Is retatrutide FDA-approved?

As of April 2026, retatrutide is investigational. It is being evaluated in Phase 3 trials for obesity and type 2 diabetes.

How does retatrutide compare to tirzepatide?

In Phase 2 trials, retatrutide produced approximately 24% mean weight loss at 48 weeks at 12 mg, compared with about 22.5% for tirzepatide at 15 mg in the SURMOUNT-1 trial — though direct head-to-head data is not yet available.

What's a typical starting dose?

Trial protocols typically start at 2 mg once weekly with monthly titration up to 12 mg.

Retatrutide Calculator

Also known as: LY3437943

GLP-1

Default: 10mg / 2mL / 2mgAdjust inputs to match your vial

About

What is Retatrutide?

Retatrutide is an investigational triple agonist of GIP, GLP-1, and glucagon receptors developed by Eli Lilly. In Phase 2 obesity trials, retatrutide produced approximately 24% mean body-weight reduction at 48 weeks at the 12 mg dose — the largest weight-loss effect reported for any GLP-1-class compound to date. It is not yet FDA-approved; access is via clinical trial enrolment or regulated compounding. Trial protocols use a stepwise titration starting at 2 mg weekly. At a 10 mg vial reconstituted with 2 mL of BAC water, a 2 mg dose draws to 40 units on a U-100 insulin syringe.

Common vial sizes

4 mg	lyophilized powder
8 mg	lyophilized powder
10 mg	lyophilized powder
12 mg	lyophilized powder
16 mg	lyophilized powder

Reference dose ranges

2 mg	≈ 40 U-100 units (at 10mg / 2mL)
4 mg	≈ 80 U-100 units (at 10mg / 2mL)
6 mg	≈ 120 U-100 units (at 10mg / 2mL)
8 mg	≈ 160 U-100 units (at 10mg / 2mL)
12 mg	≈ 240 U-100 units (at 10mg / 2mL)

Reconstitution

How it's typically prepared

Reconstitute slowly with BAC water against the inner wall, swirl, refrigerate. Storage stability data for compounded retatrutide is limited — follow your compounding pharmacy's specific guidance.

FAQ

Frequently asked questions

Is retatrutide FDA-approved?: As of April 2026, retatrutide is investigational. It is being evaluated in Phase 3 trials for obesity and type 2 diabetes.
How does retatrutide compare to tirzepatide?: In Phase 2 trials, retatrutide produced approximately 24% mean weight loss at 48 weeks at 12 mg, compared with about 22.5% for tirzepatide at 15 mg in the SURMOUNT-1 trial — though direct head-to-head data is not yet available.
What's a typical starting dose?: Trial protocols typically start at 2 mg once weekly with monthly titration up to 12 mg.

Sources

References

Other GLP-1 peptides

Notice

PeptideDose is an educational reference. It is not medical advice and does not replace consultation with a licensed healthcare provider. Doses shown in presets are derived from published protocols and product labels — they are not personal recommendations.