewerReviewed 2026-08-16open the primary sources

What later trial readouts added

The company announced these newer results, but full peer-reviewed papers were not available when this was checked. Each study stays in its own table.

TRIUMPH-1 phase 3 trial

Adults with obesity or overweight and at least one weight-related condition, without diabetes

Company announcement
2,339 participants · 80 weeks · once weekly; dose increased every 4 weeks
TRIUMPH-1 phase 3 trial Retatrutide target doses and reported outcomes
TargetDose pathMean weight change · week 80Publication status
4 mg weekly2 mg → 4 mg19% decreaseResult announced by the company
9 mg weekly2 mg → 4 mg → 6 mg → 9 mg25.9% decreaseResult announced by the company
12 mg weekly2 mg → 4 mg → 6 mg → 9 mg → 12 mg28.3% decreaseResult announced by the company
Placebo—2.2% decreaseResult announced by the company

The sponsor reported efficacy-estimand topline results. Detailed peer-reviewed results were not published with the announcement. Registry: NCT05929066. Sources retrieved 2026-08-16.

TRIUMPH-2 phase 3 trial

Adults with type 2 diabetes and obesity or overweight

Company announcement
1,152 participants · 80 weeks · once weekly; dose increased every 4 weeks
TRIUMPH-2 phase 3 trial Retatrutide target doses and reported outcomes
TargetDose pathMean weight change · week 80Publication status
4 mg weekly2 mg → 4 mg12.7% decreaseResult announced by the company
9 mg weekly2 mg → 4 mg → 6 mg → 9 mg19.1% decreaseResult announced by the company
12 mg weekly2 mg → 4 mg → 6 mg → 9 mg → 12 mg20.8% decreaseResult announced by the company
Placebo—4% decreaseResult announced by the company

The sponsor reported efficacy-estimand topline results. Detailed peer-reviewed results were not published with the announcement. Registry: NCT05929079. Sources retrieved 2026-08-14.

TRIUMPH-3 phase 3 trial

Adults with severe obesity and established cardiovascular disease

Company announcement
1,946 participants · 80 weeks · once weekly; dose increased every 4 weeks
TRIUMPH-3 phase 3 trial Retatrutide target doses and reported outcomes
TargetDose pathMean weight change · week 80Publication status
9 mg weekly2 mg → 4 mg → 6 mg → 9 mg21.6% decreaseResult announced by the company
12 mg weekly2 mg → 4 mg → 6 mg → 9 mg → 12 mg22.6% decreaseResult announced by the company
Placebo—3.2% decreaseResult announced by the company

ClinicalTrials.gov now lists actual enrollment as 1,946; the sponsor announcement describes 1,949 randomized participants. Detailed peer-reviewed results were not published with the announcement. Registry: NCT05882045. Sources retrieved 2026-08-14.

The published trial dosing program

These are the once-weekly dose plans used in the published trial. Where two groups reached the same target from different starting doses, both paths remain visible instead of being collapsed into one row. They describe a randomized protocol under monitoring, not a recommended titration schedule.

◆ 48-week phase 2 dose-finding trial338 participants · 48 weeks
Retatrutide randomized dosing regimens from 48-week phase 2 dose-finding trial
RegimenStarting doseTarget dosePath recorded by the registry
11 mg weekly1 mg weekly1 mg
22 mg weekly4 mg weekly2 mg → 4 mg
34 mg weekly4 mg weekly4 mg
42 mg weekly8 mg weekly2 mg → 4 mg → 8 mg
54 mg weekly8 mg weekly4 mg → 8 mg
62 mg weekly12 mg weekly2 mg → 4 mg → 8 mg → 12 mg

Source: NCT04881760 — A Study of LY3437943 in Participants Who Have Obesity or Are Overweight · retrieved 2026-08-14 · the paths above reproduce only the doses the source names. The source does not turn those paths into advice.

Average weight change after 48 weeks
Retatrutide average weight change after 48 weeks, by dose group
Target-dose groupMean change at 48 weeksHow the paper reports it
1 mg weekly8.7% decrease1 mg group
4 mg weekly17.1% decreasecombined result for the two 4 mg groups
8 mg weekly22.8% decreasecombined result for the two 8 mg groups
12 mg weekly24.2% decrease12 mg group
Placebo2.1% decreasePlacebo group

Source: Jastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med 2023;389:514-26 (PMID 37366315) · retrieved 2026-08-12. Where multiple starting-dose regimens share a target, the combined figure is reproduced exactly as the paper reports it; it is not split into invented estimates.

