How do you dose retatrutide?

It's a once-weekly subcutaneous injection. In the trials almost everyone started at 2 mg and stayed there about 4 weeks before going up, and that slow ramp is what kept the nausea in check. The maintenance doses studied were 4 mg, 8 mg, and 12 mg. Bigger doses meant more weight loss but also more stomach trouble. Set your target dose in the calculator to see the exact syringe volume.

What is the retatrutide titration schedule?

Roughly: 2 mg/week for weeks 1 to 4, then 4 mg through week 8, 8 mg through week 12, and 12 mg from week 13 on. You only step up every 4 weeks if the side effects are tolerable. Plenty of people stop at 4 or 8 mg once that dose is doing the job. Nothing says you have to reach 12 mg.

How many units is a 4 mg dose of retatrutide?

Depends how you mixed the vial. A 10 mg vial in 2 ml of bacteriostatic water comes out to 5 mg/ml, so 4 mg is 0.8 ml, or 80 units on a 100-unit insulin syringe. Use more or less water and that number shifts. The calculator handles whatever mix you actually used.

How long does a retatrutide vial last?

Divide the vial size by your weekly dose. A 10 mg vial at 2 mg/week is five weeks; at 4 mg/week it's about two and a half. One catch: reconstituted retatrutide only keeps about 4 weeks in the fridge (2 to 8°C), so a low-dose vial can expire before you finish it. Mix a smaller vial or a more concentrated solution if you're dosing low.

Is retatrutide approved?

No. As of 2026 it's still in clinical trials, not approved by the FDA, and not sold in pharmacies. Everything here comes from published phase 2 research and is for education only. It isn't medical advice or a protocol to follow.

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Retatrutide Dosage Calculator

LY3437943 (investigational)

Retatrutide (the triple GLP-1/GIP/glucagon agonist, code-named LY3437943) is still investigational. There's no FDA label yet, so the numbers below come from Eli Lilly's phase 2 trials rather than a pharmacy insert. In the obesity trial, people started at 2 mg once weekly and stepped up every 4 weeks or so toward a 4, 8, or 12 mg maintenance dose. The 12 mg group lost about 24% of their body weight by week 48. Enter your vial size and target dose and the calculator tells you exactly what to draw.

Common Retatrutide doses (once weekly)

Vial Size

BAC Water

Weekly Dose

Concentration

5.00

mg/ml

5000 mcg/ml

Volume per Dose

0.400

Draw this amount

Syringe Draw

100-unit insulin syringe

Supply per Vial

5.0

weeks

At 2 mg/week

Draw to

100

40.0 units

Draw to this line

Retatrutide Titration Schedule & Dose Chart

Syringe units below assume a 10 mg vial in 2 ml of BAC water (5.0 mg/ml). Adjust the calculator above for your own mix.

Week	Weekly Dose	Volume	Syringe Draw
1-4	2 mg	0.40 ml	40 IU
5-8	4 mg	0.80 ml	80 IU
9-12	8 mg	1.60 ml	160 IU
13+	12 mg	2.40 ml	240 IU

Maximum studied dose: 12 mg once weekly. Step up only if side effects are tolerable.

Retatrutide is investigational and not FDA-approved. These figures come from published clinical-trial data, not a pharmacy label, and are for research and educational purposes only. This is not medical advice.

Retatrutide Dosing FAQ

Research basis

More Retatrutide Resources

Retatrutide compound page Retatrutide dosage guide & protocols How to reconstitute Retatrutide Where to buy Retatrutide Retatrutide vs Tirzepatide: full comparison

Free 2026 Peptide Cheat Sheet (PDF)

Reconstitution math, concentration charts, half-lives, and vendor links. The reference we wish we had on day one.

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