Retatrutide dosing chart
Retatrutide ("reta") has no approved dose, because it is not FDA-approved. The TRIUMPH phase 3 trials tested 4 mg, 9 mg and 12 mg injected once a week, and the phase 2 trial started people at 2 mg or 4 mg. In a vial mixed to 10 mg/mL, each 1 mg is 10 units on a U-100 syringe.[1,2,3]
These are the doses the published studies used, shown so you can read the units on a syringe. They are not a recommendation. Education only, not medical advice. PepDose sells no peptides.
What doses of retatrutide were used in the trials?
- Phase 2 (338 adults, 48 weeks): 1 mg, 4 mg, 8 mg or 12 mg once a week. The 4 mg and 8 mg groups started at either 2 mg or 4 mg; the 12 mg group started at 2 mg.[3]
- TRIUMPH-1 (phase 3, 2,339 adults with obesity, 80 weeks): 4 mg, 9 mg or 12 mg once a week. Average weight change was −17.6%, −23.7% and −25.0%, versus −3.9% on placebo.[1]
- TRIUMPH-2 (phase 3, 1,152 adults with obesity and type 2 diabetes, 80 weeks): the same 4 mg, 9 mg and 12 mg weekly doses. Weight change was −11.9%, −16.8% and −18.8%, versus −5.1% on placebo.[2]
- Every dose in these trials was one injection under the skin, once a week.[3,1,2]
How many units is 1 mg of retatrutide?
Units on a U-100 syringe = dose (mg) ÷ concentration (mg/mL) × 100. The concentration is the vial size divided by the water you added, so the same dose is a different number of units in each mix below.
| Dose | 10 mg vial + 1 mL10 mg/mL | 10 mg vial + 2 mL5 mg/mL | 20 mg vial + 2 mL10 mg/mL | 20 mg vial + 4 mL5 mg/mL | 30 mg vial + 3 mL10 mg/mL | 30 mg vial + 2 mL15 mg/mL |
|---|---|---|---|---|---|---|
| 1 mg | 10 units | 20 units | 10 units | 20 units | 10 units | 6.67 units |
How do you reconstitute a retatrutide vial?
Add bacteriostatic water to the powder and note the strength. A 10 mg vial with 1 mL is 10 mg/mL. A 10 mg vial with 2 mL is 5 mg/mL. A 20 mg vial with 2 mL is 10 mg/mL. More water makes each unit weaker, which makes small doses easier to measure.
- Step 1
Clean
Wipe the vial stopper with an alcohol swab and let it dry.
- Step 2
Add water
Let the bacteriostatic water run slowly down the inside wall of the vial.
- Step 3
Swirl
Swirl or roll gently until clear. Don't shake.
- Step 4
Label and chill
Write the date and strength (mg/mL) on the vial and keep it in the fridge.
Do side effects change with the dose?
- In phase 2, stomach and gut side effects were dose-related, mostly mild to moderate, and partially mitigated by a lower starting dose (2 mg rather than 4 mg).[3]
- Heart rate rose with dose, peaked at 24 weeks and then declined.[3]
- In TRIUMPH-2, stopping because of side effects was more common at 9 mg (12%) and 12 mg (8%) than at 4 mg (4%) or on placebo (5%).[2]
Research, side effects and legal status in full: Retatrutide guide
Common questions about retatrutide dosing
How many units is 1 mg of retatrutide?
It depends on how the vial was mixed. At 10 mg/mL (a 10 mg vial with 1 mL, or a 30 mg vial with 3 mL), 1 mg is 10 units on a U-100 syringe. At 5 mg/mL (a 10 mg vial with 2 mL), 1 mg is 20 units.
What is the highest retatrutide dose studied?
12 mg once a week, in both the phase 2 trial and the TRIUMPH phase 3 trials.
How often was retatrutide taken in the trials?
Once a week, as an injection under the skin. The phase 2 trial ran for 48 weeks and the phase 3 trials for 80 weeks.
Is there an approved retatrutide dose?
No. Retatrutide is not FDA-approved for any use, so there is no label dose. The doses on this page are the ones the published trials used, shown to help you read the units, not as advice.
Sources
Last reviewed Oct 6, 2026. Every dose and result above is copied from these sources.
- 1.Retatrutide, a triple hormone receptor agonist, for treatment of obesity (TRIUMPH-1)
Jastreboff AM et al. N Engl J Med 2026 (online Sep 29) · Human trial - 2.Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2)
Bellido V et al. Lancet 2026 (online Sep 29) · Human trial - 3.Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial
Jastreboff AM et al. N Engl J Med 2023;389:514-526 · Human trial
Education only, not medical advice. PepDose sells no peptides.