Steps from the phase 2 trial's 12 mg group (New England Journal of Medicine, 2023), each held for about four weeks. Retatrutide is investigational: there is no approved label or dose.
Retatrutide titration schedule in U-100 units
| DoseTrial step | 10 mg + 2 mL5 mg/mL | 20 mg + 2 mL10 mg/mL | 30 mg + 3 mL10 mg/mL |
|---|---|---|---|
| 2 mgStart | 40 u(0.4 mL)5 per vial | 20 u(0.2 mL)10 per vial | 20 u(0.2 mL)15 per vial |
| 4 mgStep 2 | 80 u(0.8 mL)2 per vial | 40 u(0.4 mL)5 per vial | 40 u(0.4 mL)7 per vial |
| 8 mgStep 3 | 160 u(1.6 mL)1 per vial · over 1 mL | 80 u(0.8 mL)2 per vial | 80 u(0.8 mL)3 per vial |
| 12 mgTop dose | 240 u(2.4 mL)<1 per vial · over 1 mL | 120 u(1.2 mL)1 per vial · over 1 mL | 120 u(1.2 mL)2 per vial · over 1 mL |
Swipe the table to see every vial →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100); “per vial” is how many of that dose the vial holds, before the small dead-space loss on each draw. Confirm against your own vial, diluent, and clinician or pharmacy instructions.
- Status
- Investigational, not approved
- Trial starting dose
- 2 mg weekly
- Phase 3 maintenance
- 4, 9 or 12 mg weekly
- Last reviewed
How to read the retatrutide dosing schedule
The rows follow the phase 2 trial's 12 mg group, which started at 2 mg once a week and stepped up through 4 mg and 8 mg before reaching 12 mg, holding each step for about four weeks. Other groups in the same trial started at 2 or 4 mg and stopped at 4 or 8 mg, and a 1 mg group stayed at 1 mg throughout. There is no approved retatrutide label, so this is a summary of what was studied, not a recommended schedule.
Each cell converts that step into units on a U-100 syringe for a common vial set-up, plus how many doses the vial holds. A 10 mg vial runs out quickly as the dose rises: it holds five 2 mg doses but only one 8 mg dose.
- 10 mg + 2 mL = 5 mg/mL → 2 mg = 0.4 mL = 40 units
- 20 mg + 2 mL = 10 mg/mL → 2 mg = 0.2 mL = 20 units · 4 mg = 40 units
- 30 mg + 3 mL = 10 mg/mL → 12 mg = 1.2 mL (over one 1 mL syringe)
See also: Retatrutide dosage calculator
Phase 3 maintenance doses: 4, 9 and 12 mg in units
The phase 3 TRIUMPH trials escalate participants over 16 weeks to a weekly maintenance dose of 4, 9 or 12 mg. The 9 mg dose is new compared with phase 2, so it is worth knowing what it looks like on a syringe: from a 20 mg vial in 2 mL (10 mg/mL) it is 90 units.
At these doses a 10 mg vial holds one 9 mg dose and not even one 12 mg dose, so vial size and water volume matter more than at the start of the schedule.
Retatrutide phase 3 maintenance doses in U-100 units
| Dose | 10 mg + 2 mL5 mg/mL | 20 mg + 2 mL10 mg/mL | 30 mg + 3 mL10 mg/mL |
|---|---|---|---|
| 4 mg | 80 u(0.8 mL)2 per vial | 40 u(0.4 mL)5 per vial | 40 u(0.4 mL)7 per vial |
| 9 mg | 180 u(1.8 mL)1 per vial · over 1 mL | 90 u(0.9 mL)2 per vial | 90 u(0.9 mL)3 per vial |
| 12 mg | 240 u(2.4 mL)<1 per vial · over 1 mL | 120 u(1.2 mL)1 per vial · over 1 mL | 120 u(1.2 mL)2 per vial · over 1 mL |
Swipe the table to see every vial →
Educational reference only — not a dose recommendation. Units assume a U-100 insulin syringe (100 units = 1 mL on U-100); “per vial” is how many of that dose the vial holds, before the small dead-space loss on each draw. Confirm against your own vial, diluent, and clinician or pharmacy instructions.
Planning vials across the retatrutide schedule
A 20 mg vial in 2 mL (10 mg/mL) keeps every step inside a 1 mL syringe up to 10 mg, and holds ten 2 mg doses at the start or five 4 mg doses at step 2. A 30 mg vial in 3 mL gives the same concentration with half as many doses again, which can outlast the vial's beyond-use date at the low steps.
Whatever you choose, recalculate whenever the dose or the vial changes. The units for 4 mg from a 10 mg vial (80 units) are four times the units for 4 mg from a 20 mg vial in 1 mL (20 units).
- 10 mg vial: 5 doses at 2 mg, 2 at 4 mg, 1 at 8 mg
- 20 mg vial: 10 doses at 2 mg, 5 at 4 mg, 2 at 8 mg
- 30 mg vial: 15 doses at 2 mg, 7 at 4 mg, 2 at 12 mg
See also: How much BAC water for retatrutide
Why there is no approved retatrutide dose
Retatrutide is an investigational triple agonist (GIP, GLP-1 and glucagon receptors) from Eli Lilly that is still in phase 3 trials. Products sold outside those trials are not approved medicines, and their contents and strength are not verified. The trial schedules on this page are reported so the maths can be checked, not as a recommendation to use it.
See also: Retatrutide vs tirzepatide
Frequently asked questions
What is the retatrutide dosing schedule?
How many units is 2 mg of retatrutide?
How many units is 4 mg of retatrutide?
What is the highest retatrutide dose studied?
Primary sources
The schedules on this page come from these documents. PepSync converts them into units; it does not recommend a dose.
- 1Triple-hormone-receptor agonist retatrutide for obesity — a phase 2 trialNew England Journal of Medicine · 2023
- 2Retatrutide for obesity, obstructive sleep apnea and knee osteoarthritis: rationale and design of the TRIUMPH trialsDiabetes, Obesity and Metabolism · 2026