Retatrutide dosage calculator

Where retatrutide stands

Retatrutide (LY3437943) is Lilly's follow-on to tirzepatide, and as of November 2, 2026 the FDA has not approved it for anything. In the 48-week phase 2 trial (Jastreboff et al., NEJM 2023), the 12 mg group lost an average of 24.2% of body weight, against 2.1% with placebo. TRIUMPH-1 and TRIUMPH-2 were published in September 2026, and Lilly says it plans to submit retatrutide to the FDA in the first quarter of 2027. Access runs through clinical trials and a narrow early-access program that Lilly confirmed in August 2026, which physicians request for patients who cannot join a trial. No retail product exists. The retatrutide overview covers the results, and the FDA status tracker records any change.

Why publish a calculator for an unapproved drug?

The arithmetic is the same as for any freeze-dried peptide: what concentration a vial becomes with a given amount of water, and how many units a given milligram dose takes up. People ask, and a plain answer with the status in the first line beats leaving that question to sellers. The calculator is limited to doses the trials reported, so nobody has to guess at a number, and it stops there. No dose has been established for use outside those trials.

Vials sold as "research" retatrutide are not legal to use on people, and the math cannot make them safer. It assumes the milligrams on the label are real, and nobody has verified that. For a prescribed peptide, the reconstitution calculator does the same math with any numbers.

What the trial doses do not tell you

• Trial participants reached the higher doses over many weeks of stepwise escalation, under medical supervision and with scheduled lab work. The retatrutide dosage page shows what each trial did.
• Gastrointestinal side effects were dose-related and were the main reason for stopping at higher doses. Up to 11.3% stopped because of side effects in TRIUMPH-1, and up to 18.2% in TRIUMPH-4.
• A burning or altered skin sensation called dysesthesia was reported in 4% to 21% across the phase 3 trials, versus about 1% on placebo.
• Heart rate rose with dose in the phase 2 trial, peaking at 24 weeks. Phase 3 heart rate figures have not appeared in the public summaries.

The full tables are on the retatrutide side effects page. If retatrutide is approved, its label will set the schedule, and until then a trial dose is a record of what researchers did.