The study reports a range of 1–12 mg once weekly. Doses outside that range were not studied in this trial and are not reported here at any strength of claim.

Retatrutide dosage. There is no approved label. These are the arms of a 48-week phase 2 dose-finding trial, not a schedule. It had 338 participants. The arms were 1 mg, 4 mg, 8 mg, 12 mg, each once a week. Source: the registered study.
The same arms rendered as a standalone chart, generated from the page above. It states on its face that there is no approved label. An image separated from this page would otherwise read as a schedule, which is exactly the error this page exists to avoid.

What each of these arms produced, with the placebo comparison →

Why there is no Retatrutide dosage chart

A dosage chart is a regulatory artifact before it is an editorial one. It exists when an agency has reviewed a sponsor’s trials, agreed a schedule, and bound the manufacturer to a product of stated identity and potency. Retatrutide has none of that yet.

One trial cannot prove long-term safety or show that the result applies to everyone. The highest dose tested is a study dose, not a target for personal use.

FDA has not approved retatrutide.

It is still in trials and has no dosing label. Any product sold today is unapproved. The doses here describe study groups, not advice.

Sites that publish a titration chart for a compound at this stage have built it by inference. They take a trial’s target dose and reverse-engineer a plausible ramp toward it. The result looks exactly like a supported schedule and should not be read as one. The table shows only the trial arms that were actually studied.

3Reference detailsSyringe sizes, concentration math, and dosing context

Which syringe barrel the units are read on

A unit is not a unit. A U-100 and a U-50 barrel both print 0.01 mL per graduation; a U-40 barrel prints 0.025 mL. The same printed number therefore measures 2.5× the volume on a U-40. That is why every unit figure on this page names its barrel. It is also why a unit count copied from someone else’s syringe means nothing on its own.

Retatrutide draw volumes on three syringe barrels. U-100, U-50 and U-40, drawn to one volume scale. The marked volume is 0.5 mL, which is one full U-50 barrel. It reads as 50 units on a U-100 barrel. It reads as 50 units on a U-50 barrel. It reads as 20 units on a U-40 barrel. One U-40 unit holds 0.025 mL. One U-100 or U-50 unit holds 0.010 mL. So the same printed number is 2.5 times the volume on a U-40.
The three barrels drawn to one volume scale — 0.5 mL is the same length in each drawing, so the only thing that changes between them is the number printed under the plunger. Marked volume: one full U-50 barrel.
Insulin syringe barrels: capacity, the volume of one graduation, and what 0.5 mL reads as on each
BarrelCapacityOne graduation0.5 mL reads as
U-100 insulin syringe · 1 mL · lines every 2 units1 mL0.010 mL50 units
U-100 insulin syringe · 0.5 mL · lines every 1 unit0.5 mL0.010 mL50 units
U-40 insulin syringe · 1 mL · lines every 1 unit1 mL0.025 mL20 units

Barrel capacities and graduation spacing are the printed scales this site’s calculator measures against, not estimates. Three barrels carry only two scales: a U-50 is a half-length U-100, so it reads identically per unit and simply runs out sooner.

What one graduation is worth at each concentration

Reconstitution fixes a concentration, and the concentration fixes what a single graduation carries — before anyone decides what to draw. Below is every pairing of this page’s vial sizes and water volumes, as a concentration and as the mass one U-100 graduation holds at it. No dose is implied by any cell; it is division.

Retatrutide concentration by vial size and bacteriostatic water volume, with the mass one U-100 graduation carries
Vial+ 1 mL water+ 2 mL water
10 mg10 mg/mL100 mcg per unit5 mg/mL50 mcg per unit
20 mg20 mg/mL200 mcg per unit10 mg/mL100 mcg per unit
30 mg30 mg/mL300 mcg per unit15 mg/mL150 mcg per unit

Vial strengths and water volumes are the Retatrutide record’s own presets. One U-100 graduation is 0.01 mL, so the mass it carries is the concentration times that volume. That is the entire reason the same milligram figure produces a different unit count in every row.

How dosing works in this class

Why the dose escalates instead of starting where it ends

The dose climbs in steps for one reason: how well people tolerate it, not how well it works. The receptors that produce the effect you want are the same ones that slow your stomach down, and your gut reacts hardest when the exposure is new. Hold it steady and the reaction fades. Stepping up gradually is a way of using that — each step is a stretch of time for your body to settle at where it is before the next increase arrives.

The length of each step matters. Shortening it moves the next increase into a period when the body may not have adjusted. Labels and trial plans state the intervals that were tested. A faster ramp was not tested.

Why trial dose groups are not a dosing schedule

A dose-finding trial is an experiment about doses, not a recommendation of one. Its arms exist to spread people across a range so researchers can see the shape of the curve. Some arms are set deliberately low, where too little effect is expected. Others are set high, where people are expected to struggle. Reading the top arm as the target gets the design backwards: the reason for running the whole range was that nobody yet knew which part of it was right.

Trial doses came with screening, monitoring, a set schedule and drug of tested strength and purity. Removing a milligram figure from those conditions removes much of what made it meaningful. The table therefore shows what researchers tested, not a schedule to follow.

Concentration changes the units, not the dose

The dose and the syringe draw are two different things. The dose is a mass in milligrams. The draw is a volume in syringe units. It depends on the concentration after mixing. Adding more bacteriostatic water changes the unit reading, but not the dose.

This matters because a unit count copied from someone else’s vial means nothing without their concentration. That mismatch is the most common way a self-injected dose ends up ten times off. The arithmetic is fixed and safe to state as fact. The dose you apply it to is a clinical decision, and it is not.

Compounded vial?

No approved Retatrutide product exists, so nothing here describes one. The calculator does arithmetic only: it converts a milligram figure and a reconstitution into a volume and a unit count, and it takes no position on which figure belongs in the box.

Open the Retatrutide calculator →

Questions about Retatrutide dosing

What doses were used in the later Retatrutide trials?

The later trials studied 4 mg, 9 mg, or 12 mg weekly. Each recorded escalation path is printed in its study table. These are monitored trial protocols, not an approved schedule.

Are the latest Retatrutide trial results peer reviewed?

No. The company announced the later results, but they have not been peer reviewed. The older dosing study below has been peer reviewed.

How was Retatrutide dosed in the phase 2 trial?

The trial ran 6 once-weekly regimens between 1 mg and 12 mg for 48 weeks. The pageed paths were 1, 2→4, 4, 2→4→8, 4→8, 2→4→8→12 mg. These are study regimens, not an approved dosing schedule.

How did the Retatrutide trial increase the dose?

The registry records the dose order for each randomized group: 1, 2→4, 4, 2→4→8, 4→8, 2→4→8→12 mg. Its study-group descriptions do not state an interval between those steps, so no interval is estimated.

What if side effects make the next step too hard?

The next increase is optional, not automatic. The label allows a longer stay at the current step when needed. A clinician decides what happens after a dose is hard to handle; the schedule alone cannot make that decision.

Was 1 mg of Retatrutide studied?

Yes. One randomized group received 1 mg once weekly for 48 weeks and the group changed by an average of -8.7% by week 48. That proves the dose was studied; it does not make it an approved starting dose or a recommendation.

Did the Retatrutide trial start some groups at 2 mg?

Yes. The registry records 2 mg once weekly as the starting dose for paths ending at 4 mg, 8 mg and 12 mg. Other groups began at the starting doses shown in the table above. Those assignments belong to the phase 2 protocol; they are not a universal starting instruction.

What is the highest Retatrutide dose on the page?

The highest arm studied was 12 mg once weekly. It is simply the highest amount the trial tested. It is not a maximum dose, because no regulator has set one.

Does a compounded vial change the schedule?

No. The dose is a mass in milligrams and comes from the source; the draw is a volume in syringe units and comes from dividing that mass by the concentration reconstitution produced. Adding more bacteriostatic water to the same vial changes every unit figure and changes no dose at all. That is also why a unit count copied from someone else’s vial means nothing without their concentration.

Why do some compounds here have a chart and others do not?

Because a chart is a claim about provenance, not a formatting choice. Where an FDA-approved label specifies a schedule, this site quotes it row by row and cites the label under the table. Where no label exists, the guide shows what trials tested and says plainly that it is not a schedule. For Retatrutide, that is the 48-week phase 2 dose-finding trial above.

Which retatrutide reactions warrant medical attention

No boxed warning applies to retatrutide, which reflects the review it has not had.

Retatrutide vs tirzepatide, from the retatrutide side

No randomized trial compares retatrutide vs tirzepatide. This sits beyond retatrutide.

Vial, water and dose for any peptide, with retatrutide as one example

U-100, U-50 and U-40 barrels each read differently, including retatrutide

Every dosing schedule, including retatrutide

6 pages carry trial arms — which is a different object from a chart, with retatrutide as context

The dated regulatory page for retatrutide and the rest

Every entry cites its source. It comes from the Federal Register or fda.gov, with retatrutide as context

Where retatrutide sits among the source-checked pages

See the strongest source available for every compound, with retatrutide as context

7primary sources, each with the day we read it — open the documents used on this page